A pre-drying oven

Abstract

This invention relates to the field of drying equipment, specifically a pre-drying oven, including a box body and a shelf. The shelf is equipped with several supporting mechanisms for carrying materials, and the box body is equipped with a weighing mechanism that can selectively lift a designated position of the supporting mechanism to weigh the material. This invention uses a drive component to drive a designated pull plate to lift the corresponding shelf, thereby independently and precisely weighing the material on that shelf. It can accurately obtain the real-time moisture content difference of the material in different areas and layers of the shelf, avoiding the problem of some materials being over-dried or under-dried due to the inability to perceive the drying progress difference due to overall weighing. When the shelf is lifted for weighing, the shielding component on the shelf can automatically block the hot air flowing up and down from blowing on the surface of the material, effectively preventing the circulating hot air flow from disturbing the material weight reading, and the weighing can be completed without stopping the hot air circulation, thus ensuring both weighing accuracy and maintaining the continuity of the drying process.

Description

Technical Field

[0001] This invention relates to the field of drying equipment, specifically a pre-drying oven. Background Technology

[0002] A pre-drying oven is a common type of drying equipment. Its main function is to preheat, pre-dry, or pre-treat materials before the main processing steps to remove excess moisture and create ideal processing conditions for subsequent processes. A typical pre-drying oven mainly consists of a chamber, an electric heating system, a temperature control system, and a hot air circulation system. It achieves uniform heating and drying of materials through forced hot air circulation.

[0003] During the drying process, precise control of the material moisture content is a key process indicator to ensure product quality. Insufficient drying will lead to excessive moisture content, affecting subsequent processing or the quality of the final product; while over-drying may cause the material to scorch, lose nutrients, or waste energy. For some heat-sensitive materials, the harm caused by over-drying is particularly prominent.

[0004] For example, in the field of drying Chinese medicinal materials, materials such as wolfberry, honeysuckle, and angelica contain rich sugars, volatile oils, and heat-sensitive active ingredients. If they are over-dried, they will not only cause surface charring and color deterioration, but also lead to polysaccharide decomposition and loss of volatile oils, resulting in a significant degradation of the medicinal components and loss of commercial value. Therefore, it is necessary to conduct real-time or phased precise monitoring of the degree of drying of the materials during the drying process in order to accurately determine the drying endpoint and avoid irreversible quality damage.

[0005] Currently, the common method used in industrial production is to monitor the overall weight of the racks or trays that carry the materials. This method treats the rack and all the materials it carries as a whole object to be weighed. By weighing the change in total weight during the drying process, the average weight loss rate of the entire batch of materials is calculated, thereby determining the drying endpoint and guiding the control of the drying process.

[0006] However, although the hot air circulating oven uses forced convection by fans to achieve uniform temperature, uneven temperature distribution and dead air zones are still unavoidable in actual operation. Since the overall weighing method can only obtain the average weight loss curve of the entire batch of materials, it cannot perceive the differences in drying progress of materials in different areas and layers of the rack. When the materials in some areas have reached the target moisture content, the materials in other areas may still be under-dried or over-dried.

[0007] Secondly, during the drying process, the circulating hot air continuously blows on the surface of the material, and the resulting airflow disturbance acts on the material, causing the weight reading to fluctuate continuously, which seriously affects the accuracy and stability of online weighing. If the method of stopping the airflow and letting it stand still before weighing is adopted, the continuity of the drying process will be interrupted and the production efficiency will be reduced.

[0008] To address the aforementioned issues, existing technologies have developed solutions that involve installing multiple load cells on different shelves or at the bottom of different trays to monitor the weight of materials at different locations. However, in such solutions, the load cells are directly exposed to the high-temperature environment inside the oven. Prolonged exposure to high temperatures can exacerbate temperature drift in the zero point and sensitivity of the sensors, resulting in problems such as short equipment lifespan, deterioration of monitoring accuracy over time, and high maintenance costs. This makes it difficult to meet the requirements of industrial production for equipment reliability and long-term stable operation.

[0009] Therefore, there is an urgent need for a new type of pre-drying oven structure that is structurally sound, has high weighing accuracy, long service life, and can also take into account local fine monitoring, effectively avoiding damage to heat-sensitive materials due to uneven drying. Summary of the Invention

[0010] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a pre-drying oven, including a box body and a shelf, wherein the shelf is provided with a plurality of supporting mechanisms for carrying materials, and the box body is provided with a weighing mechanism for weighing materials.

[0011] The supporting mechanism includes shelves arranged in an array on the shelf, the shelves and the shelf being slidably connected vertically, and the shelves are provided with shielding components for opening and closing ventilation of their upper and lower parts. The shielding components located at the lower part of the same shelf are also used to support materials.

[0012] The weighing mechanism includes a pull plate mounted on the box body via a connecting component. A driving component is provided outside the box body to drive a designated pull plate to lift a designated shelf. A force sensor is provided on the driving component and located outside the box body.

[0013] During weighing, the force sensor located outside the chamber is not affected by the high temperature inside the chamber. The pull plate lifts the designated shelf, and the shielding component on the shelf automatically blocks the hot air flowing up and down from blowing on the material, thus weighing the material layer by layer.

[0014] Preferably, the shielding assembly includes an upper perforated plate and a lower perforated plate arranged vertically and stacked together. The upper perforated plate is fixedly connected to the shelf, and the lower perforated plate is slidably connected to the shelf from left to right. The lower perforated plates on the same shelf are fixedly connected together by a connecting plate.

[0015] Preferably, the shielding assembly further includes a helical spring disposed between the lower perforated plate and the shelf, and a baffle for supporting each shelf is fixedly installed on the shelf, with a gap between two shelves in the same vertical position.

[0016] Preferably, the right side of the lower perforated plate has an inclined structure, and a triangular block is fixedly installed on the upper side of the lower right part of the shelf and the baffle located on the right side of the shelf. When the shelf is not lifted, the triangular block pushes the inclined structure of the corresponding lower perforated plate to the left.

[0017] Preferably, when the shelf is not lifted, the holes of the stacked upper and lower perforated plates correspond to each other; when the shelf is lifted, the lower perforated plate moves to the left, so that the holes of the stacked upper and lower perforated plates are staggered.

[0018] Preferably, the shelf consists of two frames located at the top and bottom, respectively, and a tube connecting the two frames. The shelf is slidably connected to the shelf by its tube structure.

[0019] Preferably, the lower part of the shelf is equipped with several lockable casters, and the rear side of the shelf is fixedly equipped with a limiting fork for restraining the shelf's position inside the box.

[0020] Preferably, the connecting assembly includes two symmetrically arranged sliding plates that are sealed and slidably connected to each pull plate on the corresponding side of the housing.

[0021] Preferably, the drive assembly includes two hydraulic cylinders fixedly installed on the upper side of the housing, and the telescopic section of the hydraulic cylinder is fixedly connected to the corresponding slide plate.

[0022] Preferably, the drive assembly further includes two electric sliders that are respectively slidably disposed on the left and right sides of the housing. A hydraulic cylinder for lifting the pull plate is fixedly installed on the lower side of the electric slider, and the telescopic end of the hydraulic cylinder is connected to a force sensor.

[0023] The beneficial effects of this invention are as follows: First, this invention uses a drive component to drive a designated pull plate to lift the corresponding shelf, thereby enabling independent and precise weighing of the material on that shelf. This allows for accurate acquisition of the real-time moisture content differences of materials in different areas and on different shelves, avoiding the problem of some materials being over-dried or under-dried due to the inability to perceive differences in drying progress during overall weighing. When the shelf is lifted for weighing, the shielding component on the shelf can automatically block the hot air flowing up and down from blowing onto the material surface, effectively preventing the circulating hot airflow from disturbing the material weight reading. Weighing can be completed without stopping the hot air circulation, ensuring both weighing accuracy and maintaining the continuity of the drying process.

[0024] Second, this invention uses an electric slider to move the second hydraulic cylinder to the corresponding position of the shelf to be weighed. The extension section of the second hydraulic cylinder pushes the corresponding pull plate to the height of the shelf. Then, the first hydraulic cylinder drives the pull plate to connect with the shelf to be weighed. After that, the extension section of the second hydraulic cylinder is extended again to weigh the material on the shelf, realizing localized and precise weighing of any shelf position.

[0025] Third, this invention uses an upper and lower perforated plate on the shelf to shield the upper and lower parts of the material. In the non-weighing state, the perforations of the upper and lower perforated plates correspond to each other, allowing circulating hot air to pass smoothly and heat and dry the material evenly. In the weighing state, the perforations of the upper and lower perforated plates are staggered, effectively blocking the passage of hot air and preventing hot air from blowing onto the material and causing fluctuations in the weighing reading. Thus, the accuracy and stability of the weighing process are guaranteed without affecting the normal drying efficiency.

[0026] Fourth, this invention uses a force sensor located at the end of the second telescopic section of the hydraulic cylinder to weigh the materials on the shelf. This ensures that the force sensor is always located outside the oven during the entire operation, fundamentally avoiding the problem of the force sensor being directly exposed to the high temperature environment inside the oven for a long time. This effectively eliminates the zero-point drift and sensitivity temperature drift of the sensor caused by high temperature, significantly improves the weighing accuracy and long-term monitoring reliability, and extends the service life of the force sensor. Attached Figure Description

[0027] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0028] Figure 1 This is a schematic diagram of the overall structure of the present invention;

[0029] Figure 2 This is a front view of the box, shelf, rack and electric slider in this invention;

[0030] Figure 3 This is a schematic diagram of the structure of the shelf, baffle, triangular block and connecting plate in this invention;

[0031] Figure 4 This is a partial sectional view of the box body, shelf, baffle and triangular block in this invention;

[0032] Figure 5 This is a schematic diagram of the structure of the middle shelf, lower perforated plate and connecting plate of the present invention;

[0033] Figure 6 This is a partial cross-sectional view of the shelf, connecting plate, upper perforated plate and lower perforated plate in this invention;

[0034] Figure 7 This is a partial cross-sectional view of the shelf, shelf unit, lower perforated plate, and triangular block in this invention;

[0035] Figure 8 This is a schematic diagram of the structure of the housing, slide plate, hydraulic cylinder one, and hydraulic cylinder two in this invention.

[0036] In the diagram: 1. Box body; 2. Shelf; 3. Load-bearing mechanism; 4. Weighing mechanism; 21. Casters; 22. Limiting fork; 31. Shelf; 32. Covering assembly; 41. Connecting assembly; 42. Pull plate; 43. Drive assembly; 321. Upper perforated plate; 322. Lower perforated plate; 323. Baffle; 324. Triangular block; 325. Connecting plate; 411. Slide plate; 431. Hydraulic cylinder one; 432. Electric slider; 433. Hydraulic cylinder two. Detailed Implementation

[0037] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in the art or in accordance with the product manual.

[0038] See Figure 1 , Figure 2 and Figure 4 A pre-drying oven includes a box body 1 and a shelf 2. The shelf 2 is provided with a plurality of supporting mechanisms 3 for carrying materials. The box body 1 is provided with a weighing mechanism 4 that can selectively lift the supporting mechanisms 3 to a designated position to weigh the materials.

[0039] Before drying, the operator pushes the rack 2 containing the material to the designated position inside the box 1. Circulating hot air is then introduced into the box 1 to dry the material on the rack 2. During drying, the material is placed on the support mechanism 3. When it is necessary to weigh the dried material, the weighing mechanism 4 lifts the support mechanism 3 to the designated position, thereby performing localized and precise weighing of the material at that position. During weighing, the support mechanism 3 can shield the hot air above and below the material being weighed, thus preventing the material from being affected by the hot air blowing and affecting the weighing reading.

[0040] See Figure 1 , Figure 2 , Figure 3 and Figure 4 The supporting mechanism 3 includes shelves 31 arranged in an array on the shelf 2. The shelves 31 are slidably connected to the shelf 2. The shelves 31 are provided with shielding components 32 for opening and closing ventilation of their upper and lower parts.

[0041] Before drying the material, the operator places the material on the shelf 31, ensuring that the material is within the shielding component 32 of the shelf 31, and that the material is supported by the lower shielding component 32 on the same shelf 31. When not weighing material, hot air can pass smoothly through the shielding component 32, allowing the hot air to contact the material for drying. When weighing material on a designated shelf 31, the shielding component 32 on the shelf 31 automatically blocks the hot air that is circulating up and down, thereby preventing the hot air from blowing onto the material and affecting the accuracy of the weighing reading.

[0042] Continue reading Figure 1 , Figure 2 , Figure 3 and Figure 4 The weighing mechanism 4 includes a pull plate 42 mounted on the housing 1 via a connecting component 41. A drive component 43 is provided outside the housing 1 to drive the designated pull plate 42 to lift the designated shelf 31. A force sensor is provided on the drive component 43 and located outside the housing 1.

[0043] When weighing the material on the designated shelf 31, the drive component 43 moves to the position of the pull plate 42 corresponding to the material to be weighed. Then, the drive component 43 drives the pull plate 42 at that position to the height position of the shelf 31 corresponding to the material to be weighed. After that, the drive component 43 lifts the shelf 31 at that position through the pull plate 42, thereby weighing the material on the shelf 31 through the force sensor on the drive component 43. This achieves independent and precise weighing of the material at the designated position, which can accurately obtain the real-time moisture content difference of the material in different areas and layers of the shelf 2, avoiding the problem of some materials being over-dried or under-dried due to the inability to perceive the drying progress difference due to overall weighing.

[0044] For example, when it is necessary to weigh the material at the frontmost and topmost position on the shelf 2, the drive assembly 43 moves to the position of the frontmost pull plate 42. Then, the drive assembly 43 lifts the frontmost pull plate 42, causing the frontmost pull plate 42 to rise to the position of the corresponding topmost shelf 31. Then, the drive assembly 43 drives the frontmost pull plate 42 to connect with the topmost shelf 31. Finally, the drive assembly 43 lifts the topmost shelf 31 again through the frontmost pull plate 42, thereby weighing the material in the topmost shelf 31 through the force sensor on the drive assembly 43.

[0045] Furthermore, during weighing, the force sensor located outside the chamber 1 is not affected by the high temperature inside the chamber 1, ensuring that the force sensor remains outside the chamber 1 throughout the entire operation. This fundamentally avoids the problem of the force sensor being directly exposed to the high temperature environment inside the oven for a long time, effectively eliminating the zero-point drift and sensitivity temperature drift of the sensor caused by high temperature, significantly improving weighing accuracy and long-term monitoring reliability, and extending the service life of the force sensor.

[0046] To facilitate the handling of dried materials, the present invention is designed with the following structure: (See attached diagram) Figure 1 , Figure 2 , Figure 3 , Figure 5 and Figure 6 The shielding assembly 32 includes an upper perforated plate 321 and a lower perforated plate 322 arranged vertically and stacked together. The upper perforated plate 321 is fixedly connected to the shelf 31, and the lower perforated plate 322 is slidably connected to the shelf 31. The lower perforated plates 322 on the same shelf 31 are fixedly connected together by a connecting plate 325. When drying materials, the operator places the materials on the lower upper perforated plate 321 in the same shelf 31.

[0047] To facilitate the smooth passage of hot air through the upper perforated plate 321 and the lower perforated plate 322, thereby allowing the hot air to contact the material and dry it, the present invention designs the following structure: (See reference) Figure 2 , Figure 3 , Figure 5 and Figure 6 The shielding assembly 32 also includes a helical spring disposed between the lower perforated plate 322 and the shelf 31. A baffle 323 for supporting each shelf 31 is fixedly installed on the shelf 2, and there is a gap between two shelves 31 in the same vertical position.

[0048] See Figure 3 , Figure 4 , Figure 5 , Figure 6 and Figure 7 The shelf 31 consists of two frames located at the top and bottom, and a tube connecting the two frames. The shelf 31 is slidably connected to the shelf 2 through its tube structure. The lower perforated plate 322 has a sloping structure on the right side. A triangular block 324 is fixedly installed on the lower right side of the shelf 2 and on the upper side of the baffle 323 located on the right side of the shelf 2. When the shelf 31 is not lifted, the triangular block 324 pushes the sloping structure of the lower perforated plate 322 to the left.

[0049] During drying, under the weight of the upper perforated plate 321, lower perforated plate 322, and shelf 31 at corresponding positions, the shelf 31 abuts against the corresponding baffle 323. This causes the inclined structure of the lower perforated plate 322 at the bottom of the same shelf 31 to abut against the inclined structure of the corresponding triangular block 324. This causes the triangular block 324 to push the lower perforated plate 322 to the left and compress the corresponding helical spring. When the shelf 31 is not lifted, the holes of the stacked upper perforated plate 321 and lower perforated plate 322 correspond, allowing the circulating hot air to pass smoothly and heat and dry the material evenly.

[0050] When weighing materials, the corresponding shelf 31 is lifted, causing the lower perforated plate 322 on the lower part of the shelf 31 to disengage from the corresponding triangular block 324. This causes the helical spring at the corresponding position to push the lower perforated plate 322 to the right through its elastic force. The lower perforated plate 322, through the connecting plate 325, drives the lower perforated plate 322 on the upper part of the same shelf 31 to move synchronously, causing the lower perforated plate 322 to move to the left, so that the holes of the stacked upper perforated plate 321 and the lower perforated plate 322 are staggered.

[0051] This results in the holes of the upper perforated plate 321 and the lower perforated plate 322 being staggered during the weighing process, effectively blocking the passage of hot air and mitigating the fluctuations in the weighing reading caused by hot air blowing on the material. This ensures the accuracy and stability of the weighing process without affecting the normal drying efficiency.

[0052] It should be noted that the hot air inside the housing 1 flows up and down, and is effectively blocked by the upper perforated plate 321 and the lower perforated plate 322 with their holes arranged in an alternating manner. However, this invention does not completely block the hot air from contacting the material, but effectively prevents the hot air from blowing directly onto the material, thereby causing fluctuations in the weighing reading of the material.

[0053] To enable quick movement and lifting of the designated pull plate 42, the present invention designs the following structure: (See attached diagram) Figure 1 , Figure 2 and Figure 8 The connecting component 41 includes two symmetrically arranged sliding plates 411 that are slidably connected to the upper side of the housing 1. The sliding plates 411 are slidably connected to the pull plates 42 on the corresponding side. The driving component 43 includes two hydraulic cylinders 431 that are fixedly installed on the upper side of the housing 1. The telescopic section of the hydraulic cylinder 431 is fixedly connected to the corresponding sliding plate 411.

[0054] Continue reading Figure 1 , Figure 2 and Figure 8 The drive assembly 43 also includes two electric sliders 432 that are respectively slidably disposed on the left and right sides of the housing 1. A hydraulic cylinder 433 for lifting the pull plate 42 is fixedly installed on the lower side of the electric slider 432. The telescopic section end of the hydraulic cylinder 433 is connected to a force sensor.

[0055] When it is necessary to lift the designated shelf 31, the electric slider 432 moves back and forth, driving the two hydraulic cylinders 433 to the corresponding front and rear positions of the designated shelf 31, so that the hydraulic cylinders 433 are located under the corresponding pull plate 42. Then, the telescopic section of the hydraulic cylinders 433 extends, so that the hydraulic cylinders 433 lift the pull plate 42 at the corresponding position, so that the lower end of the pull plate 42 moves up to the height position of the designated shelf 31.

[0056] Then, the telescopic sections of the two hydraulic cylinders 431 are simultaneously contracted, causing the two sliding plates 411 to move closer to each other synchronously. The sliding plates 411 drive the pull plates 42 on the left and right sides to move synchronously, so that the pull plates 42 extend into the lower part of the corresponding shelf 31. After that, the telescopic section of the hydraulic cylinder 431 is extended again, so that the shelf 31 corresponding to the material to be weighed is lifted by the pull plates 42. Then, the force sensor on the hydraulic cylinder 433 weighs the material on the shelf 31, realizing the real-time moisture content difference of the material in different areas and different layers of the shelf 2, avoiding the problem of some materials being over-dried or under-dried due to the inability to detect the difference in drying progress when weighing the whole.

[0057] To ensure that the pull plate 42 can accurately extend into the lower part of the corresponding shelf 31 and thus support the shelf 31, the shelf 2 needs to be placed and locked in a central position inside the box 1. Therefore, the present invention designs the following structure: (See attached diagram) Figure 1 , Figure 2 , Figure 3 and Figure 4 The lower part of the shelf 2 is equipped with several lockable casters 21, and the rear side of the shelf 2 is fixedly equipped with a limiting fork 22 for restraining the shelf 2 inside the box 1.

[0058] During drying, the shelf 2 is pushed into the box 1, so that the limiting fork 22 is covered and connected inside the box 1, thereby placing the shelf 2 in the center position inside the box 1. Then, the casters 21 are locked to fix the position of the shelf 2, so that the pull plate 42 can accurately extend into the lower part of the corresponding shelf 31.

[0059] Although this invention employs a sliding shelf 31, an upper perforated plate 321, and a lower perforated plate 322, which slightly increases the initial investment cost compared to traditional drying structures, it achieves independent and accurate weighing of materials at any location within the chamber 1 under hot air shielding during the drying process. Simultaneously, it ensures that the force sensor remains in a normal temperature environment outside the chamber 1, completely eliminating high-temperature drift and significantly improving weighing accuracy and long-term reliability. It can also obtain real-time moisture content differences in different areas of the material, avoiding over-drying or under-drying. This allows for a rapid balance between initial investment and reduced material loss and improved drying quality. Furthermore, this invention is primarily designed for materials sensitive to the degree of drying.

[0060] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0061] Furthermore, the terms "first," "second," "number one," and "number two" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first," "second," "number one," or "number two" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0063] The embodiments described herein are preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, all equivalent changes made in accordance with the structure, shape, and principle of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A pre-drying oven, comprising a cabinet and a shelf, characterized in that, The shelf is equipped with several supporting mechanisms for carrying materials, and the box is equipped with a weighing mechanism for weighing the materials. The supporting mechanism includes shelves arranged in an array on the shelf, the shelves and the shelf are slidably connected vertically, and the shelves are provided with shielding components for opening and closing ventilation of their upper and lower parts. The shielding components located at the lower part of the same shelf are also used to support materials. The weighing mechanism includes a pull plate mounted on the box body via a connecting component, a driving component mounted outside the box body to drive a designated pull plate to lift a designated shelf, and a force sensor mounted on the driving component and located outside the box body. During weighing, the force sensor located outside the chamber is not affected by the high temperature inside the chamber. The pull plate lifts the designated shelf, and the shielding component on the shelf automatically blocks the hot air flowing up and down from blowing on the material, thus weighing the material layer by layer.

2. A pre-drying oven according to claim 1, characterized in that, The shielding assembly includes an upper perforated plate and a lower perforated plate arranged vertically and stacked together. The upper perforated plate is fixedly connected to the shelf, and the lower perforated plate is slidably connected to the shelf from left to right. The lower perforated plates on the same shelf are fixedly connected together by a connecting plate.

3. A pre-drying oven according to claim 2, characterized in that, The shielding assembly also includes a helical spring disposed between the lower perforated plate and the shelf, and a baffle for supporting each shelf is fixedly installed on the shelf, with a gap between two shelves in the same vertical position.

4. A pre-drying oven according to claim 3, characterized in that, The lower perforated plate has a sloping structure on the right side. A triangular block is fixedly installed on the upper part of the lower right side of the shelf and the baffle located on the right side of the shelf. When the shelf is not lifted, the triangular block pushes the sloping structure of the corresponding lower perforated plate to the left.

5. A pre-drying oven according to claim 2, characterized in that, When the shelf is not lifted, the holes of the stacked upper and lower perforated plates correspond to each other; when the shelf is lifted, the lower perforated plate moves to the left, so that the holes of the stacked upper and lower perforated plates are staggered.

6. A pre-drying oven according to claim 1, characterized in that, The shelf consists of two frames located at the top and bottom, respectively, and tubing connecting the two frames. The shelf is slidably connected to the storage rack by its tubing structure.

7. A pre-drying oven according to claim 1, characterized in that, The lower part of the shelf is equipped with several lockable casters, and a limiting fork is fixedly installed on the rear side of the shelf to constrain the position of the shelf inside the box.

8. A pre-drying oven according to claim 1, characterized in that, The connecting assembly includes two symmetrically arranged sliding plates on the upper side of the housing, which are sealed and slidably connected from the top and bottom. The sliding plates are sealed and slidably connected from the top and bottom to each pull plate on the corresponding side.

9. A pre-drying oven according to claim 8, characterized in that, The drive assembly includes two hydraulic cylinders fixedly installed on the upper side of the housing, and the telescopic section of the hydraulic cylinder is fixedly connected to the corresponding slide plate.

10. A pre-drying oven according to claim 8, characterized in that, The drive assembly also includes two electric sliders that are respectively slidably disposed on the left and right sides of the housing. A hydraulic cylinder for lifting the pull plate is fixedly installed on the lower side of the electric slider, and the telescopic end of the hydraulic cylinder is connected to a force sensor.

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