Efficient ore dressing electromechanical device for iron ore
By designing an efficient iron ore ore electromechanical device, and using screening mechanism and pneumatic spring to cooperate, the problem of screening mesh blockage during iron ore particle grading is solved, efficient screening is achieved, and screening efficiency and stability are improved.
Patent Information
- Application Number
- CN202422130875.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2034-09-02
AI Technical Summary
In the process of iron ore particle size classification, the problem of screening is difficult, especially due to irregular shapes and sharp protrusions, which leads to clogging of screen holes and affects screening efficiency.
An efficient iron ore ore processing electromechanical device is designed, including screening mechanism, screening disk, moving plate, slider, push block and other components. The screening disk is driven to rotate through the rotating rod, and the automatic clearing and screening of the screen holes is achieved by combining air pressure and spring to ensure the smooth passage of the ore.
Effectively prevent ore from clogging the screen holes, improve screening speed and efficiency, and ensure the continuity and stability of the screening process.
Smart Images
Figure CN223249392U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the field of mineral separation, in particular to a high-efficiency electromechanical device for iron ore separation. Background Art
[0002] Iron ore, defined as an ore or mineral aggregate containing refinable iron, is a primary raw material for the steel industry. It is widely distributed throughout the Earth's crust, typically existing as oxides, carbonates, or sulfides, such as magnetite, hematite, and limonite. Through mining, beneficiation, and smelting processes, iron can be extracted from iron ore and subsequently made into metal materials such as pig iron and steel.
[0003] At present, in the process of iron ore beneficiation, it is often necessary to crush the iron ore first, and then classify the crushed iron ore according to particle size for subsequent processing. At present, in the process of size classification of iron ore, it is often necessary to process it through vibration screening.
[0004] At present, in the process of size classification of iron ore particles, due to the irregular shape of the iron ore and the presence of sharp protrusions, during the screening process, some iron ore that is not much different in size from the screen holes may be stuck in the holes and unable to move, resulting in the remaining iron ore being unable to pass through the holes, making screening difficult. Therefore, an efficient iron ore beneficiation electromechanical device is proposed to solve the above problem. Utility Model Content
[0005] In order to make up for the above shortcomings, the utility model provides an electromechanical device for efficient iron ore beneficiation, which aims to improve the problem in the prior art that ore may clog the screen holes during the screening process.
[0006] In order to achieve the above-mentioned purpose, the present invention adopts the following technical solutions: an electromechanical device for efficient iron ore beneficiation, comprising a body, a door hinged on the left side of the front end of the body, a feed hopper fixedly connected to the top of the body, a crushing roller arranged inside the body, a starting assembly arranged jointly inside and at the rear end of the body, the starting assembly comprising a rotating rod, the outer wall of the rotating rod passes through and is rotatably connected to the inner wall of the body, a screening mechanism is arranged jointly inside the body below the crushing roller and outside the rotating rod, the screening mechanism comprising a screening slot, the screening slot is opened on the inner wall of the body, a sieve plate is inserted into the outer wall of the rotating rod, the inner wall of the sieve plate is slidably connected to a movable plate, and the end of the movable plate close to the rotating rod is elastically connected to the inner wall of the sieve plate by a spring.
[0007] As a further description of the above technical solution:
[0008] A sieve hole is provided at the top of the sieve plate, a movable hole is provided at the top of the movable plate, an air pressure chamber is provided on the inner wall of the movable plate, a slider is connected to the inner wall piston of the movable plate, a fixed plate is fixedly connected to the inner wall of the air pressure chamber, an end of the fixed plate away from the rotating rod and an end of the slider close to the rotating rod are elastically connected by a spring, a push block is connected to the inner wall piston of the air pressure chamber, and a collecting plate is slidably provided at the bottom end of the screening trough.
[0009] As a further description of the above technical solution:
[0010] The number of the rotating rods is set to be multiple, and the multiple rotating rods are arranged in a horizontal array in a vertical direction.
[0011] As a further description of the above technical solution:
[0012] The starting assembly also includes a mounting plate, the front end of the mounting plate is fixedly connected to the rear end of the machine body, the top of the mounting plate is fixedly connected to a motor, the output shaft of the motor is fixedly connected to the rear end of the uppermost rotating rod, the outer wall of the rotating rod is fixedly connected to a rotating block, the rear end of the sieve plate is provided with a fixed groove, and the adjacent rotating rods are connected by a conveyor belt transmission.
[0013] As a further description of the above technical solution:
[0014] The shape of the screening slot is a shape formed by connecting a plurality of arc surfaces, and the number of the screening slots is consistent with the number of the rotating rods.
[0015] As a further description of the above technical solution:
[0016] The distance between the inner wall of the upper half of the screening trough on the lower side of the rotating rod and the rotating rod is equal to the distance between the slider and the rotating rod when the slider and the movable plate are moved to the farthest distance from the rotating rod. The distance between the top end of the screening trough and the rotating rod is consistent with the distance between the edge of the sieve plate and the rotating rod. The area of the screening trough above the rotating rod is set as an arc surface connecting the line segment where the top end of the screening trough is located and the area of the screening trough below the rotating rod. The inner wall of the lower half of the screening trough on the lower side of the rotating rod is an arc surface connecting the bottom end of the upper half of the screening trough on the lower side of the rotating rod and the top end of the screening trough below the screening trough.
[0017] As a further description of the above technical solution:
[0018] The diameter of the push block is slightly smaller than the diameter of the sieve hole, and the distance between each two sieve holes is greater than the diameter of the sieve hole.
[0019] As a further description of the above technical solution:
[0020] The number of the sieve plates is consistent with that of the rotating rods, and the sieve holes opened on the sieve plates decrease in size from top to bottom.
[0021] The utility model has the following beneficial effects:
[0022] 1. In the utility model, through the arrangement of the screening trough, sieve plate, movable plate, sieve hole, movable hole, air pressure chamber, slider, fixed plate, spring 2, spring 1, push block and collecting plate, the movable plate and the slider can move left and right when the sieve plate rotates left and right, so that when the sieve plate is in the upper half of the rotating rod, the sieve hole can be occupied by the push block, so that the ore stuck in the sieve hole can be pushed out, preventing the ore from clogging the sieve hole and affecting the screening speed.
[0023] 2. In the utility model, the sieve plate can be taken out of the machine body through the arrangement of the rotating rod, the mounting plate, the motor, the rotating block, the fixed groove, the conveyor belt, the spring 1, the spring 2, the slider and the movable plate, and can be rotated under the drive of the rotating rod after being placed into the machine body. It can also ensure that the sieve plate just placed into the machine body is in a horizontal state each time it is placed into the machine body, thereby ensuring that the material removal and reuse are not affected. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 It is a three-dimensional structural diagram of the overall structure of the utility model;
[0025] Figure 2 It is a three-dimensional structural diagram of the overall structure of the utility model;
[0026] Figure 3 It is a schematic diagram of the three-dimensional structure of the sieve plate, the three-dimensional structure section of the machine body and the three-dimensional structure of part of the starting component in the present invention;
[0027] Figure 4 It is a schematic sectional view of a three-dimensional structure of a part of the screening mechanism in the present invention;
[0028] Figure 5 It is a schematic sectional view of a three-dimensional structure of part of the screening mechanism in the present invention.
[0029] Legend:
[0030] 1. Machine body; 2. Machine door; 3. Feed hopper; 4. Crushing roller; 5. Screening mechanism; 6. Starting assembly; 51. Screening trough; 52. Sieve plate; 53. Moving plate; 54. Sieve hole; 55. Moving hole; 56. Air pressure chamber; 57. Slider; 58. Fixed plate; 59. Spring 2; 510. Spring 1; 511. Push block; 512. Collecting plate; 61. Rotating rod; 62. Mounting plate; 63. Motor; 64. Rotating block; 65. Fixed trough; 66. Conveyor belt. DETAILED DESCRIPTION
[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.
[0032] Reference Figure 1 and Figure 2 The utility model provides an embodiment: an electromechanical device for efficient iron ore beneficiation, including a body 1, which is in the shape of a rectangular parallelepiped, with a door 2 hinged on the left side of the front end of the body 1, and a feed hopper 3 fixedly connected to the top of the body 1. The feed hopper 3 is in the shape of a quadrangular pyramid, and the top area of the feed hopper 3 is larger than the bottom area. A crushing roller 4 is provided inside the body 1, and the rotating shaft of the crushing roller 4 is connected to a driving member that drives it to rotate. This technology is an existing technology and can be implemented by technicians in this field, so it will not be described in detail in this case.
[0033] Reference Figure 2 and Figure 3 The interior and rear end of the body 1 are jointly provided with a starting assembly 6, which includes a rotating rod 61, the front end of the rotating rod 61 is set to a step-shaped shape, and the shape of the rotating rod 61 is set to ensure that objects inserted outside the rotating rod 61 can be easily inserted into the outside of the rotating rod 61, the outer wall of the rotating rod 61 passes through and is rotatably connected to the inner wall of the body 1, the number of rotating rods 61 is set to multiple, and multiple rotating rods 61 are arranged in a horizontal array in the vertical direction, the starting assembly 6 also includes a mounting plate 62, the front end of the mounting plate 62 is fixedly connected to the rear end of the body 1, the top of the mounting plate 62 is fixedly connected to the motor 63, the output shaft of the motor 63 is fixedly connected to the rear end of the uppermost rotating rod 61, the outer wall of the rotating rod 61 is fixedly connected to a rotating block 64, the shape of the rotating block 64 is stepped, and the outer wall of the rotating block 64 is provided with a plurality of protruding blocks, and two adjacent rotating rods 61 are connected by a conveyor belt 66 for transmission, and the setting of the conveyor belt 66 ensures that multiple rotating rods 61 can rotate simultaneously.
[0034] Reference Figure 1 、 Figure 3 and Figure 4The body 1 is located below the crushing roller 4 and is provided with a screening mechanism 5 on the outside of the rotating rod 61. The screening mechanism 5 includes a screening slot 51. The screening slot 51 is provided on the inner wall of the body 1. The shape of the screening slot 51 is a shape formed by connecting multiple arc surfaces. The number of the screening slots 51 is consistent with the number of the rotating rod 61. The outer wall of the rotating rod 61 is plugged with a sieve plate 52. The rear end of the sieve plate 52 is provided with a fixed slot 65. The shape of the fixed slot 65 matches the shape of the rotating block 64. The shape of the rotating block 64 and the shape of the fixed slot 65 are set to ensure that the rotating block 64 is smooth. After entering the fixed groove 65, the movable block 64 can drive the sieve plate 52 to rotate through the fixed groove 65. A sieve hole 54 is provided at the top of the sieve plate 52. The number of sieve plates 52 is consistent with the rotating rod 61. By setting the number of the rotating rod 61, the sieve plates 52 and the screening grooves 51, it is ensured that each sieve plate 52 can rotate inside the screening groove 51 under the drive of the rotating rod 61, and the sieve holes 54 opened on the sieve plate 52 decrease from top to bottom. By setting the sieve holes 54 of different sizes, it is ensured that after the screening is completed, the iron ores in different sieve plates 52 are of different sizes.
[0035] Reference Figure 1 、 Figure 4 and Figure 5 The inner wall of the sieve plate 52 is slidably connected with a movable plate 53, and a movable hole 55 is provided at the top of the movable plate 53. The size of the movable hole 55 is consistent with the sieve hole 54. One end of the movable plate 53 close to the rotating rod 61 is elastically connected to the inner wall of the sieve plate 52 through a spring 510, one end of the spring 510 is fixedly connected to one end of the rotating rod 61, and the other end of the spring 510 is fixedly connected to the inner wall of the sieve plate 52. An air pressure chamber 56 is provided on the inner wall of the movable plate 53. The shape of the air pressure chamber 56 is a rectangular parallelepiped without multiple cylinders with a diameter larger than the movable hole 55. The inner wall piston of the movable plate 53 is connected with a slider 57, and the heights of the multiple sliders 57 decrease from top to bottom.
[0036] Reference Figure 1 、 Figure 4 and Figure 5The distance between the inner wall of the upper half of the screening trough 51 at the lower side of the rotating rod 61 and the rotating rod 61 is equal to the distance between the slider 57 and the rotating rod 61 when both the slider 57 and the movable plate 53 are moved to the farthest position from the rotating rod 61. By setting the position of the inner wall of the upper half of the screening trough 51 at the lower side of the rotating rod 61, it is ensured that when the movable plate 53 rotates to this position, the slider 57 and the movable plate 53 can be moved to the farthest position from the rotating rod 61 under the elastic force of the spring 2 59 and the spring 1 510 respectively, so that the position of the sieve hole 54 and the movable hole 55 coincide with each other, so that the ore smaller than the diameter of the sieve hole 54 can pass through the common area of the sieve hole 54 and the movable hole 55 and move to the screening area below. The distance between the top of the screening trough 51 and the rotating rod 61 is consistent with the distance between the edge of the sieve plate 52 and the rotating rod 61. , ensuring that when the sieve plate 52 rotates to the topmost position, the slider 57 and the movable plate 53 are both moved to the position closest to the rotating rod 61 under the squeezing action of the inner wall of the screening tank 51. The area of the screening tank 51 above the rotating rod 61 is set as an arc surface connecting the line segment where the top of the screening tank 51 is located and the area of the screening tank 51 below the rotating rod 61. Through the setting of the arc surface, it is ensured that the slider 57 and the movable plate 53 can slowly move from the position farthest from the rotating rod 61 to the position closest to the rotating rod 61 under the control of the arc surface. The inner wall of the lower half of the screening tank 51 under the lower side of the rotating rod 61 is an arc surface connecting the bottom end of the upper half of the lower side of the rotating rod 61 and the top end of the screening tank 51 below the screening tank 51. Through the setting of this arc surface, it is ensured that the ore passing through the sieve plate 52 can be moved to the inside of the screening tank 51 below under the control of the arc surface.
[0037] Referring to the figure, the inner wall of the air pressure chamber 56 is fixedly connected with a fixed plate 58. The setting of the fixed plate 58 ensures that the slider 57 can move to a limited position to enter the interior of the air pressure chamber 56. The end of the fixed plate 58 away from the rotating rod 61 is elastically connected to the end of the slider 57 close to the rotating rod 61 through a spring 2 59. One end of the spring 2 59 is fixedly connected to the end of the fixed plate 58 away from the rotating rod 61, and the other end of the spring 2 59 is fixedly connected to the end of the slider 57 close to the rotating rod 61. The inner wall piston of the air pressure chamber 56 is connected to a push block 511. The upper and lower ends of the push block 511 are both provided with baffles larger than the hole opened on the upper surface of the movable plate 53 for the push block 511 to pass through. By setting the baffle, the movement range of a single push block 511 is limited, thereby ensuring that the final movement amplitude of all push blocks 511 is consistent under the action of air pressure. The diameter of the push block 511 is slightly smaller than the diameter of the sieve hole 54. By setting the diameter, it is ensured that the push block 511 can completely enter the interior of the sieve hole 54, and the distance between the two sieve holes 54 is greater than the diameter of the sieve hole 54. By setting the distance, it is ensured that the middle part of the sieve hole 54 is provided with a hole for the push block 511 to pass through and connected to the air pressure chamber 56. A collecting plate 512 is sliding at the bottom end of the screening trough 51. Through the setting of the collecting plate 512, the ore fragments screened out by the bottom sieve plate 52 can be collected.
[0038] Working principle: When in use, the staff puts iron ore raw materials into the feed hopper 3, and when the iron ore raw materials are crushed by the crushing roller 4, they enter the interior of the screening tank 51.
[0039] At this time, the output shaft of the motor 63 drives the uppermost rotating rod 61 to rotate, and the rotating rod 61 drives the rotating rod 61 below it to rotate under the drive of the conveyor belt 66, so that multiple rotating rods 61 rotate at the same time. During the rotation of the rotating rod 61, the rotating block 64 is driven to rotate, so that the protrusion of the rotating block 64 contacts the inner wall of the fixed groove 65 and drives the sieve plate 52 to rotate.
[0040] When the motor 63 drives the sieve plate 52 to rotate to one side and move from the horizontal state to the upper end of the screening tank 51, the slider 57 inside the upwardly moving sieve plate 52 is squeezed by the inner wall of the screening tank 51, so there is a force moving toward the direction close to the rotating rod 61. Since the movable plate 53 is in a state where the sieve hole 54 and the movable hole 55 are in the same plane at this time, the push block 511 and the sieve hole 54 are in different planes at this time. Therefore, the push block 511 is squeezed by the inner wall of the sieve plate 52 and cannot move upward. Therefore, the slider 57 cannot move toward the direction of entering the air pressure chamber 56 under the action of air pressure. When the movable plate 53 cannot move any further, the push block 511 is in the same plane as the sieve hole 54. Therefore, when the slider 57 is squeezed again, the slider 57 moves toward the direction of entering the air pressure bin 56. Therefore, when the slider 57 enters the air pressure bin 56, the air pressure inside the air pressure bin 56 increases, so that the push block 511 moves upward under the action of the air pressure, thereby entering the sieve hole 54, thereby squeezing out the ore stuck inside the sieve hole 54.
[0041] When one side of the movable plate 53 moves to the upper end of the screening slot 51, the output shaft of the motor 63 rotates in the opposite direction, and then rotates in the opposite direction to move the movable plate 53 originally at the upper end of the rotating rod 61 to a horizontal state. In the process, the slider 57 and the movable plate 53 are respectively subjected to the elastic force of the spring 2 59 and the spring 1 510 to move away from the rotating rod 61. Since the push block 511 is inside the sieve hole 54 at this time, the movable plate 53 cannot move temporarily, so the slider 57 is first reset under the drive of the spring 2 59. When the slider 57 moves, the gas pressure inside the air pressure chamber 56 decreases. Therefore, at this time, the push block 511 moves in the direction of entering the air pressure chamber 56 under the action of the air pressure. When the push block 511 moves to leave the inside of the sieve hole 54, the movable plate 53 is reset again under the elastic force of the spring 1 510.
[0042] When the movable plate 53 continues to rotate downward driven by the rotating rod 61, since the distance between the inner wall of the screening trough 51 and the rotating rod 61 remains unchanged, when the movable plate 53 is below the rotating rod 61, the sieve hole 54 and the movable hole 55 are in the same vertical plane, and the ore moves toward this side under the action of gravity. Therefore, the ore smaller than the diameter of the sieve hole 54 can pass through the sieve hole 54 and fall into the screening area below.
[0043] When the movable plate 53 moves to the bottom end of the upper part of the screening trough 51 below the rotating rod 61, the motor 63 changes direction again, and so on, so that the movable plate 53 rotates left and right multiple times, so that the ore inside the movable plate 53 can push out the ore stuck in the sieve hole 54 during the screening process.
[0044] When the screening is completed, the staff opens the machine door 2 and pulls out the sieve plate 52 and the collection plate 512, so that the ore particles after screening inside the sieve plate 52 and the collection plate 512 can be sorted by appropriate sorting equipment according to their size. After taking out the ore, the staff puts the sieve plate 52 into the machine body 1. Since the slider 57 and the movable plate 53 have the force to move the straw brick away from the machine body 1 under the joint action of the spring 2 59 and the spring 1 510 respectively, and when the movable plate 53 is tilted, the slider 57 inside the movable plate 53 on one side can have an extrusion force under the extrusion of the inner wall of the screening trough 51, so when placed inside the machine body 1, it can be ensured that the sieve plate 52 is in a horizontal state.
[0045] When the movable plate 53 moves to completely enter the body 1, the rotating block 64 just enters the fixed groove 65. Due to the shape of the rotating block 64, when the movable plate 53 is taken out and is in different states, the movable plate 53 can horizontally allow the rotating block 64 to enter the fixed groove 65, so it can ensure that it is more convenient to use the device again.
[0046] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or make equivalent replacements for some of the technical features therein. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.
Claims
1. An electromechanical device for efficient iron ore beneficiation, comprising a body (1), characterized in that: The front left side of the machine body (1) is hinged with a door (2), the top of the machine body (1) is fixedly connected to a hopper (3), a crushing roller (4) is provided inside the machine body (1), and a starting assembly (6) is provided inside and at the rear end of the machine body (1), the starting assembly (6) includes a rotating rod (61), the outer wall of the rotating rod (61) passes through and is rotatably connected to the inner wall of the machine body (1), the interior of the machine body (1) below the crushing roller (4) and the exterior of the rotating rod (61) are provided with a screening mechanism (5), the screening mechanism (5) includes a screening slot (51), the screening slot (51) is opened on the inner wall of the machine body (1), the outer wall of the rotating rod (61) is plugged with a sieve plate (52), the inner wall of the sieve plate (52) is slidably connected to a movable plate (53), and the end of the movable plate (53) close to the rotating rod (61) is elastically connected to the inner wall of the sieve plate (52) through a spring (510).
2. The electromechanical device for efficient iron ore beneficiation according to claim 1, characterized in that: The top of the sieve plate (52) is provided with a sieve hole (54), the top of the movable plate (53) is provided with a movable hole (55), the inner wall of the movable plate (53) is provided with an air pressure chamber (56), the inner wall piston of the movable plate (53) is connected to a slider (57), the inner wall of the air pressure chamber (56) is fixedly connected to a fixed plate (58), the end of the fixed plate (58) away from the rotating rod (61) and the end of the slider (57) close to the rotating rod (61) are elastically connected through a spring 2 (59), the inner wall piston of the air pressure chamber (56) is connected to a push block (511), and a collecting plate (512) is slidably provided at the bottom end of the screening trough (51).
3. The electromechanical device for efficient iron ore beneficiation according to claim 1, characterized in that: The number of the rotating rods (61) is set to be multiple, and the multiple rotating rods (61) are arranged in a horizontal array in a vertical direction.
4. The electromechanical device for efficient iron ore beneficiation according to claim 1, characterized in that: The starting assembly (6) further comprises a mounting plate (62), the front end of the mounting plate (62) being fixedly connected to the rear end of the machine body (1), the top end of the mounting plate (62) being fixedly connected to a motor (63), the output shaft of the motor (63) being fixedly connected to the rear end of the topmost rotating rod (61), the outer wall of the rotating rod (61) being fixedly connected to a rotating block (64), the rear end of the sieve plate (52) being provided with a fixing groove (65), and the two adjacent rotating rods (61) being connected by transmission via a conveyor belt (66).
5. The electromechanical device for efficient iron ore beneficiation according to claim 1, characterized in that: The shape of the screening slot (51) is a shape formed by connecting a plurality of arc surfaces, and the number of the screening slots (51) is consistent with the number of the rotating rods (61).
6. The electromechanical device for efficient iron ore beneficiation according to claim 2, characterized in that: The distance between the inner wall of the upper half of the screening trough (51) located below the rotating rod (61) and the rotating rod (61) is equal to the distance between the slider (57) and the rotating rod (61) when the slider (57) and the movable plate (53) are both moved to the farthest distance from the rotating rod (61); the distance between the top end of the screening trough (51) and the rotating rod (61) is consistent with the distance between the edge of the sieve plate (52) and the rotating rod (61); the area of the screening trough (51) located above the rotating rod (61) is set as an arc surface connecting the line segment where the top end of the screening trough (51) is located and the area of the screening trough (51) located below the rotating rod (61); the inner wall of the lower half of the screening trough (51) located below the rotating rod (61) is a arc surface connecting the bottom end of the upper half of the screening trough (51) located below the rotating rod (61) and the top end of the screening trough (51) below the screening trough (51).
7. The electromechanical device for efficient iron ore beneficiation according to claim 2, characterized in that: The diameter of the push block (511) is slightly smaller than the diameter of the sieve hole (54), and the distance between two sieve holes (54) is greater than the diameter of the sieve hole (54).
8. The electromechanical device for efficient iron ore beneficiation according to claim 1, characterized in that: The number of the sieve plates (52) is consistent with the number of the rotating rods (61), and the sieve holes (54) opened on the sieve plates (52) decrease in size from top to bottom.