A ductile cast iron pipe socket welding ring polishing device

Abstract

The present application relates to the technical fields of pipe machining and surface treatment equipment, in particular to a ductile cast iron pipe socket welding ring polishing device, which comprises a supporting rotary frame and a translating boom. The translating boom is provided with an outer peripheral surface polishing assembly and two symmetrically distributed corner polishing assemblies. The corner polishing assembly comprises an obliquely telescopic polishing head, which comprises a mounting table, an abutting wheel, a driving wheel and a narrow sand belt sleeved on the two wheels. The diameter of the abutting wheel is smaller than that of the driving wheel and the abutting wheel is located on the side close to the connecting corner. A resilient member is arranged between the abutting wheel and the mounting table to apply an outward elastic force to the abutting wheel. The present application can realize synchronous and collaborative polishing of the outer peripheral surface of the welding ring and the two corners. The design of the asymmetric polishing head with the front small and the rear large effectively avoids spatial interference and eliminates polishing dead angles. The resilient member enables the sand belt to have flexible adhesion and self-adaptive buffer retreat functions, prevents the sand belt from overloading and breaking, and improves the stability of the device operation.

Description

Technical Field

[0001] This invention relates to the field of pipe fitting processing and surface treatment equipment technology, specifically to a grinding device for the weld ring of ductile iron pipe spigot. Background Technology

[0002] In the production and connection process of ductile iron pipes, the spigot end of the pipe fitting is usually formed with a spigot weld ring through a welding process. This ring is mainly used to provide a seal and limit movement during pipe spigot connections. Due to the metal deposition characteristics of the welding process, the surface and edges of the formed weld ring often have relatively rough weld slag and irregular protrusions. In order to eliminate stress concentration points and avoid subsequent assembly interference, the outer circumference of the spigot weld ring and the connection corners between its two sides and the ductile iron pipe wall must be ground and cleaned.

[0003] However, existing pipe grinding equipment generally suffers from the following technical deficiencies when dealing with the aforementioned weld ring and its surrounding complex area:

[0004] First, existing grinding equipment can often only process the outer surface of a single pipe fitting. It is difficult to simultaneously grind the outer circumference of the weld ring and the corners on both sides in one workstation. It usually requires multiple processes or manual hand tools for welding and grinding, resulting in low processing efficiency and difficulty in maintaining consistent grinding quality.

[0005] Secondly, the connection corner formed by the intersection of the two sides of the weld ring and the ductile iron pipe wall is a long and deep right-angled area with extremely strict space constraints. Traditional grinding actuators, such as conventional grinding wheels or symmetrical belt sanders, typically have relatively wide end structures. When attempting to reach the root of the corner for cleaning, their support components or power structures are prone to physical interference with the tall weld ring sidewalls or the wide pipe walls. This structural interference prevents the grinding surface from truly reaching the deepest part of the connection corner, leaving grinding dead corners that are difficult to remove.

[0006] Finally, due to the characteristics of the welding process, the corner joints are often not perfectly flat, but rather randomly distributed with numerous irregular and hard weld beads. Existing corner grinding equipment typically uses rigid contact cutting feed. When faced with these irregular protrusions, the grinding components cannot achieve local adaptive contouring and buffering. This rigid contact not only prevents the grinding surface from closely conforming to the complex corner curves, but also causes the grinding components to be overloaded when encountering large pieces of hard weld slag, easily leading to severe vibration or even breakage of the grinding wheel, seriously restricting the operational stability and service life of the equipment under harsh working conditions. Summary of the Invention

[0007] Therefore, it is necessary to provide a grinding device for the weld ring of ductile iron pipe spigot to address the problems of the existing technology.

[0008] To address the problems of existing technologies, the technical solution adopted in this invention is: a grinding device for weld rings at the spigot of ductile iron pipes, comprising:

[0009] The slewing frame is used to horizontally support the ductile iron pipe to be ground and drive it to rotate around its own axis.

[0010] A translation boom is located beside the supporting slewing frame and can be translated along the axial direction of the ductile iron pipe;

[0011] The outer peripheral surface grinding assembly is mounted on the translational boom and can be raised and lowered in the vertical direction. The outer peripheral surface grinding assembly includes a grinding wheel for grinding the outer peripheral surface of the socket welding ring.

[0012] Two corner grinding components are symmetrically arranged on the translational boom, and are respectively located on both sides of the outer peripheral grinding component along the axial direction of the ductile iron pipe;

[0013] Each of the corner grinding assemblies includes a grinding head that can extend and retract obliquely in an inclined direction to approach or move away from the connection corner between the two sides of the socket welding ring and the ductile iron pipe wall. The grinding head includes a mounting platform, an abutment wheel, a drive wheel, and a narrow sanding belt. The drive wheel is rotatably connected to the mounting platform, the abutment wheel is movably connected to the mounting platform, and the narrow sanding belt is sleeved on the abutment wheel and the drive wheel.

[0014] The diameter of the abutting wheel is smaller than that of the driving wheel, and the abutting wheel is located on the side of the driving wheel near the connecting corner. An elastic element is provided between the abutting wheel and the mounting platform. The elastic element is used to apply an elastic force to the abutting wheel to make it bulge outward, so that the narrow sanding belt is elastically attached to the corresponding connecting corner.

[0015] Furthermore, the abutting wheel is movably connected to the mounting platform via the first wheel frame. The mounting platform has several parallel columnar through slots, the axial direction of each columnar through slot is parallel to the extension and retraction direction of the grinding head, and each columnar through slot includes a guide section in the middle and enlarged sections at both ends. The inner diameter of the guide section is smaller than the inner diameter of the enlarged section, and a stepped portion is formed between the end of the guide section and the corresponding enlarged section. Several guide rods corresponding one-to-one with the columnar through slots are fixed on the first wheel frame, and each guide rod slides through the corresponding guide section. The elastic element is a spring sleeved on the guide rod, the spring is located in the enlarged section near the first wheel frame, and the two ends of the spring abut against the first wheel frame and the corresponding stepped portion, respectively.

[0016] Furthermore, each of the guide rods is screwed with a limiting nut, which is located in the enlarged section away from the first wheel frame, and the limiting nut is used to abut against the corresponding stepped portion to limit the extension stroke of the guide rod.

[0017] Furthermore, a first mounting bracket is fixedly provided on the mounting platform, and a first motor is fixedly mounted on the first mounting bracket. The output end of the first motor is coaxially connected to the drive wheel through a first coupling.

[0018] Furthermore, several auxiliary wheels are rotatably connected to the mounting platform, and each of the auxiliary wheels tightens the narrow sanding belt from the inside out.

[0019] Furthermore, each corner grinding assembly also includes an inclined guide sliding mechanism and a first slide cylinder. The inclined guide sliding mechanism includes a first fixed base, a first slider, and an inclined guide rail. The first fixed base is connected to the translational boom via a first connecting seat. The inclined guide rail is fixedly installed on the first fixed base. The angle between the extension direction of the inclined guide rail and the vertical direction is 45°, and the inclined guide rail extends obliquely from top to bottom, with its lower end pointing to the corresponding connecting corner. The first slider is slidably connected to the inclined guide rail. The mounting platform is fixedly installed on the first slider. The first slide cylinder is fixedly installed on the first fixed base and is used to drive the first slider to slide obliquely along the inclined guide rail towards or away from the connecting corner.

[0020] Furthermore, the outer peripheral surface grinding assembly also includes a vertical guide sliding mechanism and a second slide cylinder. The vertical guide sliding mechanism includes a second fixed base, a second slider, and a vertical guide rail. The second fixed base is connected to the translational boom through a second connecting seat. The vertical guide rail is fixedly installed on the second fixed base. The second slider is slidably connected to the vertical guide rail. The grinding wheel is connected to the second slider so as to rise and fall synchronously with the second slider.

[0021] Furthermore, a bracket is fixedly provided on the second slider, and the grinding wheel is connected to the bracket through a second wheel frame. The bracket is provided with a rotary drive mechanism for driving the grinding wheel to rotate.

[0022] Furthermore, a drive shaft is rotatably connected to the second wheel frame, the axial direction of which extends along the width direction of the insertion welding ring, and the grinding wheel includes a plurality of thread wheels that are fixedly sleeved on the drive shaft in parallel along the width direction of the insertion welding ring.

[0023] Furthermore, the rotary drive mechanism includes a second motor and a synchronous belt drive component. The second motor is fixedly connected to the bracket via a second mounting bracket. A drive shaft is rotatably connected to the bracket. The output end of the second motor is coaxially fixedly connected to the drive shaft via a second coupling. The drive shaft is connected to the drive shaft via the synchronous belt drive component.

[0024] The beneficial effects of this invention compared to the prior art are:

[0025] This invention achieves simultaneous and coordinated grinding of the outer circumferential surface and two symmetrically distributed corner grinding components on the same workstation, eliminating multiple processing steps and significantly improving processing efficiency and grinding quality consistency. Addressing the interference problem caused by narrow and deep corners, the corner grinding head employs an asymmetrical drive structure with a smaller front and larger rear. This allows the smaller diameter abutment wheel to guide the narrow abrasive belt to penetrate and conform to the deep root of the corner to the maximum extent, effectively avoiding interference with high-profile surfaces. The spatial interference of the weld ring or wide pipe wall completely eliminates grinding dead angles. In addition, by setting an elastic element between the abutment wheel and the mounting table, the grinding head is given an elastic pre-tightening force to push outward, which allows the narrow sanding belt to flexibly fit the corner processing surface. When faced with irregular protruding weld beads, it can achieve local adaptive yielding and buffering, which not only ensures the tight fit between the sanding belt and the complex curve, but also avoids instantaneous overload and sanding belt breakage caused by rigid cutting, significantly improving the operating stability and service life of the equipment under harsh working conditions. Attached Figure Description

[0026] Figure 1 This is a three-dimensional structural schematic diagram of the present invention;

[0027] Figure 2 This is a three-dimensional structural diagram of the outer peripheral surface grinding component and the corner grinding component. Figure 1 ;

[0028] Figure 3 This is a three-dimensional structural diagram of the outer peripheral surface grinding component and the corner grinding component. Figure 2 ;

[0029] Figure 4 This is a three-dimensional structural diagram of the outer peripheral surface grinding component;

[0030] Figure 5 This is a planar schematic diagram of the outer peripheral surface grinding component;

[0031] Figure 6 This is a 3D structural diagram of the corner grinding component;

[0032] Figure 7 This is a top view of the corner polishing component;

[0033] Figure 8 yes Figure 7 Sectional view along line AA;

[0034] Figure 9 This is a side view of the corner polishing component;

[0035] Figure 10 yes Figure 9 Sectional view along line BB.

[0036] The following components are labeled in the diagram: 1. Supporting rotating frame; 2. Translational boom; 3. Outer circumferential surface grinding assembly; 4. Grinding wheel; 5. Corner grinding assembly; 6. Mounting platform; 7. Abutment wheel; 8. Drive wheel; 9. Narrow sanding belt; 10. First wheel frame; 11. Guide section; 12. Hole enlarging section; 13. Step section; 14. Guide rod; 15. Spring; 16. Limit nut; 17. First mounting frame; 18. First motor; 19. First coupling; 20. Auxiliary wheel. ; 21. First slide cylinder; 22. First fixed base; 23. First slider; 24. Inclined guide rail; 25. First connecting seat; 26. Second slide cylinder; 27. Second fixed base; 28. Second slider; 29. ​​Vertical guide rail; 30. Second connecting seat; 31. Bracket; 32. Second wheel frame; 33. Drive shaft; 34. Lead wheel; 35. Second motor; 36. Synchronous belt transmission component; 37. Drive shaft; 38. Second coupling. Detailed Implementation

[0037] To further understand the features, technical means, and specific objectives and functions achieved by the present invention, the present invention will be described in further detail below with reference to the accompanying drawings and specific embodiments.

[0038] In the production and connection process of ductile iron pipes, a spigot ring is usually required at the spigot end of the pipe fitting. This spigot ring mainly serves to provide sealing and limiting functions during pipe spigot connection, and its position is near the pipe end of the ductile iron pipe. This spigot ring is generally formed on the outer wall of the ductile iron pipe through a welding process. Due to the metal deposition characteristics of the welding process, the surface and edges of the formed ring often have relatively rough weld slag and irregular protrusions. Therefore, when actually grinding the formed pipe fitting, it is necessary not only to grind the outer circumference of the spigot ring to ensure its radial dimensional accuracy, but also to focus on grinding the connection corners between the two sides of the spigot ring and the ductile iron pipe wall to eliminate stress concentration points and avoid assembly interference.

[0039] To address the complex grinding requirements of the aforementioned socket welding ring and its two corners, refer to Figures 1 to 10As shown, this invention provides a grinding device for the weld ring of a ductile iron pipe spigot. Its overall basic structure includes a supporting rotary frame 1 and a translating boom 2. The supporting rotary frame 1 horizontally supports the ductile iron pipe to be ground and drives it to rotate around its own axis to achieve continuous circumferential feeding of the pipe during the grinding process. The supporting rotary frame 1 can adopt a mature rotary roller mechanism from the prior art. The translating boom 2 is located beside the supporting rotary frame 1 and can translate along the axial direction of the ductile iron pipe. In actual use, the translating boom 2 is mounted on a linear drive assembly. This linear drive assembly can directly adopt a lead screw guide module from the prior art. Its main function is to drive the translating boom 2 to move axially along the pipe, accurately aligning it to the working area where the weld ring is located.

[0040] Based on the stable moving platform constructed by the aforementioned translational boom 2, this invention provides an outer peripheral surface grinding assembly 3 and two corner grinding assemblies 5 on the translational boom 2. Specifically, as... Figure 2 and Figure 3 As shown, the outer peripheral surface grinding assembly 3 is mounted on the translational boom 2 and can be raised and lowered vertically. The outer peripheral surface grinding assembly 3 includes a grinding wheel 4 for grinding the outer peripheral surface of the weld ring. Two corner grinding assemblies 5 are symmetrically arranged on the translational boom 2, and are located on both sides of the outer peripheral surface grinding assembly 3 along the axial direction of the ductile iron pipe. This relative positional arrangement ensures that when the grinding wheel 4 is grinding the outer peripheral surface of the weld ring, the corner grinding assemblies 5 on both sides can simultaneously approach the connecting corners on both sides of the weld ring for processing, thereby improving the efficiency of multi-station collaborative grinding.

[0041] To achieve precise lifting and cutting feed of the outer peripheral surface grinding component 3, such as Figure 4 and Figure 5 As shown, the outer peripheral surface grinding assembly 3 also includes a vertical guide mechanism and a second slide cylinder 26. The vertical guide mechanism includes a second fixed base 27, a second slider 28, and a vertical guide rail 29. The second fixed base 27 is connected to the translational boom 2 via a second connecting seat 30, serving as a fixation and foundation support. The vertical guide rail 29 is fixedly installed on the second fixed base 27 to provide vertical guidance. The second slider 28 is slidably connected to the vertical guide rail 29, and the grinding wheel 4 is connected to the second slider 28 to rise and fall synchronously with the second slider 28. The second slide cylinder 26 serves as an automated power source, driving the second slider 28 to move stably up and down, enabling the grinding wheel 4 to precisely press against the outer peripheral surface of the welding ring for cutting, or to quickly detach from the workpiece after processing.

[0042] To provide the grinding wheel 4 with strong and stable cutting power, such as Figure 4 and Figure 5As shown, a bracket 31 is fixedly mounted on the second slider 28, and the grinding wheel 4 is connected to the bracket 31 via a second wheel frame 32. The bracket 31 is equipped with a rotary drive mechanism for driving the grinding wheel 4 to rotate. Specifically, a drive shaft 33 is rotatably connected to the second wheel frame 32, and the axial direction of the drive shaft 33 extends along the width direction of the insertion welding ring. The grinding wheel 4 includes several threaded wheels 34 that are fixedly mounted side by side on the drive shaft 33 along the width direction of the insertion welding ring. It is worth noting that the wire wheel 34 has a flexible structure (e.g., composed of radially arranged flexible abrasive strips). This structure of multiple relatively flexible wire wheels 34 arranged in parallel not only increases the coverage of a single grinding pass, but more importantly, the flexible wire wheel 34 can produce a certain degree of elastic conformal yielding when rotating at high speed and contacting the workpiece. This compliant cutting method can effectively grind away the protruding weld slag on the surface while strictly preventing rigid over-cutting of the outer circumference of the spigot weld ring. This avoids the problem of shrinkage of the outer diameter of the spigot weld ring due to over-grinding, and accurately ensures the standard outer diameter and sealing performance required for subsequent socket connection of the pipe fitting. In addition, to ensure reliable power transmission, the rotary drive mechanism includes a second motor 35 and a synchronous belt drive 36. The second motor 35 is fixedly connected to the bracket 31 via a second mounting bracket. A drive shaft 37 is rotatably connected to the bracket 31. The output end of the second motor 35 is coaxially fixedly connected to the drive shaft 37 via a second coupling 38. The drive shaft 37 is connected to the drive shaft 33 via the synchronous belt drive 36. This transmission arrangement effectively avoids the processing area and achieves smooth transmission of high-speed power.

[0043] Considering the stringent spatial interference constraints at the right-angled areas where the weld ring meets the pipe wall on both sides, and the fact that conventional uniaxial feed is prone to causing uneven grinding force, each corner grinding assembly 5 also includes an inclined guide sliding mechanism and a first slide cylinder 21 to achieve precise and interference-free feeding to this complex connection corner. Figure 3 and Figure 6 As shown, the inclined guide sliding mechanism includes a first fixed base 22, a first slider 23, and an inclined guide rail 24. The first fixed base 22 is connected to the translational boom 2 via a first connecting seat 25, and the inclined guide rail 24 is fixedly installed on the first fixed base 22. It is particularly noteworthy that the angle between the extension direction of the inclined guide rail 24 and the vertical direction is 45°, and the inclined guide rail 24 extends obliquely from top to bottom, with its lower end precisely pointing to the corresponding connecting corner. The first slider 23 is slidably connected to the inclined guide rail 24. The first slide cylinder 21 is fixedly installed on the first fixed base 22 and is used to drive the first slider 23 to slide obliquely along the inclined guide rail 24 towards or away from the connecting corner. The 45° feed angle best matches the right-angle geometry of the weld ring intersecting the pipe wall, providing uniform cutting pressure for subsequent grinding operations.

[0044] To address the challenge of close-fitting cutting within narrow, dead-end corners, each corner grinding assembly 5 is equipped with a dedicated end-effector. Specifically, such as... Figures 6 to 8 As shown, each corner grinding assembly 5 includes a grinding head that can extend and retract obliquely in the inclined direction to approach or move away from the connection corner between the two sides of the weld ring and the pipe wall of the ductile iron pipe. As the main supporting component of this assembly, the mounting platform 6 is fixedly mounted on the first slider 23; specifically, the grinding head includes the mounting platform 6, the abutment wheel 7, the drive wheel 8, and the narrow abrasive belt 9. The drive wheel 8 is rotatably connected to the mounting platform 6, the abutment wheel 7 is movably connected to the mounting platform 6, and the narrow abrasive belt 9 is fitted onto the abutment wheel 7 and the drive wheel 8, thereby utilizing the flexibility of the narrow abrasive belt 9 to highly adapt to the processing curve of the narrow corner. The diameter of the abutment wheel 7 is smaller than the diameter of the drive wheel 8, and the abutment wheel 7 is located on the side of the drive wheel 8 closest to the connection corner. This asymmetrical transmission arrangement, with a smaller front and larger rear, allows the small-diameter abutment wheel 7 to guide the narrow abrasive belt 9 to penetrate and conform to the deep root of the connecting corner to the maximum extent, while ensuring that the large-diameter drive wheel 8 at the rear will not structurally interfere with the towering weld ring or wide pipe wall. To provide stable and high-speed cutting power to the narrow abrasive belt 9, a first mounting frame 17 is fixedly installed on the mounting platform 6. A first motor 18 is fixedly installed on the first mounting frame 17, and the output end of the first motor 18 is coaxially connected to the drive wheel 8 via a first coupling 19. Furthermore, since the abrasive belt is a flexible transmission component, several auxiliary wheels 20 are rotatably connected to the mounting platform 6. Each auxiliary wheel 20 tightens the narrow abrasive belt 9 from the inside out, effectively preventing high-frequency vibration or accidental detachment of the abrasive belt during high-speed operation and forceful cutting.

[0045] In actual grinding operations, we found that the joints formed by the welding process are often not perfectly flat, but rather have a large number of irregular weld beads. To enable the grinding head to adapt to these protrusions and maintain continuous processing, an elastic element is provided between the abutment wheel 7 and the mounting platform 6. Specifically, such as... Figure 9 and Figure 10As shown, the abutment wheel 7 is movably connected to the mounting platform 6 via the first wheel frame 10. The mounting platform 6 has several parallel columnar through slots, each with its axial direction parallel to the extension / retraction direction of the grinding head. Each columnar through slot includes a guide section 11 in the middle and enlarged sections 12 at both ends. The inner diameter of the guide section 11 is smaller than the inner diameter of the enlarged sections 12, and a stepped portion 13 is formed between the end of the guide section 11 and the corresponding enlarged section 12. Several guide rods 14, corresponding one-to-one with the columnar through slots, are fixedly mounted on the first wheel frame 10. Each guide rod 14 slides through its corresponding guide section 11, providing precise guidance for the extension / retraction of the first wheel frame 10. The elastic element is a spring 15 sleeved on the guide rod 14. The spring 15 is located within the enlarged section 12 near the first wheel frame 10, and its two ends abut against the first wheel frame 10 and the corresponding stepped portion 13, respectively. The spring 15 is used to apply an elastic force to the abutment wheel 7 to make it bulge outward, so that the narrow sanding belt 9 can be elastically attached to the corresponding connecting corner. When the narrow sanding belt 9 encounters a large, hard, protruding weld slag, the first wheel frame 10 can overcome the elastic force of the spring 15 and automatically retract inward, thereby effectively preventing the sanding belt from breaking due to excessive instantaneous force.

[0046] Finally, to prevent the abutment wheel 7 from being excessively pushed out by the spring 15 when it is detached from the workpiece and in a stress-free state, which could cause the internal guide structure to fall off or cause movement jamming during refeeding, such as... Figure 10 As shown, each guide rod 14 is screwed with a limiting nut 16. The limiting nut 16 is located in the enlarged section 12 away from the first wheel frame 10, and the limiting nut 16 is used to abut against the corresponding stepped part 13 to limit the extension stroke of the guide rod 14. Through this stroke limiting design, it is ensured that the abutting wheel 7 has sufficient elastic recoil buffer space during grinding, and its extreme position of safe extension is strictly defined, thereby ensuring the long-term stable operation of the entire high-frequency vibration grinding device under harsh working conditions.

[0047] The above embodiments only illustrate one or more implementations of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A grinding device for the weld ring of a ductile iron pipe spigot, characterized in that, include: The rotating support frame (1) is used to horizontally support the ductile iron pipe to be ground and drive it to rotate around its own axis. The translation boom (2) is located on the side of the supporting slewing frame (1) and can be translated along the axial direction of the ductile iron pipe; The outer peripheral surface grinding assembly (3) is mounted on the translational boom (2) and can be raised and lowered in the vertical direction. The outer peripheral surface grinding assembly (3) includes a grinding wheel (4) for grinding the outer peripheral surface of the socket welding ring. Two corner grinding components (5) are symmetrically arranged on the translational boom (2) and are located on both sides of the outer peripheral grinding component (3) along the axial direction of the ductile iron pipe. Each of the corner grinding components (5) includes a grinding head that can extend and retract obliquely in the inclined direction to approach or move away from the connection corner between the two sides of the socket welding ring and the ductile iron pipe wall. The grinding head includes a mounting platform (6), an abutment wheel (7), a drive wheel (8), and a narrow sanding belt (9). The drive wheel (8) is rotatably connected to the mounting platform (6), the abutment wheel (7) is movably connected to the mounting platform (6), and the narrow sanding belt (9) is sleeved on the abutment wheel (7) and the drive wheel (8). The diameter of the abutting wheel (7) is smaller than that of the driving wheel (8), and the abutting wheel (7) is located on the side of the driving wheel (8) near the connecting corner; an elastic element is provided between the abutting wheel (7) and the mounting platform (6), and the elastic element is used to apply an elastic force to the abutting wheel (7) to make it bulge outward, so that the narrow sanding belt (9) is elastically attached to the corresponding connecting corner.

2. The grinding device for the weld ring of a ductile iron pipe spigot according to claim 1, characterized in that, The abutting wheel (7) is movably connected to the mounting platform (6) via the first wheel frame (10). The mounting platform (6) has several parallel columnar through slots. The axial direction of each columnar through slot is parallel to the extension / retraction direction of the grinding head. Each columnar through slot includes a guide section (11) in the middle and enlarged sections (12) at both ends. The inner diameter of the guide section (11) is smaller than the inner diameter of the enlarged section (12), and a groove is formed between the end of the guide section (11) and the corresponding enlarged section (12). The stepped portion (13) has a plurality of guide rods (14) fixedly provided on the first wheel frame (10) that correspond one-to-one with the columnar through grooves. Each guide rod (14) is slidably inserted into the corresponding guide section (11). The elastic element is a spring (15) sleeved on the guide rod (14). The spring (15) is located in the enlarged hole section (12) near the first wheel frame (10). The two ends of the spring (15) abut against the first wheel frame (10) and the corresponding stepped portion (13) respectively.

3. The grinding device for the weld ring of a ductile iron pipe spigot according to claim 2, characterized in that, Each of the guide rods (14) is screwed with a limiting nut (16), which is located in the enlarged section (12) away from the first wheel frame (10), and the limiting nut (16) is used to abut against the corresponding step (13) to limit the extension stroke of the guide rod (14).

4. The grinding device for the weld ring of a ductile iron pipe spigot according to claim 1, characterized in that, The mounting platform (6) is fixedly provided with a first mounting bracket (17), and a first motor (18) is fixedly installed on the first mounting bracket (17). The output end of the first motor (18) is coaxially connected to the drive wheel (8) through a first coupling (19).

5. The grinding device for the weld ring of a ductile iron pipe spigot according to claim 1, characterized in that, The mounting platform (6) is rotatably connected to several auxiliary wheels (20), each of which tightens the narrow sand belt (9) from the inside out.

6. The grinding device for the weld ring of a ductile iron pipe spigot according to claim 1, characterized in that, Each corner grinding assembly (5) further includes an inclined guide sliding mechanism and a first slide cylinder (21). The inclined guide sliding mechanism includes a first fixed base (22), a first slider (23), and an inclined guide rail (24). The first fixed base (22) is connected to the translational boom (2) through a first connecting seat (25). The inclined guide rail (24) is fixedly installed on the first fixed base (22). The angle between the extension direction of the inclined guide rail (24) and the vertical direction is 45°. The inclined guide rail (24) extends obliquely from top to bottom, and its lower end points to the corresponding connecting corner. The first slider (23) is slidably connected to the inclined guide rail (24). The mounting platform (6) is fixedly installed on the first slider (23). The first slide cylinder (21) is fixedly installed on the first fixed base (22) and is used to drive the first slider (23) to slide obliquely along the inclined guide rail (24) towards or away from the connecting corner.

7. The grinding device for the weld ring of a ductile iron pipe spigot according to claim 1, characterized in that, The outer peripheral surface grinding assembly (3) also includes a vertical guide sliding mechanism and a second slide cylinder (26). The vertical guide sliding mechanism includes a second fixed base (27), a second slider (28), and a vertical guide rail (29). The second fixed base (27) is connected to the translational boom (2) through a second connecting seat (30). The vertical guide rail (29) is fixedly installed on the second fixed base (27). The second slider (28) is slidably connected to the vertical guide rail (29). The grinding wheel (4) is connected to the second slider (28) to rise and fall synchronously with the second slider (28).

8. The grinding device for the weld ring of a ductile iron pipe spigot according to claim 7, characterized in that, The second slider (28) is fixedly provided with a bracket (31), and the grinding wheel (4) is connected to the bracket (31) through the second wheel frame (32). The bracket (31) is provided with a rotary drive mechanism for driving the grinding wheel (4) to rotate.

9. A grinding device for the weld ring of a ductile iron pipe spigot according to claim 8, characterized in that, The second wheel frame (32) is rotatably connected to a drive shaft (33), the axial direction of which extends along the width direction of the insertion welding ring, and the grinding wheel (4) includes a plurality of thread wheels (34) which are fixedly sleeved on the drive shaft (33) in parallel along the width direction of the insertion welding ring.

10. A grinding device for the weld ring of a ductile iron pipe spigot according to claim 9, characterized in that, The rotary drive mechanism includes a second motor (35) and a synchronous belt drive (36). The second motor (35) is fixedly connected to the bracket (31) through a second mounting bracket. A drive shaft (37) is rotatably connected to the bracket (31). The output end of the second motor (35) is coaxially fixedly connected to the drive shaft (37) through a second coupling (38). The drive shaft (37) is connected to the drive shaft (33) through the synchronous belt drive (36).

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