High-efficiency and high-precision magnetic powder core pressing system

Abstract

The utility model discloses a high-efficiency high-precision magnetic powder core pressing system, which relates to the technical field of magnetic powder core preparation, and comprises a storage device for storing powder, a quantitative weighing device, a feeding device and a pressing die, the quantitative weighing device and the feeding device are arranged between a discharge port of the storage device and a feed port of the pressing die, and the quantitative weighing device is connected with the feeding device. The quantitative weighing device is used for weighing the powder output by the storage device, the powder is conveyed into the pressing mold through the feeding device so as to be pressed into the magnetic powder core, the feeding device comprises a feeding pipe and a rotating part, and the rotating part is connected with the feeding pipe. Through the arrangement, it is guaranteed that the weight of powder entering the pressing mold every time is consistent, the technical problem that in the prior art, the weight of a magnetic powder core deviates is solved, the powder with the consistent weight every time is utilized, the powder scraping procedure does not need to be carried out, powder waste caused by powder storage on the surface of the pressing mold is avoided, and the production efficiency is improved. And the service life of the pressing die is further guaranteed.

Description

Technical Field

[0001] The utility model relates to the technical field of magnetic powder core preparation, in particular to a high-efficiency and high-precision magnetic powder core pressing system. Background Art

[0002] Magnetic powder core is a key part of electronic power components such as inductors, filters, and transformers under high-frequency working conditions. Magnetic powder core is a composite material made by mixing and pressing multiple powders, which contain soft magnetic powder and insulating material.

[0003] At present, during the pressing process of magnetic powder cores, various powders need to be loaded manually into the scraper box of a semi-automatic scraper device. The reciprocating motion of the scraper box causes the powder in the scraper box to automatically fall into the pressing mold, and the pressing mold is used to press the powder into a magnetic powder core.

[0004] However, due to the different densities between different powders, air gaps are likely to exist between different powders, such as the air gap between soft magnetic powder and insulating material. The air gap will cause the weight of the powder loaded into the pressing mold to deviate, ultimately affecting the performance of the magnetic powder core. In addition, the automatic powder scraping device is likely to leave powder on the surface of the pressing mold after scraping the powder, resulting in waste of powder. In addition, during the long-term pressing process, the pressing mold is easily scratched, resulting in a shortened production life of the pressing mold and increased production costs. Utility Model Content

[0005] Based on this, the purpose of the present utility model is to provide an efficient and high-precision magnetic powder core pressing system to solve the technical problem in the existing magnetic powder core pressing process in the background technology, in which air gaps are easily present between different powders due to the different densities between different powders. The air gaps will cause deviations in the powder and weight loaded into the pressing mold, ultimately affecting the performance of the magnetic powder core.

[0006] The utility model provides a high-efficiency and high-precision magnetic powder core pressing system, comprising a storage device for storing powder, a quantitative weighing device, a feeding device and a pressing mold;

[0007] The quantitative weighing device and the feeding device are arranged between the discharge port of the storage device and the feed port of the pressing die. The quantitative weighing device is used to weigh the powder output from the storage device and transfer the powder to the pressing die through the feeding device to be pressed into a magnetic powder core.

[0008] Wherein, the feeding device includes a feeding pipe and a rotating part, the rotating part is connected to the feeding pipe, and the rotating part is used to drive the feeding pipe to rotate so that the two ends of the feeding pipe are respectively facing the quantitative weighing device and the pressing mold.

[0009] Furthermore, the storage device includes a storage barrel, at least one rotating screw and at least one feeding screw;

[0010] The rotating screw and the feeding screw are both rotatably connected in the storage barrel, and the feeding screw is used to transport the powder stored in the storage barrel toward the quantitative weighing device.

[0011] Furthermore, the storage barrel includes a first barrel and a second barrel communicated with the first barrel;

[0012] Wherein, the rotating screw is arranged in the first barrel, and the feeding screw is arranged in the second barrel.

[0013] Furthermore, the outer diameter of the first cylinder extends from large to small toward the second cylinder.

[0014] Furthermore, the storage device also includes an ultrasonic probe and a powder flow sensor;

[0015] The ultrasonic probe and the powder flow sensor are both arranged in the second cylinder.

[0016] Furthermore, a plurality of ultrasonic probes are provided, and the plurality of ultrasonic probes are arranged at intervals along the length direction of the second cylinder.

[0017] Furthermore, the quantitative weighing device includes a distribution hopper, and a discharge plate, a discharge sensor and a precision electronic scale provided on the distribution hopper;

[0018] Wherein, the discharge plate is rotatably connected to the output port of the distribution hopper.

[0019] Furthermore, the size of the distribution hopper extends from large to small toward the other end.

[0020] Compared with the prior art, the beneficial effects of the present invention are:

[0021] In the high-efficiency and high-precision magnetic powder core pressing system provided by the present invention, a quantitative weighing device and a feeding device are arranged between the discharge port of the storage device and the feed port of the pressing mold, so that when the magnetic powder core is prepared, the quantitative weighing device is used to control the weight of the powder, so that the weight of the powder transferred to the pressing mold each time is consistent, and when the weight of the powder is qualified, the feeding pipe in the feeding device is used to transport the powder that meets the weight to the pressing mold for pressing, thereby changing the existing technology of using an automatic powder scraping device to load and scrape powder, ensuring that the weight of the powder entering the pressing mold is consistent each time, solving the technical problem of weight deviation of the magnetic powder core in the existing technology, and using powder with consistent weight each time, so that there is no need to perform a powder scraping process, avoiding powder accumulation on the surface of the pressing mold, resulting in powder waste, and further ensuring the service life of the pressing mold. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a structural schematic diagram of a high-efficiency and high-precision magnetic powder core pressing system according to an embodiment of the present invention.

[0023] In the figure: 100, storage device; 110, storage barrel; 111, first barrel; 112, second barrel; 120, rotating screw; 130, feeding screw; 140, ultrasonic probe; 150, powder flow sensor; 200, quantitative weighing device; 210, distribution hopper; 220, discharge plate; 230, discharge sensor; 240, precision electronic scale; 300, feeding device; 310, feeding pipe; 320, rotating part; 400, pressing mold. DETAILED DESCRIPTION

[0024] To facilitate understanding of the present invention, a more comprehensive description of the present invention will be provided below with reference to the accompanying drawings. The drawings illustrate several embodiments of the present invention. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and comprehensive understanding of the present invention.

[0025] It should be noted that when an element is referred to as being "fixed to" another element, it may be directly on the other element or there may be an intermediate element. When an element is referred to as being "connected to" another element, it may be directly connected to the other element or there may be an intermediate element. The terms "vertical," "horizontal," "left," "right," and similar expressions used herein are for illustrative purposes only.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this invention pertains. The terms used herein in the specification of this invention are intended only to describe specific embodiments and are not intended to limit the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] See also Figure 1 , shown is a high-efficiency and high-precision magnetic powder core pressing system in one embodiment of the present invention, comprising a storage device 100 for storing powder, a quantitative weighing device 200, a feeding device 300 and a pressing mold 400;

[0028] The quantitative weighing device 200 and the feeding device 300 are arranged between the discharge port of the storage device 100 and the feed port of the pressing mold 400. The quantitative weighing device 200 is used to weigh the powder output from the storage device 100 and transfer the powder to the pressing mold 400 through the feeding device 300 to be pressed into a magnetic powder core.

[0029] Among them, the feeding device 300 includes a feeding tube 310 and a rotating member 320. The rotating member 320 is connected to the feeding tube 310. The rotating member 320 is used to drive the feeding tube 310 to rotate so that the two ends of the feeding tube 310 are respectively facing the quantitative weighing device 200 and the pressing mold 400.

[0030] That is, by arranging a quantitative weighing device 200 and a feeding device 300 between the discharge port of the storage device 100 and the feed port of the pressing mold 400, when preparing the magnetic powder core, the quantitative weighing device 200 is used to control the weight of the powder, so that the weight of the powder transferred to the pressing mold 400 each time is consistent, and when the weight of the powder is qualified, the feeding tube 310 in the feeding device 300 is used to transport the powder that meets the weight to the pressing mold 400 for pressing, thereby changing the existing technology of using an automatic powder scraping device to load and scrape powder, ensuring that the weight of the powder entering the mold is consistent each time, solving the technical problem of weight deviation of the magnetic powder core in the existing technology, and using powder with consistent weight each time, so that there is no need to perform a powder scraping process, avoiding the accumulation of powder on the surface of the pressing mold, resulting in waste of powder, and further ensuring the service life of the pressing mold.

[0031] Specifically, to facilitate understanding of this case, in this embodiment, the storage device 100 includes a storage barrel 110, at least one rotating screw 120 and at least one feeding screw 130. The rotating screw 120 and the feeding screw 130 are both rotatably connected to the storage barrel 110, and the feeding screw 130 is used to transport the powder stored in the storage barrel 110 toward the quantitative weighing device 200.

[0032] It should be noted that in this embodiment, power outputs for rotating the rotating screw 120 and the feeding screw 130 are arranged on the outside of the storage barrel 110, such as two servo motors, which respectively drive the rotating screw 120 and the feeding screw 130 to rotate in the storage barrel 110.

[0033] Furthermore, the storage barrel 110 includes a first barrel 111 and a second barrel 112 interconnected with the first barrel 111, wherein the rotating screw 120 is arranged in the first barrel 111, and the feeding screw 130 is arranged in the second barrel 112. The operation of the rotating screw 120 can avoid the bridging phenomenon of the powder in the first barrel 111, and the operation of the feeding screw 130 can transport the powder in the first barrel 111.

[0034] In some preferred embodiments, in order to facilitate the transmission of powder, the outer diameter of the first cylinder 111 extends from large to small toward the second cylinder 112. Specifically, the first cylinder 111 may be arranged in a conical shape.

[0035] In addition, the storage device 100 also includes an ultrasonic probe 140 and a powder flow sensor 150. The ultrasonic probe 140 and the powder flow sensor 150 are both arranged in the second cylinder 112. In some preferred implementations, multiple ultrasonic probes 140 are provided, and the multiple ultrasonic probes 140 are arranged at intervals along the length direction of the second cylinder 112. The powder flow sensor 150 is used to detect the flow properties of the powder. When the powder does not flow, the vibration of the ultrasonic probe 140 can be used to increase the flowability of the powder.

[0036] In addition, the quantitative weighing device 200 includes a distribution hopper 210, and a discharge plate 220, a discharge sensor 230 and a precision electronic scale 240 arranged on the distribution hopper 210, wherein the discharge plate 220 is rotatably connected to the output port of the distribution hopper 210, and the size of the distribution hopper 210 extends from large to small toward the other end.

[0037] That is, the powder in the distribution hopper 210 can be weighed using a precision electronic scale 240. When the weight meets the preset weight, the feeding screw 130 will stop running and the discharge plate 220 will move. The powder in the distribution hopper 210 will be transferred to the pressing mold 400 through the feeding pipe 310. After the transmission is completed, the rotating part 320 drives the feeding pipe 310 to rotate to ensure the normal operation of the pressing mold 400. At the same time, the discharge sensor 230 is used to detect that the discharge is completed, and the discharge plate 220 closes the distribution hopper 210. When the pressing mold 400 is pressed, the feeding screw 130 continues to run to achieve the next pressing of the powder.

[0038] It should be noted that, in this embodiment, the storage device 100, the quantitative weighing device 200, the feeding device 300 and the pressing mold 400 can be automatically controlled by arranging a PLC controller, and in this embodiment, the ultrasonic probe 140, the powder flow sensor 150, the discharge sensor 230, the precision electronic scale 240, the power output of the rotation of the rotating screw 120, the power output of the rotation of the feeding screw 130, the rotating part 320, and the power output of the discharge plate 220 all belong to conventional existing technologies and are not specifically explained here.

[0039] In some optional embodiments, the rotating member 320 may be a servo motor, and the power output for driving the discharge plate 220 may be a cylinder.

[0040] In this example, the pressing die 400 belongs to the conventional prior art in the art, and in some optional embodiments, the pressing die 400 may be composed of an upper punch, a middle die, a lower punch and a core rod.

[0041] In summary, the high-efficiency and high-precision magnetic powder core pressing system in one embodiment of the present invention has at least the following beneficial effects compared to the conventional method of pressing magnetic powder cores:

[0042] In the high-efficiency and high-precision magnetic powder core pressing system provided by the present invention, a quantitative weighing device 200 and a feeding device 300 are arranged between the discharge port of the storage device 100 and the feed port of the pressing mold 400, so that when the magnetic powder core is prepared, the quantitative weighing device 200 is used to control the weight of the powder, so that the weight of the powder transferred to the pressing mold 400 each time is consistent, and when the weight of the powder is qualified, the feeding tube 310 in the feeding device 300 is used to transport the powder that meets the weight to the pressing mold 400 for pressing, thereby changing the existing technology of using an automatic powder scraping device to load and scrape powder, ensuring that the weight of the powder entering the pressing mold 400 is consistent each time, solving the technical problem of weight deviation of the magnetic powder core in the existing technology, and using powder with consistent weight each time, so that there is no need to perform a powder scraping process, avoiding the accumulation of powder on the surface of the pressing mold, resulting in waste of powder, and further ensuring the service life of the pressing mold.

[0043] For easier understanding of this case, please refer to the first to eighth embodiments and the first to eighth comparative examples for comparison.

[0044] First embodiment

[0045] In this example, the powder material is compacted by using the high-efficiency and high-precision magnetic powder core compacting system provided above.

[0046] Specifically, the pressing mold used in this embodiment is a 270-size mold, and the powder material is Fe-Si-Al. 10 PCS are pressed, and the height tolerance of the final magnetic powder core is ±0.1 mm, and the weight tolerance is ±0.1 g.

[0047] Second embodiment

[0048] In this example, the powder material is compacted by using the high-efficiency and high-precision magnetic powder core compacting system provided above.

[0049] Specifically, the pressing mold used in this embodiment is a 270-size mold, and the powder material is Fe-Si. 10 PCS are pressed, and the height tolerance of the final magnetic powder core is ±0.1 mm, and the weight tolerance is ±0.1 g.

[0050] Third embodiment

[0051] In this example, the powder material is compacted by using the high-efficiency and high-precision magnetic powder core compacting system provided above.

[0052] Specifically, the pressing mold used in this embodiment is a 270-size mold, and the powder material is amorphous powder. 10 PCS are pressed, and the height tolerance of the final magnetic powder core is ±0.1 mm, and the weight tolerance is ±0.1 g.

[0053] Fourth embodiment

[0054] In this example, the powder material is compacted by using the high-efficiency and high-precision magnetic powder core compacting system provided above.

[0055] Specifically, the pressing mold used in this embodiment is a 270-size mold, and the powder material is nanocrystalline powder for pressing 10 PCS. The height tolerance of the final magnetic powder core is ±0.1 mm, and the weight tolerance is ±0.1 g.

[0056] Fifth embodiment

[0057] In this example, the powder material is compacted by using the high-efficiency and high-precision magnetic powder core compacting system provided above.

[0058] Specifically, the pressing mold used in this embodiment is a 330-size mold, and the powder material is Fe-Si-Al. 10 PCS are pressed, and the height tolerance of the final magnetic powder core is ±0.1 mm, and the weight tolerance is ±0.1 g.

[0059] Sixth embodiment

[0060] In this example, the powder material is compacted by using the high-efficiency and high-precision magnetic powder core compacting system provided above.

[0061] Specifically, the pressing mold used in this embodiment is a 330-size mold, and the powder material is Fe-Si. 10 PCS are pressed, and the height tolerance of the final magnetic powder core is ±0.1 mm, and the weight tolerance is ±0.1 g.

[0062] Seventh embodiment

[0063] In this example, the powder material is compacted by using the high-efficiency and high-precision magnetic powder core compacting system provided above.

[0064] Specifically, the pressing mold used in this embodiment is a 330-size mold, and the powder material is amorphous powder. 10 PCS are pressed, and the height tolerance of the final magnetic powder core is ±0.1 mm, and the weight tolerance is ±0.1 g.

[0065] Eighth embodiment

[0066] In this example, the powder material is compacted by using the high-efficiency and high-precision magnetic powder core compacting system provided above.

[0067] Specifically, the pressing mold used in this embodiment is a 330-size mold, and the powder material is nanocrystalline powder for pressing 10 PCS. The height tolerance of the final magnetic powder core is ±0.1 mm, and the weight tolerance is ±0.1 g.

[0068] The first comparison

[0069] It should be noted that, in this comparative example, the powder material is charged and pressed into shape using an automatic scraping device in the prior art.

[0070] Specifically, the pressing mold used in this comparative example is a 270-size mold, and the powder material is Fe-Si-Al. The powder material is placed in the scraper box of the automatic scraping device, and the scraper box moves back and forth. After the powder is scraped into the pressing mold, the scraper box returns to its original position, and then the pressing mold is started to press 10 PCS. The final height tolerance of the magnetic powder core is ±0.25mm, and the weight tolerance is ±0.2g.

[0071] The second comparison

[0072] It should be noted that, in this comparative example, the powder material is charged and pressed into shape using an automatic scraping device in the prior art.

[0073] Specifically, the pressing mold used in this comparative example is a 270-size mold, and the powder material is Fe-Si. The powder material is placed in the scraper box of the automatic scraping device, and the scraper box moves back and forth. After the powder is scraped into the pressing mold, the scraper box returns to its original position, and then the pressing mold is started to press 10 PCS. The final height tolerance of the magnetic powder core is ±0.2mm, and the weight tolerance is ±0.3g.

[0074] The third comparison

[0075] It should be noted that, in this comparative example, the powder material is charged and pressed into shape using an automatic scraping device in the prior art.

[0076] Specifically, the pressing mold used in this comparative example is a 270-size mold, and the powder material is amorphous powder. The powder material is placed in the scraper box of the automatic scraping device, and the scraper box moves back and forth. After the powder is scraped into the pressing mold, the scraper box returns to its original position, and then the pressing mold is started to press 10 PCS. The final height tolerance of the magnetic powder core is ±0.3mm, and the weight tolerance is ±0.3g.

[0077] The fourth comparison

[0078] It should be noted that, in this comparative example, the powder material is charged and pressed into shape using an automatic scraping device in the prior art.

[0079] Specifically, the pressing mold used in this comparative example is a 270-size mold, and the powder material is nanocrystalline powder. The powder material is placed in the scraper box of the automatic scraping device, and the scraper box moves back and forth. After the powder is scraped into the pressing mold, the scraper box returns to its original position, and then the pressing mold is started to press 10 PCS. The final height tolerance of the magnetic powder core is ±0.25mm, and the weight tolerance is ±0.35g.

[0080] Fifth comparison

[0081] It should be noted that, in this comparative example, the powder material is charged and pressed into shape using an automatic scraping device in the prior art.

[0082] Specifically, the pressing mold used in this comparative example is a 330-size mold, and the powder material is Fe-Si-Al. The powder material is placed in the scraper box of the automatic scraping device, and the scraper box moves back and forth. After the powder is scraped into the pressing mold, the scraper box returns to its original position, and then the pressing mold is started to press 10 PCS. The final height tolerance of the magnetic powder core is ±0.3mm, and the weight tolerance is ±0.25g.

[0083] Sixth comparison

[0084] It should be noted that, in this comparative example, the powder material is charged and pressed into shape using an automatic scraping device in the prior art.

[0085] Specifically, the pressing mold used in this comparative example is a 330-size mold, and the powder material is Fe-Si. The powder material is placed in the scraper box of the automatic scraping device, and the scraper box moves back and forth. After the powder is scraped into the pressing mold, the scraper box returns to its original position, and then the pressing mold is started to press 10 PCS. The final height tolerance of the magnetic powder core is ±0.25mm, and the weight tolerance is ±0.35g.

[0086] Seventh comparison

[0087] It should be noted that, in this comparative example, the powder material is charged and pressed into shape using an automatic scraping device in the prior art.

[0088] Specifically, the pressing mold used in this comparative example is a 330-size mold, and the powder material is amorphous powder. The powder material is placed in the scraper box of the automatic scraping device, and the scraper box moves back and forth. After the powder is scraped into the pressing mold, the scraper box returns to its original position, and then the pressing mold is started to press 10 PCS. The final height tolerance of the magnetic powder core is ±0.35mm, and the weight tolerance is ±0.35g.

[0089] Eighth comparison

[0090] It should be noted that, in this comparative example, the powder material is charged and pressed into shape using an automatic scraping device in the prior art.

[0091] Specifically, the pressing mold used in this comparative example is a 330-size mold, and the powder material is nanocrystalline powder. The powder material is placed in the scraper box of the automatic scraping device, and the scraper box moves back and forth. After the powder is scraped into the pressing mold, the scraper box returns to its original position, and then the pressing mold is started to press 10 PCS. The final height tolerance of the magnetic powder core is ±0.35mm, and the weight tolerance is ±0.4g.

[0092] Please refer to Table 1, which compares the height tolerance and weight tolerance of the first to eighth embodiments and the first to eighth comparative examples.

[0093]

[0094]

[0095]

[0096] Table 1

[0097] In summary, as shown in Table 1, the magnetic powder cores prepared by the high-efficiency and high-precision magnetic powder core pressing system provided by the utility model are compared with the magnetic powder cores prepared by manual powder loading and automatic scraping devices in the prior art. The magnetic powder cores prepared by the high-efficiency and high-precision magnetic powder core pressing system provided by the utility model have consistency in height and weight, which greatly ensures the yield rate of the magnetic powder cores.

[0098] Throughout this specification, reference to terms such as "one embodiment," "some embodiments," "examples," "specific examples," or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0099] The above embodiments merely illustrate several implementations of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the concept of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A high-efficiency and high-precision magnetic powder core pressing system, characterized in that: It includes a storage device for storing powder, a quantitative weighing device, a feeding device and a pressing mold; The quantitative weighing device and the feeding device are arranged between the discharge port of the storage device and the feed port of the pressing die. The quantitative weighing device is used to weigh the powder output from the storage device and transfer the powder to the pressing die through the feeding device to be pressed into a magnetic powder core. Wherein, the feeding device includes a feeding pipe and a rotating part, the rotating part is connected to the feeding pipe, and the rotating part is used to drive the feeding pipe to rotate so that the two ends of the feeding pipe are respectively facing the quantitative weighing device and the pressing mold.

2. The high-efficiency and high-precision magnetic powder core pressing system according to claim 1 is characterized in that: The storage device includes a storage barrel, at least one rotating screw and at least one feeding screw; The rotating screw and the feeding screw are both rotatably connected in the storage barrel, and the feeding screw is used to transport the powder stored in the storage barrel toward the quantitative weighing device.

3. The high-efficiency and high-precision magnetic powder core pressing system according to claim 2 is characterized in that: The storage barrel comprises a first barrel and a second barrel communicated with the first barrel; Wherein, the rotating screw is arranged in the first barrel, and the feeding screw is arranged in the second barrel.

4. The high-efficiency and high-precision magnetic powder core pressing system according to claim 3 is characterized in that: The outer diameter of the first cylinder extends from larger to smaller toward the second cylinder.

5. The high-efficiency and high-precision magnetic powder core pressing system according to claim 4 is characterized in that: The storage device also includes an ultrasonic probe and a powder flow sensor; The ultrasonic probe and the powder flow sensor are both arranged in the second cylinder.

6. The high-efficiency and high-precision magnetic powder core pressing system according to claim 5, characterized in that: There are multiple ultrasonic probes, and the multiple ultrasonic probes are spaced apart along the length direction of the second cylinder.

7. The high-efficiency and high-precision magnetic powder core pressing system according to claim 1 is characterized in that: The quantitative weighing device includes a distribution hopper, a discharge plate, a discharge sensor and a precision electronic scale arranged on the distribution hopper; Wherein, the discharge plate is rotatably connected to the output port of the distribution hopper.

8. The high-efficiency and high-precision magnetic powder core pressing system according to claim 7, characterized in that: The size of the distribution hopper extends from large to small toward the other end.

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