A ductile iron manhole cover and its production apparatus and method

Abstract

This application discloses a ductile iron manhole cover and its production apparatus and method, relating to the technical field of ductile iron manhole covers. The device includes a workbench, a fixed cylinder, and a movable cylinder, with the fixed cylinder located above the workbench. The movable cylinder is inserted through and slidably connected to the fixed cylinder. Inside the fixed cylinder, on both sides of the movable cylinder, are independently located a first hopper and a second hopper, respectively used to hold lime or fine sand of different colors. A detection ball bearing is rolled at the bottom of the movable cylinder. The first and second hoppers each have a first discharge port and a second discharge port at the bottom of their respective inner walls, with the first discharge port located below the second discharge port. The movable cylinder has a first connecting port and a second connecting port on its two side walls. When the movable cylinder slides up and down, the first connecting port connects to the first discharge port, or the second connecting port connects to the second discharge port. This application improves the production efficiency of ductile iron manhole covers.

Description

Technical Field

[0001] This application relates to the technical field of ductile iron manhole covers, and in particular to a ductile iron manhole cover and its production apparatus and production method. Background Technology

[0002] Manhole covers are covers used to cover underground facilities such as roads, sewers, and cable wells. They protect these facilities from damage, prevent debris and garbage from falling in, ensure the smoothness of roads and sidewalks, prevent accidents caused by uneven road surfaces, and facilitate workers to open them to enter the manhole for maintenance.

[0003] Ductile iron manhole covers are a type of ductile iron product. Compared to ordinary cast iron manhole covers, ductile iron manhole covers have higher toughness and plasticity, which can effectively improve the strength and durability of the manhole cover. At the same time, ductile iron manhole covers also have good corrosion resistance and can adapt well to various application environments.

[0004] The production of ductile iron manhole covers typically includes processes such as melting, casting, cooling and forming, surface heat treatment, machining, and quality inspection. Among these processes, the quality inspection involves checking the cast ductile iron manhole covers for aspects such as dimensions, hardness, appearance, and flatness. Conventionally, the flatness of manhole covers is checked manually by measuring each cover surface one by one using a steel ruler. This method is inefficient and greatly increases the labor intensity of workers, which can negatively impact the production efficiency of manhole covers. Summary of the Invention

[0005] To address the issue that manual inspection of manhole cover flatness is inefficient and labor-intensive, thus affecting overall manhole cover production efficiency, this application provides a ductile iron manhole cover, its production apparatus, and production method.

[0006] On the one hand, this application provides a ductile iron manhole cover production device, which adopts the following technical solution:

[0007] A ductile iron manhole cover production apparatus, comprising

[0008] The workbench, placed horizontally, is used to hold the manhole covers to be inspected;

[0009] A fixed cylinder is located above the worktable;

[0010] A movable cylinder is inserted through and slidably connected to a fixed cylinder. The fixed cylinder has a first hopper and a second hopper that are independent of each other on both sides of the movable cylinder. The first hopper and the second hopper are respectively used to hold lime or fine sand of different colors. A detection ball is rolled at the bottom of the movable cylinder. The detection ball is used to contact the manhole cover to be tested.

[0011] The first hopper and the second hopper are respectively provided with a first discharge port and a second discharge port at the bottom of their respective inner side walls. The first discharge port is located below the second discharge port. The moving cylinder is provided with a first connecting port and a second connecting port on its two side walls. When the moving cylinder slides up and down, the first connecting port is connected to the first discharge port, or the second connecting port is connected to the second discharge port. The bottom of the moving cylinder is provided with a discharge port that is connected to the first connecting port and the second connecting port.

[0012] Optionally, a return element is provided inside the fixed cylinder. The return element is placed vertically above the moving cylinder, with one end connected to the inner wall of the fixed cylinder and the other end connected to the top of the moving cylinder.

[0013] Optionally, the outer wall of the movable cylinder is covered with a sealing element, the outer wall of which is in close contact with the inner wall of the fixed cylinder, for filling the gap between the movable cylinder and the fixed cylinder to achieve a sealed connection.

[0014] Optionally, the bottom walls of the first and second hoppers gradually slope downwards toward the first and second discharge ports, respectively.

[0015] Optionally, a vertical detection rod is provided at the bottom of the movable cylinder, the detection ball is rotatably connected to the bottom of the detection rod, the outer diameter of the detection rod is smaller than the outer diameter of the movable cylinder, and the material discharge port is opened close to the detection rod.

[0016] Optionally, a locking member is horizontally inserted through the side wall of the fixed cylinder. The locking member is capable of horizontal movement. When the locking member moves, one end of the locking member located inside the fixed cylinder abuts against the bottom of the moving cylinder to restrict the vertical movement of the moving cylinder.

[0017] Optionally, the locking component includes a locking bolt and a locking block. The locking bolt passes through and is threadedly connected to the fixed cylinder. The locking block is located at the end of the locking bolt near the moving cylinder and is rotatably connected to the locking bolt. The top surface of the locking block near the moving cylinder is provided with a transition slope. The transition slope gradually slopes downward towards the moving cylinder. When the end of the locking block contacts the detection rod, the top surface of the locking block abuts against the bottom surface of the moving cylinder.

[0018] Optionally, multiple fixing cylinders are provided, and the multiple fixing cylinders are distributed radially at intervals along the manhole cover to be inspected. A support frame is provided on the top of each fixing cylinder, and the support frame is connected to all the fixing cylinders. The support frame is rotatably connected to the worktable to drive all the fixing cylinders to rotate around the center of the manhole cover to be inspected.

[0019] On the one hand, this application provides a method for producing ductile iron manhole covers, which uses the ductile iron manhole cover production apparatus described above to perform production testing on the ductile iron manhole covers, including the following steps:

[0020] S1: Place the ductile iron manhole cover to be tested horizontally on the workbench, and lower all the fixed cylinders until all the testing balls are in contact with the surface of the manhole cover to be tested;

[0021] S2: All fixed cylinders rotate simultaneously around the center of the manhole cover to be inspected, and the detection balls roll along the surface of the manhole cover to be inspected.

[0022] When the detection ball rolls to the flat area of ​​the manhole cover to be tested, the moving cylinder does not move relative to the fixed cylinder or moves only a small amount. At this time, the first connecting port is not connected to the first discharge port, and the second connecting port is not connected to the second discharge port.

[0023] When the detection ball rolls to the area where the manhole cover to be detected is sunken, the moving cylinder moves downward relative to the fixed cylinder, the first connecting port connects with the first discharge port, and the lime or fine sand in the first hopper falls out from the discharge port of the moving cylinder;

[0024] When the detection ball rolls to the convex area on the manhole cover to be inspected, the moving cylinder moves upward relative to the fixed cylinder, the second connecting port connects with the second discharge port, and the lime or fine sand in the second hopper falls out from the discharge port of the moving cylinder.

[0025] S3: During the rotation of the fixed cylinder, if there is no lime or fine sand on the surface of the manhole cover to be inspected, it indicates that the manhole cover to be inspected is flat. If lime or fine sand appears on the surface of the manhole cover to be inspected, the area of ​​the manhole cover where the lime or fine sand appears can be judged as sunken or convex based on the color of the lime or fine sand on the manhole cover.

[0026] On the one hand, this application provides a ductile iron manhole cover, produced using the ductile iron manhole cover production method described above, characterized in that, by weight percentage, its composition is as follows:

[0027] C: 3.1-3.45%;

[0028] Si: 4.8-5.2%;

[0029] Mo: 0.75-1.45%;

[0030] P: 0.027-0.032%;

[0031] S: 0.011-0.015%;

[0032] Cr: 0.057-0.07%;

[0033] Ni: 0.2-0.22%; and

[0034] Balance of Fe.

[0035] In summary, this application includes at least one of the following beneficial effects:

[0036] 1. The manhole cover of the present invention is made of ductile iron alloy, and a certain percentage of silicon, molybdenum and nickel are added to the composition of the cast iron alloy, which can significantly improve the corrosion resistance of the cast iron alloy, and at the same time provide the manhole cover with higher strength and better machinability, so that the produced manhole cover is of better quality and more environmentally friendly.

[0037] 2. The ductile iron manhole cover production device of the present invention employs a movable cylinder that slides up and down within a fixed cylinder. The movable cylinder is equipped with a rolling detection ball via a detection rod at its bottom. During detection, the detection ball contacts the surface of the manhole cover. The fixed cylinder, via the detection rod, moves the detection ball along the surface of the manhole cover, while the distance between the fixed cylinder and the manhole cover remains constant. As the detection ball moves along the surface of the manhole cover, it rolls, ensuring that it always moves along the surface. When the detection ball reaches a relatively flat surface of the manhole cover, it continues to roll along this flat surface, with minimal or no displacement in the height direction. At this time, the moving cylinder will not move or will move very little in the vertical direction. The first connecting port is not connected to the first discharge port, and the second connecting port is not connected to the second discharge port. No lime or fine sand falls from the moving cylinder. When the detection ball rolls to the area where the manhole cover to be tested is sunken or convex, the detection ball drives the moving cylinder to descend or rise through the detection rod. Therefore, the first connecting port is connected to the first discharge port, or the second connecting port is connected to the second discharge port. In both cases, lime or fine sand will fall from the moving cylinder to the surface of the manhole cover. Therefore, the flatness of the manhole cover can be judged by whether lime or fine sand appears on the manhole cover, without the need for manual inspection.

[0038] 3. By using different colored lime or fine sand in the first and second silos, with the first connecting port located at the bottom of the first silo and the second connecting port located at the bottom of the second silo, and the first connecting port located below the second connecting port, when the moving cylinder descends, the first connecting port connects to the first discharge port, and when the moving cylinder rises, the second connecting port connects to the second discharge port. That is, the color of the lime or fine sand falling on the manhole cover is different when the moving cylinder rises or falls. Therefore, the color of the lime or fine sand appearing on the manhole cover can be used to determine whether the manhole cover is sunken or convex. Attached Figure Description

[0039] Figure 1 This is a schematic diagram of the overall structure of the manhole cover production device shown in Embodiment 2 of this application;

[0040] Figure 2 This is a cross-sectional schematic diagram illustrating the internal structure of the fixed cylinder in Embodiment 2 of this application;

[0041] Figure 3 yes Figure 2 An enlarged view at point A;

[0042] Figure 4 This is a schematic diagram illustrating the operation of the production device detecting the sunken area of ​​the manhole cover in Embodiment 2 of this application;

[0043] Figure 5 This is a schematic diagram illustrating the operation of the production device detecting the convex area on the manhole cover in Embodiment 2 of this application.

[0044] Explanation of reference numerals in the attached drawings: 1. Workbench; 11. Manhole cover; 12. Lifting rod; 13. First driving component; 14. Fixed frame; 15. Second driving component; 16. Support frame; 2. Fixed cylinder; 21. Detection channel; 22. First hopper; 221. First discharge port; 23. Second hopper; 231. Second discharge port; 3. Moving cylinder; 31. Detection rod; 32. Detection ball; 33. First connecting port; 34. Second connecting port; 35. Drop port; 4. Return component; 5. Sealing component; 6. Locking component; 61. Locking bolt; 62. Locking block; 63. Transition slope. Detailed Implementation

[0045] The following is in conjunction with the appendix Figure 1-5 This application will be described in further detail. Example 1

[0046] Embodiment 1 of this application discloses a ductile iron manhole cover comprising the following components by weight percentage: C: 3.1-3.45%, Si: 4.8-5.2%, Mo: 0.75-1.45%, P: 0.027-0.032%, S: 0.011-0.015%, Cr: 0.057-0.07%, Ni: 0.2-0.22%, and the balance Fe.

[0047] The manhole cover provided in Embodiment 1 of this application is made of ductile iron alloy, with a certain percentage of silicon, molybdenum, and nickel added to the original cast iron alloy composition. For example, the composition is C: 3.25%, Si: 5%, Mo: 1.1%, P: 0.03%, S: 0.013%, Cr: 0.064%, Ni: 0.21%, and the remainder being Fe. The ductile iron manhole cover provided in Embodiment 1 of this application has good corrosion resistance, higher strength, toughness, and better machinability, resulting in a higher quality manhole cover. Furthermore, the addition of less chromium makes it more environmentally friendly. Example 2

[0048] Embodiment 2 of this application discloses a ductile iron manhole cover production apparatus, referring to... Figure 1The ductile iron manhole cover production device includes a horizontally placed workbench 1. The manhole cover 11 to be inspected is placed horizontally on the workbench 1. The workbench 1 can be equipped with clamps or positioning blocks to fix the position of the manhole cover 11, so that the manhole cover 11 can always remain stable and horizontally placed during the production and inspection process.

[0049] A vertical lifting rod 12 is also provided on the workbench 1. The lifting rod 12 is located on one side of the manhole cover 11, and a first driving component 13 is provided at the bottom of the lifting rod 12. The first driving component 13 can be a vertically placed hydraulic cylinder. The first driving component 13 is fixed to the top surface of the workbench 1, and the output shaft of the first driving component 13 is vertically upward and coaxially fixed with the lifting rod 12, so that the first driving component 13 can drive the lifting rod 12 to move up and down in the vertical direction. A horizontal fixing frame 14 is fixedly connected to the top of the lifting rod 12. One end of the fixing frame 14 extends above the manhole cover 11. A second driving component 15 is fixed to the bottom of the fixing frame 14 at the position corresponding to the manhole cover 11. The second driving component 15 can be a servo motor. The output shaft of the second driving component 15 is vertically downward and fixedly connected to a horizontal support frame 16. Multiple fixing cylinders 2 are provided at the bottom of the support frame 16. Each fixing cylinder 2 is vertically placed, and the distance between each fixing cylinder 2 and the center of the manhole cover 11 is different. The fixing cylinders 2 extend along the radial direction of the manhole cover 11 and are distributed at intervals.

[0050] After the manhole cover 11 to be inspected is placed on the workbench 1, the first drive component 13 drives the fixing frame 14 to move up and down vertically via the lifting rod 12. The fixing frame 14 drives the second drive component 15 to move up and down. The second drive component 15 drives all the fixing cylinders 2 to move up and down via the support frame 16. Finally, the second drive component 15 drives all the fixing cylinders 2 to rotate around the central axis of the manhole cover 11 via the support frame 16. In this embodiment, the number of fixing cylinders 2 is set to three. In other embodiments, the number of fixing cylinders 2 can be increased or decreased according to the actual diameter of the manhole cover 11, so that the rotating fixing cylinders 2 can cover most of the area of ​​the manhole cover 11 as much as possible.

[0051] Reference Figure 1 and Figure 2 To check the flatness of the manhole cover 11 surface, a detection channel 21 is coaxially provided inside the fixed cylinder 2. The detection channel 21 extends downward through the bottom surface of the fixed cylinder 2. A vertical movable cylinder 3 is provided inside the fixed cylinder 2. The movable cylinder 3 is vertically slidably connected to the detection channel 21, and the bottom of the movable cylinder 3 can slide out of the bottom of the fixed cylinder 2 through the detection channel 21.

[0052] A vertical detection rod 31 is coaxially fixed at the bottom of the movable cylinder 3. The outer diameter of the detection rod 31 is smaller than the outer diameter of the movable cylinder 3. The detection rod 31 extends vertically downward, and a detection ball 32 is rolled on the bottom surface of the detection rod 31. The detection ball 32 is used to contact the surface of the manhole cover 11, so that the fixed cylinder 2 can drive the detection ball 32 to roll along the surface of the manhole cover 11 through the movable cylinder 3.

[0053] Since the height of the fixed cylinder 2 remains constant, when the detection ball 32 moves along the surface of the manhole cover 11, when the detection ball 32 moves to an uneven surface of the manhole cover 11, the detection ball 32 will rise or fall along the surface of the manhole cover 11. During this process, the rising or falling detection ball 32 drives the moving cylinder 3 to rise or fall relative to the fixed cylinder 2 in the detection channel 21 through the detection rod 31.

[0054] To ensure that the detection ball 32 remains in contact with the surface of the manhole cover 11 during detection, a return element 4 is provided inside the fixed cylinder 2. The return element 4 can be a compression spring. The return element 4 is placed vertically above the moving cylinder 3, with its top end fixedly connected to the inner wall of the fixed cylinder 2 and its bottom end fixedly connected to the top of the moving cylinder 3. When the detection rod 31 and the moving cylinder 3 move downwards as a whole, the return element 4 can hold the moving cylinder 3 in place, preventing it from falling out of the fixed cylinder 2. When the detection rod 31 and the moving cylinder 3 move upwards as a whole, the moving cylinder 3 compresses the return element 4, generating a downward restoring force. Through the moving cylinder 3 and the detection rod 31, the detection ball 32 is driven to remain in close contact with the surface of the manhole cover 11. During this process, the stretching or compression of the return element 4 provides a buffering effect.

[0055] Reference Figure 2 To further facilitate the assessment of the flatness of the manhole cover 11 surface, the fixed cylinder 2 is provided with a first hopper 22 and a second hopper 23 on both sides of the movable cylinder 3. The first hopper 22 and the second hopper 23 surround the movable cylinder 3 from both sides to form a detection channel 21. The first hopper 22 and the second hopper 23 can be symmetrically distributed relative to one of the diameters of the fixed cylinder 2, and the first hopper 22 and the second hopper 23 are respectively used to hold lime or fine sand of different colors.

[0056] The first silo 22 and the second silo 23 each have a first discharge port 221 and a second discharge port 231 at the bottom of their respective inner side walls. Vertically, the first discharge port 221 is located below the second discharge port 231. The lime or fine sand contained in the first silo 22 and the second silo 23 can fall out through the first discharge port 221 and the second discharge port 231 respectively, relying on their own weight. The detection sensitivity of the production device can be determined by controlling the opening positions of the first discharge port 221 and the second discharge port 231. For example, if the allowable error in the surface flatness of the manhole cover 11 is small, the distance between the first discharge port 221 and the second discharge port 231 can be relatively reduced; conversely, the distance between the first discharge port 221 and the second discharge port 231 can be relatively increased.

[0057] To facilitate the falling of lime or fine sand in the silos, the bottom walls of the first silo 22 and the second silo 23 gradually slope downward toward the first discharge port 221 and the second discharge port 231, respectively. That is, the bottom walls of the first silo 22 and the second silo 23 both gradually slope downward toward the moving cylinder 3. The downward slope of the bottom walls is more conducive to the lime or fine sand sliding out of the corresponding silos by its own gravity.

[0058] Correspondingly, the movable cylinder 3 has a first connecting port 33 and a second connecting port 34 on its two side walls, respectively. The first connecting port 33 corresponds to the first hopper 22, and the second connecting port 34 corresponds to the second hopper 23. In the vertical direction, the first connecting port 33 is located below the second connecting port 34, and the distance between the first discharge port 221 and the second discharge port 231 is greater than the distance between the first connecting port 33 and the second connecting port 34. This creates a section during the up-and-down sliding of the movable cylinder 3 in which the first connecting port 33 is not connected to the first discharge port 221, and the second connecting port 34 is not connected to the second discharge port 231.

[0059] Reference Figures 2 to 5 The moving cylinder 3 slides up and down within the detection channel 21. When the moving cylinder 3 slides down to the point where the first connecting port 33 connects with the first discharge port 221, the lime or fine sand contained in the first hopper 22 falls into the moving cylinder 3 along the connecting first discharge port 221 and the first connecting port 33. When the moving cylinder 3 slides up to the point where the second connecting port 34 connects with the second discharge port 231, the lime or fine sand contained in the second hopper 23 falls into the moving cylinder 3 along the connecting second discharge port 231 and the second connecting port.

[0060] The bottom of the movable cylinder 3 is provided with a discharge port 35 corresponding to the first connecting port 33 and the second connecting port 34 respectively. The discharge port 35 can be a funnel shape that gradually narrows downward. The discharge port 35 is opened around and close to the outer ring of the detection rod 31, so that the fine sand falling into the movable cylinder 3 from the first hopper 22 or the second hopper 23 can continue to fall from the discharge port 35 respectively, and finally fall to the uneven surface position of the manhole cover 11.

[0061] To prevent lime or fine sand from falling through the gap between the moving cylinder 3 and the fixed cylinder 2, the outer wall of the moving cylinder 3 is covered with a sealing element 5. The sealing element 5 can be a rubber sealing ring, and the sealing element 5 has openings at positions corresponding to the first connecting port 33 and the second connecting port 34, thereby keeping the first connecting port 33 and the second connecting port 34 unobstructed. The outer wall of the sealing element 5 is in close contact with the inner wall of the fixed cylinder 2, so that the sealing element 5 can fill the gap between the moving cylinder 3 and the fixed cylinder 2 to achieve a sealed connection.

[0062] Reference Figure 2 and Figure 3 To prevent lime or fine sand from leaking out of the fixed cylinder 2 when it is not in use, a locking element 6 is horizontally installed on the side wall near the bottom of the fixed cylinder 2. The locking element 6 includes a locking bolt 61 and a locking block 62. The locking bolt 61 passes through and is threadedly connected to the fixed cylinder 2. The locking block 62 is located at the end of the locking bolt 61 near the moving cylinder 3 and is rotatably connected to the locking bolt 61. When an external force is applied to tighten the locking bolt 61, the locking bolt 61 will drive the locking block 62 to move closer to or further away from the detection rod 31.

[0063] The top surface of the locking block 62 near the moving cylinder 3 has a transition slope 63. The transition slope 63 gradually slopes downward towards the moving cylinder 3. When the end of the locking block 62 contacts the detection rod 31, the top surface of the locking block 62 abuts against the bottom surface of the moving cylinder 3, thereby achieving the purpose of locking the moving cylinder 3. When it is necessary to lock the moving cylinder 3, the locking block 62 moves closer to the moving cylinder 3, and the transition slope 63 will contact the bottom of the moving cylinder 3. When the locking block 62 moves horizontally, the transition slope 63 drives the moving cylinder 3 to rise until the top surface of the locking block 62 abuts against the bottom surface of the moving cylinder 3. At this time, the first connecting port 33 is not connected to the first discharge port 221, and the second connecting port 34 is not connected to the second discharge port 231.

[0064] Reference Figures 2 to 5 During testing, the detection ball 32 contacts the surface of the manhole cover 11. The fixed cylinder 2 drives the detection ball 32 to move along the surface of the manhole cover 11, while the distance between the fixed cylinder 2 and the manhole cover 11 remains constant. When the detection ball 32 moves to a relatively flat surface of the manhole cover 11 (such as...), Figure 2At this time, the detection ball 32 always rolls along the flat surface of the manhole cover 11. The detection ball 32 will not be displaced or will be displaced very little in the height direction. At this time, the moving cylinder 3 will also not be displaced or will be displaced very little in the vertical height direction. The first connecting port 33 is not connected to the first discharge port 221, and the second connecting port 34 is not connected to the second discharge port 231. No lime or fine sand falls from the moving cylinder 3.

[0065] When the detection ball 32 rolls to the area where the manhole cover 11 is sunken or convex (such as... Figure 4 , Figure 5 The detection ball 32 drives the moving cylinder 3 to descend or rise through the detection rod 31. When the moving cylinder 3 descends to the first connecting port 33 and connects with the first discharge port 221, or when the moving cylinder 3 rises to the second connecting port 34 and connects with the second discharge port 231, lime or fine sand will fall from the moving cylinder 3 onto the surface of the manhole cover 11. Therefore, whether the manhole cover 11 is flat can be judged by whether lime or fine sand appears on the manhole cover 11, without the need for manual inspection, which effectively reduces the labor intensity of workers.

[0066] Meanwhile, since the lime or fine sand contained in the first hopper 22 and the second hopper 23 are of different colors, when the moving cylinder 3 descends, the first connecting port 33 connects to the first discharge port 221, at which time the lime or fine sand in the first hopper 22 falls; while when the moving cylinder 3 rises, the second connecting port 34 connects to the second discharge port 231, at which time the lime or fine sand in the second hopper 23 falls, and the two different colored lime or fine sand can fall directly onto the corresponding sunken or convex positions on the manhole cover 11. That is, the color of the lime or fine sand falling on the manhole cover 11 is different when the moving cylinder 3 rises or falls, so the color of the lime or fine sand appearing on the manhole cover 11 can be used to determine whether the manhole cover 11 is sunken or convex, and it is also possible to directly observe which specific areas on the manhole cover 11 are uneven.

[0067] The implementation principle of the ductile iron manhole cover production device in Embodiment 2 of this application is as follows: the detection ball 32 rolls along the surface of the manhole cover 11. When the detection ball 32 moves to the position where the surface of the manhole cover 11 is sunken or convex, the moving cylinder 3 will follow the detection ball 32 to descend or rise. If the moving cylinder 3 descends to the point where the first connecting port 33 is connected to the first discharge port 221, the lime or fine sand in the first hopper 22 will fall from the discharge port 35 to the corresponding sunken position of the manhole cover 11. If the moving cylinder 3 rises to the point where the second connecting port 34 is connected to the second discharge port 231, the lime or fine sand in the second hopper 23 will fall from the discharge port 35 to the corresponding convex position of the manhole cover 11. Thus, by observing whether lime or fine sand appears on the surface of the manhole cover 11, it can be determined whether the manhole cover 11 is flat. It can also be determined by observing what color lime or fine sand appears on the surface of the manhole cover 11, which areas of the manhole cover 11 are convex or sunken. Example 3

[0068] Embodiment 3 of this application discloses a method for producing ductile iron manhole covers, which uses the ductile iron manhole cover production apparatus as described in Embodiment 2 to perform production testing on the ductile iron manhole covers, including the following steps:

[0069] S1: Place the ductile iron manhole cover 11 to be tested horizontally on the workbench 1, and lower all the fixed cylinders 2 until all the testing balls 32 are in contact with the surface of the manhole cover 11 to be tested.

[0070] S2: All fixed cylinders 2 rotate around the center of the manhole cover 11 to be inspected at the same time, and the detection ball 32 rolls along the surface of the manhole cover 11 to be inspected.

[0071] When the detection ball 32 rolls to the flat area of ​​the manhole cover 11 to be tested, the moving cylinder 3 does not move relative to the fixed cylinder 2 or moves only a small amount. At this time, the first connecting port 33 is not connected to the first discharge port 221, and the second connecting port 34 is not connected to the second discharge port 231.

[0072] When the detection ball 32 rolls to the area where the manhole cover 11 is sunken, the moving cylinder 3 moves downward relative to the fixed cylinder 2, the first connecting port 33 connects with the first discharge port 221, and the lime or fine sand in the first hopper 22 falls out from the discharge port 35 of the moving cylinder 3.

[0073] When the detection ball 32 rolls to the convex area on the manhole cover 11 to be tested, the moving cylinder 3 moves upward relative to the fixed cylinder 2, the second connecting port 34 connects with the second discharge port 231, and the lime or fine sand in the second hopper 23 falls out from the discharge port 35 of the moving cylinder 3.

[0074] S3: During the rotation of the fixed cylinder 2, if there is no lime or fine sand on the surface of the manhole cover 11 to be tested, it indicates that the manhole cover 11 to be tested is flat. If lime or fine sand appears on the surface of the manhole cover 11 to be tested, the area of ​​the manhole cover 11 where lime or fine sand appears is determined to be sunken or convex based on the color corresponding to the lime or fine sand on the manhole cover 11.

[0075] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A production device for ductile iron manhole covers, characterized in that: include The workbench, placed horizontally, is used to hold the manhole covers to be inspected; A fixed cylinder is located above the worktable; A movable cylinder is inserted through and slidably connected to a fixed cylinder. The fixed cylinder has a first hopper and a second hopper that are independent of each other on both sides of the movable cylinder. The first hopper and the second hopper are respectively used to hold lime or fine sand of different colors. A detection ball is rolled at the bottom of the movable cylinder. The detection ball is used to contact the manhole cover to be tested. The first hopper and the second hopper are respectively provided with a first discharge port and a second discharge port at the bottom of their respective inner side walls. The first discharge port is located below the second discharge port. The moving cylinder is provided with a first connecting port and a second connecting port on its two side walls. The bottom of the moving cylinder is provided with a discharge port that communicates with the first connecting port and the second connecting port. The distance between the first discharge port and the second discharge port is greater than the distance between the first connecting port and the second connecting port, so that there is a range during the up-and-down sliding of the moving cylinder. Within this range, the first connecting port is not connected to the first discharge port, and the second connecting port is not connected to the second discharge port. When the moving cylinder descends, the first connecting port connects with the first discharge port, at which time the lime or fine sand in the first hopper falls; and when the moving cylinder rises, the second connecting port connects with the second discharge port, at which time the lime or fine sand in the second hopper falls.

2. The ductile iron manhole cover production apparatus according to claim 1, characterized in that: The fixed cylinder is equipped with a return component, which is placed vertically above the moving cylinder. One end of the return component is connected to the inner wall of the fixed cylinder, and the other end is connected to the top of the moving cylinder.

3. The ductile iron manhole cover production device according to claim 1, characterized in that: The outer wall of the movable cylinder is covered with a sealing element, and the outer wall of the sealing element is in close contact with the inner wall of the fixed cylinder to fill the gap between the movable cylinder and the fixed cylinder to achieve a sealed connection.

4. The ductile iron manhole cover production device according to claim 1, characterized in that: The bottom walls of the first and second hoppers gradually slope downwards toward the first and second discharge ports, respectively.

5. The ductile iron manhole cover production apparatus according to claim 1, characterized in that: A vertical detection rod is provided at the bottom of the moving cylinder, and the detection ball is rotatably connected to the bottom of the detection rod. The outer diameter of the detection rod is smaller than the outer diameter of the moving cylinder, and the material discharge port is opened close to the detection rod.

6. The ductile iron manhole cover production apparatus according to claim 5, characterized in that: A locking element is horizontally inserted through the side wall of the fixed cylinder. The locking element can move horizontally. When the locking element moves, one end of the locking element inside the fixed cylinder abuts against the bottom of the moving cylinder to restrict the moving cylinder from moving up and down.

7. The ductile iron manhole cover production apparatus according to claim 6, characterized in that: The locking component includes a locking bolt and a locking block. The locking bolt passes through and is threadedly connected to the fixed cylinder. The locking block is located at the end of the locking bolt near the moving cylinder and is rotatably connected to the locking bolt. The top surface of the locking block near the moving cylinder is provided with a transition slope. The transition slope gradually slopes downward towards the moving cylinder. When the end of the locking block contacts the detection rod, the top surface of the locking block abuts against the bottom surface of the moving cylinder.

8. The ductile iron manhole cover production apparatus according to claim 1, characterized in that: Multiple fixed cylinders are provided, and the multiple fixed cylinders are distributed radially at intervals along the manhole cover to be inspected. A support frame is provided on the top of each fixed cylinder, and the support frame is connected to all the fixed cylinders. The support frame is rotatably connected to the worktable to drive all the fixed cylinders to rotate around the center of the manhole cover to be inspected.

9. A method for producing ductile iron manhole covers, characterized in that: The production inspection of ductile iron manhole covers using the ductile iron manhole cover production apparatus as described in any one of claims 1-8 includes the following steps: S1: Place the ductile iron manhole cover to be tested horizontally on the workbench, and lower all the fixed cylinders until all the testing balls are in contact with the surface of the manhole cover to be tested; S2: All fixed cylinders rotate simultaneously around the center of the manhole cover to be inspected, and the detection balls roll along the surface of the manhole cover to be inspected. When the detection ball rolls to the flat area of ​​the manhole cover to be tested, the moving cylinder does not move relative to the fixed cylinder or moves only a small amount. At this time, the first connecting port is not connected to the first discharge port, and the second connecting port is not connected to the second discharge port. When the detection ball rolls to the area where the manhole cover to be detected is sunken, the moving cylinder moves downward relative to the fixed cylinder, the first connecting port connects with the first discharge port, and the lime or fine sand in the first hopper falls out from the discharge port of the moving cylinder; When the detection ball rolls to the convex area on the manhole cover to be inspected, the moving cylinder moves upward relative to the fixed cylinder, the second connecting port connects with the second discharge port, and the lime or fine sand in the second hopper falls out from the discharge port of the moving cylinder. S3: During the rotation of the fixed cylinder, if there is no lime or fine sand on the surface of the manhole cover to be inspected, it indicates that the manhole cover to be inspected is flat. If lime or fine sand appears on the surface of the manhole cover to be inspected, the area of ​​the manhole cover where the lime or fine sand appears can be judged as sunken or convex based on the color of the lime or fine sand on the manhole cover.

10. A ductile iron manhole cover, produced using the method for producing a ductile iron manhole cover as described in claim 9, characterized in that, Its composition by weight percentage is: C：3.1-3.45％； Si: 4.8-5.2%; Mo: 0.75-1.45%; P：0.027-0.032％； S：0.011-0.015％； Cr：0.057-0.07％； Ni: 0.2-0.22%; and Balance of Fe.

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