Rotatable porous nozzle for concrete spraying mechanical arm

Abstract

The utility model provides a rotatable multi-hole spray head for a concrete spraying mechanical arm, which relates to the technical field of tunnel construction equipment and comprises the concrete spraying mechanical arm and an omni-directional rotating spray head component arranged on a joint shaft at the tail end of the concrete spraying mechanical arm. The omni-directional rotating nozzle assembly is composed of an annular supporting base plate, a multi-fulcrum adjusting assembly, a motion control platform and a multi-hole nozzle. The multi-fulcrum adjusting assembly is distributed in an equilateral triangle shape with the circle center of the annular supporting base plate as the symmetry center. Through cooperation of the structures, compared with the prior art, the mechanical arm has the following beneficial effects that firstly, the spray head can achieve + / -60-degree horizontal rotation fine adjustment, and fine fine adjustment can be conducted on the spraying angle on the basis of overall movement of the mechanical arm; and secondly, the angle and the injection pressure of the multi-hole nozzle can be dynamically matched with the shape of the section of the tunnel, the local flow can be precisely adjusted according to the specific requirements of different construction areas, the concrete injection uniformity is remarkably improved, and material waste is reduced.

Description

Technical Field

[0001] This utility model relates to the field of tunnel construction equipment technology, and in particular to a rotatable multi-hole nozzle for a shotcrete robotic arm. Background Technology

[0002] In tunnel construction, shotcrete robotic arms are key equipment for achieving concrete spraying operations. The spraying effect of their nozzles directly affects the construction quality of concrete. Although existing shotcrete robotic arms can achieve omnidirectional coverage within a certain range through the overall movement of the robotic arm.

[0003] However, its nozzles are usually fixedly installed, relying solely on the wide-range movements of a robotic arm to adjust the spray direction, a design with significant technical flaws:

[0004] On the one hand, although the overall movement of the robotic arm can achieve macroscopic angle adjustment, when facing complex curved surfaces, local uneven structures, or narrow construction areas of the tunnel wall, the fixed nozzle cannot make fine-tuning of the angle. For example, when it is necessary to spray special locations such as the edge of the tunnel arch and the inside and outside corners of the side walls, the spraying angle of the fixed nozzle is not well adapted to the target area, which can easily cause the concrete spraying trajectory to deviate from the ideal path, resulting in excessively large or small spraying angles in local areas. This can lead to local concrete accumulation or uneven coverage, forming construction blind spots and affecting the quality of the project.

[0005] On the other hand, the fixed-angle design of existing nozzles creates "dead zones" in the spraying range. Even with omnidirectional movement of the robotic arm, the non-adjustable angle of the nozzle itself can still cause some areas to be difficult to cover effectively due to spray angle deviations. For example, when the robotic arm moves to its limit position, the spraying direction of the fixed nozzle may form an excessively large or small angle with the construction surface, resulting in insufficient concrete impact pressure or an increased rebound rate. This not only wastes materials but also affects the density and strength of the concrete.

[0006] To address the aforementioned issues, while existing technologies enhance flexibility by increasing the degrees of freedom of the robotic arm joints, they do not make targeted improvements to the nozzle's structure, thus failing to achieve precise fine-tuning of the spray angle. Therefore, a structure is needed that enables fine adjustment of the nozzle's angle based on the overall movement of the robotic arm. Utility Model Content

[0007] To address the shortcomings of the existing technology, the technical problem to be solved by this utility model is to provide a rotatable multi-hole nozzle for a shotcrete robotic arm, which can be structured to add the nozzle's own angle adjustment freedom on the basis of the overall movement of the robotic arm, so as to cooperate with the movement of the robotic arm to achieve 360° coverage without dead angles, avoid spraying blind spots, reduce material waste and improve construction quality.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows: This utility model provides a rotatable multi-hole nozzle for a shotcrete robotic arm, including a shotcrete robotic arm and an omnidirectional rotating nozzle assembly disposed on the joint axis at the end of the shotcrete robotic arm. The omnidirectional rotating nozzle assembly is characterized by being composed of an annular support base plate, a multi-point adjustment assembly, a motion control platform and a multi-hole nozzle. The multi-point adjustment assembly is arranged in an equilateral triangle with the center of the annular support base plate as the center of symmetry.

[0009] In a preferred embodiment, each set of multi-point adjustment components includes at least two multi-point linkage adjustment structures orthogonally distributed along three-dimensional space and arranged symmetrically in a V-shape. One end of each multi-point linkage adjustment structure is rotatably connected to the top surface of the annular support base plate through a spherical rotating pair, and the other end is driven and connected to the motion control platform through a universal coupling.

[0010] In the preferred embodiment, the motion control platform has a regular hexagonal plate structure. The geometric center of the motion control platform and the center of the annular support base plate are coaxial in the vertical direction. Multiple universal couplings are respectively located at the six vertices of the motion control platform to form a linkage adjustment mechanism.

[0011] In a preferred embodiment, a connecting hole is provided axially at the center of the motion control platform. A positioning sleeve is fixed to the inner wall of the connecting hole. The axis of the positioning sleeve coincides with the geometric center axis of the motion control platform. The multi-hole nozzle is fixedly connected to the motion control platform through the positioning sleeve that passes through the center of the motion control platform. The inner wall of the positioning sleeve is fixed to the outer wall of the multi-hole nozzle. The feed inlet of the multi-hole nozzle is provided with a flexible conveying pipe. The multi-hole nozzle is connected to the concrete conveying pipeline inside the shotcrete robotic arm through the flexible conveying pipe.

[0012] In the preferred embodiment, the spray end of the multi-hole nozzle is a circular flat plate, and a seven-star nozzle layout is formed with the geometric center of the multi-hole nozzle as the origin of symmetry.

[0013] The seven-star nozzle layout includes a central nozzle at the center of the nozzle's spray end, and six circumferential nozzles evenly distributed in a regular hexagonal array around the central nozzle at the nozzle's spray end, forming a full circumferential spray coverage without blind spots.

[0014] In the preferred embodiment, the central nozzle and each circumferential nozzle have a converging flow channel structure. The inner diameter of the inlet end of the central nozzle and each circumferential nozzle is larger than the inner diameter of the outlet end of the central nozzle and each circumferential nozzle. The outlet axis of the central nozzle coincides with the central axis of the multi-hole nozzle.

[0015] In a preferred embodiment, the multi-point linkage adjustment structure includes a base plate connected to an annular support base plate via a spherical rotating pair, and a drive housing disposed on one side of the base plate, wherein a T-shaped guide cavity is formed inside the drive housing;

[0016] The T-shaped guide cavity consists of a vertical section and a horizontal section. The axis of the vertical section of the T-shaped guide cavity intersects perpendicularly with the length direction of the base plate. The inner diameter of the vertical section of the T-shaped guide cavity is D1, and the inner diameter of the horizontal section of the T-shaped guide cavity is D2, where D2 > D1.

[0017] In a preferred embodiment, a protective shell is provided on the base plate, which is opposite to and fixed to the drive housing by a bolt group. A micro servo motor is fixed inside the protective shell. A lead screw is provided in the vertical section of the T-shaped guide cavity, with one end rotatably connected to the bottom wall of the T-shaped guide cavity via a bearing. The other end of the lead screw passes through one side of the drive housing and extends to the outside of the drive housing. A three-stage gear transmission assembly is provided between the lead screw and the outer side of the output shaft of the micro servo motor. The three-stage gear transmission assembly transmits rotational power to the lead screw.

[0018] In a preferred embodiment, the three-stage gear transmission assembly includes an input gear, an intermediate gear, and an output gear that mesh with each other from right to left. The input gear, intermediate gear, and output gear are parallel to each other and all perpendicular to the axis of the lead screw.

[0019] The input gear is located at the end of the output shaft of the micro servo motor. A circular through hole is provided between the base plate and the protective shell on the opposite side. A rotating pivot is provided on the circular through hole. Both ends of the rotating pivot are rotatably connected to the inner wall of the through hole through bearings. The outer wall of the middle position of the rotating pivot is fixed to the inner wall of the intermediate gear, and the output gear is fixed to the outer wall of the lead screw.

[0020] In a preferred embodiment, a trapezoidal thread is provided on the outer wall of the lead screw and a guide slide is threadedly connected thereto. The inner wall of the guide slide is provided with a corresponding trapezoidal thread groove. Limiting grooves extending axially are provided on the inner walls of both sides of the T-shaped guide cavity. The two limiting grooves are arranged opposite to each other. Two travel limiting blocks that move axially are provided on the outer wall of the guide slide in a mirror image. The outer end face of the travel limiting block and the bottom surface of the limiting groove form a sliding fit. The two sides of the travel limiting block and the sides of the limiting groove form a guiding fit.

[0021] This utility model provides a rotatable multi-hole nozzle for a shotcrete robotic arm. Through the cooperation of the above structures, it has the following advantages compared to the prior art:

[0022] First, the nozzle itself can achieve ±60° horizontal rotation and fine adjustment, which can finely adjust the spray angle based on the overall movement of the robotic arm. After coordinating with the large-scale movement of the robotic arm, it forms a 360° coverage without dead angles, effectively eliminating spraying blind spots in complex parts such as the arch and the junction of the side walls, reducing the frequency of manual spraying, and avoiding local concrete accumulation or uneven coverage in complex curved surfaces, narrow areas, and special locations such as the edge of the arch and the inside corner of the tunnel.

[0023] Secondly, the angle and spraying pressure of the multi-hole nozzle can be dynamically adapted to the shape of the tunnel cross section, and the local flow rate can be precisely adjusted according to the specific needs of different construction areas, which significantly improves the uniformity of concrete spraying and reduces material waste. The local fine-tuning function of the nozzle reduces the need for frequent and large swings of the robotic arm, which not only extends the service life of the robotic arm, but also reduces energy consumption and operational complexity. Attached Figure Description

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments:

[0025] Figure 1 This is the overall appearance and structural diagram of this utility model;

[0026] Figure 2 This is a utility model Figure 1 Schematic diagram of the omnidirectional rotating nozzle assembly;

[0027] Figure 3 This is a utility model Figure 2 Schematic diagram of the cross-sectional view of the omnidirectional rotating nozzle assembly;

[0028] Figure 4 This is a utility model Figure 3 Right view schematic diagram of the multi-hole nozzle;

[0029] Figure 5 This is a utility model Figure 2 The multi-point linkage adjustment structure diagram in the middle;

[0030] Figure 6 This is a utility model Figure 5 A magnified view of part A in the image.

[0031] In the figure: 10 shotcrete robotic arm, 20 omnidirectional rotating nozzle assembly, 21 annular support base plate, 22 multi-point linkage adjustment structure, 221 base plate, 222 drive housing, 223 protective housing, 224 micro servo motor, 225 three-stage gear transmission assembly, 226 lead screw, 227 guide slide, 228 stroke limit block, 23 motion control platform, 24 multi-hole nozzle, 25 flexible material conveying pipe. Detailed Implementation

[0032] To better understand the purpose, structure, and function of this utility model, the embodiments and features described herein can be combined with each other without conflict. The utility model will now be described in detail with reference to the accompanying drawings and embodiments.

[0033] Example 1

[0034] like Figures 1-6As shown in the figure, this embodiment illustrates a rotatable multi-hole nozzle for a shotcrete robotic arm, including an omnidirectional rotating nozzle assembly 20 fixedly connected to the end joint shaft of the shotcrete robotic arm 10 via a flange. The omnidirectional rotating nozzle assembly 20 consists of an annular support base plate 21, a multi-point adjustment assembly, a motion control platform 23, and a multi-hole nozzle 24. The center of the annular support base plate 21 is coaxially arranged with the rotation center of the end joint shaft of the shotcrete robotic arm 10. The bottom surface of the annular support base plate 21 is rigidly connected to the end flange of the shotcrete robotic arm 10 via a high-strength bolt group. On the opposite side, three sets of multi-point adjustment assemblies are arranged in an equilateral triangle with the center of the circle as the center of symmetry.

[0035] In this embodiment, as shown Figure 2 As shown, each set of multi-point adjustment components includes at least two multi-point linkage adjustment structures 22 orthogonally distributed along the three-dimensional spatial direction. The two multi-point linkage adjustment structures 22 intersect to form a V-shape and the included angle ranges from 30° to 70°. One end of each multi-point linkage adjustment structure 22 is rotatably connected to the top surface of the annular support base plate 21 through a spherical rotating pair, and the other end is driven connected to the motion control platform 23 through a universal coupling.

[0036] The spherical rotating pair includes a joint bearing seat embedded in the annular support base plate 21, and a ball head rod end installed at one end of the multi-point linkage adjustment structure 22 and cooperating with the joint bearing seat of the annular support base plate 21. The ball head rod end has ≥3 degrees of rotational freedom and a rotation range ≥±45°.

[0037] The universal joint coupling adopts a cross shaft structure, with an included angle compensation capability of ≥15° between the two shafts, and achieves torque transmission through the spline pair and the end of the multi-point linkage adjustment structure 22.

[0038] The motion control platform 23 has a regular hexagonal plate structure. The geometric center of the motion control platform 23 and the center of the annular support base plate 21 are coaxial in the vertical direction. Multiple universal couplings are respectively set at the six vertices of the motion control platform 23. The motion control platform 23 is driven by the coordinated telescopic motion of at least two multi-point linkage adjustment structures 22 to realize the motion adjustment of six degrees of freedom of rotation around the X / Y / Z axes in three-dimensional space, forming a linkage adjustment mechanism.

[0039] A connecting hole is provided axially at the center of the motion control platform 23. A positioning sleeve is fixed to the inner wall of the connecting hole. The axis of the positioning sleeve coincides with the geometric center axis of the motion control platform 23. The multi-hole nozzle 24 is fixedly connected to the motion control platform 23 through the positioning sleeve that passes through the center of the motion control platform 23. The inner wall of the positioning sleeve is fixed to the outer wall of the multi-hole nozzle 24. The feed inlet of the multi-hole nozzle 24 is provided with a flexible material conveying pipe 25, which is connected to the concrete conveying pipeline inside the shotcrete robotic arm 10. The flexible material conveying pipe 25 is made of high-pressure wear-resistant rubber material, and its working pressure range is 2-10MPa.

[0040] Further as Figure 3 , 4 As shown, the spray end of the multi-hole nozzle 24 is a circular flat plate. A seven-star nozzle layout is formed with the geometric center of the multi-hole nozzle 24 as the origin of symmetry. There is a central nozzle at the center of the spray end of the multi-hole nozzle 24. Six circumferential nozzles are evenly distributed in a regular hexagonal array around the central nozzle at the spray end of the multi-hole nozzle 24. The distance between the center of the central nozzle and the center of each circumferential nozzle is 50mm±2mm, forming a spray area with a coverage radius of ≥300mm, forming a full circumferential spray coverage without blind spots.

[0041] The central nozzle and all circumferential nozzles have a converging flow channel structure with an inlet diameter of 8-12 mm and an outlet diameter of 3-6 mm. The inner wall taper is 15°±2°. The outlet axis of the central nozzle coincides with the central axis of the multi-hole nozzle 24 to achieve direct frontal spraying.

[0042] Specifically, through the seven-star nozzle layout and angle design, the spray coverage angle of a single circumferential nozzle is ≥30°. When the six circumferential nozzles spray together, they can achieve 360° full circumferential coverage. Combined with the direct spray function of the central nozzle, a composite spray mode of "central direct spray + circumferential fan-shaped spray" is formed. When the multi-hole nozzle 24 is driven by the multi-point linkage adjustment structure 22 to achieve ±60° horizontal rotation, the actual spray coverage range of the circumferential nozzles can be extended to the entire space (coverage angle deviation ≤±2°), effectively solving the spray blind zone problem of traditional fixed nozzles.

[0043] In this embodiment, as Figure 5 , 6As shown, the multi-point linkage adjustment structure 22 includes a base plate 221 connected to the annular support base plate 21 via a spherical rotating pair, and a drive housing 222 disposed on one side of the base plate 221. The drive housing 222 forms a T-shaped guide cavity inside, which is composed of a vertical section and a horizontal section. The vertical section axis of the T-shaped guide cavity intersects perpendicularly with the length direction of the base plate 221. The inner diameter of the vertical section of the T-shaped guide cavity is D1, and the inner diameter of the horizontal section of the T-shaped guide cavity is D2, and D2 > D1, so as to accommodate subsequent transmission components. A protective shell 223 is also provided on the base plate 221, which is opposite to and fixed to the drive housing 222 by a bolt group. The bolt group uses M6×16 internal hexagonal head screws, and there are 4 of them distributed along a rectangular array to prevent concrete dust and water vapor from entering.

[0044] A micro servo motor 224 is fixed inside the protective shell 223. A lead screw 226 is provided in the vertical section of the T-shaped guide cavity, with one end rotatably connected to the bottom wall of the T-shaped guide cavity via a bearing. The other end of the lead screw 226 passes through one side of the drive housing 222 and extends to the outside of the drive housing 222. A three-stage gear transmission assembly 225 is provided between the lead screw 226 and the outer side of the output shaft of the micro servo motor 224. The three-stage gear transmission assembly 225 is used to transmit rotational power to the lead screw 226.

[0045] The three-stage gear transmission assembly 225 includes an input gear, an intermediate gear, and an output gear that mesh with each other from right to left. The input gear, intermediate gear, and output gear are parallel to each other and all perpendicular to the axis of the lead screw 226, forming a three-stage reduction transmission structure.

[0046] The input gear is fixedly mounted on the output shaft end of the micro servo motor 224 and is circumferentially positioned by a flat key. A circular through hole is provided between the base plate 221 and the protective shell 223 on opposite sides. A rotating pivot is provided on the circular through hole. Both ends of the rotating pivot are rotatably connected to the inner wall of the through hole by bearings. The outer wall of the middle position of the rotating pivot is fixed to the inner wall of the intermediate gear by thermoforming interference fit. The output gear is engaged with the keyway on the outer wall of the lead screw 226 by spline to realize torque transmission, which is used to convert the high-speed rotation of the micro servo motor 224 into the low-speed high-torque rotation of the lead screw 226.

[0047] The outer wall of the lead screw 226 is machined with a trapezoidal thread and threadedly connected to a guide slide 227. The inner wall of the guide slide 227 is provided with a trapezoidal thread groove. On the inner walls of both sides of the T-shaped guide cavity, there are axially extending limiting grooves. The two limiting grooves are arranged opposite to each other. On the outer wall of the guide slide 227, there are two axially movable travel limiting blocks 228 that are mirror-equipped opposite each other. The outer end face of the travel limiting block 228 forms a sliding fit with the bottom surface of the limiting groove. The two sides of the travel limiting block 228 form a guiding fit with the sides of the limiting groove. The travel limiting block 228 is made of polytetrafluoroethylene composite material to reduce frictional resistance during sliding. When the micro servo motor 224 drives the lead screw 226 to rotate through the three-stage gear transmission assembly 225, the guide slide 227 moves linearly along the axial direction of the lead screw 226. With the cooperation of the limiting grooves and the travel limiting blocks 228, the rotational motion of the lead screw 226 is completely constrained to the linear motion of the guide slide 227.

[0048] In practice, the micro servo motor 224 is driven by a signal and, after being reduced in speed and increased in torque by the three-stage gear transmission assembly 225, drives the lead screw 226 to rotate, converting the rotational motion into the axial linear motion of the guide slide 227. When the lead screws 226, which are orthogonally distributed in multiple multi-point linkage adjustment structures 22, work together, they can drive the motion control platform 23 to achieve rotational adjustment around the X / Y / Z axes, thereby controlling the precise six-degree-of-freedom positioning of the multi-hole nozzle 24 in three-dimensional space.

[0049] To enable those skilled in the art to better understand the present invention, the above embodiments are merely preferred technical solutions of the present invention and should not be considered as limitations on the present invention. The scope of protection of the present invention should be the technical solution described in the claims, including equivalent substitutions of the technical features described in the claims. That is, equivalent substitutions and improvements within this scope are also within the scope of protection of the present invention.

[0050] It should also be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this utility model described herein.

Claims

1. A rotatable multi-hole nozzle for a shotcrete robotic arm, comprising a shotcrete robotic arm (10) and an omnidirectional rotating nozzle assembly (20) disposed on the end joint shaft of the shotcrete robotic arm (10), characterized in that, The omnidirectional rotating nozzle assembly (20) consists of an annular support base plate (21), a multi-point adjustment assembly, a motion control platform (23), and a multi-hole nozzle (24). The multi-point adjustment assembly is arranged in an equilateral triangle with the center of the annular support base plate (21) as the center of symmetry.

2. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 1, characterized in that, Each set of multi-point adjustment components includes at least two multi-point linkage adjustment structures (22) orthogonally distributed in three-dimensional space and arranged symmetrically in a V-shape. One end of each multi-point linkage adjustment structure (22) is rotatably connected to the top surface of the annular support base plate (21) through a spherical rotating pair, and the other end is driven connected to the motion control platform (23) through a universal coupling.

3. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 2, characterized in that, The motion control platform (23) has a regular hexagonal plate structure. The geometric center of the motion control platform (23) and the center of the annular support base plate (21) are coaxial in the vertical direction. Multiple universal couplings are respectively set at the six vertices of the motion control platform (23) to form a linkage adjustment mechanism.

4. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 3, characterized in that, A connecting hole is provided along the axial direction at the center of the motion control platform (23). A positioning sleeve is fixed on the inner wall of the connecting hole. The axis of the positioning sleeve coincides with the geometric center axis of the motion control platform (23). The multi-hole nozzle (24) is fixedly connected to the motion control platform (23) through the positioning sleeve that passes through the center of the motion control platform (23). The inner wall of the positioning sleeve is fixed to the outer wall of the multi-hole nozzle (24). The inlet of the multi-hole nozzle (24) is provided with a flexible material conveying pipe (25). The multi-hole nozzle (24) is connected to the concrete conveying pipeline inside the shotcrete robot arm (10) through the flexible material conveying pipe (25).

5. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 4, characterized in that, The spray end of the multi-hole nozzle (24) is a circular flat plate, and a seven-star nozzle layout is formed with the geometric center of the multi-hole nozzle (24) as the origin of symmetry. The seven-star nozzle layout includes a central nozzle at the center of the nozzle (24) and six circumferential nozzles evenly distributed in a regular hexagonal array at the nozzle (24) with the central nozzle as the axis, forming a full circumferential spray coverage without blind spots.

6. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 5, characterized in that, The central nozzle and each circumferential nozzle have a converging flow channel structure. The inner diameter of the inlet end of the central nozzle and each circumferential nozzle is larger than the inner diameter of the outlet end of the central nozzle and each circumferential nozzle. The outlet axis of the central nozzle coincides with the central axis of the multi-hole nozzle (24).

7. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 1, characterized in that, The multi-point linkage adjustment structure (22) includes a base plate (221) connected to the annular support base plate (21) via a spherical rotating pair, and a drive housing (222) provided on one side of the base plate (221), with a T-shaped guide cavity formed inside the drive housing (222); The T-shaped guide cavity consists of a vertical section and a horizontal section. The vertical section axis of the T-shaped guide cavity intersects perpendicularly with the length direction of the base plate (221). The inner diameter of the vertical section of the T-shaped guide cavity is D1, and the inner diameter of the horizontal section of the T-shaped guide cavity is D2, where D2 > D1.

8. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 7, characterized in that, A protective shell (223) is provided on the base plate (221) and is fixed to the drive housing (222) by bolts. A micro servo motor (224) is fixed inside the protective shell (223). A lead screw (226) is provided in the vertical section of the T-shaped guide cavity, with one end rotatably connected to the bottom wall of the T-shaped guide cavity via a bearing. The other end of the lead screw (226) passes through one side of the drive housing (222) and extends to the outside of the drive housing (222). A three-stage gear transmission assembly (225) is provided between the lead screw (226) and the outside of the output shaft of the micro servo motor (224). The three-stage gear transmission assembly (225) transmits rotational power to the lead screw (226).

9. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 8, characterized in that, The three-stage gear transmission assembly (225) includes an input gear, an intermediate gear and an output gear that mesh with each other from right to left. The input gear, intermediate gear and output gear are parallel to each other and all perpendicular to the axis of the lead screw (226). The input gear is located at the output shaft end of the micro servo motor (224). A circular through hole is provided between the base plate (221) and the protective shell (223) on opposite sides. A rotating pivot is provided on the circular through hole. Both ends of the rotating pivot are rotatably connected to the inner wall of the through hole through bearings. The outer wall of the middle position of the rotating pivot is fixed to the inner wall of the intermediate gear. The output gear is fixed to the outer wall of the lead screw (226).

10. The rotatable multi-hole nozzle for a shotcrete robotic arm according to claim 8 or 9, characterized in that, A trapezoidal thread is provided on the outer wall of the lead screw (226) and a guide slide (227) is threadedly connected thereto. A trapezoidal thread groove is provided on the inner wall of the guide slide (227). A limiting groove extending along the axial direction is provided on the inner walls of both sides of the T-shaped guide cavity. The two limiting grooves are arranged opposite to each other. Two travel limiting blocks (228) that move along the axial direction are provided on the outer wall of the guide slide (227) in a mirror image. The outer end face of the travel limiting block (228) forms a sliding fit with the bottom surface of the limiting groove. The two sides of the travel limiting block (228) form a guiding fit with the sides of the limiting groove.

Images