Center positioning device for pile casing

Abstract

The utility model belongs to the technical field of pile foundation construction measuring tools, and discloses a pile casing center positioning device which comprises a supporting assembly, two clamping assemblies, a positioning assembly and a leveling assembly, and the two clamping assemblies are arranged at the bottom of the supporting assembly at intervals with the central axis of the supporting assembly as the symmetry axis. The two opposite ends of the pile casing in the diameter direction can be correspondingly clamped; the positioning assembly comprises a positioning piece, a tape and a prism, the positioning piece is rotationally arranged at the top of the supporting assembly, the central axis of the positioning piece coincides with the central axis of the supporting assembly, the tape is arranged on the side wall of the positioning piece, and the prism is vertically installed at the central position of the top face of the positioning piece; the leveling assembly comprises two adjusting pieces and a first level bubble instrument, the two adjusting pieces correspond to the two clamping assemblies, each adjusting piece is clamped between the supporting assembly and the corresponding clamping assembly and can adjust the distance between the supporting assembly and the corresponding clamping assembly, and the first level bubble instrument is arranged on the positioning piece. The pile casing center positioning device can efficiently and accurately position the center of a pile casing.

Description

TECHNICAL FIELD

[0001] The utility model relates to pile foundation construction measuring tool technical field especially relates to a casing center positioning device. BACKGROUND

[0002] In the pile foundation construction process, the casing lofting as the primary and key link, its precision directly concerns the smoothness of follow -up construction and the overall engineering quality. But due to the complex and changeable construction site environment, such as uneven site, the existence of various obstacles around and the bad weather condition etc. Influence, cause the casing lofting process to be full of a large number of uncertainty.

[0003] At present, the center positioning device for conventional casing lofting, adopts the measurement mode based on total station instrument cooperation prism rod. In actual operation, the operator needs to wear a safety belt, and handholds the prism rod in the construction site. Total station instrument transmits signal, measures distance and angle through prism rod reflection, to determine the center position of casing. This kind of center positioning device meets the basic lofting demand to some extent, and is widely used in the past pile foundation construction project.

[0004] However, relying on manual holding prism rod positioning, the operator needs to repeatedly adjust the position and angle of prism rod, the operation difficulty is big, consumes long time, and long time manual holding can lead to the fatigue of survey personnel, influence the accuracy of measurement, it is difficult to meet the current efficient, accurate operation requirement. UTILITY MODEL CONTENT

[0005] The utility model aims at providing a casing center positioning device, which can efficiently and accurately position the center of the casing.

[0006] To achieve this purpose, the utility model adopts the following technical solutions:

[0007] The casing center positioning device comprises:

[0008] A support assembly;

[0009] Two clamping assemblies are symmetrically arranged on the bottom of the support assembly with the center axis of the support assembly as the symmetry axis, and can clamp the two ends of the casing corresponding to the diameter direction;

[0010] A positioning assembly comprising a positioning member, a tape measure and a prism, the positioning member is rotationally arranged on the top of the support assembly, and the center axis thereof coincides with the center axis of the support assembly, the tape measure is arranged on the side wall of the positioning member, and the prism is vertically installed on the center position of the top surface of the positioning member;

[0011] The leveling assembly comprises two sets of adjusting members and a first level bubble, the two sets of adjusting members correspond to the two clamping assemblies, each set of adjusting members is clamped between the support assembly and the corresponding clamping assembly and can adjust the distance between the support assembly and the clamping assembly, and the first level bubble is arranged on the positioning member.

[0012] Preferably, the support assembly comprises a support body and two support arms, the two support arms are adjustably connected to the two ends of the support body in the length direction, the two clamping assemblies are arranged on the two support arms, and the positioning member is rotatably arranged on the support body.

[0013] Preferably, the support assembly further comprises a locking member, the support arm is sleeved on the support body, and the locking member is adjustably connected to the support arm and can abut against the support body.

[0014] Preferably, the casing center positioning device further comprises a telescopic scale, the telescopic scale comprises a fixed part and two telescopic parts, the two telescopic parts are slidably connected to the opposite ends of the fixed part in the length direction, the fixed part is connected to the support body, and the two telescopic parts are connected to the two support arms.

[0015] Preferably, the leveling assembly further comprises a second level bubble, and the second level bubble is arranged on the top surface of the support assembly.

[0016] Preferably, the top surface of the support assembly is provided with a first positioning groove in the length direction and a second positioning groove in the width direction, the first positioning groove and the second positioning groove are in communication, and the intersection point is the center point of the top surface of the support assembly.

[0017] Preferably, the support assembly is in a strip shape, the casing center positioning device further comprises an auxiliary positioning member, the positioning member is rotatably arranged on the auxiliary positioning member, the auxiliary positioning member is arranged on the top of the support assembly, the center axis of the auxiliary positioning member coincides with the center axis of the support assembly, the two ends of the auxiliary positioning member protrude from the opposite sides of the support assembly in the width direction of the support assembly, a third positioning groove is arranged in the length direction through the top surface of the auxiliary positioning member, and a fourth positioning groove is arranged in the width direction through the top surface of the auxiliary positioning member, and the intersection point of the third positioning groove and the fourth positioning groove is the center point of the top surface of the auxiliary positioning member.

[0018] Preferably, the adjusting member comprises a fixed block and an adjusting knob, the fixed block is connected to the support assembly, the adjusting knob is rotatably arranged on the clamping assembly and is provided with a screw rod part, and the screw rod part is screwed to the fixed block.

[0019] As preferred, the clamping assembly comprises a limiting member and a fastener, the adjusting member is clamped between the limiting member and the supporting assembly, the limiting member is provided with a limiting groove, the casing wall body can be inserted into the limiting groove and abut against the bottom of the limiting groove, the fastener is adjustably connected to the limiting member, and the fasteners of the two clamping assemblies can abut against the side walls of the opposite sides of the casing.

[0020] As preferred, the fastener is screwed to the limiting member.

[0021] The utility model discloses beneficial effects:

[0022] By erecting the supporting assembly on the casing top, the two symmetrical clamping assemblies are clamped at the opposite ends of the casing to complete preliminary positioning, then the current casing inclination is judged by observing the first horizontal bubble instrument, the spacing between the supporting assembly and the clamping assembly is changed according to the bubble deviation direction to operate the corresponding adjusting member, and the bubble is gradually adjusted to the center to complete coarse leveling, then the distance from the multiple edge positions of the casing to the limiting member is measured by rotating the limiting member through the tape measure, the eccentricity is checked, the clamping assembly or the overall moving device is adjusted, so that the limiting member is preliminarily located on the center axis of the casing, the actual center coordinates of the casing are obtained through the prism, the deviation is calculated by comparing the design coordinates, the clamping assembly is finely adjusted to make the prism coordinates consistent with the design value, after confirming that the prism coordinates are correct, the first horizontal bubble instrument is observed again to perform fine leveling. In the whole positioning process, the five steps of clamping and fixing, coarse leveling, tape verification, prism positioning and fine leveling are closely connected, the accurate completion of the previous operation provides strong support for the smooth development of the subsequent link, gradually improves the accuracy of the casing center positioning, and the complex measurement and positioning task is divided into several simple and controllable steps, and the operator only needs to execute the established process to quickly complete the center positioning of the casing. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is the top view of the casing center positioning device of the utility model embodiment;

[0024] Figure 2 is the front view of the casing center positioning device of the utility model embodiment.

[0025] In the drawings:

[0026] 1, supporting assembly; 10, first positioning groove; 11, supporting body; 12, support arm; 13, locking member;

[0027] 2, clamping assembly; 21, limiting member; 210, limiting groove; 211, supporting plate; 212, side plate; 22, fastener;

[0028] 3, positioning assembly; 31, limiting member; 32, tape measure;

[0029] 4. leveling assembly; 41, adjusting member; 42, first level bubble; 43, second level bubble;

[0030] 5. telescopic scale;

[0031] 6. auxiliary positioning member; 61, third positioning groove; 62, fourth positioning groove;

[0032] 100. casing. DETAILED DESCRIPTION

[0033] The embodiments of the present application are described below in detail, examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar parts or parts having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary, and are intended to explain the present application, and cannot be understood as a limitation of the present application.

[0034] In the description of the present application, unless explicitly defined and limited otherwise, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, it can be mechanically connected, or it can be electrically connected, it can be directly connected, or it can be indirectly connected through an intermediate medium, it can be the internal communication of two elements or the interaction relationship between two elements. For ordinary skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0035] In the description of the present application, unless explicitly defined and limited otherwise, the feature "on" or "under" the first feature can include the direct contact between the feature and the first feature, or it can include the contact between the feature and the first feature through another feature between them. Moreover, the feature "on", "above" and "above" the first feature includes the feature directly above and obliquely above the first feature, or only indicates that the feature is higher than the first feature in horizontal height. The feature "under", "below" and "below" the first feature includes the feature directly below and obliquely below the first feature, or only indicates that the feature is lower than the first feature in horizontal height.

[0036] The technical scheme of the present application is further illustrated below by combining the drawings and through the specific embodiments.

[0037] As Figures 1-2The utility model provides a kind of protector center positioning device, including support assembly 1, two clamping assemblies 2, positioning assembly 3 and leveling assembly 4, two clamping assemblies 2 are symmetrically spaced with the center axis of support assembly 1 as symmetry axis to be set in support assembly 1 bottom, and can correspond to the two ends of the diameter direction relative clamping protector 100;Positioning assembly 3 includes positioning piece 31, tape 32 and prism, positioning piece 31 rotationally set in support assembly 1 top, and wherein center axis coincides with the center axis of support assembly 1, tape 32 is set in the side wall of positioning piece 31, prism is vertically installed in the center position of the top surface of positioning piece 31;Adjusting assembly 4 includes two groups of adjusting piece 41 and first horizontal bubble instrument 42, two groups of adjusting piece 41 correspond to two clamping assemblies 2, and each group of adjusting piece 41 is clamped between support assembly 1 and its corresponding clamping assembly 2 and can adjust the spacing between support assembly 1 and clamping assembly 2, and first horizontal bubble instrument 42 is set in positioning piece 31.

[0038] First, by erecting support assembly 1 on the top of protector 100, two symmetrically distributed clamping assemblies 2 are clamped on the two ends of protector 100 opposite, preliminary positioning is completed;Then observe first horizontal bubble instrument 42, judge the inclination of current protector 100, according to the bubble deviation direction, operate corresponding adjusting piece 41 to change the spacing between support assembly 1 and clamping assembly 2, gradually adjust to bubble center, complete coarse leveling;Then rotate positioning piece 31 to measure the distance from the edge position of protector 100 to positioning piece 31 by tape 32, check eccentricity, adjust clamping assembly 2 or overall moving device, so that positioning piece 31 is initially located on the center axis of protector 100;Again, the actual center coordinates of protector 100 are obtained by prism, the deviation is calculated by comparing the design coordinates, and the clamping assembly 2 is fine adjusted so that the prism coordinates coincide with the design value;After confirming that the prism coordinates are correct, observe first horizontal bubble instrument 42 again, and fine leveling is carried out.The whole positioning process, clamping, coarse adjustment, tape 32 verification, prism positioning and fine adjustment are closely connected, and the accurate operation of the previous operation provides strong support for the smooth development of the subsequent link, gradually improves the accuracy of the center positioning of protector 100, and decomposes the complex measurement positioning task into several simple and controllable steps, and the operator only needs to execute according to the established process, so that the center positioning of protector 100 can be quickly completed.

[0039] Specifically, as Figure 1As shown, the support assembly 1 comprises a support body 11 and two support arms 12, which are adjustably connected to the two ends of the support body 11 in the length direction, two clamping assemblies 2 are correspondingly arranged on the two support arms 12, and the positioning member 31 is rotatably arranged on the support body 11. Through telescopic adjustment, the entire positioning device can be conveniently moved on the top surface of the casing 100 to correct the positioning deviation, so that the positioning member 31 gradually approaches the central axis of the casing 100; and by adjusting the positions of the support arms 12 on the support body 11, the distance between the two clamping assemblies 2 can be changed, so that the two clamping assemblies 2 can stably clamp casings 100 of different diameters, thereby widening the application range of the positioning device, reducing the need for frequent replacement of the device for casings 100 of different specifications, effectively reducing the construction cost, and improving the construction efficiency.

[0040] In this embodiment, the support body 11 and the support arm 12 are both made of aluminum alloy.

[0041] More specifically, the support assembly 1 further comprises a locking member 13, the support arm 12 is sleeved on the support body 11, and the locking member 13 is adjustably connected to the support arm 12 and can abut against the support body 11. After adjusting the distance between the two support arms 12, the construction personnel can adjust the locking member 13 to tightly abut against the surface of the support body 11 to firmly fix the support arm 12 at the current position, preventing the support arm 12 from sliding due to vibration, collision or external factors during subsequent positioning operations.

[0042] In this embodiment, the locking member 13 is screwed on the support arm 12, and by rotating the locking member 13, the locking member 13 can be tightly combined with the support arm 12, and then firmly abut against the support body 11.

[0043] In other embodiments, a plurality of connecting grooves can also be formed on the support body 11, the connecting grooves are arranged at intervals along the length direction of the support body 11, a connecting hole is formed on the support arm 12, and the locking member 13 can be inserted into the connecting hole and clamped in the corresponding connecting groove.

[0044] More specifically, as shown, Figure 2 The casing center positioning device further comprises a telescopic scale 5, which comprises a fixed part and two telescopic parts, the two telescopic parts are slidably connected to the two ends of the fixed part in the length direction, the fixed part is connected to the support body 11, and the two telescopic parts are correspondingly connected to the two support arms 12. During the adjustment of the positions of the support arms 12 by the construction personnel, the change in the scale of the two telescopic parts with the movement of the support arms 12 can be clearly seen through the telescopic scale 5, so that the distance between the two clamping assemblies 2 can be accurately controlled, and the clamping positioning deviation caused by inaccurate distance can be avoided.

[0045] In the embodiment, the center of the fixed part is the zero scale position, the scale values gradually increase from the center to the two ends, and the prism is located at the zero scale position. In actual construction, if it is necessary to ensure that the adjustment distances of the two side arms 12 are consistent, the construction personnel can observe the scale values corresponding to the two side telescopic parts to ensure that the scale values are the same, so as to realize accurate and symmetrical adjustment.

[0046] Specifically, as shown in Figure 1 The top surface of the support assembly 1 is provided with a first positioning groove 10 in the length direction and a second positioning groove in the width direction. The first positioning groove 10 and the second positioning groove are in communication, and the intersection is the center point of the top surface of the support assembly 1. When the construction personnel measures the distance from the edge of the casing 100 to the positioning member 31 using the tape measure 32, it is difficult to ensure the accuracy of the direction of the tape measure 32 due to the interference of the surrounding environment. The first positioning groove 10 and the second positioning groove can provide clear visual guidance marks, and the trend of the first positioning groove 10 or the second positioning groove is used as a reference during the stretching process of the tape measure 32.

[0047] In the embodiment, the first positioning groove 10 is provided in the length direction of the support assembly 1, and the second positioning groove is provided in the width direction of the support assembly 1.

[0048] More specifically, the support assembly 1 is strip-shaped, and the casing center positioning device further comprises an auxiliary positioning member 6. The positioning member 31 is rotatably arranged on the auxiliary positioning member 6. The auxiliary positioning member 6 is arranged on the top of the support assembly 1, and the center axis of the auxiliary positioning member 6 coincides with the center axis of the support assembly 1. The two ends of the auxiliary positioning member 6 protrude from the opposite sides of the support assembly 1 in the width direction of the support assembly 1. The top surface of the auxiliary positioning member 6 is provided with a third positioning groove 61 in the length direction and a fourth positioning groove 62 in the width direction. The intersection of the third positioning groove 61 and the fourth positioning groove 62 is the center point of the top surface of the auxiliary positioning member 6.

[0049] The support assembly 1 is strip-shaped, simple in structure, and capable of reducing material waste, processing difficulty and cost during manufacturing. In addition, the strip-shaped structure is regular and easy to place and fix on the construction site. When the support assembly 1 is strip-shaped, the length of the second positioning groove is insufficient. At this time, the two ends of the auxiliary positioning member 6 protrude from the opposite sides of the support assembly in the width direction of the support assembly 1, providing sufficient reference length for the measurement operation. In addition, the cross-shaped groove structure formed by the intersection of the third positioning groove 61 and the fourth positioning groove 62 realizes multi-directional rapid positioning and improves the positioning accuracy.

[0050] In the embodiment, the auxiliary positioning member 6 is a rectangular aluminum alloy plate and is detachably connected to the support assembly 1 through bolts and nuts.

[0051] Specifically, as shown in Figure 2As shown, the clamping assembly 2 comprises a limiting piece 21 and a fastener 22, the adjusting piece 41 is clamped between the limiting piece 21 and the support assembly 1, the limiting piece 21 is provided with a limiting groove 210, the wall body of the casing 100 can be inserted into the limiting groove 210 and abut against the groove bottom of the limiting groove 210, the fastener 22 is adjustably connected to the limiting piece 21, and the fasteners 22 of the two clamping assemblies 2 can abut against the side walls of the opposite sides of the casing 100. The two limiting grooves 210 can quickly position the opposite sides of the casing 100, the support assembly 1 is erected on the casing 100, and the fastener 22 is adjusted to tightly abut against the side walls of the opposite sides of the casing 100, thereby enhancing the stability of the entire positioning device.

[0052] In the embodiment, the limiting piece 21 comprises a support plate 211 and two side plates 212, the two side plates 212 are spaced apart on the support plate 211 and surround the support plate 211 to form the limiting groove 210, and the adjusting piece 41 is clamped between the support plate 211 and the support arm 22.

[0053] In other embodiments, the clamping assembly 2 can also be a ring-shaped clamping assembly, which is composed of two movable clamping arms, and the two clamping arms move towards each other to clamp the casing 100.

[0054] More specifically, the fastener 22 is screwed to the limiting piece 21. The screwing connection mode is not only firm but also convenient to adjust.

[0055] Optionally, the positioning piece 31 is a cube of nodular cast iron material, which not only has corrosion resistance but also has a certain weight, and can provide stable support during positioning and is not easy to displace due to external interference.

[0056] In the embodiment, the top of the positioning piece 31 is provided with a socket groove for installing a prism.

[0057] In the embodiment, the first horizontal bubble instrument 42 is provided with two square horizontal bubble instruments, and the two first horizontal bubble instruments 42 are separately arranged on the opposite sides of the positioning piece 31.

[0058] Specifically, as shown, Figure 1 The leveling assembly 4 further comprises a second horizontal bubble instrument 43, which is arranged on the top surface of the support assembly 1. The second horizontal bubble instrument 43 can be mutually verified with the first horizontal bubble instrument 42. In a complex construction site environment, a single horizontal bubble instrument may be affected by factors such as installation position deviation and local light interference, which affects the accuracy of observation. Moreover, the second horizontal bubble instrument 43 arranged on the top surface of the support assembly 1 can monitor the horizontal state of the positioning device from another position, and the construction personnel can comprehensively judge whether the positioning device is in a horizontal state according to the display of the two bubble instruments.

[0059] In the embodiment, the second level bubble apparatus 43 is provided with two circular level bubble apparatuses, and the two level bubble apparatuses 43 are arranged on the two supporting arms 12 and located in the first positioning groove 10, so as to facilitate the operator to observe when adjusting the adjusting member 41.

[0060] Specifically, the adjusting member 41 comprises a fixing block and an adjusting knob, the fixing block is connected to the supporting assembly 1, the adjusting knob is rotationally arranged on the clamping assembly 2 and is provided with a screw rod part, and the screw rod part is screwed to the fixing block. When the leveling operation is needed, the construction personnel need not use complex tools, and only need to manually rotate the adjusting knob, so as to realize the accurate control of the distance through the threaded transmission of the screw rod part and the fixing block.

[0061] In other embodiments, the adjusting member 41 can also be an electric push rod, one end of which is fixed to the supporting assembly 1, and the other end of which is connected to the clamping assembly 2.

[0062] In the embodiment, each group of adjusting members 41 comprises two adjusting members 41, and the two adjusting members 41 are arranged at intervals.

[0063] In other embodiments, each group of adjusting members 41 can also comprise three adjusting members 41, and the number of the adjusting members 41 in each group of adjusting members 41 is not specifically limited.

[0064] Obviously, the above embodiments of the utility model are only examples for clearly explaining the utility model, and are not the limitation of the embodiments of the utility model. For the ordinary skilled in the art, other different forms of changes or variations can be made on the basis of the above description. Here, all the embodiments need not and cannot be exhausted. Any modification, equivalent replacement and improvement made in the spirit and principle of the utility model should be included in the protection scope of the utility model claim.

Claims

1. A casing center positioning device, characterized in that, include: Support component (1); Two clamping components (2) are symmetrically spaced at the bottom of the support component (1) with the central axis of the support component (1) as the axis of symmetry, and can correspondingly clamp the two ends of the protective cylinder (100) opposite to each other along the diameter direction; The positioning component (3) includes a positioning element (31), a measuring tape (32) and a prism. The positioning element (31) is rotatably disposed on the top of the support component (1), and its central axis coincides with the central axis of the support component (1). The measuring tape (32) is disposed on the side wall of the positioning element (31), and the prism is vertically installed at the center of the top surface of the positioning element (31). The leveling component (4) includes two sets of adjusting members (41) and a first leveling bubble meter (42). The two sets of adjusting members (41) correspond to the two clamping components (2). Each set of adjusting members (41) is clamped between the support component (1) and its corresponding clamping component (2) and can adjust the distance between the support component (1) and the clamping component (2). The first leveling bubble meter (42) is disposed on the positioning component (31).

2. The casing center positioning device according to claim 1, characterized in that, The support assembly (1) includes a support body (11) and two support arms (12). The two support arms (12) are tunably connected to the two ends of the support body (11) along its length. The two clamping assemblies (2) are correspondingly disposed on the two support arms (12). The positioning member (31) is rotatably disposed on the support body (11).

3. The casing center positioning device according to claim 2, characterized in that, The support assembly (1) further includes a locking member (13), the support arm (12) is sleeved on the support body (11), the locking member (13) is adjustablely connected to the support arm (12) and can abut against the support body (11).

4. The casing center positioning device according to claim 2, characterized in that, The protective sleeve center positioning device also includes a telescopic scale (5), which includes a fixed part and two telescopic parts. The two telescopic parts are slidably connected to the two opposite ends of the fixed part along the length direction. The fixed part is connected to the support body (11), and the two telescopic parts are correspondingly connected to the two support arms (12).

5. The casing center positioning device according to claim 1, characterized in that, The leveling component (4) further includes a second leveling bubble meter (43), which is disposed on the top surface of the support component (1).

6. The casing center positioning device according to claim 1, characterized in that, The support component (1) has a first positioning groove (10) along the length direction and a second positioning groove along the width direction on its top surface. The first positioning groove (10) and the second positioning groove are connected, and the intersection point is the center point of the top surface of the support component (1).

7. The casing center positioning device according to claim 6, characterized in that, The support component (1) is strip-shaped. The protective sleeve center positioning device also includes an auxiliary positioning component (6). The positioning component (31) is rotatably mounted on the auxiliary positioning component (6). The auxiliary positioning component (6) is located on the top of the support component (1), and its central axis coincides with the central axis of the support component (1). The two ends of the auxiliary positioning component (6) protrude from the opposite sides of the support component (1) along the width direction. The top surface of the auxiliary positioning component (6) is provided with a third positioning groove (61) along the length direction and a fourth positioning groove (62) along the width direction. The intersection of the third positioning groove (61) and the fourth positioning groove (62) is the center point of the top surface of the auxiliary positioning component (6).

8. The casing center positioning device according to claim 1, characterized in that, The adjusting component (41) includes a fixing block and an adjusting knob. The fixing block is connected to the support assembly (1). The adjusting knob is rotatably mounted on the clamping assembly (2) and has a screw portion. The screw portion is screwed to the fixing block.

9. The casing center positioning device according to any one of claims 1-8, characterized in that, The clamping assembly (2) includes a limiting member (21) and a fastener (22). The adjusting member (41) is clamped between the limiting member (21) and the supporting assembly (1). The limiting member (21) is provided with a limiting groove (210). The wall of the protective cylinder (100) can be inserted into the limiting groove (210) and abut against the bottom of the limiting groove (210). The fastener (22) is adjustablely connected to the limiting member (21), and the fasteners (22) of the two clamping assemblies (2) can abut against the side walls of opposite sides of the protective cylinder (100).

10. The casing center positioning device according to claim 9, characterized in that, The fastener (22) is screwed onto the limiting member (21).

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