Round steel bending stopper

Abstract

The invention discloses a round steel bent material stopper, which relates to the technical field of round steel production, and comprises a base, a stopping assembly, a material receiving assembly and a material receiving assembly, the replacing assembly is arranged on the stopping assembly, so that the stopping assembly can quickly switch the size of the stopping inner diameter; the adjusting assembly is arranged on the stopping assembly and used for adjusting the stopping assembly; the driving assembly is arranged on the stopping assembly and used for providing power for the adjusting assembly; the measuring assembly is arranged on the stopping assembly and used for providing a specific numerical value for the adjusting quantity of the stopping assembly; through the arrangement of the replacement assembly, a fixing bolt is fixed in a limiting hole of a guide sleeve and a fixing hole of a barrel cover through the elastic force of a telescopic spring, so that the guide sleeve is fixed to a stopping barrel, when the guide sleeve needs to be replaced, the fixing bolt is pulled away from the limiting hole and the fixing hole through the magnetic force of an electromagnet, and the barrel cover is conveniently opened to replace the guide sleeve; and therefore, the inner diameter of the stopper can be quickly and conveniently changed, and the working efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of round steel production technology, and in particular to a round steel bending material preventer. Background Technology

[0002] The automatic flaw detection line in the finishing plant consists of magnetic flux leakage and ultrasonic equipment. The flaw detection equipment requires the straightness of the incoming round steel to be 2‰. If the bent steel exceeds the standard and enters the equipment, it will damage the probe of the flaw detection equipment. Although there is a straightening process before entering the flaw detection equipment, some bent steel cannot be completely straightened. Therefore, a bending material blocker needs to be added before the flaw detection equipment to prevent bent steel from entering the flaw detection equipment.

[0003] Chinese patent CN207119554U discloses a bending prevention device for round steel bars. Left and right side columns are connected to a lifting guide plate via through slots, thus restricting the lifting guide plate's freedom of movement in all directions except vertically. A lifting screw is welded to the lifting guide plate; rotating the screw allows the lifting guide plate to move up and down. A guide cylinder is mounted on the lifting guide plate; adjusting the lifting screw adjusts the center of the guide cylinder. When the round steel bar passes through the V-shaped roller, if the bending degree exceeds the limit, it will be stuck inside the guide cylinder, thus preventing the bent steel bar from passing through. This effectively prevents round bars with excessive bending at the head and tail, as well as those exceeding the bending degree per unit length, from passing through. Replacement is easy; simply adjust the height of the guide cylinder by moving the lifting screw up and down.

[0004] Although the aforementioned bending resistance device can adjust the height of the guide cylinder by lifting the screw, it uses multiple screws to mount the guide cylinder onto the lifting guide plate. When replacing the guide cylinder, it requires the use of specialized tools for disassembly, which makes changing the inner diameter of the blocking device time-consuming and laborious, reducing work efficiency. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a round steel bending material stopper, which aims to solve the technical problem that the above-mentioned devices are time-consuming and laborious to change the inner diameter of the stopping device, thus reducing work efficiency.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A round steel bending material stopper includes a base and further includes:

[0008] A blocking component, disposed on the base, is used to prevent the bending of the round steel.

[0009] Replace the component and install it on the blocking component so that the blocking component can quickly switch the size of the blocking inner diameter;

[0010] An adjustment component, disposed on the blocking component, is used to adjust the blocking component;

[0011] A drive component, disposed on the blocking component, is used to provide power to the regulating component;

[0012] A measuring component, disposed on the blocking component, is used to provide a specific value for the adjustment amount of the blocking component.

[0013] Preferably, the blocking component includes:

[0014] A fixing plate is detachably connected to the base;

[0015] A sliding groove is provided on the fixed plate;

[0016] A slider is disposed on the slide groove and slidably connected to the fixed plate;

[0017] A stop cylinder, which is fixedly connected to the slider, is used to prevent the round steel from bending.

[0018] The guide sleeve is slidably connected to the stop cylinder;

[0019] A limiting hole is provided on the guide sleeve.

[0020] Preferably, the replacement component includes:

[0021] The chain is fixedly connected to the stop cylinder;

[0022] The cylinder cap is fixedly connected to the hinge;

[0023] An electromagnet is fixedly connected to the stop cylinder;

[0024] The mounting plate is fixedly connected to the electromagnet;

[0025] A telescopic spring is fixedly connected to the mounting plate;

[0026] A fixing bolt is slidably connected to the stop cylinder, and the fixing bolt is fixedly connected to the telescopic spring;

[0027] A fixing hole is provided on the cylinder cover.

[0028] Preferably, the adjustment component includes:

[0029] A limiting plate is disposed on the fixing plate and is detachably connected to the fixing plate;

[0030] Driven pulley, rotatably connected to the limiting plate;

[0031] A base is disposed on the stop cylinder and is fixedly connected to the stop cylinder;

[0032] A threaded rod is rotatably connected to the base, the threaded rod is threadedly connected to the limiting plate, and the threaded rod is threadedly connected to the driven pulley.

[0033] Preferably, the driving component includes:

[0034] The mounting frame is fixedly connected to the limiting plate;

[0035] A shock-absorbing spring is mounted on the mounting frame and fixedly connected to the mounting frame.

[0036] The mounting block is slidably connected to the mounting frame, and the mounting block is fixedly connected to the shock-absorbing spring.

[0037] A drive motor is mounted on the mounting block and fixedly connected to the mounting block;

[0038] The drive pulley is fixedly connected to the output shaft of the drive motor;

[0039] A transmission belt is tumblingly connected to the driving pulley, and the transmission belt is tumblingly connected to the driven pulley.

[0040] Preferably, the measuring component includes:

[0041] A connecting rod is disposed on the stop cylinder and is fixedly connected to the connecting rod;

[0042] A scale is fixedly connected to the fixed plate;

[0043] The pointer is fixedly connected to the connecting rod;

[0044] A fixing post is provided on the connecting rod and is fixedly connected to the connecting rod;

[0045] The magnified viewing window is fixedly connected to the fixed column.

[0046] Preferably, the fixing bolt is slidably connected to the cylinder cover and is clearance-fitted with the fixing hole on the cylinder cover.

[0047] Preferably, the fixing bolt is slidably connected to the guide sleeve and is clearance-fitted with the limiting hole on the guide sleeve.

[0048] Preferably, the fixing bolt is made of cobalt metal, which has strong permanent magnetism, high hardness, and corrosion resistance.

[0049] Preferably, the stop cylinder and the guide sleeve are made of high-chromium alloy cast iron with high hardness and high wear resistance.

[0050] Preferably, there are several guide sleeves, and the inner diameter of each guide sleeve corresponds one-to-one with a round steel bar of different specifications.

[0051] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0052] By changing the component settings, the tension spring is used to fix the fixing bolt in the limiting hole of the guide sleeve and the fixing hole of the cylinder cover, so that the guide sleeve is fixed on the stop cylinder. When the guide sleeve needs to be replaced, the magnetic force of the electromagnet is used to pull the fixing bolt away from the limiting hole and the fixing hole, so that the cylinder cover can be opened to replace the guide sleeve. In this way, the inner diameter of the stopper can be changed quickly and conveniently, improving work efficiency. Attached Figure Description

[0053] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0054] Figure 1 A three-dimensional structural schematic diagram of a round steel bending material stopper is shown.

[0055] Figure 2 A first partial cross-sectional view of a round steel bending material stopper is shown.

[0056] Figure 3 It shows Figure 2 A magnified view of a portion of point A in the middle.

[0057] Figure 4 A second partial cross-sectional view of a round steel bending material stopper is shown.

[0058] Figure 5 It shows Figure 4 A magnified view of a portion of point B in the middle.

[0059] Figure 6 A third partial cross-sectional view of a round steel bending material stopper is shown.

[0060] Figure 7 It shows Figure 6 A magnified view of a portion of point C.

[0061] Figure 8 A fourth partial cross-sectional view of a round steel bending material stopper is shown.

[0062] Figure 9 It shows Figure 8 A magnified view of a portion of point D.

[0063] Legend:

[0064] 1. Base; 2. Stop cylinder; 3. Hinge; 4. Cylinder cover; 5. Electromagnet; 6. Mounting plate; 7. Telescopic spring; 8. Fixing bolt; 9. Fixing hole; 10. Fixing plate; 11. Slide groove; 12. Slider; 13. Guide sleeve; 14. Limiting hole; 15. Limiting plate; 16. Driven pulley; 17. Base; 18. Threaded rod; 19. Mounting frame; 20. Shock-absorbing spring; 21. Mounting block; 22. Drive motor; 23. Drive pulley; 24. Transmission belt; 25. Connecting rod; 26. Scale; 27. Pointer; 28. Fixing post; 29. ​​Magnifying window. Detailed Implementation

[0065] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0066] In the description of this invention, it should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not 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.

[0067] It should be noted that when a component is described as "fixed to" another component, it can be directly on the other component or may have a component in between. When a component is considered "connected to" another component, it can be directly connected to the other component or may have a component in between. When a component is considered "set on" another component, it can be directly set on the other component or may have a component in between. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0068] Furthermore, the terms "first" and "second" 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" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0069] Reference Figures 1 to 9The following is a further description of an embodiment of a round steel bending material stopper of the present invention.

[0070] A round steel bending material stopper includes a base 1, and further includes:

[0071] A blocking component, disposed on base 1, is used to prevent the bending of the round steel bar. The blocking component includes:

[0072] The fixing plate 10 is detachably connected to the base 1;

[0073] The slide 11 is provided on the fixed plate 10;

[0074] The slider 12 is disposed on the slide groove 11 and is slidably connected to the fixed plate 10;

[0075] The stop cylinder 2 is fixedly connected to the slider 12 and is used to prevent the round steel from bending. The stop cylinder 2 and the guide sleeve 13 are made of high-chromium alloy cast iron with high hardness and high wear resistance.

[0076] Guide sleeve 13 is slidably connected to stop cylinder 2. There are several guide sleeves 13, and the inner diameter of each guide sleeve 13 corresponds to a round steel of different specifications.

[0077] Limiting hole 14 is provided on guide sleeve 13.

[0078] Reference Figures 1 to 9 Replace components and configure the blocking component to allow for quick switching of the blocking inner diameter size. Component replacement includes:

[0079] The chain is fixedly connected to the stop cylinder 2;

[0080] The cylinder cover 4 is fixedly connected to the hinge 3;

[0081] Electromagnet 5 is fixedly connected to stop cylinder 2;

[0082] Mounting plate 6 is fixedly connected to electromagnet 5;

[0083] The telescopic spring 7 is fixedly connected to the mounting plate 6;

[0084] The fixing bolt 8 is slidably connected to the stop cylinder 2. The fixing bolt 8 is fixedly connected to the telescopic spring 7. The fixing bolt 8 is slidably connected to the cylinder cover 4 and is clearance-fitted with the fixing hole 9 on the cylinder cover 4. The fixing bolt 8 is slidably connected to the guide sleeve 13 and is clearance-fitted with the limiting hole 14 on the guide sleeve 13. The fixing bolt 8 is made of cobalt metal with strong permanent magnetism, high hardness and corrosion resistance.

[0085] Fixing hole 9 is provided on cylinder cover 4.

[0086] When the electromagnet 5 is activated, the magnetic force generated by the electromagnet 5 attracts the fixing bolt 8, which is fixed to the telescopic spring 7, to move until the fixing bolt 8 disengages from the fixing hole 9. The cylinder cover 4, which is fixed to the stop cylinder 2 by the hinge 3, is then opened. Next, the guide sleeve 13, which is slidably connected to the stop cylinder 2, is pulled out and another guide sleeve 13 with an inner diameter corresponding to the diameter of the replaced round steel is inserted. The cylinder cover 4 is closed and the electromagnet 5 is turned off. The fixing bolt 8, which is no longer magnetically bound, moves towards the limiting hole 14 under the elastic force of the fixedly connected telescopic spring 7 until the fixing bolt 8 is fully inserted into the limiting hole 14 after passing through the fixing hole 9, thus achieving the effect of quickly replacing the guide sleeve 13.

[0087] By changing the component settings, the tension spring 7 is used to fix the fixing bolt 8 in the limiting hole 14 of the guide sleeve 13 and the fixing hole 9 of the cylinder cover 4, so that the guide sleeve 13 is fixed on the stop cylinder 2. When the guide sleeve 13 needs to be replaced, the magnetic force of the electromagnet 5 is used to pull the fixing bolt 8 away from the limiting hole 14 and the fixing hole 9, so that the cylinder cover 4 can be opened to replace the guide sleeve 13. This allows the stopper to quickly and conveniently change the inner diameter of the stopper, improving work efficiency.

[0088] Reference Figures 1 to 9 An adjustment component, set on the blocking component, is used to adjust the blocking component. The adjustment component includes:

[0089] The limiting plate 15 is disposed on the fixing plate 10 and is detachably connected to the fixing plate 10;

[0090] Driven pulley 16 is rotatably connected to limit plate 15;

[0091] The base 17 is mounted on the stop cylinder 2 and is fixedly connected to the stop cylinder 2;

[0092] The threaded rod 18 is rotatably connected to the base 17. The threaded rod 18 is threadedly connected to the limiting plate 15 and the driven pulley 16.

[0093] When the driven pulley 16 rotates, it drives the threaded rod 18 connected by the thread to rotate and move upward or downward at the same time. This causes the base 17, which is rotatably connected to the threaded rod 18, to move upward or downward. The movement of the base 17 causes the stop cylinder 2, which is fixedly connected to the base 17, to move. The stop cylinder 2 is fixedly connected to the slider 12 on the slide groove 11, so the stop cylinder 2 can only move vertically upward or downward along the slide groove 11 to achieve the adjustment effect.

[0094] Reference Figures 1 to 9 A drive component, disposed on the stop component, is used to provide power to the regulating component. The drive component includes:

[0095] Mounting frame 19 is fixedly connected to limiting plate 15;

[0096] The shock-absorbing spring 20 is mounted on the mounting frame 19 and is fixedly connected to the mounting frame 19.

[0097] Mounting block 21 is slidably connected to mounting frame 19, and mounting block 21 is fixedly connected to shock absorber spring 20;

[0098] The drive motor 22 is mounted on the mounting block 21 and is fixedly connected to the mounting block 21.

[0099] The drive pulley 23 is fixedly connected to the output shaft of the drive motor 22;

[0100] The transmission belt 24 is tumblingly connected to the driving pulley 23, and the transmission belt 24 is tumblingly connected to the driven pulley 16.

[0101] When the drive motor 22 is started, the output shaft of the drive motor 22 rotates, causing the drive pulley 23, which is fixedly connected to the output shaft of the drive motor 22, to rotate. This, in turn, causes the transmission belt 24, which is rolledly connected to the drive pulley 23, to move. The movement of the transmission belt 24 causes the driven pulley 16, which is rolledly connected to the transmission belt 24, to rotate, thus providing power. Furthermore, under the action of the damping spring 20, the impact force of the bent round steel impact stopper is absorbed and the adverse effects of vibration on the drive motor 22 are reduced.

[0102] Reference Figures 1 to 9 A measuring component, disposed on the blocking component, is used to provide a specific value for the adjustment amount of the blocking component. The measuring component includes:

[0103] A connecting rod 25 is mounted on the stop cylinder 2 and is fixedly connected to the connecting rod 25.

[0104] The scale 26 is fixedly connected to the fixing plate 10;

[0105] Pointer 27 is fixedly connected to connecting rod 25;

[0106] The fixing post 28 is set on the connecting rod 25 and is fixedly connected to the connecting rod 25;

[0107] The magnified viewing window 29 is fixedly connected to the fixed post 28.

[0108] When the stop cylinder 2 moves vertically upwards or downwards, it drives the connecting rod 25, which is fixedly connected to the stop cylinder 2, to move. This, in turn, drives the pointer 27, which is fixedly connected to the connecting rod 25, to move. Simultaneously, the movement of the connecting rod 25 drives the fixed column 28, which is fixedly connected to the connecting rod 25, to move. This causes the magnifying window 29 to move synchronously with the pointer 27 until the pointer 27 is seen pointing to the scale on the scale plate at the specified height in the magnifying window 29. Then, the drive motor 22 is turned off, achieving the effect of precisely adjusting the height of the stop cylinder 2.

[0109] Working principle: Refer to Figures 1 to 9When the height of the stop cylinder 2 needs to be adjusted, the drive motor 22 is started. The output shaft of the drive motor 22 rotates, which drives the drive pulley 23 fixedly connected to the output shaft of the drive motor 22 to rotate, thereby driving the transmission belt 24 rolledly connected to the drive pulley 23 to move. The movement of the transmission belt 24 drives the driven pulley 16 rolledly connected to the transmission belt 24 to rotate, thus achieving the effect of providing power. Under the action of the shock-absorbing spring 20, the impact force of the bent round steel hitting the stopper is absorbed and the adverse effects of vibration on the drive motor 22 are reduced.

[0110] Since the driven pulley 16 is rotatably connected to the limiting plate 15, and the threaded rod 18 is threadedly connected to the driven pulley 16, when the driven pulley 16 rotates, it drives the threaded rod 18 to rotate while moving upward or downward, thereby driving the base 17, which is rotatably connected to the threaded rod 18, to move upward or downward. The movement of the base 17 drives the stop cylinder 2, which is fixedly connected to the base 17, to move. The stop cylinder 2 is fixedly connected to the slider 12 on the slide groove 11, so the stop cylinder 2 can only move vertically upward or downward along the slide groove 11 to achieve the adjustment effect.

[0111] Reference Figures 1 to 8 When the stop cylinder 2 moves vertically upward or downward, it drives the connecting rod 25, which is fixedly connected to the stop cylinder 2, to move. This causes the pointer 27, which is fixedly connected to the connecting rod 25, to move. At the same time, the connecting rod 25 moves, causing the fixed column 28, which is fixedly connected to the connecting rod 25, to move. This causes the magnifying window 29 and the pointer 27 to move synchronously until the pointer 27 is seen to point to the scale on the scale plate at the specified height in the magnifying window 29. Then, the drive motor 22 is turned off, thus achieving the effect of precisely adjusting the height of the stop cylinder 2.

[0112] When changing the specifications of the round steel, the electromagnet 5 is activated. The magnetic force generated by the electromagnet 5 attracts the fixing bolt 8, which is fixed to the telescopic spring 7, to move until the fixing bolt 8 disengages from the fixing hole 9. The cylinder cover 4, which is fixed to the stop cylinder 2 by the hinge 3, is then opened. Next, the guide sleeve 13, which is slidably connected to the stop cylinder 2, is pulled out and another guide sleeve 13 with an inner diameter corresponding to the diameter of the replaced round steel is inserted. The cylinder cover 4 is closed and the electromagnet 5 is turned off. The fixing bolt 8, which is no longer magnetically bound, moves towards the limiting hole 14 under the elastic force of the fixedly connected telescopic spring 7 until the fixing bolt 8 is fully inserted into the limiting hole 14 after passing through the fixing hole 9, thus achieving the effect of quickly replacing the guide sleeve 13.

[0113] The above description of the embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A round steel bending stock stopper comprising a base (1), characterized in that, Also include: Preventive components, set on the base (1), for preventing the bending of round steel; Replacement components, set on the prevention component, so that the prevention component can quickly switch the inner diameter size; Preventive cylinder (2) for preventing the bending of round steel; The replacement component includes: Hinge (3) fixedly connected to the prevention cylinder (2); Cylinder cover (4) fixedly connected to the hinge (3); Electromagnet (5) fixedly connected to the prevention cylinder (2), Mounting plate (6) fixedly connected to the electromagnet (5); Telescopic spring (7) fixedly connected to the mounting plate (6); Fixed bolt (8) slidingly connected to the prevention cylinder (2), the fixed bolt (8) is fixedly connected with the telescopic spring (7); Fixed hole (9) provided on the cylinder cover (4); Adjusting component, provided on the prevention component, for adjusting the prevention component; Drive component, provided on the prevention component, for providing power for the adjusting component; Measuring component, provided on the prevention component, for providing specific values for the adjusting amount of the prevention component.

2. A round steel bending stock stop according to claim 1, characterized in that The prevention component includes: Fixed plate (10) detachably connected to the base (1); Slide groove (11) provided on the fixed plate (10); Slide block (12) provided on the slide groove (11) and slidingly connected with the fixed plate (10), the prevention cylinder (2) is fixedly connected with the slide block (12); Guide sleeve (13) slidingly connected to the prevention cylinder (2); Limiting hole (14) provided on the guide sleeve (13).

3. A round steel bending stock stop according to claim 2, characterized in that The adjusting component includes: Limiting plate (15) provided on the fixed plate (10) and detachably connected with the fixed plate (10); Driven pulley (16) rotatably connected to the limiting plate (15); Base (17) provided on the prevention cylinder (2) and fixedly connected with the prevention cylinder (2); Threaded rod (18) rotatably connected to the base (17), the threaded rod (18) is threadedly connected with the limiting plate (15), and the threaded rod (18) is threadedly connected with the driven pulley (16).

4. A round steel bending stock stop according to claim 3, characterized in that The drive component includes: Mounting frame (19) fixedly connected to the limiting plate (15); Damping spring (20) provided on the mounting frame (19) and fixedly connected with the mounting frame (19); Mounting block (21) slidingly connected to the mounting frame (19), the mounting block (21) is fixedly connected with the damping spring (20); Drive motor (22) provided on the mounting block (21) and fixedly connected with the mounting block (21); Driving pulley (23) fixedly connected to the output shaft of the drive motor (22); Transmission belt (24) rollingly connected to the driving pulley (23), the transmission belt (24) is rollingly connected with the driven pulley (16).

5. A round steel bending stock stop according to claim 4, characterized in that The measuring component includes: Connecting rod (25) provided on the prevention cylinder (2) and fixedly connected with the connecting rod (25); Scale (26) fixedly connected to the fixed plate (10); A pointer (27) is fixedly connected to the connecting rod (25); A fixed column (28) is arranged on the connecting rod (25) and is fixedly connected with the connecting rod (25); An enlarged window (29) is fixedly connected to the fixed column (28).

6. A round steel bending stock stop according to claim 5, characterized in that The fixed bolt (8) is in sliding connection with the barrel cover (4) and is in clearance fit with the fixed hole (9) on the barrel cover (4).

7. A round steel bending stock stop according to claim 6, characterized in that The fixed bolt (8) is in sliding connection with the guide sleeve (13) and is in clearance fit with the limiting hole (14) on the guide sleeve (13).

8. A round steel bending stock stop according to claim 7, characterized in that The fixed bolt (8) is made of metal cobalt with strong permanent magnetism, high hardness and corrosion resistance.

9. A round steel bending stock stop according to claim 8, characterized in that The blocking barrel (2) and the guide sleeve (13) are made of high chromium alloy cast iron with high hardness and high wear resistance.

10. A round steel bending stock stop according to claim 9, characterized in that The guide sleeve (13) has a plurality of inner diameters corresponding to different specifications of round steel.

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