A welded segmented cage structure

Abstract

The application discloses a welded segmented cage structure, which comprises a segmented cage composed of an inner diameter arc segment, an outer diameter arc segment and a plurality of window beams uniformly distributed and connected with each other, and a sunken groove is formed on the surface of the segmented cage along the radial direction, a wear-resistant block is inserted into the sunken groove, the wear-resistant block comprises an integrally-formed base body part and a limiting boss part, the limiting boss part is located at the two ends of the upper surface of the base body part, the two limiting boss parts are of the same height, a recessed area is formed between the two limiting boss parts, and the bottom plane of the base body part is matched with the bottom plane reference surface of the sunken groove; after the wear-resistant block is inserted into the sunken groove in an interference fit, the upper surface of the wear-resistant block is higher than the upper surface of the segmented cage body, and the joint gap between the wear-resistant block and the sunken groove is welded and connected. The large-area plane reference surface at the bottom is matched with the side interference fit to form a strong mechanical fit, so that the welding is changed from the main force bearing to the auxiliary anti-loosening, and the risk of fatigue and falling off of the welding interface is greatly reduced.

Description

Technical Field

[0001] This application belongs to the field of bearing cages, and particularly relates to a welded segmented cage structure. Background Technology

[0002] As the core equipment for tunnel excavation, the main bearing of a tunnel boring machine (TBM) is a critical component that bears enormous axial and radial loads and overturning moments. Its reliability directly determines the progress and safety of the entire project. The TBM main shaft is massive, typically ranging from several meters to over ten meters in diameter, and its supporting main bearing is an extra-large rolling bearing. These bearings usually employ a segmented cage structure, dividing a large cage into multiple arc-shaped segments with necessary clearances between each segment to accommodate thermal expansion, machining errors, and assembly requirements. However, during high-speed, heavy-load operation, relative movement and collisions inevitably occur between the segmented cages, including circumferential misalignment impacts and axial runout interference. These complex collisions and impact loads can easily cause abnormal overturning or deflection of the segmented cages, thereby interfering with the stable movement trajectory of the rolling elements and accelerating bearing wear.

[0003] To suppress the overturning of segmented cages, the current mainstream solution is to weld wear-resistant alloy blocks onto the cage surface. When the cage tends to overturn at a large angle, these paired wear-resistant blocks, protruding from the cage body surface, will preferentially contact the flanges of the inner or outer ring of the bearing, creating mechanical interference and limiting the overturning angle within a safe range, thus playing a role in motion balance and overturning restraint. However, in manufacturing, to ensure that the paired wear-resistant blocks perform their restraining function uniformly, their installation height must be strictly consistent. This typically requires high-precision, multi-process procedures such as precise positioning, individual welding, and post-weld fine grinding, which are complex, costly, and difficult to control in terms of quality. Regarding structural reliability, the wear-resistant blocks are only connected to the cage base by the weld metal around their perimeter, resulting in a limited connection area and stress concentration during welding. Under the long-term, extremely harsh operating conditions of tunnel boring machines, strong vibrations, impacts, and alternating loads can easily cause fatigue cracks at the weld interface, leading to the detachment of the wear-resistant blocks. Once the wear-resistant blocks detach, not only is the overturning protection function lost, but the detached metal pieces may also enter the raceway, causing catastrophic consequences for bearing operation. Therefore, a new type of wear-resistant cage structure design is urgently needed to fundamentally simplify the manufacturing process and improve connection reliability, thereby ensuring the stable operation of the tunnel boring machine's main bearing throughout its entire life cycle. It is evident that existing technologies require further improvement and enhancement. Summary of the Invention

[0004] This invention provides a welded segmented retainer structure, which solves the problems of traditional shield machine main bearing segmented retainers that rely on welded wear-resistant blocks to prevent overturning, which have defects such as complex manufacturing process, easy fatigue cracking and high risk of falling off.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A welded segmented retainer structure includes a segmented retainer consisting of an inner diameter arc segment, an outer diameter arc segment, and multiple window beams connecting the two and evenly distributed. The surface of the segmented retainer has radially recessed grooves. Wear-resistant blocks are inserted into the grooves. Each wear-resistant block includes an integrally formed base portion and a limiting boss portion. The limiting boss portions are located at both ends of the upper surface of the base portion, and the two limiting boss portions are at the same height, forming a recessed area between the two limiting boss portions. The bottom plane of the base portion mates with the bottom plane reference surface of the groove. After the wear-resistant block is interference-fitted into the groove, its upper surface is higher than the upper surface of the segmented retainer body. The joint between the wear-resistant block and the groove is welded together.

[0007] In a preferred implementation, the height of the wear-resistant block after installation is lower than the height of the segmented cage body that accommodates the rolling elements.

[0008] In a preferred embodiment, the groove is formed on the upper surface of the window beam and extends radially to the upper surfaces of the inner diameter arc segment and the outer diameter arc segment.

[0009] In a preferred embodiment, the lateral working surface of the wear-resistant block facing the adjacent segmented retainer is jointly formed by the side surface of the base portion and the side surface of the limiting boss portion, and there is an included angle between the side surface of the limiting boss portion and the side surface of the base portion.

[0010] In a preferred embodiment, the lateral working surface is provided with an oil guiding and resistance breaking section, and the cross-section of the oil guiding and resistance breaking section gradually widens from the side away from the wear-resistant block toward the wear-resistant block, forming a wedge-shaped resistance breaking surface.

[0011] In a preferred embodiment, the oil-guiding and de-blocking part has at least one oil passage hole on both sides of its extension direction, and the oil passage hole penetrates the lateral working surface of the wear-resistant block.

[0012] In the preferred implementation, a convergence zone is formed between the limiting boss and the oil guide and resistance breaking section, and the oil passage hole is located in the convergence zone.

[0013] In a preferred embodiment, the limiting boss has an arc-shaped contact surface.

[0014] In a preferred embodiment, the wear-resistant block is provided with a mounting hole, and the groove is provided with a through hole coaxial with the mounting hole. An energy-dissipating column is inserted into the mounting hole of the two wear-resistant blocks on the upper and lower surfaces of the segmented retainer and the through hole. The energy-dissipating column has a sealed cavity inside. The cavity is filled with multiple independent energy-dissipating medium particles that can move freely inside the cavity, and the total volume of the energy-dissipating medium particles is smaller than the volume of the cavity.

[0015] In a preferred embodiment, a first sound emitter and a second sound emitter are fixed on the inner walls of both ends of the energy-consuming sound-emitting column cavity; the material and / or shape of the energy-consuming medium particles are configured such that when they impact the first or second sound emitter with a certain kinetic energy, they can generate impact sound with specific frequency characteristics; the characteristic acoustic signal generated by the impact of the energy-consuming medium particles on the sound emitter can be detected by an acoustic emission sensor located outside the bearing and used to determine the occurrence of the impact event.

[0016] The above structure has the following beneficial effects:

[0017] 1. The segmented welded cage structure of this application forms a strong mechanical fit through the large-area planar reference fit at the bottom and the interference fit on the side, so that the welding is changed from the main load-bearing to the auxiliary anti-loosening, which greatly reduces the risk of fatigue detachment of the weld interface.

[0018] 2. The welded segmented cage structure of this application has a geometric guide surface formed by the angle between the limiting boss and the base, which can actively gather and guide the lateral lubricating oil to the middle base, and then deliver it to the key lubrication area to improve lubrication efficiency. The oil guide and deblocking part guides the lubricating grease to flow to both sides to avoid accumulation and oil resistance. The oil passage provides a lubricating oil channel to provide lubrication supply to the contact position between the rolling elements and the cage.

[0019] 3. The segmented welded cage structure of this application uses energy-dissipating columns to convert impact kinetic energy into heat energy dissipation through the collision and friction of internal particles, significantly reducing the peak dynamic load transmitted to the connection interface and fundamentally protecting the weld and mating interface. By configuring characteristic particles and resonant sound emitters, the internal impact is converted into an acoustic signal of a specific frequency, enabling external sensors to identify severe impact events. Attached Figure Description

[0020] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain this application and do not constitute an undue limitation of the invention. In the drawings:

[0021] Figure 1 A schematic three-dimensional structural diagram illustrating one embodiment of the welded segmented cage structure of this application is shown.

[0022] Figure 2 A three-dimensional structural schematic diagram of one embodiment of the wear-resistant block installation and segmented retainer of this application is shown;

[0023] Figure 3 A schematic three-dimensional structural diagram illustrating one embodiment of the welded segmented cage structure of this application is shown.

[0024] Figure 4A schematic cross-sectional view of one embodiment of the energy-dissipating column of this application is shown;

[0025] Label Explanation:

[0026] 1. Segmented retainer; 10. Inner diameter arc segment; 11. Outer diameter arc segment; 12. Window beam; 120. Slot; 2. Wear-resistant block; 20. Base part; 200. Through hole; 21. Limiting boss part; 210. Arc-shaped contact surface; 22. Recessed area; 23. Oil guide and resistance breaking part; 24. Oil passage hole; 25. Mounting hole; 3. Energy dissipation column; 30. Energy dissipation medium particles; 31. First sound source; 32. Second sound source. Detailed Implementation

[0027] In the following description, only certain exemplary embodiments are briefly described. As those skilled in the art will recognize, the described embodiments can be modified in various ways without departing from the spirit and scope of the invention. Therefore, the drawings and description are considered to be exemplary in nature and not restrictive.

[0028] The present invention will now be described with reference to the accompanying drawings.

[0029] The specific solution adopted is as follows:

[0030] like Figure 1-4 As shown, the present invention provides a welded segmented retainer structure, including a segmented retainer 1 composed of an inner diameter arc-shaped segment 10, an outer diameter arc-shaped segment 11, and a plurality of window beams 12 that connect the two and are evenly distributed. The surface of the segmented retainer is radially provided with a recessed groove 120. A wear-resistant block 2 is inserted into the recessed groove 120. The wear-resistant block 2 includes an integrally formed base part 20 and a limiting boss part 21. The limiting boss part 21 is located at both ends of the upper surface of the base part 20 and the two limiting boss parts 21 are at the same height. A recessed area 22 is formed between the two limiting boss parts 21. The bottom plane of the base part 20 is matched with the bottom plane reference plane of the recessed groove 120. After the wear-resistant block 2 is interference-fitted into the recessed groove 120, the upper surface of the wear-resistant block 2 is higher than the upper surface of the segmented retainer body. The joint gap between the wear-resistant block 2 and the recessed groove 120 is welded together.

[0031] The welded segmented cage structure of this application significantly optimizes traditional solutions in two core dimensions: structural reliability and manufacturing process, through a composite connection method of "120mm interference fit + partial welding". Traditional wear-resistant block 2 relies solely on a thin layer of weld material around its perimeter to connect with the planar substrate, resulting in a weak line-contact connection. In contrast, this design, through a large-area planar reference fit at the bottom and interference fit on the sides, first establishes a large-area mechanical fit and pre-stressed compression between the wear-resistant block 2 and the cage substrate. Subsequent welding primarily acts on the composite connection of the joint gap, greatly enhancing the interface's shear and peel resistance, effectively dispersing alternating loads and impact stresses, and fundamentally reducing the risk of fatigue cracks at the weld root leading to overall detachment. The stability of the wear-resistant block 2 no longer solely depends on weld quality.

[0032] At the manufacturing level, the traditional challenge of "post-weld grinding and height adjustment" is transformed into a process where machining ensures the benchmark and assembly determines the height. Key precision control is shifted to the machining accuracy of the bottom plane of the sink 120 and the bottom of the wear-resistant block 2 substrate, both of which can be ensured with high precision in batches through machining equipment. During assembly, the wear-resistant block 2 is pressed into the sink 120 with an interference fit, and its final installation height is directly determined by the bottom benchmark mating surface and the height of the wear-resistant block 2 itself, eliminating the need for manual grinding and adjustment after welding. This not only significantly reduces highly skilled manual processes and improves production efficiency, but also fundamentally ensures the height consistency of the limiting bosses of paired wear-resistant blocks 2, making the overturning limiting function more uniform and reliable, shifting the quality control point forward, and making standardization easier.

[0033] In a preferred embodiment of this application, the height of the wear-resistant block 2 after installation is lower than the height of the segmented cage body that accommodates the rolling elements. Only when the rolling elements are in contact with the raceway do they bear all the load transmission and motion guidance functions. The wear-resistant block 2 will only contact and interfere with the inner wall of the inner or outer ring of the bearing when the bearing encounters abnormal impact or off-center load, causing the segmented cage to have an overturning tendency beyond the design range. This mechanical hard limiting will forcibly prevent the overturning angle from further expanding, thereby restoring the stable motion trajectory of the rolling elements. Therefore, its installation height "below the working surface" is a prerequisite for ensuring normal function.

[0034] In a preferred embodiment of this application, the groove 120 is formed on the upper surface of the window beam 12 and extends radially to the upper surfaces of the inner diameter arc segment 10 and the outer diameter arc segment 11. The wear-resistant block 2 spans the window beam 12 and is supported by a continuous rigid base with strong arc rings on both sides. This allows any impact load or overturning moment borne by the wear-resistant block 2 to be directly and efficiently transmitted radially to the inner and outer rings of the cage, the two main load-bearing structures, through the elongated contact surface at its bottom. This greatly optimizes the load path, avoids excessive stress concentration on the local window beam 12, and thus significantly improves the rigidity and impact fatigue resistance of the entire wear-resistant block 2 installation structure, fundamentally enhancing the reliability of the limiting function.

[0035] In a preferred embodiment of this application, the wear-resistant block 2, facing the lateral working surface of the adjacent segmented cage, is jointly formed by the side surface of the base portion 20 and the side surface of the limiting boss portion 21, and there is an angle between the side surface of the limiting boss portion 21 and the side surface of the base portion 20. When splashed or flowing lubricating grease reaches the side surface of the wear-resistant block 2 during bearing operation, the angle between the side surface of the limiting boss portion 21 forms a geometric guide surface facing the side surface of the base portion 20. This guides the lubricating oil that may come from both sides to converge in the middle side surface area of ​​the base portion 20, and then the lubricating oil can be more effectively delivered to the critical areas between the cage and the rolling elements and raceways that require the most lubrication along the path of the side surface of the base portion 20. This significantly improves local lubrication conditions and reduces abnormal wear caused by poor lubrication.

[0036] The connection between the side of the limiting boss 21 and the side of the base 20 achieves a width transition and structural reinforcement due to the included angle. This effectively expands the effective load-bearing cross section at the root of the limiting boss, allowing the impact force to be dispersed through a wider and smoother transition structure when overturning or when the wear block 2 collides with the bearing ring retainer, avoiding sharp stress concentration. This design not only directly improves the wear block 2's resistance to deformation and fracture under impact, but also reduces local contact stress through a better force flow distribution, thereby significantly improving the service life of the wear block 2 and the long-term reliability of the limiting function. Furthermore, the contact surface of the limiting boss 21 is designed as an arc-shaped contact surface 210. Traditional planar or angular contacts can cause severe edge stress concentration due to small alignment deviations or deformations, easily leading to crushing or chipping of the contact surface. The arc-shaped contact surface significantly reduces local contact stress. This not only effectively avoids brittle damage to the contact edges, but also significantly improves the load-bearing capacity of a single impact.

[0037] In a preferred embodiment of this invention, an oil-guiding and resistance-breaking section 23 is provided on the lateral working surface. The cross-section of the oil-guiding and resistance-breaking section 23 gradually widens from the side away from the wear-resistant block 2 towards the wear-resistant block 2, forming a wedge-shaped resistance-breaking surface. By designing a wedge-shaped resistance-breaking surface with a gradually widening cross-section on the lateral working surface, when the bearing operates at high speed, the lubricating grease in it will generate significant hydrodynamic pressure. The function of this wedge structure is similar to the wave-breaking bow of a ship. The tip of the wedge first cuts into and "splits" the continuous high-pressure oil film, guiding the lubricating oil flow smoothly to both sides along its gradually widening slope, rather than forming a huge oil film accumulation on the oil-facing side that hinders movement. This process effectively reduces the hydraulic damping and drag force generated by the lubricating oil film, making the segmented movement of the cage smoother. This fundamentally improves the dynamic stability and controllability of the bearing system under high speed, heavy load, and variable operating conditions.

[0038] Furthermore, the oil-guiding and resistance-breaking section 23 has at least one oil passage hole 24 on both sides of its extension direction, and the oil passage hole 24 penetrates the lateral working surface of the wear-resistant block 2. Although the wedge-shaped resistance-breaking surface can guide the main oil flow to the sides, a local lubricating oil stagnation area may be formed behind its tip. The oil passage hole 24 provides a through-flow path for these local high-resistance areas. Lubricating grease can directly penetrate the wear-resistant block 2 through these channels, flowing efficiently from one side to the rolling elements and pocket area on the other side, maintaining a favorable lubrication condition and improving the bearing's service life.

[0039] Furthermore, a convergence zone is formed between the limiting boss 21 and the oil guiding and blocking part 23, and the oil passage hole 24 is provided in the convergence zone.

[0040] The lubricating grease guided by the limiting boss and the oil flow diverted by the wedge-shaped oil guide and deflector 23 converge in this area, placing the oil passage 24 precisely at a "window" position with low fluid kinetic energy and easy passage. The lubricating oil can pass through the channel more smoothly and stably, without being easily impacted or disturbed by the high-speed oil flow, ensuring the reliability and continuity of the oil passage process.

[0041] As a preferred embodiment of this application, the wear-resistant block 2 is provided with mounting holes 25, and the groove 120 is provided with through holes 200 coaxial with the mounting holes 25. Energy-dissipating columns 3 are provided in the mounting holes 25 and through holes 200 of the two wear-resistant blocks 2 on the upper and lower surfaces of the segmented retainer. The energy-dissipating columns 3 have a sealed cavity inside, and the cavity is filled with multiple independent energy-dissipating medium particles 30 that can move freely in the cavity. The total volume of the energy-dissipating medium particles 30 is smaller than the volume of the cavity.

[0042] When the bearing is subjected to severe vibration or impact, the load is transferred to the energy dissipation column 3 through the segmented cage. Inside the energy dissipation column 3, independent media particles, such as high-density ceramic or metal spheres, undergo disordered collisions and friction within the cavity. This process efficiently converts concentrated mechanical kinetic energy into the internal energy of the particles and dissipates it, significantly reducing the peak impact energy ultimately transferred to the connection interface of the wear-resistant block 2 and the cage body. Through the buffering effect of the energy dissipation column 3, the dynamic load transferred to the welding interface between the groove 120 and the wear-resistant block 2 becomes gradual. This fundamentally eliminates the high-cycle, high-amplitude alternating stress that leads to the initiation and propagation of weld fatigue cracks, resulting in a significant improvement in fatigue life. Simultaneously, the risk of fretting wear at the interference fit surface is greatly reduced due to the decreased impact.

[0043] The core of the energy dissipation column 3 is a sealed cavity and free particles. It lacks springs, pistons, and other precisely coordinated moving parts, resulting in an extremely simple and robust structure with very few inherent failure modes. This makes it ideal for the extremely harsh working conditions of tunnel boring machines. It represents a breakthrough design for ensuring the main bearing's service life and operational reliability.

[0044] Furthermore, a first sound emitter 31 and a second sound emitter 32 are fixed on the inner walls of both ends of the energy-consuming sound-generating column cavity; the material and / or shape of the energy-consuming medium particles 30 are configured such that when they impact the first sound emitter 31 or the second sound emitter 32 with a certain kinetic energy, they can generate impact sound with specific frequency characteristics. The characteristic acoustic signal generated by the impact of the energy-consuming medium particles 30 on the sound emitter can be detected by an acoustic emission sensor set outside the bearing and used to determine the occurrence of the impact event.

[0045] The first sound source 31 and the second sound source 32 are fixed to the inner walls at both ends of the cavity. They are not simple impact plates, but precisely designed acoustic resonators. Hard alloys such as tool steel, tungsten carbide, or special ceramics with high sound wave transmission efficiency and high natural frequency characteristics are selected. Their shapes are designed with specific geometric structures, such as bell-shaped or plate-shaped, to generate clear and stable resonant frequencies upon impact. The first and second sound sources 32 can be designed with different natural frequencies, for example, one high-frequency and the other mid-low frequency. This is equivalent to setting different acoustic judgment characteristics for impact events from different directions. The energy-dissipating medium particles 30 are designed with high-density materials such as tungsten alloys, hardened steel, and zirconia ceramics to ensure sufficient momentum and impact energy. Spherical particles produce relatively pure impact sound. When the particles impact the sound source with typical working kinetic energy, the dominant frequency or spectral characteristics of the excited sound wave are known, stable, and easily distinguishable from background noise. When the bearing is running smoothly, the particles inside the energy-consuming column 3 only undergo slight random motion, resulting in a low probability and low kinetic energy of impacting the sound-generating body. The generated acoustic signal has a low amplitude and a single frequency component. When the bearing experiences vibration or impact, the particles are activated, producing intermittent, moderate-energy impact sounds with frequency characteristics matching the natural frequency of the sound-generating body. Acoustic sensors can easily capture this signal and may be able to determine the direction of the impact by analyzing the order and intensity of the excitation of the two sound-generating bodies. By establishing an acoustic baseline through long-term monitoring, these minute changes can be identified, thus providing early warning before structural failures occur. This significantly improves the observability and operational safety of the entire transmission system.

[0046] For any parts not mentioned in this invention, existing technologies can be used or referenced.

[0047] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various variations or substitutions within the technical scope disclosed in the present invention, and these should all be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A welded segmented retainer structure, comprising a segmented retainer consisting of an inner diameter arc-shaped segment, an outer diameter arc-shaped segment, and a plurality of window beams connecting the two and evenly distributed therefrom, characterized in that, The surface of the segmented retainer has radially recessed grooves, into which wear-resistant blocks are inserted. Each wear-resistant block includes an integrally formed base and a limiting boss. The limiting bosses are located at both ends of the upper surface of the base and are at the same height, forming a recessed area between them. The bottom plane of the base mates with the bottom plane reference surface of the recess. After the wear-resistant block is interference-fitted into the recess, its upper surface is higher than the upper surface of the segmented retainer body. The joint between the wear-resistant block and the recess is welded. The lateral working surface of the wear-resistant block facing the adjacent segmented retainer is jointly formed by the side surface of the base portion and the side surface of the limiting boss portion, and there is an included angle between the side surface of the limiting boss portion and the side surface of the base portion. The lateral working surface is provided with an oil guiding and resistance breaking section. The cross-section of the oil guiding and resistance breaking section gradually widens from the side away from the wear-resistant block toward the wear-resistant block, forming a wedge-shaped resistance breaking surface.

2. The welded segmented cage structure according to claim 1, characterized in that, After the wear-resistant block is installed, its height is lower than the height of the segmented cage body that accommodates the rolling elements.

3. The welded segmented cage structure according to claim 1, characterized in that, The groove is formed on the upper surface of the window beam and extends radially to the upper surfaces of the inner diameter arc segment and the outer diameter arc segment.

4. The welded segmented cage structure according to claim 1, characterized in that, The oil-guiding and resistance-breaking part has at least one oil passage hole on both sides of its extension direction, and the oil passage hole penetrates the lateral working surface of the wear-resistant block.

5. The welded segmented cage structure according to claim 4, characterized in that, A convergence zone is formed between the limiting boss and the oil guide and resistance breaking section, and the oil passage hole is located in the convergence zone.

6. The welded segmented cage structure according to claim 1, characterized in that, The limiting boss has an arc-shaped contact surface.

7. The welded segmented cage structure according to claim 1, characterized in that, The wear-resistant block has an installation hole, and the groove has a through hole coaxial with the installation hole. Energy-dissipating columns are inserted into the installation holes of the two wear-resistant blocks on the upper and lower surfaces of the segmented retainer and into the through hole. The energy-dissipating columns have a sealed cavity inside, which is filled with multiple independent energy-dissipating medium particles that can move freely inside the cavity. The total volume of the energy-dissipating medium particles is smaller than the volume of the cavity.

8. The welded segmented cage structure according to claim 7, characterized in that, A first sound-emitting body and a second sound-emitting body are fixed on the inner walls of both ends of the energy-consuming column cavity; the material and / or shape of the energy-consuming medium particles are configured such that when they impact the first or second sound-emitting body with a certain kinetic energy, they can generate impact sound with specific frequency characteristics. The characteristic acoustic signal generated by the impact of the energy-consuming medium particles on the sound-emitting body can be detected by an acoustic emission sensor set outside the bearing and used to determine the occurrence of the impact event.

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