A pile foundation construction pile foundation hole fixed-point detection device

Abstract

The present application relates to pile foundation hole detection device technical field, disclose a kind of pile foundation construction pile foundation hole fixed-point detection device, including winch machine, the winch machine bottom is hung with lifting hook, the lifting hook bottom is rotatably hung with multiple first connecting rods, multiple first connecting rods are fanned out, and each the first connecting rod is rotatably connected with support rod at one end of diverging, the first connecting rod bottom is hung with transmission shaft, the transmission shaft outer sleeve is connected with connecting column structure, the connecting column structure bottom is rotatably connected with support beam, the support beam bottom is slidably connected with ultrasonic instrument, the support beam is installed with main transmission wheel, this pile foundation construction pile foundation hole fixed-point detection device, when transmission shaft rotates, can make overall rotation in hole, in the process that cleaning knife extends support rod, let every cleaning knife can be located in the arch of hole inner wall and is cleaned, improve the range of cleaning knife repair hole inner wall, reduce the time required for testing single hole.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of pile foundation hole detection devices, in particular to a pile foundation hole fixed-point detection device for pile foundation construction. BACKGROUND

[0002] The existing pile foundation will produce a hole on the ground after the pile drilling equipment drills a hole, and these holes usually need to be maintained, and in the maintenance process, the parameters of the hole, such as the size, depth, and regularity of the inner wall of the hole, and the height of the soil residue layer at the bottom of the hole, need to be detected in real time. The existing hole detection method usually has three steps: the first step is to preferentially detect whether the size of the hole is compliant, the second step is to detect the height of the sediment at the bottom of the hole, and the third step is to detect the perpendicularity of the hole. When detecting the size of the hole, the detection equipment is usually hung and aligned with the axis of the hole and then slowly put into the hole. The detection equipment usually includes a cage caliper and an umbrella caliper. As the names imply, both have the same usage, and are used to detect the size and shape of the hole. After detection, the equipment is replaced, and an ultrasonic probe is placed inside the hole to detect the thickness of the sediment using ultrasonic signals. Then, an electronic level is placed inside the hole, and when the electronic level contacts the inner wall of the hole, an inductor contacts the inner wall of the hole to measure the inclination of the hole in sections, and the recorded information is displayed on the computer. At this point, the parameter detection of the hole is complete. However, this way of using multiple devices to detect in sequence will increase the detection time, and the detection process usually uses a winch to continuously put the equipment into the hole by means of a rope. When the inner wall of the hole is irregular (especially for inclined pile holes), the soil inside the hole will sink and arch towards the axis of the hole under the action of gravity. However, since the rope is always in a vertical state, the above equipment will be hindered during lifting, resulting in incorrect judgments of the depth and inclination of the hole. Therefore, it is necessary to repeatedly lift the equipment multiple times to obtain accurate data, making the hole detection process cumbersome, and the winch structure cannot effectively clear the obstacles of the detection equipment. Therefore, we propose a pile foundation hole fixed-point detection device for pile foundation construction. SUMMARY

[0003] The present application relates to the technical field of pile foundation hole detection devices, in particular to a pile foundation hole fixed-point detection device for pile foundation construction.

[0004] In order to achieve the above object, the present application provides the following technical scheme: a pile foundation construction pile foundation hole fixed point detection device, including a winch, the bottom of the winch is provided with a lifting hook, the bottom of the lifting hook is rotatably provided with a plurality of first connecting rods, the plurality of first connecting rods are fan-shaped, and the end of each first connecting rod away from each other is rotatably connected with a support rod, the bottom of the plurality of first connecting rods is provided with a transmission shaft, the transmission shaft is externally sleeved with a connecting column structure, the bottom of the connecting column structure is rotatably connected with a support beam, the bottom of the support beam is slidably connected with an ultrasonic instrument, one side of the top of each support rod is fixedly connected with a second guide rail, the second guide rail is fixedly installed with a second spring, one end of the second spring is fixedly connected with a second roller, the outer ring of each second roller exceeds the outer side of the support rod, the shaft part of the second roller extends to the outer side of the second guide rail, the shaft part of the second roller is fixedly connected with a first lower folding rod, the first lower folding rod is downwardly bent at one end and forms a state of facing the surface of the support beam, the bent end of the first lower folding rod is fixedly connected with a first rack, the bottom of the first rack is fixedly connected with a driving rod, the support beam is provided with a main transmission wheel, each driving rod is inserted into the main transmission wheel, the driving rod is driven to rotate on the support beam in the tangential direction of the main transmission wheel, one side of the bottom of each support rod is fixedly connected with a sliding rail, the sliding rail is slidably connected with a pushing rod, one end of the pushing rod is engaged with the main transmission wheel, and the other end of the pushing rod is fixedly installed with a cleaning knife.

[0005] Preferably, the support beam is composed of a pair of freely rotating through rods, bearings are fixedly connected between the through rod located at the top and the connecting column structure and between the two through rods, the outer ring of the bearing located at the top is sleeved with a first gear, and the outer ring of the bearing between the two through rods is fixedly connected with a second gear.

[0006] Preferably, each first rack is engaged with the first gear, a first guide rail is fixedly installed on the other side of the bottom of each support rod, a first spring is fixedly connected to one side of the inner part of the first guide rail, a first roller is fixedly connected to the first spring, a fixed rod is fixedly connected to one side of the first roller, the fixed rod extends upward at one end, a second rack is fixedly connected to one end of the fixed rod, and the second rack is engaged with the second gear.

[0007] Preferably, the support rod is provided as at least six, and a distance sensor is fixedly connected to the bottom of each support rod.

[0008] Preferably, a second connecting rod is rotatably connected to the bottom of each support rod, one end of each second connecting rod faces the bottom of the support beam, a lifting sliding table is slidably connected to the bottom of the support beam, each second connecting rod is rotatably connected with the lifting sliding table, and the lifting sliding table and the ultrasonic instrument are fixedly connected together.

[0009] Preferably, the lifting slide top is circularly equidistantly provided with a plurality of swing rods, the inner bottom of each supporting rod is rotationally connected with a leaning rod, one end of each leaning rod away from the supporting rod is fixedly connected with a limiting block, the outer bottom of the support beam is provided with a plurality of limiting grooves for accommodating the limiting blocks, and the inner bottom of each limiting block is provided with a plurality of branch openings.

[0010] Preferably, the support beam is fixedly connected with a horizontal rod at the middle portion, and the horizontal rod is slidably connected with an inductor at both ends.

[0011] Preferably, the limiting block is provided with a common sliding area, and each branch opening is upwardly inclined at one end and communicates with the common sliding area.

[0012] Preferably, the connecting column structure and the support beam are made of light materials, and the connecting column structure is provided in a hollow form.

[0013] Preferably, the length of each supporting rod is not more than 2 m, and the limiting distance between the two supporting rods is 1.5 m.

[0014] Compared with the prior art, the beneficial effects of the present application are that when the first roller encounters the hole inner wall in the arched state, the overall passage is first blocked, in addition, after the first roller contacts the hole inner wall, the first roller will slide upwards along the hole inner wall, the first roller will compress the first spring, and under the compression of the first spring, the first roller is accommodated into the inner bottom of the supporting rod, at the same time, the second roller at the top of the supporting rod contacts the first roller on the hole inner wall to form a diagonal line, the second roller also contacts the hole inner wall, and in the process of recovering the second roller to the inner bottom of the supporting rod, the first lower folding rod connected with the second roller moves to the surface of the connecting column structure, one end of the first lower folding rod is connected with the first rack, and the bottom of the first rack drives the driving rod to rotate the main transmission wheel on the connecting column structure; when the transmission shaft rotates, the whole can rotate in the hole, and in the process that the cleaning knives extend out of the supporting rods, each cleaning knife can clean the arched part of the hole inner wall, the range of repairing the hole inner wall by the cleaning knives is improved, and the time required for testing a single hole is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 It is a schematic structural view of the whole application;

[0016] Figure 2 It is a schematic structural view of the whole application; Figure 1

[0017] Figure 3 It is a schematic structural view of the whole application from another perspective; ​

[0018] Figure 4 For the invention Figure 3 Amplification structure schematic diagram at B in the invention

[0019] Figure 5 For the invention First connecting rod and support rod and second connecting rod structure schematic diagram

[0020] Figure 6 For the invention Support rod top structure for driving cleaning knife movement schematic diagram

[0021] Figure 7 For the invention Connecting column structure and support beam structure schematic diagram

[0022] Figure 8 For the invention Connecting column structure and support beam split structure schematic diagram

[0023] Figure 9 For the invention Support beam bottom structure schematic diagram

[0024] Figure 10 For the invention Support rod structure schematic diagram for expansion

[0025] Figure 11 For the invention Limiting block structure schematic diagram

[0026] In the figure: 1-winch machine; 2-hook; 3-first connecting rod; 4-support rod; 5-connecting column structure; 501-transmission shaft; 502-support beam; 503-limiting groove; 6-ultrasonic instrument; 7-second connecting rod; 8-first lower folding rod; 9-first rack; 10-driving rod; 11-bearing; 12-first gear; 13-main transmission wheel; 14-second gear; 15-second rack; 16-first roller; 17-first guide rail; 18-first spring; 19-slideway; 20-push rod; 21-distance sensor; 22-cleaning knife; 23-fixed rod; 24-second roller; 25-second spring; 26-second guide rail; 27-horizontal rod; 28-inductor; 29-lifting slide; 30-swinging rod; 31-relying rod; 32-limiting block; 33-split gate. DETAILED DESCRIPTION

[0027] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0028] Please refer to Figures 1-11The application provides a technical scheme: a pile foundation construction pile foundation hole fixed point detection device, which comprises a winch 1, the bottom of the winch 1 is provided with a lifting hook 2, a plurality of first connecting rods 3 are rotatably arranged at the bottom of the lifting hook 2, the plurality of first connecting rods 3 are arranged in a fan shape, and the end of each first connecting rod 3 away from each other is rotatably connected with a supporting rod 4, a transmission shaft 501 is arranged at the bottom of the plurality of first connecting rods 3, a connecting column structure 5 is arranged outside the transmission shaft 501, a support beam 502 is rotatably connected to the bottom of the connecting column structure 5, and an ultrasonic instrument 6 is slidably connected to the bottom of the support beam 502, a second guide rail 26 is fixedly connected to one side of the top of each supporting rod 4, a second spring 25 is fixedly installed on the second guide rail 26, and one end of the second spring 25 is fixedly connected with a second roller 24, the outer ring of each second roller 24 exceeds the outer side of the supporting rod 4, the shaft part of the second roller 24 extends to the outer side of the second guide rail 26 and rolls, the shaft part of the second roller 24 is fixedly connected with a first lower folding rod 8, the first lower folding rod 8 is bent downward at one end and forms a shape facing the surface of the support beam 502, the bent end of the first lower folding rod 8 is fixedly connected with a first rack 9, and the bottom of the first rack 9 is fixedly connected with a driving rod 10; a main transmission wheel 13 is installed on the support beam 502, each driving rod 10 is inserted into the main transmission wheel 13, the driving rod 10 is driven to rotate on the support beam 502 in the tangential direction of the main transmission wheel 13, one side of the bottom of each supporting rod 4 is fixedly connected with a sliding rail 19, a pushing rod 20 is slidably connected to the sliding rail 19, one end of the pushing rod 20 is engaged with the main transmission wheel 13, and the other end of the pushing rod 20 is fixedly installed with a cleaning knife 22; the connecting column structure 5 and the support beam 502 are made of light materials, and the inside of the connecting column structure 5 is provided in a hollow form; further, the support beam 502 is composed of a pair of freely rotating through rods, bearings 11 are fixedly connected between the through rod at the top and the connecting column structure 5 and between the two through rods, a first gear 12 is sleeved with the outer ring of the bearing 11 at the top, and a second gear 14 is fixedly connected with the outer ring of the bearing 11 between the two through rods.

[0029] When the device is in a tilted state, the hole has the possibility of arching upwards or collapsing downwards, which cannot be used normally. When the device is transported into the hole, the first roller 16 at the bottom of the support rod 4 is in contact with the lower inner wall of the hole. When the first roller 16 encounters the arching lower inner wall, the overall passage is blocked. In addition, after the first roller 16 contacts the lower inner wall, it will slide upwards along the lower inner wall. The first roller 16 will compress the first spring 18. Under the compression of the first spring 18, the first roller 16 is retracted into the inside of the bottom of the support rod 4. At the same time, the second roller 24 at the top of the support rod 4 is in contact with the first roller 16 on the lower inner wall, forming a diagonal line. The second roller 24 also contacts the upper inner wall. During the retraction of the second roller 24 into the inside of the top of the support rod 4, the first lower folding rod 8 connected to the second roller 24 moves towards the surface of the connecting column structure 5. One end of the first lower folding rod 8 is connected to the first rack 9. The bottom of the first rack 9 drives the driving rod 10 to drive the main transmission wheel 13 to rotate on the connecting column structure 5. When the bracket beam 502 rotates, the bearings 11 installed on the upper and lower ends of the bracket beam 502 separate the upper and lower parts of the bracket beam 502. When the main transmission wheel 13 rotates, it can drive each pushing rod 20 to extend outward, so that the cleaning knife 22 on each sliding rail 19 extends outside the support rod 4. When the device is inserted into the hole, the motor for connecting the transmission shaft 501 (located inside the connecting column structure 5, not shown) and the motor for connecting the cleaning knife 22 should be immediately driven. When the transmission shaft 501 rotates, the overall device can rotate in the hole. During the extension of the cleaning knife 22 outside the support rod 4, each cleaning knife 22 can clean the arching part of the inner wall of the hole, thereby improving the cleaning range of the cleaning knife 22 and reducing the time required for testing a single hole.

[0030] When the device can freely ascend and descend in the hole, the second roller 24 does not contact the inner wall of the hole. The second roller 24 is reset, and the driving rod 10 drives the main transmission wheel 13 to reverse, until each cleaning knife 22 is reset to the inside of each support rod 4.

[0031] Furthermore, each first rack 9 is in meshing transmission with the first gear 12. The first guide rail 17 is fixedly installed on the other side of the bottom of each support rod 4. The first spring 18 is fixedly connected to the inside of the first guide rail 17. The first roller 16 is fixedly connected to the first spring 18. The fixed rod 23 is fixedly connected to one side of the first roller 16. The fixed rod 23 extends upwards at one end. The second rack 15 is fixedly connected to one end of the fixed rod 23. The second rack 15 is in meshing transmission with the second gear 14.

[0032] In addition, the first rack 9 and the first gear 12 are engaged, and the second rack 15 and the second gear 14 are engaged, and the first gear 12 and the second gear 14 are located on the upper and lower bearings 11 of the support beam 502, so that the connection between the components is contacted, and the balance of the overall weight is more balanced, and in the overall rotation process, the overall is in a dynamic balance state, and the firmness of the overall is improved.

[0033] Further, the horizontal rod 27 is fixedly connected to the middle of the support beam 502, and the inductor 28 is slidably connected to both ends of the horizontal rod 27; wherein the inductor 28 connected to the horizontal rod 27 is also arranged in the middle of the support beam 502, and the sliding distance of the inductor 28 on the horizontal rod 27 is used to judge the angle of the inner wall of the pile hole, which is used to test the inclination of the pile hole, and the whole has the above multiple functions, and can test multiple data values at a time, and has good functionality.

[0034] Further, the second connecting rod 7 is rotatably connected to the bottom of each support rod 4, one end of each second connecting rod 7 is directed to the bottom of the support beam 502, the lifting slide 29 is slidably connected to the bottom of the support beam 502, each second connecting rod 7 is rotatably connected to the lifting slide 29, and the lifting slide 29 and the ultrasonic instrument 6 are fixedly connected together.

[0035] The lifting slide 29 is circularly and equidistantly mounted with a plurality of swing rods 30 on the top, the leaning rod 31 is rotatably connected to the inner bottom of each support rod 4, the limiting block 32 is fixedly connected to one end of each leaning rod 31 away from the support rod 4, a plurality of limiting grooves 503 for accommodating the limiting block 32 are formed in the outer side of the bottom of the support beam 502, a plurality of branch openings 33 are arranged in the inside of each limiting block 32, and the swing rod 30 and the branch opening 33 are slidably connected together; the limiting block 32 is provided with a common sliding area, and each branch opening 33 is inclined upward at one end, and each branch opening 33 is connected with the common sliding area.

[0036] The winch machine 1 is placed directly above the pile hole, and the whole is directly connected through the hook 2 and the winch machine 1, and then the rope is put through the winch of the winch machine 1, and the whole is slowly put into the pile hole. During the process of putting the rope, the supporting rod 4 and the connecting column structure 5 are vertically arranged under the influence of gravity, so that the ultrasonic instrument 6 is located directly below the whole, and the ultrasonic instrument 6 is in a vertical central state. Therefore, in the initial state, the ultrasonic instrument 6 is located below the second connecting rod 7. In the initial state, the top of the swing rod 30 is located on the branch channel 33 at the lowest point of the limiting block 32, and the branch channel 33 on each limiting block 32 is in an inclined state. Therefore, the branch channel 33 can limit the ultrasonic instrument 6 and the swing rod 30 connected to the top of the lifting slide 29 which has a certain gravity, preventing the lifting slide 29 from sliding off the bottom of the support beam 502 during the lifting process. In addition, by using this structure, when the ultrasonic instrument 6 contacts the bottom sediment in the pile, the winch machine 1 can continuously put the rope, so that the ultrasonic instrument 6 stays still above the sediment after contacting the sediment. The first connecting rod 3, the supporting rod 4 and the connecting column structure 5 rely on their own gravity to make the connecting column structure 5 descend, so that the lifting slide 29 and the support beam 502 slide during the descending process. During this process, it can also be seen that the lifting slide 29 moves upward at the bottom of the support beam 502. Therefore, during the upward movement of the lifting slide 29, one end of the second connecting rod 7 will move upward along the vertical direction, so that the other end of the second connecting rod 7 will expand outward during the movement, thereby supporting the supporting rod 4 outward, so that the supporting rod 4 forms an umbrella-shaped structure around the connecting column structure 5. During the supporting process of the supporting rod 4, the limiting block 32 on the stay rod 31 is separated from the limiting groove 503, and during the separation process, the limiting block 32 on one side is resisted by the outer circle of the support beam 502 to slide downward. The distance sensor 21 on the side of the bottom of each supporting rod 4 will gradually approach the inner wall of the hole, until the distance sensor 21 is attached to the inner wall of the hole, and then the winch machine 1 stops putting the rope. At this time, the top of the swing rod 30 will be located on a branch channel 33 on the limiting block 32, and the ultrasonic instrument 6 and the lifting slide 29 will be locked again. Then control the winch machine 1 to reverse, so that the whole rises in the hole. During the sliding process of the distance sensor 21 along the inner wall of the hole, the self-elastic stretching test element (existing structure) records the size of the hole and uploads it to the computer. At this point, the pile hole detection is completed.

[0037] It is worth mentioning that the connection between the swing rod 30 and the lifting slide 29 should be provided with a torsional spring to ensure that the swing rod 30 slides on the side wall of the branch channel 33 of the limiting block 32, rather than randomly swinging.

[0038] It has to be noted that, in the present document, the terms "first", "second", etc. merely serve to identify different entities or actions from each other, without necessarily requiring or implying any actual relationship or order between these entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can include other elements not expressly listed or inherent to such process, method, article, or apparatus.

[0039] While embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, combinations, and variations of the embodiments can be undertaken without departing from the spirit and scope of the present application, which is defined by the appended claims and their equivalents.

Claims

1. A device for pinpointing and detecting pile foundation holes during pile foundation construction, comprising a winch (1), wherein a hook (2) is provided at the bottom of the winch (1), characterized in that: The bottom of the hook (2) is rotatably suspended by multiple first connecting rods (3), which are fan-shaped. Each first connecting rod (3) is rotatably connected to a support rod (4) at one end opposite to the other. A drive shaft (501) is suspended at the middle of the bottom of the multiple first connecting rods (3). A connecting column structure (5) is sleeved on the outside of the drive shaft (501). A support beam (502) is rotatably connected to the bottom of the connecting column structure (5). An ultrasonic instrument (6) is slidably connected to the bottom of the support beam (502). A second guide rail (26) is fixedly connected to one side of the top of each support rod (4). A second spring (25) is fixedly installed on the second guide rail (26). A second roller (24) is fixedly connected to one end of each second spring (25). The outer ring of each second roller (24) extends beyond the outside of the support rod (4). The shaft of the second roller (24) faces the second guide rail (26). Extending outwards, the shaft of the second roller (24) is fixedly connected to a first downward bending rod (8). One end of the first downward bending rod (8) is bent downwards and forms a shape facing the surface of the support beam (502). The bent end of the first downward bending rod (8) is fixedly connected to a first rack (9). The bottom of the first rack (9) is fixedly connected to a drive rod (10). The support beam (502) is equipped with a main drive wheel (13). Each drive rod (10) is inserted into the main drive wheel (13). The drive rod (10) drives the main drive wheel (13) to rotate on the support beam (502) in the tangential direction of the main drive wheel (13). Each support rod (4) is fixedly connected to a slide rail (19) on one side of its bottom. A push rod (20) is slidably connected to the slide rail (19). One end of the push rod (20) meshes with the main drive wheel (13) for transmission. The other end of the push rod (20) is fixedly installed with a cleaning blade (22).

2. The pile foundation hole positioning detection device according to claim 1, characterized in that: The support beam (502) is composed of a pair of freely rotating through rods. The through rod at the top and the connecting column structure (5) and the two through rods are fixedly connected with bearings (11). The outer ring of the bearing (11) at the top is fitted with a first gear (12), and the outer ring of the bearing (11) between the two through rods is fixedly connected with a second gear (14).

3. The pile foundation hole positioning detection device according to claim 2, characterized in that: Each of the first racks (9) meshes with the first gear (12) for transmission. A first guide rail (17) is fixedly installed on the other side of the bottom of each support rod (4). A first spring (18) is fixedly connected to one side of the inside of the first guide rail (17). A first roller (16) is fixedly connected to the first spring (18). A fixed rod (23) is fixedly connected to one side of the first roller (16). One end of the fixed rod (23) extends upward. A second rack (15) is fixedly connected to one end of the fixed rod (23). The second rack (15) meshes with the second gear (14) for transmission.

4. The pile foundation hole positioning detection device according to claim 1, characterized in that: The support rods (4) are configured to be at least six, and each support rod (4) is fixedly connected to a distance sensor (21) at its bottom.

5. The pile foundation hole positioning detection device according to claim 4, characterized in that: Each of the support rods (4) is rotatably connected to a second connecting rod (7) at its bottom. One end of each second connecting rod (7) faces the bottom of the support beam (502). The bottom of the support beam (502) is slidably connected to a lifting slide (29). Each second connecting rod (7) is rotatably connected to the lifting slide (29). The lifting slide (29) and the ultrasonic instrument (6) are fixedly connected together.

6. The pile foundation hole positioning detection device according to claim 5, characterized in that: The top of the lifting slide (29) is circular and equidistantly equipped with multiple swing rods (30). Each support rod (4) is rotatably connected to a backing rod (31) at its bottom. Each backing rod (31) is fixedly connected to a limit block (32) at one end away from the support rod (4). The bottom outer side of the support beam (502) is provided with multiple limit grooves (503) for receiving the limit blocks (32). Each limit block (32) is provided with multiple channel openings (33). The top of the swing rod (30) and the channel openings (33) are slidably connected together.

7. The pile foundation hole positioning detection device according to claim 5, characterized in that: A horizontal rod (27) is fixedly connected to the middle of the support beam (502), and inductors (28) are slidably connected to both ends of the horizontal rod (27).

8. The pile foundation hole positioning detection device according to claim 6, characterized in that: The limiting block (32) has a common sliding area, and each of the lane openings (33) is tilted upward at one end, and each of the lane openings (33) is connected to the common sliding area.

9. The pile foundation hole positioning detection device according to claim 1, characterized in that: Both the connecting column structure (5) and the support beam (502) are made of lightweight materials, and the interior of the connecting column structure (5) is set in a hollow shape.

10. A pile foundation hole positioning detection device according to claim 1, characterized in that: The length of each of the support rods (4) shall not exceed 2 meters, and the maximum distance between two support rods (4) shall be 1.5 meters.

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