Lifting device

Abstract

The utility model provides a lifting device. The lifting device comprises a lifting mechanism, and the lifting mechanism comprises a machine base; the support is arranged on the machine base and provided with a first connecting part, a second connecting part and a third connecting part, the first connecting part is connected with the machine base, and the second connecting part is located above the first connecting part and the third connecting part; the hoisting assembly comprises a hoisting arm and a traction assembly, the first end of the hoisting arm is connected with the second connecting part, the traction assembly comprises a first rotating wheel and a traction rope wound on the first rotating wheel, and the first rotating wheel is rotatably arranged at the second end of the hoisting arm; and the two ends of the first telescopic structure are connected with the third connecting part and the middle of the lifting arm correspondingly, and at least part of the first telescopic structure is arranged in a telescopic mode so as to adjust the height relation between the first end and the second end of the lifting arm. The belt conveyor solves the problem that in the prior art, the labor intensity of workers is increased due to the fact that a manual lifting and loading mode is adopted at the tail of the belt conveyor.

Description

Technical Field

[0001] The utility model relates to the technical field of hydraulic lifting, in particular to a lifting device. Background Art

[0002] At present, belt conveyors are a kind of mechanical equipment widely used in various industries, which are used to continuously transport materials from a starting point to an end point. In the prior art, equipment materials such as pipelines and roller frames generated at the tail of belt conveyors are usually manually lifted and loaded onto trucks.

[0003] However, manual material handling not only increases labor intensity and wastes time and effort, but also poses significant safety risks. Furthermore, when the work surface is rapidly advancing, manual material handling can no longer meet production needs, impacting work efficiency. Utility Model Content

[0004] The main purpose of the utility model is to provide a lifting device to solve the problem that the manual lifting and loading method at the tail of the belt conveyor in the prior art increases the labor intensity of the workers and is time-consuming and labor-intensive.

[0005] In order to achieve the above-mentioned purpose, the utility model provides a lifting device, including a lifting mechanism, the lifting mechanism including: a machine base; a bracket, arranged on the machine base, the bracket having a first connecting part, a second connecting part and a third connecting part, the first connecting part is connected to the machine base, and the second connecting part is located above the first connecting part and the third connecting part; a lifting assembly, including a lifting arm and a traction assembly, the first end of the lifting arm is connected to the second connecting part, the traction assembly includes a first rotating wheel and a traction rope wrapped around the first rotating wheel, and the first rotating wheel is rotatably arranged on the second end of the lifting arm; a first telescopic structure, the two ends of the first telescopic structure are respectively connected to the third connecting part and the middle part of the lifting arm, and at least a part of the first telescopic structure is telescopically arranged to adjust the height relationship between the first end and the second end of the lifting arm.

[0006] Furthermore, the lifting device also includes a platform, and the lifting assembly is arranged on the platform; the bracket also has a fourth connecting part; the lifting device also includes: a second telescopic structure, the two ends of the second telescopic structure are respectively connected to the fourth connecting part and the platform, and at least part of the second telescopic structure is telescopically arranged to adjust the positional relationship between the bracket and the platform.

[0007] Furthermore, the telescopic direction of the first telescopic structure is inclined upward; and / or the telescopic direction of the second telescopic structure is inclined upward.

[0008] Furthermore, the traction assembly also includes: a driving device, which is arranged on the machine base, and the driving device has a driving shaft; a second rotating wheel, which is driven and connected to the driving shaft, one end of the traction rope is connected to the second rotating wheel and is wound around the second rotating wheel, the middle part of the traction rope is wound around the first rotating wheel, and a hook is provided on the other end of the traction rope.

[0009] Furthermore, the traction assembly also includes: a guide wheel assembly, including an extension plate and a guide wheel, the extension plate is arranged on the lifting arm, the extension plate and the first telescopic structure are respectively located on both sides of the lifting arm, the guide wheel is rotatably arranged on the extension plate and forms a guide space with the lifting arm, and the traction rope is movably located in the guide space; wherein, there is one guide wheel assembly, or there are multiple guide wheel assemblies, and the multiple guide wheel assemblies are arranged at intervals along the extension direction of the lifting arm.

[0010] Furthermore, the platform has a first mounting hole, the machine base has a second mounting hole, and the lifting assembly also includes a connecting assembly, which includes: a bearing, the outer ring of the bearing is inserted into the first mounting hole; a first fastener, the outer ring of the bearing is connected to the platform through the first fastener; a connecting shaft, the end of the connecting shaft extends into the inner ring of the bearing and is connected to the inner ring; a locking nut, the connecting shaft extends into the second mounting hole and is locked with the machine base through the locking nut.

[0011] Furthermore, the lifting device also includes: a clamping structure having a clamping space, at least part of the first connecting part extending into the clamping space; a second fastener passing through the clamping structure, the first connecting part and the machine base to connect the machine base and the bracket.

[0012] Furthermore, the first telescopic structure and / or the second telescopic structure is a jack.

[0013] Furthermore, the driving device is connected or clamped to the machine base via a third fastener.

[0014] Furthermore, the diameter of the traction rope is greater than or equal to 16 mm and less than or equal to 20 mm.

[0015] The technical solution of the present utility model includes a lifting device comprising a lifting mechanism, the lifting mechanism comprising a base, a bracket, a lifting assembly, and a first telescopic structure. The bracket is mounted on the base and has a first connecting portion, a second connecting portion, and a third connecting portion. The first connecting portion is connected to the base, and the second connecting portion is located above the first and third connecting portions. The lifting assembly includes a lifting arm and a traction assembly. The first end of the lifting arm is connected to the second connecting portion. The traction assembly includes a first rotating wheel and a traction rope wound around the first rotating wheel. The first rotating wheel is rotatably mounted on the second end of the lifting arm. The ends of the first telescopic structure are respectively connected to the third connecting portion and the middle portion of the lifting arm. At least a portion of the first telescopic structure is telescopically configured to adjust the height relationship between the first and second ends of the lifting arm. In this way, equipment and materials such as pipelines and roller frames generated at the tail of a belt conveyor can be automatically lifted by the lifting device instead of manually. This solves the problem of manual lifting and loading at the tail of a belt conveyor in the prior art, which increases the labor intensity and wastes time and effort of workers, improves production efficiency, and avoids safety accidents. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The drawings constituting part of this application are provided to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are provided to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0017] Figure 1 A structural schematic diagram of an embodiment of a lifting device according to the present utility model is shown;

[0018] Figure 2 Shown Figure 1 An enlarged schematic diagram of point A of the lifting device.

[0019] The above drawings include the following reference numerals:

[0020] 1. Platform; 2. Bearing; 3. Connecting shaft; 4. Machine base; 5. Driving device; 6. Third fastener; 7. Second rotating wheel; 8. Traction rope; 9. Bracket; 91. First connecting part; 92. Second connecting part; 93. Third connecting part; 94. Fourth connecting part; 10. Second telescopic structure; 11. Lifting arm; 12. Guide wheel; 13. First rotating wheel; 14. First telescopic structure; 15. First fastener; 16. Hook; 17. Extension plate; 18. Locking nut; 19. Clamping structure; 20. Second fastener. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0022] It should be noted that, unless otherwise specified, all technical and scientific terms used in this application have the same meaning as commonly understood by ordinary technicians in the technical field to which this application belongs.

[0023] In the present invention, unless otherwise specified, directional words such as "up" and "down" are generally used with respect to the directions shown in the drawings, or with respect to the vertical, perpendicular or gravity direction; similarly, for ease of understanding and description, "left" and "right" are generally used with respect to the left and right shown in the drawings; "inside" and "outside" refer to the inside and outside relative to the outline of each component itself, but the above directional words are not used to limit the present invention.

[0024] In order to solve the problem in the prior art that manual lifting and loading at the tail of a belt conveyor increases the labor intensity of the workers and is time-consuming and labor-intensive, the present application provides a lifting device.

[0025] like Figure 1 and Figure 2 As shown, the lifting device includes a lifting mechanism, which includes a base 4, a bracket 9, a lifting assembly, and a first telescopic structure 14. The bracket 9 is mounted on the base 4 and has a first connecting portion 91, a second connecting portion 92, and a third connecting portion 93. The first connecting portion 91 is connected to the base 4, and the second connecting portion 92 is located above the first connecting portion 91 and the third connecting portion 93. The lifting assembly includes a lifting arm 11 and a traction assembly. The first end of the lifting arm 11 is connected to the second connecting portion 92. The traction assembly includes a first rotating wheel 13 and a traction rope 8 wound around the first rotating wheel 13. The first rotating wheel 13 is rotatably mounted on the second end of the lifting arm 11. The two ends of the first telescopic structure 14 are respectively connected to the third connecting portion 93 and the middle portion of the lifting arm 11. At least a portion of the first telescopic structure 14 is telescopically mounted to adjust the height relationship between the first and second ends of the lifting arm 11.

[0026] By applying the technical solution of this embodiment, equipment materials such as pipelines and roller frames generated at the tail of the belt conveyor can be automatically lifted by a lifting device instead of manual lifting, thereby solving the problem in the prior art that the manual lifting and loading method at the tail of the belt conveyor increases the labor intensity of the staff and is time-consuming and labor-intensive, thereby improving production efficiency and avoiding safety accidents.

[0027] like Figure 1As shown, the lifting device also includes a platform 1, on which the lifting assembly is disposed. Bracket 9 also has a fourth connecting portion 94. The lifting device also includes a second telescopic structure 10, the ends of which are connected to the fourth connecting portion 94 and the platform 1, respectively. At least a portion of the second telescopic structure 10 is telescopically configured to adjust the positional relationship between bracket 9 and platform 1. Adjustment of the second telescopic structure 10 allows the relative position between bracket 9 and platform 1 to be varied, further enhancing the adaptability of the lifting device to accommodate lifting requirements at varying heights.

[0028] Optionally, the first telescopic structure 14 extends in an upward direction, and / or the second telescopic structure 10 extends in an upward direction. This upward direction makes the lifting device more stable when adjusting the boom angle and the position of the bracket 9 and the platform 1, avoiding instability caused by vertical extension and retraction, and improving operational safety.

[0029] In this embodiment, the telescopic directions of the first telescopic structure 14 and the second telescopic structure 10 are both inclined upward, which can effectively prevent the lifting device from shaking during the lifting process, ensure the stability and safety of the operation, and reduce operational risks.

[0030] like Figure 1 As shown, the traction assembly further includes a drive device 5 and a second rotating wheel 7. The drive device 5 is mounted on the machine base 4 and includes a drive shaft. The second rotating wheel 7 is drivingly connected to the drive shaft. One end of a traction rope 8 is connected to and wound around the second rotating wheel 7. The middle portion of the traction rope 8 is wound around the first rotating wheel 13. A hook 16 is provided on the other end of the traction rope 8. This configuration of the drive device 5 enables the lifting device to automatically lift heavy objects, reducing the labor burden and improving operational efficiency.

[0031] Specifically, in actual operation, the driving device 5 can automatically control the retraction and extension of the traction rope 8, which not only improves the lifting speed, but also reduces manpower consumption, reduces operating errors, and ensures production safety.

[0032] Optionally, the driving device 5 is a motor, and the driving shaft is a motor shaft.

[0033] like Figure 1As shown, the traction assembly also includes a guide wheel assembly. The guide wheel assembly comprises an extension plate 17 and a guide wheel 12. The extension plate 17 is mounted on the lifting arm 11. The extension plate 17 and the first telescopic structure 14 are located on either side of the lifting arm 11. The guide wheel 12 is rotatably mounted on the extension plate 17, forming a guide space between the extension plate 17 and the lifting arm 11. The traction rope 8 is movably positioned within the guide space. This configuration of the guide wheel assembly ensures smooth operation of the traction rope 8 during the lifting process, reduces wear on the traction rope, and extends the service life of the equipment.

[0034] Specifically, the above-mentioned setting of the guide wheel 12 can position and guide the traction rope 8 to ensure that the traction rope 8 is tightened along the preset direction to the lifting equipment, thereby improving the lifting reliability of the lifting device.

[0035] Optionally, there is one guide wheel assembly, or there are multiple guide wheel assemblies, and the multiple guide wheel assemblies are arranged at intervals along the extension direction of the lifting arm 11. In this way, the above arrangement makes the number of guide wheel assemblies more flexible to meet different usage requirements and working conditions, and also improves the processing flexibility of the staff.

[0036] In this embodiment, there are three guide wheel assemblies, which are spaced apart along the extension direction of the lifting arm 11. The distance between each guide wheel 12 and the lifting arm 11 is consistent.

[0037] It should be noted that the number of guide wheel assemblies is not limited to this and can be adjusted according to working conditions and usage requirements. Optionally, the number of guide wheel assemblies is two, four, five, six, or more.

[0038] like Figure 2 As shown, platform 1 has a first mounting hole, base 4 has a second mounting hole, and the lifting assembly also includes a connecting assembly, which includes a bearing 2, a first fastener 15, a connecting shaft 3, and a locking nut 18. The outer ring of bearing 2 is inserted into the first mounting hole. The outer ring of bearing 2 is connected to platform 1 via first fastener 15. The end of connecting shaft 3 extends into the inner ring of bearing 2 and is connected to the inner ring. Connecting shaft 3 extends into the second mounting hole and is locked with base 4 via locking nut 18. This connection method not only ensures a stable connection between the lifting mechanism and platform 1, but also facilitates disassembly, assembly, and maintenance of the lifting device.

[0039] In this embodiment, the inner ring of bearing 2 is rotatably mounted relative to the outer ring, allowing for adjustment of the relative position between base 4 and platform 1. This allows the lifting mechanism to be rotatably mounted relative to platform 1, facilitating adjustment of the lifting mechanism's position. This connection also allows for rapid removal and reinstallation of the lifting mechanism, significantly reducing the time required for relocation and improving operational flexibility.

[0040] Optionally, the first fastener 15 is a bolt or a screw.

[0041] Optionally, there is one first fastener 15 ; or, there are multiple first fasteners 15 , which are spaced apart around the center line of the bearing 2 .

[0042] In this embodiment, the locking nut 18 is threadedly connected to the connecting shaft 3 so that the two can be disassembled and assembled.

[0043] Alternatively, there is one locking nut 18; or, there are multiple locking nuts 18, with at least one locking nut 18 located above the base 4 and at least another locking nut 18 located below the base 4. This arrangement allows for more flexibility in the number of locking nuts 18 to meet different usage requirements and working conditions, and also enhances the processing flexibility of the operator.

[0044] In this embodiment, there are two locking nuts 18 , one locking nut 18 is located above the machine base 4 , and the other locking nut 18 is located below the machine base 4 .

[0045] like Figure 1 As shown, the lifting device also includes a clamping structure 19 and a second fastener 20. The clamping structure 19 defines a clamping space, into which at least a portion of the first connecting portion 91 extends. The second fastener 20 extends through the clamping structure 19, the first connecting portion 91, and the base 4 to connect the base 4 to the bracket 9. The arrangement of the clamping structure 19 further strengthens the connection between the bracket 9 and the base 4, ensuring the overall stability of the lifting device during operation, making it suitable for operations requiring high stability.

[0046] Optionally, the second fastener 20 is a screw or a bolt.

[0047] In this embodiment, the clamping structure 19 includes two clamping plates arranged opposite to each other, and a clamping space is formed between the two clamping plates.

[0048] Optionally, the first telescopic structure 14 and / or the second telescopic structure 10 is a jack. Thus, the above arrangement makes the structure of the first telescopic structure 14 and / or the second telescopic structure 10 simpler, easier to manufacture and implement, and reduces the manufacturing cost and difficulty of the first telescopic structure 14 and / or the second telescopic structure 10.

[0049] In this embodiment, the first telescopic structure 14 is a height adjustment jack, and the second telescopic structure 10 is a swing jack.

[0050] Optionally, the drive device 5 is connected or clamped to the base 4 via a third fastener 6. This arrangement provides greater flexibility in the connection between the drive device 5 and the base 4, meeting varying usage requirements and operating conditions while also enhancing operator flexibility. Furthermore, the arrangement allows for a detachable connection between the drive device 5 and the base 4, facilitating maintenance and replacement.

[0051] In this embodiment, the driving device 5 is connected to the base 4 via a third fastener 6 .

[0052] Optionally, the third fastener 6 is a screw or a bolt.

[0053] Optionally, the diameter of the traction rope 8 is greater than or equal to 16 mm and less than or equal to 20 mm.

[0054] In this embodiment, the diameter of the traction rope 8 is 18.5 mm.

[0055] In this embodiment, the lifting device is controlled by the Matil self-moving machine tail ten-valve of the ZBZ-160 type multi-purpose tunnel boring machine, connected by a DN10 pipeline and installed with a one-way lock to solve the problems of low production efficiency, high labor intensity and low safety factor caused by manual handling in the existing technology.

[0056] In this embodiment, the working principle of the lifting device is as follows:

[0057] During installation, the platform 1 is first secured to the tail frame crossbeam of the Matilda self-propelled machine. Bearing 2 and connecting shaft 3 are installed at the center of the platform 1. Bearing 2 is fixed to the top center of the platform 1 using a first fastener 15. The drive unit 5 is then placed at the top center of the machine base 4 and fixedly connected to the machine base 4 using a third fastener 6. Once the drive unit 5 and the machine base 4 are secured, bracket 9 is connected to the machine base 4 on one side of the drive unit 5 via a pin. A lifting arm 11 is fixed to one side of the bracket 9. Next, the two ends of the second telescopic structure 10 are connected to the bracket 9 and the platform 1, respectively. The two ends of the first telescopic structure 14 are connected to the lifting arm 11 and the bracket 9, respectively. Several guide wheels 12 are installed at the top of the lifting arm 11, and a first rotating wheel 13 is installed at the front end of the lifting arm 11. A traction rope 8 is connected through the second rotating wheel 7, the guide wheel 12, and the first rotating wheel 13 at the front end of the drive unit 5 to form a lifting hook for lifting.

[0058] When in use, operate the ten-valve handle to loosen the driving motor rope. After it is in place, the hook 16 bypasses the pipeline and connects with the traction rope 8 (connected from both sides of the pipeline). After the personnel evacuate the warning area, operate the ten-valve group handle to lift it to the carriage for loading.

[0059] From the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0060] The lifting device includes a lifting mechanism comprising a base, a bracket, a lifting assembly, and a first telescopic structure. The bracket is mounted on the base and has a first connecting portion, a second connecting portion, and a third connecting portion. The first connecting portion is connected to the base, and the second connecting portion is located above the first and third connecting portions. The lifting assembly includes a lifting arm and a traction assembly. The first end of the lifting arm is connected to the second connecting portion. The traction assembly includes a first rotating wheel and a traction rope wound around the first rotating wheel. The first rotating wheel is rotatably mounted on the second end of the lifting arm. The ends of the first telescopic structure are respectively connected to the third connecting portion and the middle portion of the lifting arm. At least a portion of the first telescopic structure is telescopically configured to adjust the height relationship between the first and second ends of the lifting arm. In this way, equipment and materials such as pipelines and roller frames generated at the tail of a belt conveyor can be automatically lifted by the lifting device, eliminating the need for manual lifting and loading. This solves the problem of manual lifting and loading at the tail of a belt conveyor in the prior art, which increases labor intensity and wastes time and effort for workers, improves production efficiency, and prevents safety accidents.

[0061] Obviously, the embodiments described above are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0062] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, tasks, devices, components and / or combinations thereof.

[0063] It should be noted that the terms "first," "second," and the like in the specification and claims of this application and the accompanying drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or precedence. It should be understood that the terms used in this manner are interchangeable where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0064] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A lifting device, characterized in that: The lifting mechanism comprises: Machine base (4); A bracket (9) is arranged on the machine base (4), and the bracket (9) has a first connecting portion (91), a second connecting portion (92), and a third connecting portion (93), wherein the first connecting portion (91) is connected to the machine base (4), and the second connecting portion (92) is located above the first connecting portion (91) and the third connecting portion (93); A lifting assembly comprises a lifting arm (11) and a traction assembly, wherein the first end of the lifting arm (11) is connected to the second connecting portion (92), the traction assembly comprises a first rotating wheel (13) and a traction rope (8) wound around the first rotating wheel (13), and the first rotating wheel (13) is rotatably arranged on the second end of the lifting arm (11); A first telescopic structure (14), wherein both ends of the first telescopic structure (14) are respectively connected to the third connecting portion (93) and the middle portion of the lifting arm (11), and at least a portion of the first telescopic structure (14) is telescopically arranged to adjust the height relationship between the first end and the second end of the lifting arm (11).

2. The lifting device according to claim 1, characterized in that: The lifting device further comprises a platform (1), and the lifting assembly is arranged on the platform (1); the bracket (9) further comprises a fourth connecting portion (94); the lifting device further comprises: A second telescopic structure (10), wherein both ends of the second telescopic structure (10) are respectively connected to the fourth connecting portion (94) and the platform (1), and at least a portion of the second telescopic structure (10) is telescopically arranged to adjust the positional relationship between the bracket (9) and the platform (1).

3. The lifting device according to claim 2, characterized in that: The telescopic direction of the first telescopic structure (14) is inclined upward; and / or the telescopic direction of the second telescopic structure (10) is inclined upward.

4. The lifting device according to claim 1, characterized in that: The traction assembly further comprises: A driving device (5) is arranged on the machine base (4), and the driving device (5) has a driving shaft; The second rotating wheel (7) is connected to the driving shaft, one end of the traction rope (8) is connected to the second rotating wheel (7) and is wound around the second rotating wheel (7), the middle part of the traction rope (8) is wound around the first rotating wheel (13), and the other end of the traction rope (8) is provided with a hook (16).

5. The lifting device according to claim 1, characterized in that: The traction assembly further comprises: A guide wheel assembly, comprising an extension plate (17) and a guide wheel (12), wherein the extension plate (17) is arranged on the lifting arm (11), the extension plate (17) and the first telescopic structure (14) are respectively located on both sides of the lifting arm (11), the guide wheel (12) is rotatably arranged on the extension plate (17) and forms a guide space between the guide wheel and the lifting arm (11), and the traction rope (8) is movably located in the guide space; There is one guide wheel assembly, or there are multiple guide wheel assemblies, and the multiple guide wheel assemblies are arranged at intervals along the extension direction of the lifting arm (11).

6. The lifting device according to claim 2, characterized in that: The platform (1) has a first mounting hole, the base (4) has a second mounting hole, and the lifting assembly further includes a connecting assembly, which includes: A bearing (2), the outer ring of the bearing (2) being inserted into the first mounting hole; a first fastener (15), wherein the outer ring of the bearing (2) is connected to the platform (1) via the first fastener (15); A connecting shaft (3), the end of which extends into the inner ring of the bearing (2) and is connected to the inner ring; A locking nut (18), wherein the connecting shaft (3) extends into the second mounting hole and is locked with the machine base (4) through the locking nut (18).

7. The lifting device according to claim 1, characterized in that: The lifting device also includes: A clamping structure (19) having a clamping space, wherein at least a portion of the first connecting portion (91) extends into the clamping space; A second fastener (20) is provided through the clamping structure (19), the first connecting portion (91) and the machine base (4) to connect the machine base (4) and the bracket (9).

8. The lifting device according to claim 2, characterized in that: The first telescopic structure (14) and / or the second telescopic structure (10) is a jack.

9. The lifting device according to claim 4, characterized in that: The driving device (5) is connected or clamped to the machine base (4) via a third fastener (6).

10. The lifting device according to claim 1, characterized in that: The diameter of the traction rope (8) is greater than or equal to 16 mm and less than or equal to 20 mm.

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