Building steel structure protection welding equipment

Abstract

The invention discloses building steel structure protection welding equipment, and relates to the technical field of building steel structure welding, the building steel structure protection welding equipment comprises two mounting semi-rings, a connecting mechanism is arranged between the two mounting semi-rings, elastic pressing mechanisms are arranged on the mounting semi-rings, and the elastic pressing mechanisms are connected with moving wheel mechanisms; the moving wheel mechanism is located in the two mounting semi-rings, a rotary moving mechanism is arranged on the mounting semi-rings, a feeding welding mechanism is arranged on the rotary moving mechanism, a deflection adjusting plate mechanism is arranged on the mounting semi-rings, and a plurality of elastic barrier plate mechanisms are arranged on the deflection adjusting plate mechanism; the feeding state of the moving wheel mechanism can be adjusted by arranging the elastic pressing mechanism, so that the moving wheel mechanism abuts against the surface of a steel structure, moving welding treatment can be achieved by cooperating with the moving wheel mechanism, the state of the elastic blocking plate mechanism is adjusted through the deflection adjusting plate mechanism, and the welding quality is improved. The device adapts to protection of steel structures of different sizes, and the welding protection performance of the building steel structure is improved.

Description

Technical Field

[0001] This invention relates to the field of welding technology for building steel structures, specifically a protective welding device for building steel structures. Background Technology

[0002] Steel structures are widely used in modern construction projects such as large factories, high-rise buildings, and bridges due to their high strength, light weight, and short construction period. During steel structure installation, on-site welding is a critical process, and its quality directly affects the safety and durability of the structure. Currently, steel structure welding is mainly done manually, which has the following drawbacks: Low welding efficiency: For long welds or circumferential welds, workers need to move frequently, which is labor-intensive and makes it difficult to ensure the stability of welding speed and quality.

[0003] Severe spattering during welding: The hot slag generated during welding splashes everywhere, polluting the environment, posing a fire hazard, and endangering the safety of workers and equipment below. Traditional protection methods often use asbestos cloth or barriers for temporary shielding, but these are inconvenient to fix and cannot be moved with the welding position.

[0004] Poor adaptability: Different specifications of steel structures (such as steel pipes of different diameters and steel sections of different cross sections) require different welding equipment and protective measures, and on-site replacement and adjustment are cumbersome.

[0005] Low level of automation: Existing automated welding equipment is mostly used for factory prefabrication and is difficult to adapt to complex on-site working conditions, especially for circumferential welds for high-altitude operations, where there is a lack of dedicated equipment that can move automatically and provide synchronous protection.

[0006] Therefore, there is an urgent need for a protective welding equipment that can automatically move along the steel structure, weld in real time, effectively collect weld slag, and adapt to various specifications of steel structures. Summary of the Invention

[0007] This invention provides a protective welding device for building steel structures, which solves the problems mentioned in the background art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A protective welding device for building steel structures includes two mounting half-rings connected by a connecting mechanism. Each mounting half-ring has an elastic clamping mechanism connected to a moving wheel mechanism located within the two mounting half-rings. A rotating moving mechanism with a feeding welding mechanism is also provided on each mounting half-ring. A deflection adjusting plate mechanism with several elastic blocking plate mechanisms evenly spaced circumferentially on the deflection adjusting plate mechanism is also included. The connecting mechanism connects the two mounting half-rings. The elastic clamping mechanism drives the moving wheel mechanism to feed and shift, allowing it to move along the steel structure. The rotating moving mechanism rotates and shifts along the mounting half-rings. The feeding welding mechanism welds the steel structure. The deflection adjusting plate mechanism drives the elastic blocking plate mechanisms to deflect and shift, adapting to different sizes of steel structures for protection. The elastic blocking plate mechanisms collect welding slag generated during welding.

[0009] As a preferred embodiment of the present invention, the mounting semi-ring includes a semi-circular plate, and two symmetrically arranged connecting plates are provided on the side of the semi-circular plate, and an arc-shaped toothed rack is fixedly connected to the side of the semi-circular plate.

[0010] As a preferred embodiment of the present invention, the connecting mechanism includes a connecting bolt, which passes through a connecting plate and is threadedly connected to a nut.

[0011] As a preferred embodiment of the present invention, the elastic pressing mechanism includes a first linear motor fixed to the outside of the semicircular plate, an adjusting plate fixedly connected to the end of the first linear motor away from the semicircular plate, a pressing mechanism fixedly connected to the adjusting plate, the pressing mechanism passing through the semicircular plate, and the pressing mechanism fixedly connected to the pressing plate.

[0012] In a preferred embodiment of the present invention, the clamping mechanism includes a clamping sleeve fixed to an adjusting plate, a first elastic element fixedly connected inside the clamping sleeve, a clamping block fixedly connected to the first elastic element, the clamping block located inside the clamping sleeve, the clamping block and the clamping sleeve being slidably connected, a clamping rod fixedly connected to the clamping block, the clamping rod passing through the clamping sleeve, the clamping rod and the clamping sleeve being slidably connected, the clamping rod passing through a semi-circular plate, the clamping rod and the semi-circular plate being slidably connected, and the clamping rod and the clamping plate being fixedly connected.

[0013] As a preferred embodiment of the present invention, the movable wheel mechanism includes a movable wheel frame fixed to the pressure plate, a first motor is provided on the movable wheel frame, the output shaft of the first motor is fixedly connected to the movable wheel, the movable wheel and the movable wheel frame are rotatably connected, and the cross-section of the movable wheel has a concave structure in the middle.

[0014] As a preferred embodiment of the present invention, the rotary moving mechanism includes a movable shell that is slidably connected to a semi-circular plate. The movable shell is provided with an arc-shaped groove, the semi-circular plate is located in the arc-shaped groove, the movable shell is provided with a motor base, the motor base is provided with a second motor, the output shaft of the second motor is fixedly connected to a drive gear, and the drive gear meshes with an arc-shaped rack.

[0015] As a preferred embodiment of the present invention, the feeding welding mechanism includes a second linear motor fixed to the inside of the movable housing, with the welding head fixedly connected to the end of the second linear motor away from the movable housing, and a vision sensor provided on the inside of the movable housing.

[0016] As a preferred embodiment of the present invention, the deflection adjustment plate mechanism includes a first deflection seat fixed to the bottom of the outer side of the semicircular plate, the first deflection seat being rotatably connected to a deflection rod, the bottom of the deflection rod being fixedly connected to an arc plate, the semicircular plate being fixedly connected to a second deflection seat, the second deflection seat being rotatably connected to a third linear motor, the end of the third linear motor away from the second deflection seat being rotatably connected to the third deflection seat, and the third deflection seat and the deflection rod being fixedly connected.

[0017] As a preferred embodiment of the present invention, the elastic baffle mechanism includes a rigid elastic plate fixed to the inner side of the semicircular plate. The lower end of the rigid elastic plate passes through the semicircular plate, and the end of the rigid elastic plate is fixedly connected to a baffle. The baffle is located on the outer side of the semicircular plate. Without external force, the baffle adheres to the outer wall of the semicircular plate, and the rigid elastic plate protrudes towards the inner center.

[0018] The present invention has the following advantages: 1. Achieve automated mobile welding and improve efficiency: The elastic clamping mechanism keeps the moving wheel mechanism pressed against the steel structure surface at all times. Combined with the motor drive within the moving wheel mechanism, the equipment can move automatically along the steel structure. Simultaneously, the rotating moving mechanism can rotate along the installation semi-ring, driving the feed welding mechanism to perform circumferential welding, achieving automated circumferential weld welding, significantly reducing manual intervention and improving welding efficiency.

[0019] 2. Slag Collection and Protection for Safety: The deflection adjustment plate mechanism can drive the elastic baffle plate mechanism to deflect, causing the rigid elastic plate to adhere to the steel structure surface, forming a ring-shaped protective cover. Weld slag generated during welding is blocked and collected by the elastic baffle plate, preventing splashing, eliminating fire hazards, and protecting the safety of workers and equipment below.

[0020] 3. Adaptable to different steel structures, highly versatile: The first linear motor in the elastic clamping mechanism can adjust the clamping force, allowing the moving wheels to adapt to steel structures of different diameters. The deflection adjustment plate mechanism drives the deflection rod to swing through the third linear motor, adjusting the position of the arc plate, thereby changing the tension of the elastic blocking plate, adapting to steel pipes of different diameters or steel sections of different cross-sections, without the need to replace parts, and convenient on-site adjustment.

[0021] 4. Elastic clamping for stable movement: The clamping mechanism adopts a combination structure of sleeve, elastic element and clamping rod, so that the moving wheel has a certain elastic buffer when it comes into contact with the steel structure. This can not only ensure sufficient clamping force to prevent slippage, but also adapt to the slight unevenness of the steel structure and ensure smooth movement.

[0022] 5. High welding precision and controllable quality: The rotary moving mechanism uses gear and arc-shaped rack meshing transmission, and the moving shell slides smoothly along the semi-circular plate with precise positioning. The second linear motor in the feed welding mechanism can control the feed of the welding head, and together with the vision sensor, it realizes weld seam tracking to ensure welding quality.

[0023] 6. Compact structure and easy installation: The two installation half-rings can be quickly combined into a complete ring frame through the connecting mechanism, which is wrapped around the outside of the steel structure. It is easy to install and disassemble and is suitable for on-site high-altitude operations.

[0024] 7. Modular design, simple maintenance: The modular integration of each functional mechanism facilitates inspection and replacement, reducing maintenance costs. Attached Figure Description

[0025] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0026] Figure 1 This is a first-person structural schematic diagram of a protective welding device for building steel structures.

[0027] Figure 2 This is a second-view structural schematic diagram of a protective welding device for building steel structures.

[0028] Figure 3 This is a third-view structural schematic diagram of a protective welding device for building steel structures.

[0029] Figure 4 This is a partial structural schematic diagram of a protective welding device for building steel structures.

[0030] Figure 5 This is a cross-sectional view of the clamping mechanism in a protective welding device for building steel structures.

[0031] In the diagram: 1. Mounting semi-ring; 101. Semi-circular plate; 102. Connecting plate; 103. Arc-shaped rack; 2. Connecting mechanism; 201. Connecting bolt; 202. Nut; 3. Elastic clamping mechanism; 301. First linear motor; 302. Adjusting plate; 303. Clamping mechanism; 3031. Clamping sleeve; 3032. First elastic element; 3033. Clamping block; 3034. Clamping rod; 304. Clamping plate; 4. Moving wheel mechanism; 401. Moving wheel frame; 402. First motor; 403. Moving wheel... 5. Wheel; 6. Rotary moving mechanism; 501. Moving shell; 502. Motor base; 503. Second motor; 504. Drive gear; 7. Feed welding mechanism; 601. Second linear motor; 602. Welding head; 8. Deflection adjustment plate mechanism; 701. First deflection seat; 702. Deflection rod; 703. Arc plate; 704. Second deflection seat; 705. Third linear motor; 706. Third deflection seat; 9. Elastic blocking plate mechanism; 801. Hard elastic plate; 802. Baffle; 10. Vision sensor. Detailed Implementation

[0032] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0033] It should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "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 the present 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 the present invention.

[0034] For examples, please refer to Figures 1-5A protective welding device for building steel structures includes two mounting semi-rings 1, with a connecting mechanism 2 between them. Each mounting semi-ring 1 has an elastic clamping mechanism 3 connected to a moving wheel mechanism 4 located within the two mounting semi-rings 1. Each mounting semi-ring 1 also has a rotating moving mechanism 5, a feeding welding mechanism 6, and a deflection adjusting plate mechanism 7. The deflection adjusting plate mechanism 7 has several elastic blocking plate mechanisms 8. The deflection adjustment plate mechanism 7 is circumferentially spaced at equal intervals; the connecting mechanism 2 is used to connect the two mounting half-rings 1; the elastic clamping mechanism 3 is used to drive the moving wheel mechanism 4 to feed and change position; the moving wheel mechanism 4 is used to move along the steel structure; the rotating moving mechanism 5 is used to rotate and change position along the mounting half-ring 1; the feeding welding mechanism 6 is used to weld the steel structure; the deflection adjustment plate mechanism 7 is used to drive the elastic blocking plate mechanism 8 to deflect and change position, adapting to the protection of steel structures of different sizes; and the elastic blocking plate mechanism 8 is used to collect the welding slag generated during welding.

[0035] The mounting semi-ring 1 includes a semi-circular plate 101, and two symmetrically arranged connecting plates 102 are provided on the side of the semi-circular plate 101. An arc-shaped rack 103 is fixedly connected to the side of the semi-circular plate 101.

[0036] The connecting mechanism 2 includes a connecting bolt 201, which passes through the connecting plate 102 and is threadedly connected to a nut 202.

[0037] The elastic pressing mechanism 3 includes a first linear motor 301 fixed to the outside of the semicircular plate 101. The end of the first linear motor 301 away from the semicircular plate 101 is fixedly connected to an adjusting plate 302. The adjusting plate 302 is fixedly connected to a pressing mechanism 303. The pressing mechanism 303 passes through the semicircular plate 101 and is fixedly connected to a pressing plate 304. The clamping mechanism 303 includes a clamping sleeve 3031 fixed on the adjusting plate 302, a first elastic element 3032 fixedly connected inside the clamping sleeve 3031, a clamping block 3033 fixedly connected to the first elastic element 3032, the clamping block 3033 located inside the clamping sleeve 3031, the clamping block 3033 and the clamping sleeve 3031 slidably connected, the clamping block 3033 fixedly connected to the clamping rod 3034, the clamping rod 3034 passing through the clamping sleeve 3031, the clamping rod 3034 and the clamping sleeve 3031 slidably connected, the clamping rod 3034 passing through the semi-circular plate 101, the clamping rod 3034 and the semi-circular plate 101 slidably connected, and the clamping rod 3034 and the clamping plate 304 fixedly connected. The movable wheel mechanism 4 includes a movable wheel frame 401 fixed on the pressure plate 304. A first motor 402 is provided on the movable wheel frame 401. The output shaft of the first motor 402 is fixedly connected to the movable wheel 403. The movable wheel 403 and the movable wheel frame 401 are rotatably connected. The cross-section of the movable wheel 403 is a concave structure in the middle.

[0038] Specifically, when the first linear motor 301 drives the adjusting plate 302 to move, the force is transmitted to the pressing plate 304 through the pressing mechanism 303. The pressing plate 304 drives the moving wheel mechanism 4 to move closer to or away from the steel structure. The first elastic element 3032 provides elastic buffering, giving the pressing force a certain degree of flexibility. The cross-section of the moving wheel 403 has a concave structure in the middle, which forms a good fit with the surface of the circular steel pipe, preventing deviation during movement. Multiple elastic pressing mechanisms 3 and moving wheel mechanisms 4 can be set on each mounting semi-ring 1 (two are set on each semi-circular plate 101 in this embodiment) to ensure stable movement of the equipment.

[0039] The rotary moving mechanism 5 includes a movable housing 501 slidably connected to the semicircular plate 101. The movable housing 501 has an arc-shaped groove, and the semicircular plate 101 is located in the arc-shaped groove. The movable housing 501 has a motor base 502, and the motor base 502 has a second motor 503. The output shaft of the second motor 503 is fixedly connected to a drive gear 504, and the drive gear 504 meshes with the arc-shaped rack 103. The feeding welding mechanism 6 includes a second linear motor 601 fixed to the inside of the movable housing 501. The end of the second linear motor 601 away from the movable housing 501 is fixedly connected to a welding head 602. A vision sensor 9 is provided on the inside of the movable housing 501.

[0040] Specifically, when the second motor 503 starts, it drives the gear 504 to rotate, causing the movable housing 501 to move along the arc-shaped trajectory of the semi-circular plate 101. The second linear motor 601 can drive the welding head 602 to feed radially, so as to approach or move away from the steel structure surface. A vision sensor 9 is also provided on the inner side of the movable housing 501 to detect the weld position and achieve automatic tracking.

[0041] The deflection adjustment plate mechanism 7 includes a first deflection seat 701 fixed to the bottom of the outer side of the semicircular plate 101, the first deflection seat 701 is rotatably connected to the deflection rod 702, the bottom of the deflection rod 702 is fixedly connected to the arc plate 703, the semicircular plate 101 is fixedly connected to the second deflection seat 704, the second deflection seat 704 is rotatably connected to the third linear motor 705, the end of the third linear motor 705 away from the second deflection seat 704 is rotatably connected to the third deflection seat 706, and the third deflection seat 706 and the deflection rod 702 are fixedly connected. The elastic baffle mechanism 8 includes a rigid elastic plate 801 fixed to the inner side of the semicircular plate 101. The lower end of the rigid elastic plate 801 passes through the semicircular plate 101, and the end of the rigid elastic plate 801 is fixedly connected to a baffle 802. The baffle 802 is located on the outer side of the semicircular plate 101. Without external force, the baffle 802 adheres to the outer wall of the semicircular plate 101, and the rigid elastic plate 801 protrudes towards the inner center.

[0042] Specifically, when the third linear motor 705 extends or retracts, it drives the deflection rod 702 to swing around the first deflection seat 701, thereby changing the position of the arc-shaped plate 703. When the arc-shaped plate 703 of the deflection adjustment plate mechanism 7 moves, it can compress or release the rigid elastic plate 801, changing its protrusion and making it fit tightly against the steel structure surface to form an annular protective cover. The welding slag generated during welding is blocked and collected by the rigid elastic plate 801 and the baffle 802.

[0043] The workflow of this invention is as follows: 1. Equipment installation: Wrap the two installation half-rings 1 around the outside of the steel structure (such as steel pipe) to be welded, and lock them in place by the connecting bolts 201 and nuts 202 of the connecting mechanism 2 to fix the equipment on the steel structure.

[0044] 2. Pressing adjustment: Start the first linear motor 301 to drive the pressing mechanism 303 so that the moving wheel 403 presses against the steel structure surface to ensure stable walking and no slippage.

[0045] 3. Protection Adjustment: Based on the diameter of the steel structure, the third linear motor 705 is activated, driving the deflection rod 702 to swing, causing the arc-shaped plate 703 to press or release the rigid elastic plate 801, adjusting its protrusion so that the inner side of the rigid elastic plate 801 is tightly attached to the surface of the steel structure, forming a ring-shaped protective cover. The baffle 802 is located outside the semi-circular plate 101, used to collect any welding slag that may splash out.

[0046] 4. Welding preparation: Identify the weld position using a vision sensor, start the second linear motor 601 to adjust the radial feed of the welding head 602, and align the welding torch with the weld.

[0047] 5. Automatic Welding: The first motor 402 of the moving wheel mechanism 4 is activated, driving the moving wheel 403 to rotate, causing the equipment to move axially along the steel structure (if axial welding is required). Simultaneously, the second motor 503 of the rotating moving mechanism 5 is activated, driving the moving shell 501 to move circumferentially along the mounting semi-ring 1, thereby driving the welding head 602 to perform circumferential weld welding. During the welding process, the elastic baffle plate mechanism 8 continuously blocks the welding slag.

[0048] 6. Welding completed: After welding is completed, all mechanisms are reset, connection mechanism 2 is loosened, and the equipment is removed from the steel structure.

[0049] Through the above design, this invention enables automated walking welding and real-time slag protection for building steel structures, significantly improving the efficiency and safety of on-site welding.

[0050] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A protective welding device for building steel structures, comprising an installation semi-ring, characterized in that, The installation half-ring consists of two parts, connected by a connecting mechanism. Each half-ring has an elastic clamping mechanism connected to a moving wheel mechanism located within the two half-rings. A rotating moving mechanism with a feeding welding mechanism is also present on each half-ring. A deflection adjusting plate mechanism with several elastic blocking plate mechanisms is also present on the half-ring, spaced circumferentially. The connecting mechanism connects the two half-rings, the elastic clamping mechanism drives the moving wheel mechanism to feed and shift, allowing it to move along the steel structure, the rotating moving mechanism rotates along the half-rings, the feeding welding mechanism welds the steel structure, and the deflection adjusting plate mechanism drives the elastic blocking plate mechanisms to deflect and shift, adapting to different sizes of steel structures for protection. The elastic blocking plate mechanisms collect welding slag generated during welding.

2. The protective welding equipment for building steel structures according to claim 1, characterized in that, The mounting semi-ring includes a semi-circular plate, and two symmetrically arranged connecting plates are provided on the side of the semi-circular plate. An arc-shaped toothed rack is fixedly connected to the side of the semi-circular plate.

3. The protective welding equipment for building steel structures according to claim 2, characterized in that, The connecting mechanism includes a connecting bolt that passes through a connecting plate and is threadedly connected to a nut.

4. The protective welding equipment for building steel structures according to claim 1, characterized in that, The elastic clamping mechanism includes a first linear motor fixed to the outside of the semicircular plate. An adjusting plate is fixedly connected to the end of the first linear motor away from the semicircular plate. The adjusting plate is fixedly connected to the clamping mechanism. The clamping mechanism passes through the semicircular plate and is fixedly connected to the clamping plate.

5. The protective welding equipment for building steel structures according to claim 4, characterized in that, The clamping mechanism includes a clamping sleeve fixed to an adjusting plate, a first elastic element fixedly connected inside the clamping sleeve, a clamping block fixedly connected to the first elastic element, the clamping block located inside the clamping sleeve, the clamping block and the clamping sleeve being slidably connected, a clamping rod fixedly connected to the clamping block, the clamping rod passing through the clamping sleeve, the clamping rod and the clamping sleeve being slidably connected, the clamping rod passing through a semi-circular plate, the clamping rod and the semi-circular plate being slidably connected, and the clamping rod and the clamping plate being fixedly connected.

6. The protective welding equipment for building steel structures according to claim 4, characterized in that, The movable wheel mechanism includes a movable wheel frame fixed to the pressure plate, a first motor is provided on the movable wheel frame, the output shaft of the first motor is fixedly connected to the movable wheel, the movable wheel and the movable wheel frame are rotatably connected, and the cross-section of the movable wheel has a concave structure in the middle.

7. The protective welding equipment for building steel structures according to claim 1, characterized in that, The rotary moving mechanism includes a movable shell that is slidably connected to a semi-circular plate. The movable shell is provided with an arc-shaped groove, and the semi-circular plate is located in the arc-shaped groove. The movable shell is provided with a motor base, and the motor base is provided with a second motor. The output shaft of the second motor is fixedly connected to a drive gear, and the drive gear meshes with an arc-shaped rack.

8. The protective welding equipment for building steel structures according to claim 7, characterized in that, The feeding welding mechanism includes a second linear motor fixed inside the movable housing. The end of the second linear motor away from the movable housing is fixedly connected to the welding head. A vision sensor is provided inside the movable housing.

9. The protective welding equipment for building steel structures according to claim 1, characterized in that, The deflection adjustment plate mechanism includes a first deflection seat fixed to the bottom of the outer side of the semicircular plate, a deflection rod rotatably connected to the first deflection seat, an arc plate fixedly connected to the bottom of the deflection rod, a second deflection seat fixedly connected to the semicircular plate, a third linear motor rotatably connected to the second deflection seat, a third deflection seat rotatably connected to the end of the third linear motor away from the second deflection seat, and a fixed connection between the third deflection seat and the deflection rod.

10. The protective welding equipment for building steel structures according to claim 9, characterized in that, The elastic baffle mechanism includes a rigid elastic plate fixed to the inner side of the semicircular plate. The lower end of the rigid elastic plate passes through the semicircular plate, and the end of the rigid elastic plate is fixedly connected to a baffle. The baffle is located on the outer side of the semicircular plate. Without external force, the baffle adheres to the outer wall of the semicircular plate, and the rigid elastic plate protrudes towards the inner center.

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