Hammer detection device

Abstract

The present application relates to a kind of hammer detection device, including the device support being provided with walking wheel, the device support is guided to move and be equipped with the elastic hammer wheel that can float up and down and can rotate when moving with device support, the device support is provided with the elastic hammer wheel reset spring for keeping elastic hammer wheel and target surface contact, the device support is provided with the intermittent drive mechanism driven by power source, intermittent drive mechanism has the impact hammer for gap impact the elastic hammer wheel.Hammer detection device walks in the process, elastic hammer wheel also walks along target surface, elastic hammer wheel reset spring ensures that elastic hammer wheel is always in contact with target surface, intermittent drive mechanism drives impact hammer and gap impact elastic hammer wheel, elastic hammer wheel is impacted target surface under the impact of impact hammer, and the quality of target surface is judged according to the echo generated by target surface.In the present application, it is not necessary to manually hold impact rod to impact target surface one by one, labor intensity is saved, and it is beneficial to improve work efficiency.

Description

Technical Field

[0001] This invention relates to a defect detection device for the ground, tunnel or wall, and more particularly to a hammer impact detection device. Background Technology

[0002] The echoes produced by a solid ground, tunnel, or wall (also known as the target surface) are different from those produced by a hollow ground, tunnel, or wall. Therefore, tapping is usually used to determine whether there is a hollow space under the target surface, thereby judging the quality of the target surface.

[0003] For example, after renovation, to determine if there is hollowness under the tiles, the operator uses a hammer to tap and probe. Or, during quality inspection of railway tunnels, the operator manually uses a steel rod to strike the tunnel wall and relies on experience to listen to the sound to judge tunnel defects.

[0004] This method of judging the quality of a target surface by manual tapping has the following problems: manual tapping is labor-intensive and inefficient, and it cannot be guaranteed that the tapping force is consistent each time, which may lead to technical problems such as damage to the target surface; the different tapping forces each time result in different echoes from the target surface, and subjective judgment requires experienced personnel, and even then, it may lead to problems such as misdiagnosis and missed diagnosis. Summary of the Invention

[0005] The purpose of this invention is to provide a hammer impact detection device to solve the technical problems of high work intensity and low work efficiency caused by manually striking the target surface in the prior art.

[0006] To solve the above-mentioned technical problems, the technical solution of the impact detection device in this invention is as follows:

[0007] A hammer impact detection device includes a device bracket with a traveling wheel, a bouncing impact wheel that can float up and down and rotate as the device bracket moves, a bouncing impact wheel return spring for keeping the bouncing impact wheel in contact with a target surface, and an intermittent drive mechanism driven by a power source, the intermittent drive mechanism having an impact hammer for intermittently impacting the bouncing impact wheel.

[0008] Furthermore, the device support is equipped with a sound-collecting device for collecting the sound of the impact wheel striking the target surface.

[0009] Furthermore, the power source is an electric motor, a hydraulic motor, or a pneumatic motor.

[0010] Furthermore, the outer surface of the impact wheel is spherical, and the contact surface of the impact hammer that contacts and impacts the impact wheel is also spherical.

[0011] Furthermore, a swing arm with its axis extending in the front-rear direction is hinged to the device support, and the impact wheel is rotatably mounted on the swing arm; or, a guide structure with its guide direction extending in the up-down direction is provided on the device support, and the impact wheel axle of the impact wheel is guided and moved on the guide structure.

[0012] Furthermore, the intermittent drive mechanism includes a lower rotating member whose rotation axis extends in the vertical direction, and an upper actuating member capable of anti-rotation and guiding movement in the vertical direction. The lower rotating member is driven to rotate by the power source. A central hole is provided on the lower rotating member. The impact hammer is a vertically arranged rod-shaped structure that passes through the central hole. The upper end of the impact hammer is fixedly connected to the upper actuating member. The lower end face of the impact hammer is used to impact the impact wheel. A lower end face cam is provided at the upper end of the lower rotating member. An upper end face cam is provided at the lower end of the upper actuating member to cooperate with the lower end face cam. In the circumferential direction, the lower end face cam has an upward drive section that drives the upper actuating member to move upward as the lower rotating member rotates. The lower end face cam also has a downward section at the end of the upward drive section that disengages from the upper end face cam.

[0013] Furthermore, the upper end of the upper actuating member is provided with an actuating member return spring for pressing down the upper actuating member, and the compression amount of the actuating member return spring is adjustable.

[0014] Furthermore, when the lower end of the impact hammer strikes the impact wheel, the upper end face cam and the lower end face cam are spaced apart, and the lower end face cam contacts the upper end face cam as the lower rotating part rotates.

[0015] Furthermore, a rotating gear is fixed to the outer circumference of the lower rotating component, and a power source gear is provided at the power output end of the power source to mesh with the rotating gear.

[0016] The beneficial effects of this invention are as follows: In this invention, the device support is equipped with traveling wheels, allowing the entire hammer impact detection device to move along the target surface. During this movement, the impact wheel also moves along the target surface. The impact wheel's return spring ensures that the impact wheel remains in contact with the target surface. The intermittent drive mechanism drives the impact hammer to intermittently impact the impact wheel. The impact wheel strikes the target surface under the impact of the impact hammer, and the quality of the target surface is determined based on the echo produced. This invention eliminates the need for manual operation of the impact bar to repeatedly strike the target surface, saving labor intensity and improving work efficiency. Attached Figure Description

[0017] The above and other objects, features, and advantages of this disclosure will become readily apparent from the following detailed description of exemplary embodiments with reference to the accompanying drawings. In the drawings, several embodiments of this disclosure are illustrated by way of example and not limitation, and like or corresponding reference numerals denote like or corresponding portions, wherein:

[0018] Figure 1 This is a schematic diagram of an embodiment 1 of a hammer impact detection device;

[0019] Figure 2 This is a schematic diagram of the state of the upper moving part when it rises in Embodiment 1;

[0020] Figure 3 This is a schematic diagram of the state when the upper moving part rises to its highest height in Embodiment 1;

[0021] Figure 4 This is a schematic diagram of embodiment 2 of a hammer impact detection device;

[0022] Figure 5 yes Figure 4 Schematic diagram of the intermittent drive mechanism;

[0023] Figure 6 yes Figure 4 Top view;

[0024] Figure 7 This is a schematic diagram of the state of the hook bracket when it rotates in the opposite direction with the impact hammer via the hook mechanism in Embodiment 2.

[0025] Figure 8 This is a schematic diagram of the state after the hook mechanism comes into contact with the unlocking trigger device in Embodiment 2;

[0026] Figure 9 yes Figure 4 Enlarged view of point A in the image;

[0027] Explanation of reference numerals in the attached drawings: 1. Impact hammer; 1-1. Impact hammer hook mating part; 2. Hook mechanism; 2-1. Hook rod; 2-2. Hook; 3. Spring device; 3-1. Coil spring; 3-2. Stop bar; 4. Unlocking trigger device; 5. Magnetic ring; 6. Magnetic encoder; 7. Drive motor; 8. Walking wheel; 9. Device bracket; 10. Fixed shaft; 11. Impact part of the impact hammer; 12. Surface of the object being tested; 13. Transmission shaft; 14. Hook bracket; 15. Hook return spring; 6. Push head; 17. Impact wheel; 18. Impact wheel axle; 19. Axle return spring; 20. Power source; 21. Power source gear; 22. Rotating component gear; 23. Lower rotating component; 24. Upper moving component; 25. Moving component return spring; 26. Spring pressure plate; 27. Spring adjusting nut; 28. Pressure plate guide rod; 29. ​​Upper end face cam; 30. Lower end face cam; 31. Rising drive section; 32. Falling section; 33. Swing arm; 34. Impact wheel return spring. Detailed Implementation

[0028] To facilitate understanding of the present invention, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. Preferred embodiments of the invention are shown in the drawings. However, the invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the invention.

[0029] It should be noted that, unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention.

[0030] An embodiment 1 of the impact detection device of the present invention is as follows: Figures 1-3 As shown: The device includes a support frame 9 with wheels at the bottom. The support frame is a shell structure, indicated by diagonal lines in the figure. Not the entire support frame is shown. The wheels 8 may be without a power source; in use, the operator can manually push the support frame. Alternatively, a wheel drive motor can be installed to electrically drive the wheels, allowing the support frame to move electrically.

[0031] The device support 9 is equipped with a guide wheel 17 that can float up and down and rotate as the device support moves. The device support is also equipped with a return spring 34 for maintaining contact between the impact wheel and the target surface, which refers to the surface 12 of the object being tested. In this embodiment, a swing arm 33 with its axis extending in the front-rear direction is hinged to the device support. The swing arm 33 is an arc-shaped swing arm with its notch facing upwards. The impact wheel is rotatably mounted on the end of the swing arm away from the hinge axis. The return spring 34 is a compression spring located between the upper end of the swing arm and the device support.

[0032] The device support 9 is equipped with an intermittent drive mechanism driven by a power source, and the intermittent drive mechanism has an impact hammer 1 for intermittently impacting the impact wheel. In this embodiment, the power source is an electric motor, and the device support is equipped with a sound-collecting device for collecting the sound of the impact wheel hitting the target surface.

[0033] The outer surface of the impact wheel 17 is spherical, the contact surface of the impact hammer 1 that contacts and impacts the impact wheel is spherical, the upper end of the impact hammer and the impact wheel are in point contact, and the contact between the impact wheel and the target surface is also in point contact.

[0034] The intermittent drive mechanism includes a lower rotating member 23 whose rotation axis extends in the vertical direction. The lower rotating member is rotatably mounted on the device support via a bearing. The intermittent drive mechanism also includes an upper moving member 24 that is guided and moved in the vertical direction and mounted on the device support. The upper moving member 24 is anti-rotating in cooperation with the device support. The lower rotating member is driven to rotate by a power source.

[0035] The lower rotating member 23 has a central hole. The impact hammer 1 is a vertically arranged rod-shaped structure that passes through the central hole. The upper end of the impact hammer 1 is fixedly connected to the upper actuating member 24. The lower end face of the impact hammer forms a contact surface for impacting the impact wheel, i.e., the impact part 11 of the impact hammer. The upper end of the lower rotating member has a lower end face cam 30, and the lower end of the upper actuating member has an upper end face cam 29 that cooperates with the lower end face cam. In the circumferential direction, the lower end face cam has an upward driving section 31 that drives the upper actuating member to move upward as the lower rotating member rotates. The lower end face cam also has a downward section 32 at the end of the upward driving section that disengages from the upper end face cam. The downward section 32 is a vertically arranged facade structure, and the circumferential side of the lowest position of the upper end face cam is also a facade. That is, when the lower rotating member rotates, the upward driving section first drives the upper actuating member, causing the upper actuating member to move upward, such as... Figure 2 As shown, as the lower rotating component continues to rotate, the upper moving component rises to its highest height, as... Figure 3 As shown, when the lower rotating component continues to rotate, the rising drive section will disengage from the upper end face cam, meaning the rising drive section can no longer support the upper end face cam. Under the combined action of its own weight and the return spring of the actuating component, the impact hammer quickly moves downward and strikes the impact wheel. When the impact hammer contacts and impacts the impact wheel, the upper end face cam and the lower end face cam are spaced apart to prevent the impact force from being transmitted to the lower rotating component. When the lower rotating component continues to rotate, the lower end face cam will re-engage with the upper end face cam as the lower rotating component rotates.

[0036] An actuator return spring 25 is provided at the upper end of the upper actuator for pressing down on the upper actuator. The compression of the actuator return spring 25 is adjustable. Specifically, a vertically arranged pressure plate guide rod 28 is fixed on the device bracket. A spring pressure plate 26 for pressing down on the actuator return spring is guided and moved on the pressure plate guide rod 28. A spring adjusting nut 27 is threadedly connected to the upper side of the spring pressure plate on the pressure plate guide rod. By adjusting the height of the spring adjusting nut 27, the compression of the actuator return spring 25 can be adjusted. This compression determines the impact force of the impact wheel on the target surface.

[0037] A rotating gear 22 is fixed to the outer circumference of the lower rotating component, and a power source gear 21 that meshes with the rotating gear is provided on the motor shaft of the power output end motor of the power source 20.

[0038] In use, the traveling wheel moves along the surface 12 of the object being tested, and the impact wheel also contacts the surface 12. Under the action of friction, the impact wheel rotates accordingly. The power source drives the lower rotating component to rotate. Each rotation of the lower rotating component causes the impact hammer to move upward and then downward with the upper moving component to strike the impact wheel once. The impact wheel strikes the surface of the object being tested, and the impact sound is used to determine whether the lower surface of the object being tested is hollow. In this embodiment, a sound recording device is used to record the sound of the impact wheel striking the surface of the object being tested, and then the quality of the surface of the object being tested is automatically determined. In other embodiments of the present invention, the sound recording device may not be provided, in which case the operator can listen to the impact sound by ear to make a judgment.

[0039] In other embodiments of the present invention, the floating of the impact wheel can also be achieved by, for example, providing a guide hole extending in the vertical direction on the device bracket, the impact wheel shaft of the impact wheel being guided and moved in the guide hole, a bearing being sleeved on the impact wheel shaft, and a return spring of the impact wheel being mounted on the upper end of the bearing between the bearing and the device bracket; the intermittent drive mechanism can also be in other forms, such as a motor, with an eccentric wheel fixed on the motor shaft, and the eccentric wheel generating a downward impact every time the motor shaft rotates one revolution.

[0040] Embodiment 2 of a hammer impact detection device Figures 4-9 As shown: The difference between Embodiment 2 and Embodiment 1 is that the form of the intermittent drive mechanism in Embodiment 2 is different from that in Embodiment 1.

[0041] In this embodiment:

[0042] The intermittent drive mechanism includes a fixed shaft 10 fixed to a device support. The axis of the fixed shaft extends in the front-rear direction. The impact hammer 1 is coaxially rotatably connected to the fixed shaft 10. When the impact hammer 1 rotates in the forward direction, it impacts the outside. The center of gravity of the impact hammer 1 is located on the axis of rotation of the impact hammer. Therefore, during the reciprocating swing of the impact hammer, gravity in the impact hammer does no work. The impact hammer has an impact hammer impact part 11 for the upper surface of the impact wheel. The impact hammer impact part 11 is a ball-head structure, so the impact hammer impact part and the impact wheel are in point contact. In this invention, forward and reverse are relative. That is, when the impact hammer rotates, rotation in one direction is forward, and rotation in the other direction is reverse. In this embodiment, it is... Figure 4 The perspective changes: rotating counterclockwise becomes the positive direction, and rotating clockwise becomes the negative direction.

[0043] The front end of the fixed shaft is also coaxially rotatably connected to a hook bracket 14. A drive shaft 13 is fixed on the hook bracket 14. The drive shaft 13 is sleeved on the front end of the fixed shaft. The drive shaft constitutes a bracket torque input structure for torque input to drive the hook bracket to rotate. In this embodiment, a drive motor 7 for driving the drive shaft to rotate is provided on the device bracket.

[0044] The hook bracket is a rod-shaped structure whose length extends radially along a fixed axis. Both ends of the hook bracket are provided with hook mechanisms 2. The impact hammer 1 is provided with an impact hammer hook engagement part 1-1 for engaging with the hook of the hook mechanism. The hook engagement part includes a hook engagement groove located on the front side of the impact hammer. The hook mechanism 2 is located on the front side of the impact hammer 1. The hook mechanism includes a hook rod 2-1 rotatably mounted on the hook bracket with its rotation axis extending in the front-back direction. One end of the hook rod 2-1 is provided with a hook 2-2 for engaging with the hook engagement grass hook. The other end of the hook rod is provided with a push head 16. A hook return spring 15 is provided between the push head 16 and the hook bracket 14. The hook spring is used to apply force to the push head so that the hook rod has a clockwise rotation tendency.

[0045] The device support is also equipped with an unlocking trigger device 4 for engaging with the hook mechanism to unlock the hook engagement part of the impact hammer. In this embodiment, the unlocking trigger device is a fixed block fixed on the device support. When the hook support rotates clockwise, the push head touches the unlocking trigger device, the hook rod rotates counterclockwise, and the hook 2-2 can disengage from the hook engagement groove. At the same time, as the hook support 14 continues to rotate clockwise, the push head 16 can pass over the unlocking trigger device. In this way, the hook support only needs to maintain a clockwise unidirectional rotation, and each hook mechanism 2 can engage with the hook engagement part in sequence. The hook support does not need to rotate back and forth, making control simpler. The circumferential position of the fixed block is adjustable. By adjusting the circumferential position of the fixed block, the compression degree of the spring device can be adjusted, thereby adjusting the impact force of the impact hammer hitting the impact wheel.

[0046] The device support is also equipped with a spring device 3. The spring device 3 has a potential energy triggering part that is pushed by the impact hammer to achieve energy storage when the hook mechanism drives the impact hammer to rotate in the opposite direction. The spring device and the impact hammer are set independently. When the impact hammer strikes the outside, the impact hammer and the potential energy triggering part are set at intervals.

[0047] The spring device 3 includes a disc spring 3-1 with its inner end fixed on a fixed shaft and its outer end connected to a stop bar 3-2. The stop bar 3-2 constitutes a potential energy triggering part. The length of the stop bar extends in the front-rear direction. The axis of the disc spring is coaxial with the rotation axis of the impact hammer. The disc spring 3-1 is located between the impact hammer 1 and the hook bracket 14. The stop bar is located on the upper side of the impact hammer.

[0048] When using it, in the initial state, such as Figure 6 As shown, the impact hammer's impact part contacts the surface of the impact wheel, the hook of the hook mechanism engages with the impact hammer hook mating part on the impact hammer, the coil spring of the spring device is in a free state (zero potential energy state), and the impact hammer and the stop bar of the spring device are spaced apart in the circumferential direction; the drive motor drives the hook bracket to rotate clockwise, and the hook bracket, through the hook mechanism, causes the impact hammer to rotate clockwise. When the impact hammer contacts the stop bar, as... Figure 7 As shown, the coil spring of the spring device begins to store energy. As the hook bracket and the impact hammer continue to rotate clockwise, the push head of the hook mechanism contacts the unlocking trigger device on the device bracket, the hook rod of the hook mechanism rotates counterclockwise, and the hook of the hook mechanism disengages from the hook engagement part of the impact hammer. The coil spring begins to release energy, and the impact hammer rotates counterclockwise (i.e., forward) under the action of the coil spring. When the impact hammer disengages from the stop bar, the impact part of the impact hammer does not contact the surface of the impact wheel. As the impact hammer continues to rotate counterclockwise, the impact part of the impact hammer contacts and impacts the surface of the impact wheel. Since the impact hammer and the spring device are disengaged during impact in this invention, the spring device does not act on the impact hammer at the moment of impact. Therefore, the potential energy of the spring device can be completely converted into the kinetic energy of the impact hammer, and the impact energy of the impact hammer can be accurately set.

[0049] When continuous impact testing is required, the hook bracket continues to rotate clockwise, and another hook mechanism engages with the impact hammer hook.

[0050] In other embodiments of the present invention: there may be only one hook mechanism. In this case, the hook support can achieve multiple impacts on the impact wheel by reciprocating swing; the spring device may also be a helical spring, which may be arc-shaped or straight, as long as it can be compressed to store energy during the reverse rotation of the pendulum.

[0051] In the foregoing description of this specification, unless otherwise expressly specified and limited, the terms "fixed," "installed," "connected," or "linked" should be interpreted broadly. For example, the term "linked" can refer to a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; or it can refer to the internal communication of two components or the interaction between two components. Therefore, unless otherwise expressly limited in this specification, those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0052] Based on the above description in this specification, those skilled in the art will also understand that terms used, such as "upper," "lower," "front," "rear," "left," "right," "length," "width," "thickness," "vertical," "horizontal," "top," "bottom," "inner," "outer," "axial," "radial," "circumferential," "center," "longitudinal," "transverse," "clockwise," or "counterclockwise," are terms indicating orientation or positional relationships based on the orientation or positional relationships shown in the accompanying drawings of this specification. They are only for the purpose of facilitating the explanation of the present invention and simplifying the description, and do not imply that the devices or elements involved must have the specific orientation, or be constructed and operated in a specific orientation. Therefore, the above-mentioned orientation or positional relationship terms should not be understood or interpreted as limitations on the present invention.

[0053] Furthermore, the terms "first" or "second," etc., used in this specification to refer to numbers or ordinal numbers are for descriptive purposes only and should not be construed as indicating, explicitly or implicitly, relative importance or specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this specification, "a plurality of" means at least two, such as two, three, or more, unless otherwise explicitly specified.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hammer detection device, characterized by: The device support is provided with walking wheels, a movable percussion wheel capable of floating up and down is movably arranged on the device support and capable of rotating when the device support moves, a percussion wheel return spring for keeping the percussion wheel in contact with a target surface is arranged on the device support, an intermittent driving mechanism driven by a power source is arranged on the device support, and the intermittent driving mechanism has a percussion hammer for intermittently hitting the percussion wheel; The intermittent driving mechanism comprises a lower rotating member with a rotating axis extending in the up-down direction, and an upper action member capable of rotating in the up-down direction, the lower rotating member is driven to rotate by the power source, the lower rotating member is provided with a central hole, the percussion hammer is a vertically arranged rod structure, the percussion hammer penetrates the central hole, the upper end of the percussion hammer is fixedly connected with the upper action member, the lower end of the percussion hammer is used for hitting the percussion wheel, the upper end of the lower rotating member is provided with a lower end surface cam, the lower end of the upper action member is provided with an upper end surface cam used in cooperation with the lower end surface cam, in the circumferential direction, the lower end surface cam has a rising driving section for driving the upper action member to move upward when the lower rotating member rotates, and the lower end surface cam also has a descending section at the end of the rising driving section for supporting the upper end surface cam; the upper end of the upper action member is provided with an action member return spring for pressing the upper action member downward, and the compression amount of the action member return spring is adjustable; when the percussion hammer hits the percussion wheel, the upper end surface cam and the lower end surface cam are arranged in a spaced manner, and the lower end surface cam is in contact with the upper end surface cam when the lower rotating member rotates; the outer periphery of the lower rotating member is fixedly provided with a rotating member gear, and the power output end of the power source is provided with a power source gear engaged with the rotating member gear for transmission. The intermittent driving mechanism further comprises a fixed shaft fixed to the device support, the axis of the fixed shaft extends in the front-back direction, and the percussion hammer is coaxially and rotatably connected to the fixed shaft, the percussion hammer is externally hit when it rotates in the positive direction, the center of gravity of the percussion hammer is located on the rotating axis of the percussion hammer, and the gravity in the percussion hammer does not work during the reciprocating swing of the percussion hammer, and the device support is further provided with a spring device, the spring device has a potential energy trigger part for being pushed by the percussion hammer to store energy when the hook mechanism drives the percussion hammer to rotate in the reverse direction, the spring device is independently arranged with the percussion hammer, and the percussion hammer and the potential energy trigger part are arranged in a spaced manner when the percussion hammer hits externally.

2. The hammer detection device of claim 1, wherein: The device support is provided with a sound collecting device for collecting the sound of the percussion wheel hitting the target surface.

3. The hammer detection device of claim 1, wherein: The power source is a hydraulic motor or a pneumatic motor.

4. The hammer detection device of claim 1, wherein: The outer surface of the percussion wheel is a spherical surface, and the contact surface of the percussion hammer in contact with the percussion wheel is a spherical surface.

5. The hammer detection device of claim 1, wherein: The device support is hingedly provided with a swing arm with an axis extending in the front-back direction, and the percussion wheel is rotatably arranged on the swing arm, or the device support is provided with a guide structure extending in the up-down direction, and the percussion wheel wheel shaft of the percussion wheel is movably arranged on the guide structure.

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