Low-calorific-value coal crushing and blending device

Abstract

The utility model relates to the technical field of mixed coal, specifically is a kind of low calorific value coal crushing mixed coal device, including mixing cylinder;The mixing cylinder is arranged on the mine belt conveyor for conveying raw coal;The top surface middle part of the mixing cylinder is hinged with hopper;The both ends of the inside of the mixing cylinder are rotatably provided with a No. The both ends of the outer ring of the No. 1 rotating rod are fixed with spiral blade for pushing raw coal;By mixing coal gangue into high calorific value raw coal, high-quality raw coal is mixed into low calorific value raw coal, so that the calorific value of mined raw coal is kept within the set calorific value index range, thereby facilitating sales and use, while reducing the loss of calorific value, reducing economic benefit loss;At the same time, in the process of mixing coal, a large amount of coal gangue is consumed, effectively reducing the discharge amount of coal gangue, reducing the cost of coal gangue disposal and storage site.

Description

Technical Field

[0001] This utility model relates to the field of coal blending technology, specifically a coal crushing and blending device for low-calorific-value coal. Background Technology

[0002] During coal mining, not only a large amount of raw coal is extracted, but also a large amount of associated coal gangue. Coal gangue is a type of rock mixed in with coal seams, containing a small amount of combustible material, but it is not easily burned.

[0003] The existing coal gangue is mainly used to make building materials. However, during the long-term mining process, a large amount of coal gangue will be piled up in gangue mountains. The pile of coal gangue not only occupies a lot of land, but also causes serious pollution to the air, water and soil due to the presence of harmful substances such as sulfides and heavy metals in its composition, which is very harmful to the environment.

[0004] Meanwhile, due to the large fluctuations in the quality of raw coal, when the quality of raw coal is good, the calorific value of the blended coal will be higher than the set calorific value target, resulting in a waste of calorific value and thus a loss of economic benefits; while when the quality of raw coal is poor, the calorific value of the blended coal will be lower than the set calorific value target, resulting in substandard quality of the blended coal and affecting sales and use.

[0005] Therefore, a low-calorific-value coal crushing and blending device is proposed to address the above problems. Utility Model Content

[0006] In order to overcome the shortcomings of the prior art, at least one technical problem raised in the background art is solved.

[0007] The technical solution adopted by this utility model to solve its technical problem is as follows: The low-calorific-value coal crushing and blending device of this utility model includes a mixing cylinder; the mixing cylinder is installed on a mining belt conveyor for conveying raw coal; the bottom outer wall of the mixing cylinder is in sliding contact with the top surface of the belt of the mining belt conveyor; a hopper is bolted to the middle of the top surface of the mixing cylinder; a first rotating rod is rotatably installed at both ends of the interior of the mixing cylinder; spiral blades for pushing raw coal are fixedly connected to both ends of the outer ring of the first rotating rod; the two spiral blades are located on both sides of the discharge port of the hopper.

[0008] Preferably, a plurality of straight plates are arranged around one end of the spiral blade that is close to each other; a flap is fixed between two straight plates on both sides; the side of the flap away from the first rotating rod is in sliding contact with the inside of the mixing cylinder.

[0009] Preferably, multiple fixing blocks are fixedly connected to both ends of the mixing cylinder; an arc-shaped guide plate is bolted to the fixing block; the multiple arc-shaped guide plates form a ring structure.

[0010] Preferably, hydraulic cylinders with downwardly oriented piston rods are fixedly connected to the middle of both sides of the mixing cylinder; an arc-shaped support plate is fixedly connected to the bottom end of the piston rod of the hydraulic cylinder; the arc-shaped support plate is located at the bottom of the belt of the mining belt conveyor.

[0011] Preferably, both ends of the arc-shaped support plate are fixedly connected to semi-circular baffles.

[0012] Preferably, a horizontal cylinder is fixedly connected to the middle of the discharge port at the bottom of the hopper; both ends of the horizontal cylinder are bolted with a cover; a second rotating rod is rotatably installed between the two covers; an impeller is fixedly connected to the outer ring of the middle of the second rotating rod; a second motor is fixedly connected to the side of one of the covers away from the horizontal cylinder; the output shaft of the second motor is fixedly connected to the second rotating rod.

[0013] Preferably, the outer ring of the impeller is uniformly fixed with multiple protruding teeth.

[0014] Preferably, both ends of the impeller are fixedly connected to circular baffles; the outer ring of the circular baffles slides in fit with the inner wall of the cross cylinder.

[0015] The advantages of this utility model are:

[0016] 1. The low-calorific-value coal crushing and blending device of this utility model is equipped with a mixing cylinder, a hopper, spiral blades, a fixed arm, a rotating shaft, and a No. 1 motor. By mixing coal gangue into high-calorific-value raw coal and high-quality raw coal into low-calorific-value raw coal, the calorific value of the mined raw coal is kept within the set calorific value index range, which is beneficial to sales and use. At the same time, it reduces calorific value loss and economic benefits. In addition, the coal blending process consumes a large amount of coal gangue, effectively reducing the amount of coal gangue discharged, lowering the cost of coal gangue disposal and storage space.

[0017] 2. The low-calorific-value coal crushing and blending device of this utility model is equipped with a hydraulic cylinder, an arc-shaped support plate, and a guide rod. When the hydraulic cylinder retracts, it drives the arc-shaped support plate and the guide rod to move upward. Through the limiting guidance of the guide rod, the arc-shaped support plate lifts the belt of the mining belt conveyor to move upward, so that the belt of the belt conveyor is stably attached to the bottom of the mixing drum, thereby facilitating the entry of the mined raw coal into the mixing drum. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a perspective view of the present utility model;

[0020] Figure 2 This is a cross-sectional structural diagram of the present invention;

[0021] Figure 3 This is a schematic diagram of the exploded structure of this utility model;

[0022] Figure 4 This is a schematic diagram of the internal structure of the mixing cylinder in this utility model;

[0023] Figure 5 This is a schematic diagram of the fixed arm in this utility model;

[0024] Figure 6 This is a schematic diagram of the straight strip and the flip plate in this utility model;

[0025] Figure 7 This is a schematic diagram of the structure of the fixing block and the arc-shaped guide plate in this utility model;

[0026] Figure 8 This is a schematic diagram of the arc-shaped support plate in this utility model;

[0027] Figure 9 This is a schematic diagram of the exploded structure of the hopper in this utility model;

[0028] Figure 10 This is a schematic diagram of the impeller structure in this utility model.

[0029] In the diagram: 1. Mixing cylinder; 2. Hopper; 3. Spiral blade; 4. Fixed arm; 5. Rotating shaft; 6. Motor No. 1; 7. Rotating rod No. 1; 8. Straight bar; 9. Flip plate; 10. Fixed block; 11. Arc-shaped guide plate; 12. Hydraulic cylinder; 13. Arc-shaped support plate; 14. Guide rod; 15. Semi-circular baffle; 16. Horizontal cylinder; 17. Baffle cover; 18. Rotating rod No. 2; 19. Impeller; 20. Motor No. 2; 21. Convex tooth; 22. Circular baffle. Detailed Implementation

[0030] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present utility model.

[0031] like Figures 1 to 5As shown, a low-calorific-value coal crushing and blending device includes a mixing cylinder 1; the mixing cylinder 1 is installed on a mining belt conveyor for conveying raw coal; the bottom outer wall of the mixing cylinder 1 is in sliding contact with the top surface of the belt of the mining belt conveyor; a hopper 2 is bolted to the middle of the top surface of the mixing cylinder 1; a first rotating rod 7 is rotatably installed at both ends inside the mixing cylinder 1; spiral blades 3 for pushing raw coal are fixedly connected to both ends of the outer ring of the first rotating rod 7; the two spiral blades 3 are located on both sides of the discharge port of the hopper 2;

[0032] Specifically, both ends of the mixing cylinder 1 are open, and the bottom outer wall of the mixing cylinder 1 is in close contact with the top surface of the belt of the mining belt conveyor, so that the raw coal will pass through the mixing cylinder 1 when the mining belt conveyor transports raw coal; the top surface of the middle part of the mixing cylinder 1 is provided with a feed inlet, and the feed inlet is fixedly connected to the discharge port at the bottom of the hopper 2 by bolts; the mixing cylinder 1 and the hopper 2 are supported by columns on both sides.

[0033] The coal gangue inside hopper 2 is conveyed and fed by a belt conveyor;

[0034] Fixed arms 4 are fixedly connected to the top of both ends of the mixing cylinder 1; the bottom end of the fixed arm 4 is aligned with the axis of the mixing cylinder 1; an inner cavity is opened inside the fixed arm 4, and a rotating shaft 5 is rotatably installed at the bottom and top of the inner cavity of the fixed arm 4; a pulley is fixedly connected to the outer ring of the two rotating shafts 5 on one side, and a belt is fitted on the outer ring of the two pulleys; a rotating shaft 5 near the top of the pulley is fixedly connected to the output shaft of the first motor 6, and the first motor 6 is bolted to the top surface of the mixing cylinder 1; a first rotating rod 7 that passes through the mixing cylinder 1 is bolted between the two rotating shafts 5 on both sides of the bottom.

[0035] The inner ring of the spiral blade 3 is a fixed cylinder fitted onto the outer ring of the first rotating rod 7, and the outer ring of the fixed cylinder is a spiral blade;

[0036] In practical use, when the calorific value of the raw coal conveyed by the mining belt conveyor is higher than the set calorific value index, the coal mixing device is started. The coal gangue is conveyed into the hopper 2 by the belt conveyor. At the same time, the raw coal conveyed by the mining belt conveyor enters the mixing drum 1. At this time, the No. 1 motor 6 drives the top rotating shaft 5 to rotate. Through the transmission of the pulley and belt, the bottom rotating shaft 5 is driven to rotate, which drives the No. 1 rotating rod 7 and the two spiral blades 3 to rotate. One spiral blade 3 near the feed inlet of the mixing drum 1 spirally conveys the raw coal entering the mixing drum 1 to the middle of the mixing drum 1, that is, the bottom end of the discharge port of the hopper 2. The coal gangue inside the hopper 2 falls from the feed inlet of the mixing drum 1 into the middle of the mixing drum 1 and mixes with the raw coal in the middle of the mixing drum 1, thereby reducing the calorific value of the raw coal to the set calorific value index range. Afterwards, one spiral blade 3 near the discharge port of the mixing drum 1 spirally conveys the mixed raw coal in the mixing drum 1 out of the mixing drum 1, and then it is conveyed by the mining belt conveyor.

[0037] When the calorific value of the raw coal conveyed by the mining belt conveyor is lower than the set calorific value index, the high-quality raw coal is conveyed to the inside of the hopper 2 by the belt conveyor, and then enters the mixing drum 1 to mix with the low-calorific-value raw coal in order to increase the calorific value of the raw coal and raise the calorific value of the raw coal to the set calorific value index range.

[0038] By mixing high-calorific-value raw coal with coal gangue and low-calorific-value raw coal with high-quality raw coal, the calorific value of the mined raw coal is kept within the set calorific value index range, which is beneficial for sales and use. At the same time, it reduces calorific value loss and economic losses. In addition, the coal mixing process consumes a large amount of coal gangue, which effectively reduces the amount of coal gangue discharged, lowers the cost of coal gangue disposal and storage space.

[0039] Furthermore, such as Figures 2 to 6 As shown, a plurality of straight plates 8 are arranged around one end of the spiral blade 3 that is close to each other; a flap 9 is fixed between two straight plates 8 on both sides; the side of the flap 9 away from the first rotating rod 7 slides in contact with the inside of the mixing cylinder 1.

[0040] Specifically, the middle fixed cylinder of the spiral blade 3 has multiple fixed grooves around one end near the middle of the mixing cylinder 1; one end of the straight plate 8 is set in the fixed groove and is fixed by screws; the end of the straight plate 8 away from the first rotating rod 7 has a through groove; the flap 9 is a rectangular plate in general, and the middle of both ends of the flap 9 is fixed with protrusions that match the through grooves and is fixed by multiple bolts.

[0041] In practical use, the No. 1 rotating rod 7 drives the two spiral blades 3 to rotate, which in turn drives the multiple pairs of straight plates 8 on both sides to rotate, and drives the flipping 9 to rotate. This flips the raw coal and the mixed coal gangue or high-quality raw coal located between the two spiral blades 3, so that the raw coal and the mixed coal gangue or high-quality raw coal are fully mixed, thereby improving the efficiency of coal mixing and the consistency of the quality of the mixed raw coal.

[0042] In some embodiments, such as Figure 1 , Figure 2 and Figure 7 As shown, multiple fixing blocks 10 are fixedly connected to both ends of the mixing cylinder 1; an arc-shaped guide plate 11 is bolted to the fixing block 10; the multiple arc-shaped guide plates 11 form a ring structure;

[0043] Specifically, the fixed block 10 has a convex cross-section, the arc-shaped guide plate 11 has an arc-shaped structure, the outer ring of the arc-shaped guide plate 11 is aligned with the outer wall of the mixing cylinder 1, and the inner ring is aligned with the inner wall of the mixing cylinder 1; and multiple arc-shaped guide plates 11 can form a ring structure; the inner ring of the arc-shaped guide plate 11 has a chamfer at the end away from the mixing cylinder 1; the outer wall of the arc-shaped guide plate 11 has an installation groove that matches the fixed block 10, and is fixed by screws.

[0044] Furthermore, the fixing block 10 located at the top of the mixing cylinder 1 is not equipped with the arc-shaped guide plate 11, but is used to fix the fixing arm 4.

[0045] With the arc-shaped guide plate 11 in place, the outer wall of the arc-shaped guide plate 11 is attached to the top surface of the belt of the mining belt conveyor, so that the belt of the mining belt conveyor and the inside of the mixing cylinder 1 form an inclined slope. When the mining belt conveyor transports raw coal, the raw coal will be pushed along the chamfer of the inner circle of the arc-shaped guide plate 11 and slide into the inside of the mixing cylinder 1, thereby effectively reducing the blockage of raw coal at the end of the mixing cylinder 1 and improving the efficiency and smoothness of raw coal entering the mixing cylinder 1.

[0046] In some embodiments, such as Figure 1 , Figure 2 , Figure 3 and Figure 8 As shown, hydraulic cylinders 12 with downward-facing piston rods are fixedly connected to the middle of both sides of the mixing cylinder 1; an arc-shaped support plate 13 is fixedly connected to the bottom end of the piston rod of the hydraulic cylinder 12; the arc-shaped support plate 13 is located at the bottom of the belt of the mining belt conveyor.

[0047] Specifically, multiple fixed seats are fixedly connected to both sides of the mixing cylinder 1. A hydraulic cylinder 12 is bolted to the inside of one fixed seat in the middle, and guide rods 14 are slidably installed inside the two fixed seats on both sides. The bottom end of the guide rod 14 is fixedly connected to the side of the uniformly arc-shaped support plate 13 at the bottom end of the piston rod of the hydraulic cylinder 12.

[0048] In practical use, when it is necessary to mix coal gangue or high-quality raw coal into the mined raw coal, the hydraulic cylinder 12 retracts, driving the arc-shaped support plate 13 and guide rod 14 to move upward. Through the limiting guidance of the guide rod 14, the arc-shaped support plate 13 lifts the belt of the mining belt conveyor to move upward, so that the belt of the belt conveyor is stably attached to the bottom of the mixing drum 1, which is conducive to the mined raw coal entering the mixing drum 1.

[0049] Furthermore, such as Figure 1 , Figure 2 , Figure 3 and Figure 8 As shown, semi-circular baffles 15 are fixed to both ends of the arc-shaped support plate 13;

[0050] Specifically, when the semi-circular baffle 15 and the arc-shaped support plate 13 support the belt of the mining belt conveyor and fit it against the bottom of the mixing drum 1, the semi-circular baffles 15 on both sides are located at the bottom of both ends of the mixing drum 1. Since the two sides of the semi-circular baffles 15 are raised upwards, they surround the lower half of both ends of the mixing drum 1, thereby preventing the mined raw coal from being blocked at the end of the mixing drum 1 and falling to both sides.

[0051] In some embodiments, such as Figure 1 , Figure 2 , Figure 3 , Figure 9 and Figure 10 As shown, a horizontal cylinder 16 is fixedly connected to the middle of the discharge port at the bottom of the hopper 2; both ends of the horizontal cylinder 16 are bolted with a cover 17; a second rotating rod 18 is rotatably installed between the two covers 17; an impeller 19 is fixedly connected to the outer ring of the middle of the second rotating rod 18; a second motor 20 is fixedly connected to the side of one of the covers 17 away from the horizontal cylinder 16; the output shaft of the second motor 20 is fixedly connected to the second rotating rod 18.

[0052] Specifically, the inner cavity of the horizontal cylinder 16 is connected to the inner cavity of the discharge port of the hopper 2, the inner ring of the impeller 19 is a sleeve fitted on the outer ring of the second rotating rod 18 and is fixed by screws; the outer ring of the impeller 19 is a horizontal plate that is fixed around the outer ring of the sleeve.

[0053] In practical use, the No. 2 motor 20 drives the No. 2 rotating rod 18 to rotate, which in turn drives the impeller 19 to rotate inside the horizontal cylinder 16. The horizontal plate on the impeller 19 blocks the discharge port at the bottom of the hopper 2, preventing the coal gangue or high-quality raw coal inside the hopper 2 from falling. By rotating the impeller 19, the coal gangue or high-quality raw coal inside the hopper 2 falls steadily and orderly, thus making it easier to control the proportion of mixed coal.

[0054] Furthermore, such as Figure 9 and Figure 10 As shown, the outer ring of the impeller 19 is uniformly fixed with a plurality of protruding teeth 21;

[0055] Specifically, multiple protruding teeth are evenly fixed to the side of the outer ring horizontal plate of the impeller 19 away from the second rotating shaft 18; when the impeller 19 rotates and controls the stable and orderly feeding of coal gangue or high-quality raw coal inside the hopper 2, the protruding teeth on the outer ring of the impeller 19 scrape the coal gangue or high-quality raw coal inside the hopper 2, thereby avoiding the situation where the coal gangue or high-quality raw coal inside the hopper 2 is blocked due to mutual obstruction, which affects the feeding.

[0056] Furthermore, such as Figure 9 and Figure 10 As shown, both ends of the impeller 19 are fixedly connected to a circular baffle 22; the outer ring of the circular baffle 22 is slidably engaged with the inner wall of the cross cylinder 16;

[0057] Specifically, the baffles 22 are used to block the inner walls of both ends of the horizontal cylinder 16, preventing coal gangue or high-quality raw coal from remaining inside the horizontal cylinder 16, thus facilitating the feeding of coal gangue or high-quality raw coal.

[0058] Working principle: When the calorific value of the raw coal conveyed by the mining belt conveyor is higher than the set calorific value index, the coal mixing device is started. The coal gangue is conveyed into the hopper 2 by the belt conveyor. At the same time, the hydraulic cylinder 12 retracts, driving the arc-shaped support plate 13 and the guide rod 14 to move upward. Through the limiting guidance of the guide rod 14, the arc-shaped support plate 13 lifts the belt of the mining belt conveyor to move upward, so that the belt of the belt conveyor is stably attached to the bottom of the mixing cylinder 1.

[0059] When the mining belt conveyor transports raw coal, the raw coal is pushed along the chamfer of the inner ring of the arc-shaped guide plate 11 and slides into the interior of the mixing drum 1. At the same time, the No. 1 motor 6 drives the top rotating shaft 5 to rotate. Through the transmission of the pulley and belt, the bottom rotating shaft 5 is driven to rotate, which drives the No. 1 rotating rod 7 and the two spiral blades 3 to rotate. One of the spiral blades 3 near the feed inlet of the mixing drum 1 spirally transports the raw coal that has entered the mixing drum 1 to the middle of the mixing drum 1, that is, the bottom end of the discharge port of the hopper 2.

[0060] At this time, motor 20 drives rotor 18 to rotate, which in turn drives impeller 19 to rotate inside cylinder 16. The horizontal plate on impeller 19 blocks the discharge port at the bottom of hopper 2, preventing the coal gangue inside hopper 2 from falling. Through the rotation of impeller 19, the coal gangue inside hopper 2 falls steadily and orderly into the middle of mixing cylinder 1, where it mixes with the raw coal in the middle of mixing cylinder 1. At the same time, rotor 7 drives two spiral blades 3 to rotate, which in turn drives multiple pairs of straight plates 8 on both sides to rotate, which in turn drives the flipping 9 to rotate, flipping the raw coal and mixed coal gangue between the two spiral blades 3. After the raw coal and mixed coal gangue are fully mixed, one spiral blade 3 near the discharge port of mixing cylinder 1 conveys the mixed raw coal out of mixing cylinder 1 by spiral conveyor, and then it is transported by the mining belt conveyor.

[0061] When the calorific value of the raw coal conveyed by the mining belt conveyor is lower than the set calorific value index, the high-quality raw coal is conveyed to the inside of the hopper 2 by the belt conveyor, and then enters the mixing drum 1 to mix with the low-calorific-value raw coal in order to increase the calorific value of the raw coal and raise the calorific value of the raw coal to the set calorific value index range.

[0062] By mixing high-calorific-value raw coal with coal gangue and low-calorific-value raw coal with high-quality raw coal, the calorific value of the mined raw coal is kept within the set calorific value index range, which is beneficial for sales and use. At the same time, it reduces calorific value loss and economic losses. In addition, the coal mixing process consumes a large amount of coal gangue, which effectively reduces the amount of coal gangue discharged, lowers the cost of coal gangue disposal and storage space.

[0063] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. Those skilled in the art should understand that this utility model is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of this utility model. Various changes and modifications can be made to this utility model without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed utility model.

Claims

1. A device for crushing and blending low-calorific-value coal, characterized in that: The system includes a mixing cylinder; the mixing cylinder is mounted on a mining belt conveyor for transporting raw coal; the bottom outer wall of the mixing cylinder is in sliding contact with the top surface of the belt of the mining belt conveyor; a hopper is bolted to the center of the top surface of the mixing cylinder; a first rotating rod is rotatably mounted at both ends inside the mixing cylinder; spiral blades for pushing raw coal are fixedly connected to both ends of the outer ring of the first rotating rod; the two spiral blades are located on both sides of the discharge port of the hopper.

2. The low-calorific-value coal crushing and blending device according to claim 1, characterized in that: Multiple straight plates are arranged around one end of the spiral blade that is close to each other; a flap is fixed between two straight plates on both sides; the side of the flap away from the first rotating rod is in sliding contact with the inside of the mixing cylinder.

3. The low-calorific-value coal crushing and blending device according to claim 1, characterized in that: Multiple fixing blocks are fixedly connected to both ends of the mixing cylinder; arc-shaped guide plates are bolted to the fixing blocks; the multiple arc-shaped guide plates form a ring structure.

4. The low-calorific-value coal crushing and blending device according to claim 1, characterized in that: Hydraulic cylinders with downward-facing piston rods are fixedly connected to the middle of both sides of the mixing cylinder; an arc-shaped support plate is fixedly connected to the bottom end of the piston rod of the hydraulic cylinder; the arc-shaped support plate is located at the bottom of the belt of the mining belt conveyor.

5. A low-calorific-value coal crushing and blending device according to claim 4, characterized in that: Both ends of the arc-shaped support plate are fixed with semi-circular baffles.

6. The low-calorific-value coal crushing and blending device according to claim 1, characterized in that: A horizontal cylinder is fixedly connected to the middle of the discharge port at the bottom of the hopper; both ends of the horizontal cylinder are bolted with baffles; a second rotating rod is rotatably installed between the two baffles; an impeller is fixedly connected to the outer ring of the middle of the second rotating rod; a second motor is fixedly connected to the side of one of the baffles away from the horizontal cylinder; the output shaft of the second motor is fixedly connected to the second rotating rod.

7. A low-calorific-value coal crushing and blending device according to claim 6, characterized in that: The outer ring of the impeller is uniformly fixed with multiple protruding teeth.

8. A low-calorific-value coal crushing and blending device according to claim 7, characterized in that: Both ends of the impeller are fixedly connected to circular baffles; the outer ring of the circular baffles slides in fit with the inner wall of the cross cylinder.

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