A boring machine guide tool for folding wing component machining

Abstract

The utility model relates to mechanical processing technical field discloses a boring machine guiding frock for folding wing part machining, including device shell, the inner wall fixed connection of device shell has clamping mechanism, the inner wall sliding connection of device shell has quick detach mechanism, the clamping mechanism includes frock shell, the inner wall fixed connection of frock shell at device shell, the inner wall mounting of frock shell has the cylinder, the drive end fixed connection of cylinder has push head, the outer wall sliding connection of push head has hydraulic storage tank, the inner wall sliding connection of hydraulic storage tank has two mobile head, the inner wall rotary connection of one mobile head has port fixed column, when needing to place material, first, lift the presser plate outward, the presser plate drives the movable ring to move outward and extrude spring no.

Description

Technical Field

[0001] This utility model relates to the field of machining technology, and in particular to a boring machine guide fixture for machining folding wing components. Background Technology

[0002] On folding wing components, hinge holes, actuator connecting holes, etc., are directly related to the accuracy, reliability, and flight safety of wing folding. Therefore, higher processing requirements are required, among which the requirements for the holes are even more stringent. Multiple holes must be on an absolute straight line, otherwise the shaft cannot be installed or the movement will be obstructed. The position of the holes must be absolutely accurate to ensure assembly with the opposite side components, and it is also necessary to ensure interference or clearance fit with standard parts such as bearings and bushings. In order to meet these requirements, a boring machine guide fixture for processing folding wing components has emerged. Existing boring machine guide fixtures for folding wing component processing typically employ locating pins and clamping mechanisms. Using pre-machined process holes or datum surfaces on the workpiece as references, the fixture is firmly fixed in the product's theoretical design position. In this setup, the internal high-precision machining drill bit can calibrate the positioning drill hole on the workpiece, effectively eliminating errors caused by workpiece displacement. Existing boring machine guide fixtures for machining folding wing components are all pre-set to specifications, which cannot meet all user needs. Furthermore, conventional machining fixtures lack professional guide heads, resulting in significantly reduced machining accuracy. Additionally, their single-sided clamping introduces certain errors. To meet additional requirements and address the issues of insufficient machining accuracy and unstable fixture fixation in existing technologies, a new boring machine guide fixture for machining folding wing components is proposed to solve these problems. Summary of the Invention

[0003] To overcome the above shortcomings, this utility model provides a boring machine guide fixture for machining folding wing components, aiming to improve the problems of insufficient machining accuracy and unstable fixture fixation in the prior art.

[0004] To achieve the above objectives, the present invention adopts the following technical solution: A boring machine guide fixture for machining folding wing components includes a device housing, a clamping mechanism fixedly connected to the inner wall of the device housing, and a quick-release mechanism slidably connected to the inner wall of the device housing. The clamping mechanism includes a tooling housing, one side of which is fixedly connected to the inner wall of the device housing. A cylinder is installed on the inner wall of the tooling housing, and a push head is fixedly connected to the drive end of the cylinder. A hydraulic tank is slidably connected to the outer wall of the push head. Two moving heads are slidably connected to the inner wall of the hydraulic tank. One of the moving heads has a port fixing column rotatably connected to its inner wall, and two rotating arms are rotatably connected to one side of the other moving head. Two corner extrusion blocks are rotatably connected to one side of each of the two rotating arms. A pressing assembly is fixedly connected to one side of the tooling housing. As a further description of the above technical solution: The quick-release mechanism includes a central connecting column, a spring 2 sleeved on the outer wall of the central connecting column, an outer sliding ring slidably connected to the outer wall of the central connecting column, a retaining ring fixedly connected to the inner wall of the outer sliding ring, multiple movable locking balls slidably connected to the inner wall of the central connecting column, a limit ring fixedly connected to the outer wall of the central connecting column, a calibration column fixedly connected to the inner wall of the central connecting column, a blade connecting column slidably connected to the inner wall of the central connecting column, and multiple locking blocks fixedly connected to the outer wall of the blade connecting column. As a further description of the above technical solution: The tablet pressing assembly includes multiple support plates, one side of each support plate is fixedly connected to one side of the tooling housing, and the other side of each support plate is fixedly connected to a support connecting column. A spring is sleeved on the outer wall of the support connecting column, a top plate is fixedly connected to one end of the support connecting column, a movable ring is slidably connected to the outer wall of the support connecting column, a pressure plate is fixedly connected to one side of the movable ring, and two calibration ports are fixedly connected to the outer wall of the tooling housing. As a further description of the above technical solution: One side of each of the two rotating arms is slidably connected to the inner wall of the tooling housing, and the outer wall of the two corner extrusion blocks is slidably connected to the inner wall of the tooling housing. As a further description of the above technical solution: One side of the hydraulic tank is fixedly connected to the inner wall of the device housing, and the outer wall of the port fixing column is slidably connected to the inner wall of the tooling housing. As a further description of the above technical solution: One end of the spring is in contact with the movable ring, and the other end of the spring is in contact with one side of the top plate; As a further description of the above technical solution: The cross-section of the calibration column is circular, and one end of the second spring is in contact with one side of the retaining ring; As a further description of the above technical solution: The outer wall of the locking block is slidably connected to the inner wall of the central connecting column, and the inner wall of the outer sliding ring is slidably connected to the outer wall of the limiting ring.

[0005] This utility model has the following beneficial effects: 1. In this utility model, when it is necessary to place materials, the high-pressure plate is first lifted outward. The pressure plate drives the movable ring to move outward and squeezes the spring. At this time, the top plate acts as a limit to prevent the movable ring from moving outward. Then, the workpiece is placed into the fixture. Subsequently, the cylinder is started. The cylinder drives the push head to retract inward. Because the hydraulic tank is full of hydraulic oil, it will push the moving head to move inward. The two moving heads move inward synchronously, thereby driving the port fixing column to move inward. At the same time, the rotating arm pulls the two corner extrusion blocks inward, so that the two corner extrusion blocks move inward synchronously, thus completing the fixing of the workpiece.

[0006] 2. In this utility model, when the cutter head needs to be replaced, pull the outer sliding ring backward. The outer sliding ring drives the retaining ring to move backward synchronously, so that the notch of the retaining ring is aligned with the notch of the central connecting post. At this time, the movable locking ball can move in the gap between the retaining ring, the central connecting post and the cutter head connecting post. Pull the cutter head connecting post outward, and the movable locking ball will be squeezed into the gap between the central connecting post and the retaining ring, so that the old cutter head can be removed. The limiting ring can limit the movement range of the retaining ring to prevent it from deviating. The calibration post and the calibration port are coupled. When installing the new cutter head, align the two to ensure that the cutter head is in the specified cutting position and the replacement is completed. Attached Figure Description

[0007] Figure 1 This is a three-dimensional schematic diagram of a boring machine guide fixture for machining folding wing components according to the present invention; Figure 2 This is a schematic diagram of the pressure plate of a boring machine guide fixture for machining folding wing components according to this utility model; Figure 3 This is a schematic diagram of the cylinder of a boring machine guide fixture for machining folding wing components according to the present invention. Figure 4 This is a schematic diagram of the spring 2 of the boring machine guide fixture for machining folding wing components proposed in this utility model; Figure 5 This is a schematic diagram of the outer sliding ring of a boring machine guide fixture for machining folding wing components proposed in this utility model.

[0008] Legend: 1. Device casing; 2. Clamping mechanism; 21. Tooling housing; 22. Cylinder; 23. Push head; 24. Hydraulic tank; 25. Moving head; 26. Port fixing post; 27. Rotating arm; 28. Two corner extrusion blocks; 29. Tablet compression assembly; 291. Support plate; 292. Support connecting column; 293. Spring 1; 294. Top plate; 295. Movable ring; 296. Pressure plate; 297. Calibration port; 3. Quick release mechanism; 31. Central connecting column; 32. Spring 2; 33. Outer sliding ring; 34. Snap ring; 35. Movable locking ball; 36. Limiting ring; 37. Calibration column; 38. Cutter head connecting column; 39. Locking block. Detailed Implementation

[0009] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model. Example

[0010] A boring machine guide fixture for machining folding wing components, as shown in the reference. Figures 1 to 3 The device includes a housing 1, and a clamping mechanism 2 is fixedly connected to the inner wall of the housing 1. The housing 1 provides a mounting base for the clamping mechanism 2 to ensure stable clamping action. A quick-release mechanism 3 is slidably connected to the inner wall of the housing 1. The housing 1 provides sliding space for the quick-release mechanism 3 to facilitate the disassembly and replacement of the cutter head. Specifically, the device housing 1 is equipped with a clamping mechanism 2 inside, which can tightly clamp the workpiece to be processed. The top of the device housing 1 is equipped with a quick-release mechanism 3, which makes it more convenient and faster to change the cutting head.

[0011] The clamping mechanism 2 includes a tooling housing 21. One side of the tooling housing 21 is fixedly connected to the inner wall of the device housing 1. The device housing 1 fixes the tooling housing 21, providing protection for the internal components of the clamping mechanism 2. A cylinder 22 is installed on the inner wall of the tooling housing 21, providing an installation position for the cylinder 22 and ensuring its normal operation. A push head 23 is fixedly connected to the drive end of the cylinder 22. The cylinder 22 drives the push head 23 to move, providing initial power for the clamping action. A hydraulic tank 24 is slidably connected to the outer wall of the push head 23. The push head 23 slides within the hydraulic tank 24, changing the internal pressure of the hydraulic tank 24. Two moving heads 25 are slidably connected to the inner wall of the hydraulic tank 24. Pressure changes drive the two moving heads 25 to move synchronously to achieve clamping. One of the moving heads 25 has a port fixing post 26 rotatably connected to its inner wall. The moving head 25 drives the port fixing post 26 to move and fix the port of the folding wing component. The other moving head 25 has two rotating arms 27 rotatably connected to one side. The moving head 25 drives the rotating arms 27 to rotate and transmit the clamping force. Two corner pressing blocks 28 are rotatably connected to one side of each of the two rotating arms 27. The rotating arms 27 drive the two corner pressing blocks 28 to move and press and fix the two corners of the folding wing component. A pressure plate assembly 29 is fixedly connected to one side of the tooling shell 21. The tooling shell 21 fixes the pressure plate assembly 29 to enhance the pressing and fixing effect on the folding wing component. Specifically, the outer casing 1 of the device, through the fixed tooling casing 21, provides protection for the internal components of the clamping mechanism 2. The tooling casing 21 carries the cylinder 22, ensuring that the cylinder 22 outputs driving force stably. The cylinder 22 drives the push head 23 to move linearly, providing initial power for the clamping action. The push head 23 slides in the hydraulic tank 24, changing the pressure inside the tank. The pressure change inside the hydraulic tank 24 drives the two moving heads 25 to move synchronously in opposite directions, forming a clamping engagement. One of the moving heads 25 drives the port fixing post 26 to move, thereby fixing the port of the folding wing component. The other moving head 25 drives the two rotating arms 27 to rotate around the axis, transmitting the clamping force. The two rotating arms 27 respectively drive the two corner pressing blocks 28 to move, completing the pressing and fixing of the two corners of the folding wing component. At the same time, the tooling casing 21 fixes the pressure plate assembly 29. The pressure plate assembly 29, in conjunction with the above structure, enhances the pressing and fixing effect on the folding wing component, fully ensuring the clamping stability.

[0012] The tablet compression assembly 29 includes multiple support plates 291. One side of each support plate 291 is fixedly connected to one side of a fixture housing 21, which provides a support base for the tablet compression assembly 29. The other side of each support plate 291 is fixedly connected to a support connecting column 292, which provides mounting support. A spring 293 is sleeved on the outer wall of the support connecting column 292, limiting the deformation direction of the spring 293 and ensuring its elastic return. One end of the support connecting column 292... A top plate 294 is fixedly connected, and a supporting connecting column 292 fixes the top plate 294, limiting the maximum movement range of the movable ring 295. The outer wall of the supporting connecting column 292 is slidably connected to the movable ring 295, which slides on the supporting connecting column 292. A pressure plate 296 is fixedly connected to one side of the movable ring 295. The movable ring 295 drives the pressure plate 296 to press the folding wing component to prevent the component from shifting during processing. Two calibration ports 297 are fixedly connected to the outer wall of the tooling housing 21, and the tooling housing 21 fixes the calibration ports 297 to provide a matching structure for the calibration of the quick-release mechanism 3. Specifically, the tooling housing 21 fixes the support plate 291, providing a high-strength support foundation for the pressing assembly 29. Multiple support plates 291 drive the support connecting column 292 to maintain stability, combining rigidity and lightweight characteristics, providing precise installation support for subsequent components. The support connecting column 292 restricts the deformation direction of the spring 293, ensuring that the spring 293 can quickly and elastically return to its original position after being subjected to force. The support connecting column 292 drives the top plate 294 to be positioned, which not only limits the maximum movement range of the movable ring 295, but also avoids hard collisions between metals. When the movable ring 295 slides on the support connecting column 292, it drives the pressure plate 296 to move synchronously, which can achieve flexible pressing of the folding wing component and prevent component displacement or surface scratches during processing. At the same time, the tooling housing 21 drives the two brass calibration ports 297 to be fixed. Utilizing the wear resistance and good guiding properties of brass, it provides a high-precision matching structure for the calibration of the quick-release mechanism 3, ensuring the overall assembly accuracy and stability of repeated disassembly and assembly.

[0013] One side of each of the two rotating arms 27 is slidably connected to the inner wall of the tooling housing 21. The tooling housing 21 restricts the movement trajectory of the rotating arms 27, ensuring precise transmission of the rotating arms 27. The outer wall of the two corner pressing blocks 28 is slidably connected to the inner wall of the tooling housing 21. The tooling housing 21 guides the movement of the two corner pressing blocks 28, ensuring precise clamping position. One side of the hydraulic tank 24 is fixedly connected to the inner wall of the device housing 1. The device housing 1 fixes the hydraulic tank 24, ensuring stable position of the hydraulic tank 24 during operation. The outer wall of the port fixing post 26 is slidably connected to the inner wall of the tooling housing 21. The tooling housing 21 guides the movement of the port fixing post 26, enhancing the stability of the port fixing post 26. One end of the spring 293 is in contact with the movable ring 295. One end of the spring 293 acts on the movable ring 295, providing the elastic force required for pressing. The other end of the spring 293 is in contact with one side of the top plate 294. The other end of the spring 293 is subjected to force by the top plate 294, ensuring stable transmission of elastic force. Specifically, the two rotating arms 27 slide on one side to the inner wall of the tooling housing 21. The tooling housing 21 limits their trajectory by a preset slide rail to ensure accurate transmission of clamping force and prevent deviation. The outer walls of the two corner extrusion blocks 28 slide to the inner wall of the tooling housing 21. The tooling housing 21 guides them to move along a fixed path by a guide groove to ensure accurate clamping position and reliable fixation. The hydraulic tank 24 is made of stainless steel with excellent sealing properties. It is fixed on one side to the inner wall of the device housing 1. The device housing 1 is fastened to the hydraulic tank 24 with bolts to prevent vibration from causing oil leakage or unstable pressure. The surface of the port fixing column 26 is hardened. Its outer wall slides to the inner wall of the tooling housing 21. The tooling housing 21 guides its linear movement by a bushing to increase stability. The spring 293 is made of fatigue-resistant spring steel. Its two ends contact the movable ring 295 and the top plate 294 respectively to provide flexible pressing pressure for the pressure plate 296 to ensure stability during the processing of the folding wing component.

[0014] Reference Figure 4 and Figure 5The quick-release mechanism 3 includes a central connecting column 31. A second spring 32 is sleeved on the outer wall of the central connecting column 31, providing mounting support for the second spring 32 and ensuring its elastic return. An outer sliding ring 33 is slidably connected to the outer wall of the central connecting column 31, sliding on the central connecting column 31 to control the locking and unlocking states of the quick-release mechanism 3. A retaining ring 34 is fixedly connected to the inner wall of the outer sliding ring 33, causing the retaining ring 34 to move synchronously. Multiple movable locking balls 35 are slidably connected to the inner wall of the central connecting column 31, sliding within the central connecting column 31 to achieve the connection or separation of the central connecting column 31. A limiting ring 36 is fixedly connected to the outer wall of the column 31, and the limiting ring 36 is fixed to the central column 31 to limit the sliding range of the outer sliding ring 33. A calibration column 37 is fixedly connected to the inner wall of the central column 31. The calibration column 37 is fixed to the central column 31, and precise positioning is achieved by the calibration column 37 cooperating with the calibration port 297. A cutter head connecting column 38 is slidably connected to the inner wall of the central column 31. The central column 31 provides installation space for the cutter head connecting column 38 to facilitate the installation and fixation of the cutter head. Multiple locking blocks 39 are fixedly connected to the outer wall of the cutter head connecting column 38. The cutter head connecting column 38 is locked and fixed to the central column 31 by the locking blocks 39 cooperating with the movable locking ball 35. Specifically, the quick-release mechanism 3 includes a steel central connecting column 31. A high-elasticity spring 32 is fitted on the outer wall of the central connecting column 31, providing stable installation support for the spring 32 and ensuring accurate elastic reset. A chrome-plated outer sliding ring 33 is slidably connected to the outer wall of the central connecting column 31. When the outer sliding ring 33 slides along the central connecting column 31, it can control the locking and unlocking state of the quick-release mechanism 3. The outer sliding ring 33 drives the inner alloy retaining ring 34 to move synchronously, cooperating with multiple wear-resistant moving parts on the inner wall of the central connecting column 31. The movable locking ball 35 enables quick connection or separation of the central connecting column 31. The central connecting column 31 is fixed with a limiting ring 36 to limit the sliding range of the outer sliding ring 33 to prevent it from falling off. The central connecting column 31 is fixed with a calibration column 37, which achieves high-precision positioning by cooperating with the calibration port 297. The inner wall is slidably connected to the cutter head connecting column 38 to provide installation space for the cutter head. Multiple locking blocks 39 on the outer wall of the cutter head connecting column 38 cooperate with the movable locking ball 35 to achieve a stable lock with the central connecting column 31, which facilitates quick assembly and disassembly of the cutter head.

[0015] The cross-section of the calibration column 37 is circular. The circular cross-section makes it easier for the calibration column 37 to fit with the calibration port 297, improving calibration efficiency. One end of the second spring 32 is in contact with one side of the retaining ring 34. The other end of the second spring 32 acts on the retaining ring 34, pushing the retaining ring 34 to keep it locked. The outer wall of the locking block 39 is slidably connected to the inner wall of the central connecting column 31. The central connecting column 31 guides the locking block 39 to slide, ensuring that the tool head connecting column 38 is installed accurately. The inner wall of the outer sliding ring 33 is slidably connected to the outer wall of the limiting ring 36. The limiting ring 36 restricts the sliding direction of the outer sliding ring 33 and prevents the outer sliding ring 33 from deviating. Specifically, the circular cross-section of the calibration column 37 easily matches the calibration port 297, improving efficiency. One end of the spring 32 acts on the retaining ring 34 to keep it locked. The outer wall of the locking block 39 slides against the inner wall of the center connecting column 31 to ensure the accurate installation of the cutter head connecting column 38. The inner wall of the outer sliding ring 33 slides against the outer wall of the limiting ring 36 to prevent displacement.

[0016] The implementation principle of this application embodiment is as follows: When it is necessary to prevent material from moving outward, the pressure plate 296 is raised outward. At this time, the pressure plate 296 drives the movable ring 295 to move outward and squeeze the spring 293. At this time, the top plate 294 is a baffle to prevent it from moving outward. Then, the workpiece is put into the tooling and the cylinder 22 is started. At this time, the cylinder 22 drives the push head 23 to retract inward. Since the hydraulic tank 24 is full of hydraulic oil, the moving head 25 will move inward. At this time, the moving heads 25 on both sides move inward at the same time. Then, the port fixing column 26 will be driven to move inward. The two corner squeezing blocks 28 move inward and approach each other at the same time because the rotating arm 27 pulls them inward. When the cutting head needs to be replaced, pull the outer sliding ring 33 backward. The outer sliding ring 33 will then drive the retaining ring 34 to move backward, aligning the notch of the retaining ring 34 with the notch of the central connecting post 31. Then, the movable locking ball 35 will move in the gap between the retaining ring 34, the central connecting post 31, and the cutting head connecting post 38. At this time, pull the cutting head connecting post 38 outward, and the movable locking ball 35 will be squeezed into the gap between the central connecting post 31 and the retaining ring 34. The presence of the limiting ring 36 restricts the movement of the retaining ring 34 within the specified range, preventing it from shifting. The calibration post 37 is coupled to the calibration port 297. When working, aligning them together will achieve the specified cutting.

[0017] Finally, it should be noted that the above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Although the present utility model 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 utility model should be included within the protection scope of the present utility model.

Claims

1. A boring machine guide fixture for machining folding wing components, comprising a device housing (1), characterized in that: The inner wall of the device housing (1) is fixedly connected to a clamping mechanism (2), and the inner wall of the device housing (1) is slidably connected to a quick-release mechanism (3). The clamping mechanism (2) includes a tooling housing (21), one side of which is fixedly connected to the inner wall of the device housing (1). A cylinder (22) is installed on the inner wall of the tooling housing (21). A push head (23) is fixedly connected to the drive end of the cylinder (22). A hydraulic tank (24) is slidably connected to the outer wall of the push head (23). Two moving heads (25) are slidably connected to the inner wall of the hydraulic tank (24). A port fixing column (26) is rotatably connected to the inner wall of one of the moving heads (25). Two rotating arms (27) are rotatably connected to one side of the other moving head (25). Two corner extrusion blocks (28) are rotatably connected to one side of each of the two rotating arms (27). A pressing assembly (29) is fixedly connected to one side of the tooling housing (21).

2. The boring machine guide fixture for machining folding wing components according to claim 1, characterized in that: The quick-release mechanism (3) includes a central connecting column (31), a spring (32) is sleeved on the outer wall of the central connecting column (31), an outer sliding ring (33) is slidably connected to the outer wall of the central connecting column (31), a retaining ring (34) is fixedly connected to the inner wall of the outer sliding ring (33), a plurality of movable locking balls (35) are slidably connected to the inner wall of the central connecting column (31), a limit ring (36) is fixedly connected to the outer wall of the central connecting column (31), a calibration column (37) is fixedly connected to the inner wall of the central connecting column (31), a cutter head connecting column (38) is slidably connected to the inner wall of the central connecting column (31), and a plurality of locking blocks (39) are fixedly connected to the outer wall of the cutter head connecting column (38).

3. The boring machine guide fixture for machining folding wing components according to claim 1, characterized in that: The tablet pressing assembly (29) includes multiple support plates (291). One side of each of the multiple support plates (291) is fixedly connected to one side of the tooling housing (21). The other side of each of the multiple support plates (291) is fixedly connected to a support connecting column (292). A spring (293) is sleeved on the outer wall of the support connecting column (292). A top plate (294) is fixedly connected to one end of the support connecting column (292). A movable ring (295) is slidably connected to the outer wall of the support connecting column (292). A pressure plate (296) is fixedly connected to one side of the movable ring (295). Two calibration ports (297) are fixedly connected to the outer wall of the tooling housing (21).

4. The boring machine guide fixture for machining folding wing components according to claim 1, characterized in that: One side of each of the two rotating arms (27) is slidably connected to the inner wall of the tooling housing (21), and the outer wall of the two corner extrusion blocks (28) is slidably connected to the inner wall of the tooling housing (21).

5. The boring machine guide fixture for machining folding wing components according to claim 1, characterized in that: One side of the hydraulic tank (24) is fixedly connected to the inner wall of the device housing (1), and the outer wall of the port fixing column (26) is slidably connected to the inner wall of the tooling housing (21).

6. The boring machine guide fixture for machining folding wing components according to claim 3, characterized in that: One end of the spring (293) is in contact with the movable ring (295), and the other end of the spring (293) is in contact with one side of the top plate (294).

7. The boring machine guide fixture for machining folding wing components according to claim 2, characterized in that: The cross-section of the calibration column (37) is circular, and one end of the second spring (32) is in contact with one side of the retaining ring (34).

8. The boring machine guide fixture for machining folding wing components according to claim 2, characterized in that: The outer wall of the locking block (39) is slidably connected to the inner wall of the central connecting column (31), and the inner wall of the outer sliding ring (33) is slidably connected to the outer wall of the limiting ring (36).

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