WO2025075577A1 - Innovation in the rotary knife system of rotobar type cotton ginning machines - Google Patents

Abstract

The invention is related to the rotary knife system developed for use in rotobar type cotton gins.

Description

INNOVATION IN THE ROTARY KNIFE SYSTEM OF ROTOBAR TYPE COTTON

GINNING MACHINES

Technical Field

The invention is related to the new rotary knife system developed for rotobar type cotton gin stands.

Art

Cotton ginning process is the separation of cotton fibers from their seeds. After the separation process, these fibers are turned into yam and used in textiles.

Two different cotton ginning methods are mainly used around the world today: saw gin and roller gin. Depending on the striping blade design, roller gins are divided into two versions: eccentric knife roller gins and rotary knife roller gins. Rotary knife roller gin stands are also known as rotobar. The rotobar gin is essentially a modern version of the eccentric knife roller gin with increased production capacity by changing the stripping blade design and enlarging the gin roller diameter.

Saw ginning machines have high production capacity and are therefore economical in terms of operating costs. On the other hand, since cotton fibers are separated from the seed by cutting with saws rotating at high speed, it causes some quality problems in cotton fibers such as staple length shortening and fiber neps formation. Roller gins, on the other hand, have a relatively lower production capacity, but they separate the cotton fibers from the seed by pulling them, not by cutting them. Roller ginning machines perform ginning in a way that causes the least damage to cotton fibers. Yarn producers prefer fiber cotton processed in roller gins due to their superiority in terms of fiber technological properties.

Ginning the long and extra-long type cotton varieties known as pima (gossypium barbadense) with saw gins is already undesirable because it damages the fiber technological properties. It is possible to improve the fiber technological properties of medium and medium-long fiber cotton varieties known as upland (gossypium hirsutum) by ginning them with roller gin machines. Despite their advantages in terms of improving fiber quality of upland varieties, the use of roller gins has been largely limited either to the processing of pima and hybrid-pima, or to relatively small capacity gin plants using eccentric knife roller gin stands ginning upland varieties (both single roller and its relatively newer version of double roller type).

In the 1970s, rotobar gins were developed in united states to replace eccentric knife roller gins as a solution to the needs of machine harvesting. In the early 2010s, highspeed versions of rotobar gins began to be used. The aim here was to increase the production capacity of rotobar gins to the level of saw gins. In this way, it was aimed to economically process the upland varieties. Despite these developments, the production speed of rotobar machines has not reached to a level that can compete with saw gins in the "problem-free" processing of upland varieties.

In the current rotobar system, the most important problem that prevents the increase in production capacity is that the seed cotton cannot be fed to the rotary knife with the desired smoothness and stability. This situation becomes more decisive especially in the processing of upland cotton varieties. In upland type cotton varieties, it is much more difficult to separate the fibers from the seed than in pima varieties due to the strong bond between the cotton fiber and the seed. This situation not only reduces the production capacity in ginning upland cotton in rotobar machines, but also results in the higher percentage of fiber remaining unscraped on the seed after ginning than the other ginning methods. Upland type cotton varieties need to spend longer time at the ginning point to be completely stripped of their fibers. In case of operation at high speeds, this condition can only be met by more uniform and stable feeding of the seed cotton to the rotary knife.

Another problem in the current rotobar system when ginning upland type cotton varieties is the potential for damage to the cottonseed, depending on the characteristics of the variety. The upland seeds may be damaged during ginning due to the strong bond between the cotton fibers and the seed. These damages may occur in the form of cracking and breaking. While the cracking problem creates problems especially for the seed industry; Breakage, on the other hand, creates a problem in the production of yam as the broken shell pieces mix with the cotton fiber, and reduces the quality of the yarn.

There are various design improvement proposals regarding rotobar ginning machines in the state of the art. References are given below only to those patents that form the basis of our invention.

Rotobar machines used straight blade rotary knife in the first years of their introduction to the market. In straight blade rotary knife, the seeds corresponding to each blade are separated from their fibers at the same time during the passage of that blade. For this reason, straight blade rotary knives are exposed to excessive load and high vibration amplitudes occur. Because of this reason straight blade rotary knives don’t allow reaching high production capacities. To solve this problem, a rotary knife with a spiral blade structure was developed towards the end of the 1970s, as described in the patent named "US 4,153,976 Roller Gin with Spiral Blade Rotobar", which is in the state of the art and mentioned above. Because of increased production, this spiral blade rotary knife has begun to be widely used mainly in processing of pima varieties.

As a result of our comprehensive literature review, it was seen that in the 1970s, during the transition from straight blade rotary knifes to spiral blade rotary knifes, there was no comparative study on the seed damage caused by the blade shape when ginning upland varieties. In our comparative field trials between straight blade rotary knife and spiral blade rotary knife, we have determined that the seed damage with straight blade rotary knife is less than with spiral blade rotary knife. However, as expected, it has been observed firsthand that straight blade rotary knife cannot reach high capacity due to their flexing under load.

The use of an additional auxiliary roller to ensure more regular and stable feeding of the rotary knife was first published in the patents “US 4,094,043 Roller Gin with Grooved Square” and “US 4,153,976 Roller Gin with Spiral Blade Rotobar”. The patents mentioned above were filed on the same date by the same inventor. The purpose of these patents is to regulate the feeding as well as to increase the attraction effect between the cotton fibers and the gin roller by pressing the seed cotton onto the gin roller. According to these patents, the proposed auxiliary roller should have a smooth surface. No specifications regarding the auxiliary roller rotation speed and drive mechanism are given in the patents in question. It is also not known whether this suggestion has been tested in the field. There is neither such information in the literature nor a product put on the market in this way. In our field tests, it was observed that the smooth surface of this roller did not contribute to the performance of the rotobar gin. On the other hand, it has been observed that adding blade-shaped elements on this roller at a height of approximately one seed diameter creates significant performance advantages. It has been determined in field trials that by using such an auxiliary feeding roller, significant increase in production is achieved whereas the fibers are stripped leaving less fibers on the seed.

Summary of Invention

The invention is related to the new rotary knife system developed to be added to the existing rotobar machines, meeting the above-mentioned requirements, eliminating all disadvantages, and bringing some additional advantages.

The most important purpose of the invention is to improve the quality of cotton fiber and its seed ginned in rotobar machines compared to low production capacity eccentric knife roller gins, while the production capacity is brought closer to the modern saw gins. In this case, a system that is suitable for both quality and production speed will emerge.

Another aim of the invention is to reduce the percentage of fibers remaining on the cottonseed after the ginning process. In this way, fiber cotton turnout is increased.

Brief Description of Drawings

FIGURE 1 ; The main components of the rotobar type cotton gin.

FIGURE-2; Rotary knives with straight and spiral blades in the current technique.

FIGURE-3; 12, 18 and 24-bladed z-bar type rotary knives

FIGURE-4; The flattened surface of a sample z-bar type rotary knives with irregular blade structure. FIGURE-5; New rotary knife system in new rotobar type cotton gin.

FIGURE-6; 6-bladed straight, 12-bladed z-bar type and 6-spiral bladed auxiliary rollers in new rotobar type cotton gin.

FIGURE-7; Auxiliary roller drive system in new rotobar type cotton gin.

FIGURE-8; Pivoted arm type rotary knife bearing system in new rotobar type cotton gin.

List of Reference Numerals

In order to better explain the new rotary knife system developed with this invention, the elements in the figures are numbered and the description of each number is given below:

1. Gin roller

2. Stationary knife

3. Rotary knife

4. Spiral blade rotary knife

5. Straight blade rotary knife

6. Spiral blade

7. Straight blade

8. Z-bar type rotary knife

9. Irregular bladed z-bar

10. Auxiliary roller 11. Flat-blade auxiliary roller

12. Round steel bars

13. Z-bar type auxiliary roller

14. Spiral bladed auxiliary roller

15. Idler pulley support bracket

16. Driver gear pulley

17. Auxiliary roller gear pulley

18. Idler pulley

19. Timing belt

20. Electric motor

21 . Shaft adaptor

22. Pivoted arm

23. Upper cover

24. Connecting bolt

25. Adjustable bearing

26. Rotary knife bearing

27. Bearing seat adapter rings

28. Idler pulley mounting hole

29. Pneumatic air cylinder

30. Pivot point Detailed Disclosure of the Invention

The invention is related to the new rotary knife system to be retrofitted to existing rotobar gin stands. Figure-1 shows the general structure of conventional rotobar cotton gin stands. Rotobar machines essentially have 3 main components: gin roller (1 ), stationary knife (2) and rotary knife (3). The ginning process of cotton fibers occurs with the pulling effect created by the friction force between the gin roller (1 ) rotating at a certain speed and the stationary knife (2) pressing tangentially on this gin roller (1 ). This tangential pressure point is also known as the ginning point. By design, the peripheral speed of the rotary knife (3) is slower than the peripheral speed of the gin roller (1 ). In this way, it slows down the seed cotton fed towards the ginning point by means of the blades on the rotary knife (3) and ensures that the cotton fibers are held by the gin roller (1 ). The next blade passing removes the seed away from the ginning point by stripping from its fibers.

Mainly two different types of rotary knife designs are used in rotobar machines. These are the spiral blade rotary knife (4) and the straight blade rotary knife (5) seen in figure- 2. The most used and preferred type of rotary knife today are spiral blade rotary knives due to their high production capacity (4). Spiral blade rotary knives (4) containing 4 or 6 spiral blades (6) are generally used in the field. Spiral angle is generally chosen between 150-180 degrees. Spiral angle defines how much the spiral blades (6) rotate angularly along the blade (approximately 1 meter).

Straight blade rotating knives (5) are rarely used today. Models containing 4 or 6 solid straight blades (7) had been used in the field. The biggest problem of straight blade rotary knife (5) is that they do not allow capacity increase due to excessive deflection during high-capacity operation. In straight blade rotary knives (5), the seeds corresponding to each solid straight blade (7) are separated from their fibers at the same time during the passage of the straight blade (7). For this reason, the straight blade rotary knife (5) is exposed to excessive load and excessive vibration amplitudes occur.

In Rotobar ginning machines, the spiral blade rotary knives (4), which are widely used today, have an outer diameter of 69.85 mm, 6 blades, a 150 degree spiral angle, a length of 1022 mm, and are manufactured from steel material. The height of the spiral blade (6) can be 7.4 mm or 9.9 mm. Depending on the width of the machine on which it will be used, the length of the rotary knife (3) can be 1022 mm or 1232 mm. The invention subject to the application can be applied to spiral blade rotary knife (4) of both blade heights and lengths.

In the system developed with the invention, z-bar type rotary knives (8), which are designed to work at high capacity, are used instead of conventional straight blade rotary knives (5) to cause less damage to the upland seeds. Z-bar type rotary knife (8) principally use straight blades, but instead of each continuous straight blade (7) from end to end, they contain blades that are segmented and angularly displaced relative to each other. For example, instead of six continuous straight blades (7), each straight blade is segmented in half and one part is positioned in the middle of the blade pitch gap relative to the other part. In this way, the number of seeds that will correspond to each continuous straight blade (7) and therefore the instantaneous loading force on the rotary knife (3) are reduced by half. Thus, the flexing and vibration amplitude of the z-bar type rotary knife (8) will be halved. Each of the continuous straight blades (7) on the straight blade rotary knife (5) can be divided into the desired number of pieces and different designs can be created by shifting each piece by the desired amount within the blade pitch space.

The z-bar type rotary knife (8) that are the subject of the invention have 069.85 mm outer diameter, 12 blades, and 7.4 mm blade height. The rotation speed varies between 380 rpm and 1620 rpm. It is driven by a 3 HP, 1500 rpm (2.2 kW, 1500 rpm), 4-pole standard asynchronous electric motor (20) with the help of a frequency converter.

As can be seen in Figure-4, the angular translation of all the continuous straight blades (7) by splitting them in the middle creates a discontinuity at the midpoint of the z-bar type rotary knives (8). The discontinuity points on each blade can be distributed to different points in the axial direction to prevent the discontinuity from gathering at a single point. The irregular bladed z-bar (9), whose flattened surface is shown in Figure- 4, is an example of this.

The way to increase the production capacity of the rotobar machine is to feed the seed cotton to the ginning point as steadily and uniformly as possible. This principle is also valid for all types of rotary knives (3). For this purpose, a feed roller designated as auxiliary roller (10) was used. Standard round steel rods (12) with a diameter of 6 mm were welded on a straight shaft with a diameter of 58 mm using chain intermittent welding method as shown in figure-6. Using this method, straight blade auxiliary roller (11 ) and spiral bladed auxiliary roller (14) were manufactured.

Welding the round steel bars (12) onto the round shaft using chain intermittent welding method was preferred because it provides ease of manufacturing. In welded manufacturing, it is also possible to use steel bars with other geometric cross-sections instead of round steel bars. To include the desired blade structure, the auxiliary roller (10) can also be machined from a solid steel shaft using the complete machining method. The main function of the blades used here is to bring the seeds into a single alignment. To ensure this, the operating speed of the auxiliary roller (10) is important. By trying different speeds, it has been found that the most suitable operating point is to work at the speed corresponding to the average of the peripheral speeds of the gin roller (1 ) and the rotary knife (3). This speed preference is determined after field trials. Different speeds can create more favorable working conditions for different types of cotton.

The use of z-bar types rotary knives (8) together with the auxiliary roller (10) creates significant benefits in terms of both production capacity and product quality. As a result of field trials, it appears that all targets have been met by exceeding.

The blades on the auxiliary roller (10) may be in spiral form, such as in spiral blade rotary knives (4). If a spiral blade rotary knife (4) is used, the use of a spiral blade auxiliary roller (14) in the same spiral shape may be beneficial. If a z-bar type rotary knife (8) is used, a z-bar type auxiliary roller (13) with the same blade segmentation can be used. It is not a necessity for the rotary knife (3) and the auxiliary roller (10) to be in the same forms. Both types of rotary knives (3) can work with the straight blade auxiliary roller (11 ).

In order to understand the invention more easily, details of the drive system that moves the auxiliary roller (10) are shown in figure-7. To ensure synchronization between the auxiliary roller (10) and the rotobar rotary knife (3), it is preferred to use a timing belt (19). The auxiliary roller gear pulley (17) receives its motion from the driver gear pulley (16), which is connected to the rotary knife (3) shaft with a shaft adaptor (21 ). Thanks to the shaft adaptor (21 ), rotary knife (3) with different shaft diameters can be used with the same driver gear pulley (16). Instead of being driven by the rotary knife (3), the auxiliary roller can also be driven by a separate electric motor. However, in this case, synchronization of the rotary knife (3) and the auxiliary roller (10) will not be possible.

In the auxiliary roller drive system, the idler pulley (18) is used to tension the timing belt (19). In the field trials, it was seen from the measured motor torque values that the synchronization between the rotary knife (3) and the auxiliary roller (10) is important in terms of capacity.

Another important aspect of the rotary knife (3) system developed with the invention is the pivoted arm (22) system in which the rotobar rotary knife (3) and the auxiliary roller (10) are supported together. The rotary knife (3) takes the ginning position thanks to a pivoted arm (22) that rotates by the act of the pneumatic air cylinder (29). The pivoted arm (22) in question can rotate around the pivot point (30) shown in figure-8. Rotating blade bearings, auxiliary roller bearings and idler pulley support bracket (17) elements are all mounted on the pivoted arm (22). The idler pulley support bracket (15) is fixed on the pivoted arm (22) using the idler pulley mounting hole (28). To fulfill these functions, the pivoted arm (22) design has a rigid structure and a large surface. The pivoted arm (22) was precisely cut from thick steel plate with a laser and processed using the machining methods. Thanks to the LICFA 200 type adjustable bearing (25) used, the distances between the auxiliary roller (10), the gin roller (1 ) and the rotary knife (3) can be easily adjusted relative to each other. The pivoted arm (22) system is designed as two easily separable parts, connected to each other with cover connection bolts (24). The rotary knife (3) can be easily replaced by removing the upper cover (23) shown in Figure-7. Instead of machining the rotating knife bearing (26) seat directly on the pivoted arm (22) by machining method, two-piece bearing seat adapter rings (27) that can be easily separated are used. In this way, rotary knife (3) of different diameters can be used with bearing seat adapter rings (27) of the same outer diameter on the same pivoted arm (22).

Claims

1. A new rotary knife system developed for Rotobar type cotton gins, characterized by comprising;

• In order to reduce the instantaneous impact intensity and therefore the rotating blade vibration displacement amplitude that occurs during the passage of the full-length solid straight blades (7) used in conventional straight blade rotary knives (5) from the ginning point, each full-length solid straight blade (7) is divided into at least two parts and the segmented parts are angularly moved relative to each other along the perimeter, forming a rotary knife called z-bar rotary knife (8),

• It contains an auxiliary roller (10) positioned in upstream of the rotary knife (3) that provides steady and uniform seed cotton flow to the rotary knife (3) by bringing the seed cotton into a single alignment through its specially designed blades, thereby increasing the production capacity and reducing the percentage of fiber remaining on the seed.

2. A system according to claim 1 , characterized by comprising a z-bar type rotary knife (8) with an outer diameter of 69.85 mm and a blade height of 7.4 mm.

3. A system according to claim 1 , characterized by comprising a z-bar type rotary knife

(8) that can be used as a replacement of 1232 mm long as well as 1022 mm long conventional rotary knives (3).

4. A system according to claim 1 , characterized by comprising a irregular bladed z-bar (9) which ensures that the discontinuity points formed by the segmented straight blades do not come to the same point in the axial direction of the rotary knife.

5. A system according to claim 1 , characterized by comprising an auxiliary roller (10) that can be completely produced by machining from a solid steel shaft to include the desired blade structure.

6. A system according to claim 1 , characterized by comprising a straight bladed auxiliary roller (11 ) manufactured by welding round steel rods (12) in a straight form from end to end on a steel shaft.

7. A system according to claim 1 , characterized by comprising a straight bladed auxiliary roller (11 ) manufactured by welding steel materials with square and polygonal geometry onto a steel shaft.

8. A system according to claim 1 , characterized by comprising a spiral bladed auxiliary roller (14) in which round steel rods (12) are welded in a spiral form from end to end on a steel shaft.

9. A system according to claim 1 , characterized by comprising the drive system includes a timing belt (19) in order to ensure synchronization between the auxiliary roller (10) and the rotary knife (3).

10. A system according to claim 1. characterized by comprising an shaft adaptor (21 ) that provides the connection of the driver gear pulley (16) on the rotary knife (3) shaft, which drives the auxiliary roller gear pulley (18).

11 . A system according to claim 1 .characterized in that the auxiliary roller (10) contains at least one idler pulley (18) for tensioning the timing belt (19).

12. A system according to claim ^characterized by comprising LICFA 200 type adjustable bearing (25) so that the distances between the auxiliary roller (10), the gin roller (1 ) and the rotary knife (3) can be easily adjusted.

13. A system according to claim 1 .characterized by comprising a detachable two-piece pivoted arm (22) system in which the upper cover (23) is connected to the lower part with connection bolts (24). allowing the rotary knife (3) to be easily removed and installed over the pivoted arm (22).

14. A system according to claim ^characterized by comprising detachable two-piece bearing seat adapter rings (27) that allow the bearing of rotary knife (3) of different diameters on the pivoted arm (22).