A device for polishing the inner wall of a hole and a polishing method thereof

Abstract

This invention discloses a grinding device and method for the inner wall of an opening. The grinding device includes a grinding pen, a grinding head, a limiting fixture, and a pressure tube seat. The grinding head is mounted on the bottom of the grinding pen. The limiting fixture is mounted on the pressure tube seat, which has a positioning groove. The bottom of the limiting fixture has a positioning boss that matches the positioning groove. A circular hole is formed inside the positioning boss. An opening corresponding to the circular hole is formed at the bottom of the positioning groove. A thin-walled bent pipe is connected to the bottom of the opening. The grinding method includes the following steps: S1: drilling; S2: pre-grinding cleaning; S3: assembly; S4: grinding the inner wall of the opening; S5: post-grinding cleaning; S6: endoscopic inspection; S7: passability check. This invention, through the design and layout of the grinding path, achieves sufficient and effective grinding of the inner wall of the opening after the thin-walled bent pipe is welded and sealed to the pressure tube seat, improving grinding efficiency and quality. This invention uses an inner wall grinding limiting fixture to avoid damage to the small hole and the surrounding area of ​​the product during the grinding process.

Description

Technical Field

[0001] This invention belongs to the field of borehole inner surface grinding technology, specifically relating to a grinding device and grinding method for the inner wall of a thin-walled bent pipe after welding and sealing with a tube sheet (pressure tube seat). Background Technology

[0002] Currently, there are some main problems in the assembly welding, pinhole preparation, and fitter processing: When the outer diameter of the tube is small and the inner diameter of the bend is large, a drill bit is used to create a hole after the bend is welded to the tube sheet. The drilling depth has specific requirements, and there are usually two scenarios: the hole is not drilled through, or it is drilled through. In the case of not drilling through, the actual operation will further deepen the drilling depth until it is complete. This is mainly because the depth to which the molten metal sinks into the end during the welding and sealing process cannot be precisely controlled. This can easily lead to excessive filler metal deposition, causing the drilling depth to increase. The small hole processing depth exceeds the length of the vertical end of the thin-walled bend, causing local over-cutting of the inner wall of the bend, and in severe cases, damage to the bend, resulting in the scrapping of the entire product.

[0003] On the other hand, after the small hole is fully penetrated, due to the thin-walled inner diameter of the small hole and the welded filling metal cannot be completely removed after drilling, an irregular metal surface will be generated at the transition position of the weld filling between the small hole and the inner diameter of the bend due to the uneven filling of molten metal. After drilling, there are sharp corners and burrs at the end of the bend, and there is a gap between the inner wall filling metal and the inner diameter of the bend that is not fused. It is difficult to remove the sharp corners, burrs and excess filling metal present in the small hole, the inner wall of the bend and the filling metal.

[0004] To address the aforementioned problems, some existing technologies have been provided, but these technologies all have shortcomings. For example, Chinese patent application number CN201810072518.4 discloses a method for grinding and cleaning the inner wall of curved oil pipelines. This method uses multiple transmission joints and a rotating shaft to achieve grinding and cleaning of the inner wall of curved pipelines, but it is only applicable to oil pipelines with the same inner diameter and has size limitations on the pipeline diameter. Similarly, Chinese patent application number CN201310663844.X discloses a device and method for grinding the inner wall of pipe fittings. This method uses a base, support rod, and a branch with a rotating shaft to achieve inner wall grinding, but it is only applicable to pipe fittings with the same inner diameter. Furthermore, it uses a handle to drive the rotating shaft to achieve inner wall grinding, which has high requirements for the inner diameter of the pipe fittings and is characterized by low efficiency.

[0005] Furthermore, regarding the post-weld drilling and inner wall grinding process of the bend and tube sheet (pressure tube seat), if the drilling depth reaches the process requirements but the hole remains a blind hole, the drilling depth will be continuously increased until the blind hole becomes a round hole. Throughout the drilling process, the drill bit will continuously approach the bending part of the thin-walled bend. Since the bend is a single-piece assembly, the vertical depth is uneven. As the drilling depth increases, it will damage the inner wall of the thin-walled bend, potentially causing the bending part of the thin-walled bend to crack.

[0006] Burrs at the opening location are removed using either blind hooking or localized exploratory grinding (blind polishing). Blind hooking involves using a round bar with an edged end to hook around the perimeter of the small hole; localized exploratory grinding involves using a pneumatic polishing pen to test and polish burrs in a non-visualized area. Neither method can completely remove burrs and other debris from the transition area between the small hole and the bend, potentially leading to breakage of the thin-walled bend. Welding the thin-walled bend to the tube sheet is the most crucial and challenging part of the entire product welding and assembly process. Uneven filler metal depth and the fact that grinding occurs in a non-visible area can cause quality abnormalities in the thin-walled bend, leading to processing delays, unstable product quality, increased life-cycle costs, and becoming a key bottleneck restricting production efficiency and product quality. Summary of the Invention

[0007] The purpose of this invention is to provide a device and method for grinding the inner wall of an opening, addressing the technical problems described in the background art.

[0008] The technical solution of this invention: A device for grinding the inner wall of an opening includes a grinding pen, a grinding head, a limiting fixture, and a pressure tube seat. The grinding head is installed at the bottom of the grinding pen. The limiting fixture is installed on the pressure tube seat, which has a positioning groove. The bottom of the limiting fixture has a positioning boss that matches the positioning groove. A circular hole is opened inside the positioning boss. The bottom of the positioning groove has an opening corresponding to the circular hole. A thin-walled bent pipe is connected to the bottom of the opening.

[0009] The polishing pen is a pneumatic polishing pen, which is equipped with a chuck, and the polishing head is attached to the bottom of the polishing pen by the chuck.

[0010] The chuck comes in two types: 2.35mm and 3.0mm.

[0011] The limiting fixture is an inner wall grinding limiting fixture.

[0012] The grinding heads include arrow-shaped grinding heads and spherical grinding heads.

[0013] The maximum outer diameter of the grinding head is less than or equal to the inner diameter of the opening, and the inner diameter of the opening is greater than 1 / 2 the difference between the inner diameter of the thin-walled bend and the inner diameter of the opening.

[0014] The limiting fixture is fixed to the pressure pipe seat by bolts.

[0015] A grinding method for an aperture inner wall grinding device includes the following steps: S1: Drilling process. Install the pressure pipe seat onto the machining center of the machining equipment, ensure secure clamping, locate the reference point using the machining equipment, and then perform the drilling operation. S2: Cleaning before grinding. After completing step S1, clean the inside and outside of the hole and the surrounding area to remove chips. S3: Assembly. After completing step S2, determine the state of the opening. If the opening is a through hole, install the spherical grinding head and use bolts to fix the assembly limit fixture. If the opening is a blind hole, first install the arrow-shaped grinding head, and after fixing the assembly limit fixture, grind the blind hole to a through hole state, and then replace the spherical grinding head. S4: Grinding the inner wall of the opening: After completing step S3, use a grinding pen to drive the grinding head to move the small hole axially and radially inside the opening. S5: Cleaning after grinding. After completing step S4, remove the limiting fixture and grinding head, and use compressed air to remove grinding debris from inside the opening. S6: Endoscopic inspection. After completing step S5, the welding and grinding position of the thin-walled bend is magnified and visually inspected using an endoscope to ensure that there are no burrs or sharp residues in the fusion area between the filler metal and the pipe wall, and that the transition between the thin-walled bend and the opening is uniform and smooth. S7: Passability check. After completing step S6, place steel balls with a diameter of 60% of the inner diameter of the thin-walled bend into both ends of the bend. Through gravity, ensure that the steel balls can pass through smoothly to obtain a qualified product.

[0016] In step S1, the drilling depth is fixed at 7 mm.

[0017] In step S1, compressed air and a wire brush are used to clean the inside, outside and surrounding areas of the hole.

[0018] The beneficial effects of this invention are: This invention combines the bottle-shaped design concept of small outer diameter and large inner diameter. Through the design and layout of the grinding path, it achieves full and effective grinding of the inner wall of the opening after the thin-walled bend and pressure pipe seat are welded and sealed, which improves grinding efficiency and quality and solves the problem of welding and grinding small-sized pressure pipe seats.

[0019] This invention solves the problems of numerous burrs, large differences in opening quality, low grinding efficiency, and easy cracking of thin-walled bends after welding and sealing with pressure pipe seats. It also has significant implications for the grinding and processing of thin-walled bends.

[0020] This invention employs an inner wall grinding limiting fixture, which on the one hand avoids damage to the small hole and the product periphery during the grinding process, and on the other hand, through the rational design of the grinding passage and the inner diameter of the opening, combined with the grinding head, refines and quantifies the grinding range, avoiding damage to thin-walled bent pipes caused by excessive grinding.

[0021] This invention provides two types of grinding heads for different opening conditions, ensuring protection of thin-walled bent pipes during the grinding process. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the grinding structure in the case of an opening that is not fully penetrated in this invention; Figure 2 This is a schematic diagram of the grinding structure in the fully penetrated state of the present invention; Figure 3 This is a schematic diagram of the completed structure of the wall bend and pressure pipe seat after grinding in this invention. Figure 4 This is a schematic diagram of the inner wall grinding and limiting fixture in this invention; Figure 5 This is the present invention. Figure 4 Cross-sectional view of AA.

[0023] Reference numerals: 1-Pressure tube seat, 2-Grinding head, 3-Grinding pen, 4-Limiting fixture, 5-Positioning groove, 6-Positioning boss, 7-Round hole, 8-Opening, 9-Thin-walled bend. Detailed Implementation

[0024] refer to Figures 1-5 A device for grinding the inner wall of an opening includes a grinding pen 3, a grinding head 2, a limiting fixture 4, and a pressure tube seat 1. The grinding head 2 is installed at the bottom of the grinding pen 3. The limiting fixture 4 is installed on the pressure tube seat 1. A positioning groove 5 is provided on the pressure tube seat 1. A positioning boss 6 that matches the positioning groove 5 is provided at the bottom of the limiting fixture 4. A round hole 7 is provided inside the positioning boss 6. An opening 8 corresponding to the round hole 7 is provided at the bottom of the positioning groove 5. A thin-walled bent pipe 9 is connected to the bottom of the opening 8.

[0025] The polishing pen 3 is a pneumatic polishing pen, which is equipped with a chuck (not shown in the figure), and the polishing head 2 is attached to the bottom of the polishing pen 3 by the chuck.

[0026] The chuck comes in two types: 2.35mm and 3.0mm.

[0027] In this application, the pneumatic polishing pen belongs to industrial pneumatic tools, and its chuck is divided into two types: 2.35mm and 3mm. The 2.35mm chuck is used in this invention. The polishing head is an alloy polishing head with a shank diameter of 2.35mm and a maximum polishing head diameter of 3.0mm.

[0028] Mount the polishing head 2 onto the clamping end of the pneumatic polishing pen via its handle, ensuring a secure installation.

[0029] The limiting fixture 4 is an inner wall grinding limiting fixture.

[0030] In this invention, the inner wall grinding limiting fixture is made of high-strength, high-hardness materials, such as 45 steel and other materials. It is mainly used to protect the original opening position during the grinding process, and can also limit the grinding path to determine the maximum grinding range.

[0031] The grinding head 2 includes an arrow-shaped grinding head and a ball-shaped grinding head.

[0032] It is mainly used to grind open holes 8 that are not fully open, so that the open holes 8 are fully open; the ball-shaped grinding head is mainly used to grind the inner wall of the fully open holes 8; it removes burrs and removes excess material from the inner wall, ensuring that the open holes 8 are completely unobstructed and ensuring that the product is delivered in good condition.

[0033] The maximum outer diameter of the grinding head 2 is less than or equal to the inner diameter of the opening 8, and the inner diameter of the opening 8 is greater than 1 / 2 the difference between the inner diameter of the thin-walled bend 9 and the inner diameter of the opening 8.

[0034] In this invention, the difference between the grinding head 2 and its shank diameter is less than or equal to the difference between the thin-walled bent tube and the inner diameter of the through hole.

[0035] The maximum outer diameter of the grinding head is less than or equal to the inner diameter of the opening 8. This setting is mainly to ensure that the grinding head 2 passes through smoothly, thereby facilitating the grinding operation. The inner diameter of the opening 8 is greater than 1 / 2 the difference between the inner diameter of the thin-walled bend 9 and the inner diameter of the opening 8. This setting is mainly to ensure that the grinding coverage area of ​​the grinding head passing through the opening 8 is not less than the inner diameter of the thin-walled bend 9, thus ensuring the completeness of the grinding.

[0036] The limiting fixture 4 is fixed to the pressure tube seat 1 by bolts.

[0037] Specifically, before grinding, the inner wall grinding limiting fixture is placed in the designated position of the pressure tube seat 1 according to its shape and fixed with bolts to ensure a tight and reliable fit; and in this invention, the assembly gap between the limiting fixture 4 and the pressure tube seat 1 is 0.05mm to 0.10mm.

[0038] In this invention, before grinding, the inner wall grinding limiting fixture is first placed in the designated position of the pressure tube seat 1 according to its shape and fixed with bolts to ensure a tight and reliable fit. If the hole is not fully penetrated after drilling according to the technical requirements, a pneumatic grinding pen with a special (arrow-shaped) grinding head is held and aligned with the un-drilled position at the center point. The pen is then ground back and forth along the axis of the hole to achieve the penetration of the small hole without damaging the inner wall and the curved parts.

[0039] After hole 8 is completed, burrs and machining chips will remain around hole 8 and the inner wall of the bend. After installing the special (spherical) grinding head on the grinding pen, use the pen to perform two grinding operations: rotating and grinding along the axial direction of the inner wall of the hole. This effectively removes burrs and excess material from the inner wall, ensuring the hole is completely unobstructed and guaranteeing a qualified product delivery.

[0040] The maximum outer diameter of the grinding head 2 is less than or equal to the inner diameter of the opening 8, while the inner diameter of the opening 8 is greater than 1 / 2 the difference between the inner diameter of the thin-walled bend 9 and the inner diameter of the opening.

[0041] After polishing, burrs and sharp corners are eliminated, and debris generated during machining is removed, resulting in the finished product.

[0042] A grinding method for an aperture inner wall grinding device includes the following steps: S1: Drilling process. Install the pressure tube seat 1 to the machining center of the machining equipment, ensure that the clamping is secure, and find the reference point through the machining equipment, and then perform the drilling operation. The specific steps are as follows: Install the pressure pipe seat 1 to the machining center of the processing equipment, ensuring a secure clamping, and use the equipment to locate the reference point. The assembly surface should be flat, smooth, and free of burrs, and should be free of rust, oil, oxides, and foreign matter. In this application, the drilling depth is a fixed value of 7mm, and the length of the vertical portion of the thin-walled bend end is 10mm.

[0043] In this application, the processing equipment is a DUM machine or a DUM200T machine, and the machining center is the machining center of the DUM200T machine.

[0044] S2: Cleaning before grinding. After completing step S1, clean the inside and outside of the hole and the surrounding area to remove chips. The specific steps are as follows: Use compressed air and a wire brush to clean the inside, outside and around the opening 8 to remove chips.

[0045] S3: Assembly. After completing step S2, determine the state of hole 8. If hole 8 is a through hole, install the spherical grinding head and use bolts to fix the assembly limit fixture 4. If hole 8 is a blind hole, first install the arrow-shaped grinding head, and after fixing the assembly limit fixture 4, grind the blind hole to a through hole state, and then replace the spherical grinding head. The specific steps are as follows: First, pre-install a dedicated grinding head. The diameter of the dedicated grinding head should match the diameter of the through hole, and the shape of the dedicated grinding head should be determined based on the drilling condition. If it is a through hole, install a spherical grinding head and use bolts to fix and assemble the limiting fixture 4. If the hole is a blind hole, first install an arrow-shaped grinding head, and after fixing and assembling the limiting fixture 4, grind the blind hole to a through hole state, then replace it with a spherical grinding head.

[0046] In the assembly process of the inner wall grinding limiting fixture of this invention, the fixture is fixed by bolts through coaxial holes, and the assembly gap is 0.05mm to 0.10mm (the difference between the grinding head 2 and its shank diameter is less than or equal to the difference between the inner diameter of the thin-walled bent pipe 9 and the opening 8). The shank of the grinding head 2 is installed on the clamping end of the grinding pen 3 to ensure a tight installation.

[0047] S4: Grinding the inner wall of the opening: After completing step S3, use the grinding pen 3 to drive the grinding head 2 to move the small hole axially and radially within the opening 8. The specific steps are as follows: Use a pneumatic polishing pen to move the small hole axially and radially. During the polishing process, under the size limitation of the polishing protective fixture, the maximum value of the polishing diameter caused by the polishing tilt angle is not greater than the sum of 0.5% of the inner diameter of the thin-walled bend and the wall thickness of the pipe.

[0048] S5: Cleaning after grinding. After completing step S4, remove the limiting fixture 4 and the grinding head 2, and use compressed air to remove the grinding debris inside the opening 8. The specific steps are as follows: After grinding is completed, remove the inner wall grinding limit fixture and grinding head 2, and use compressed air to remove grinding debris.

[0049] S6: Endoscopic inspection. After completing step S5, the welding and grinding position of the thin-walled bend 9 is magnified and visually inspected through an endoscope to ensure that there are no burrs or sharp residues in the fusion area between the filler metal and the pipe wall, and that the transition between the thin-walled bend 9 and the opening 8 is uniform and smooth. The specific steps are as follows: The welding and grinding position of the thin-walled bend 9 is magnified and visually inspected using an endoscope to ensure that there are no burrs or sharp residues in the fusion area between the filler metal and the pipe wall, and that the transition between the thin-walled bend and the small-sized through hole is uniform and smooth.

[0050] S7: Passability check. After completing step S6, place steel balls with a diameter of 60% of the inner diameter of the thin-walled bend 9 at both ends. Through gravity, ensure that the steel balls can pass smoothly to obtain a qualified product.

[0051] This invention combines the bottle-shaped design concept of small outer diameter and large inner diameter. Through the design and layout of the grinding path, it achieves full and effective grinding of the inner wall of the opening after the thin-walled bent tube 9 and the pressure tube seat 1 are welded and sealed, which improves grinding efficiency and quality and solves the problem of welding and grinding of small-sized pressure tube seat 1.

[0052] This invention solves the problems of numerous burrs, large differences in opening quality, low grinding efficiency, and easy breakage of thin-walled bends after welding and sealing thin-walled bends 9 and pressure pipe seats 1. It also has significant implications for the grinding and processing of thin-walled bends 9.

[0053] This invention employs an inner wall grinding limiting fixture, which on the one hand avoids damage to the small hole and the product periphery during the grinding process, and on the other hand, through the rational design of the grinding passage and the inner diameter of the opening 8, combined with the grinding head, refines and quantifies the grinding range, thus avoiding damage to the thin-walled bent pipe 9 caused by excessive grinding.

[0054] This invention provides two grinding heads for different opening states, ensuring protection of thin-walled bent pipes during the grinding process.

Claims

1. A device for grinding the inner wall of an opening, characterized in that... The device includes a polishing pen (3), a polishing head (2), a limiting fixture (4), and a pressure tube seat (1). The polishing pen (3) has a polishing head (2) installed at its bottom. The limiting fixture (4) is installed on the pressure tube seat (1). The pressure tube seat (1) has a positioning groove (5). The bottom of the limiting fixture (4) has a positioning boss (6) that matches the positioning groove (5). The positioning boss (6) has a round hole (7) inside. The bottom of the positioning groove (5) has an opening (8) that corresponds to the round hole (7). The bottom of the opening (8) is connected to a thin-walled bent pipe (9).

2. The hole inner wall grinding device according to claim 1, characterized in that: The polishing pen (3) is a pneumatic polishing pen. The polishing pen (3) is equipped with a chuck, and the polishing head (2) is attached to the bottom of the polishing pen (3) by the chuck.

3. The hole inner wall grinding device according to claim 2, characterized in that: The chuck comes in two types: 2.35mm and 3.0mm.

4. The device for grinding the inner wall of an opening according to claim 1, characterized in that: The limiting fixture (4) is an inner wall grinding limiting fixture.

5. The device for grinding the inner wall of an opening according to claim 2, characterized in that: The grinding head (2) includes an arrow-shaped grinding head and a ball-shaped grinding head.

6. The hole inner wall grinding device according to claim 2, characterized in that: The maximum outer diameter of the grinding head (2) is less than or equal to the inner diameter of the opening (8), and the inner diameter of the opening (8) is greater than 1 / 2 the difference between the inner diameter of the thin-walled bend (9) and the inner diameter of the opening (8).

7. The device for grinding the inner wall of an opening according to claim 1, characterized in that: The limiting fixture (4) is fixed to the pressure pipe seat (1) by bolts.

8. The grinding method of the aperture inner wall grinding device according to any one of claims 1-7, characterized in that: Includes the following steps: S1: Drilling process, install the pressure pipe seat (1) to the machining center of the machining equipment, ensure that the clamping is secure, and find the reference point through the machining equipment, and then perform the drilling operation; S2: Cleaning before grinding. After completing step S1, clean the inside and outside of the hole and the surrounding area to remove chips. S3: Assembly. After completing step S2, determine the state of the opening (8). If the opening (8) is a through hole, install the ball grinding head and use bolts to fix the assembly limit fixture (4). If the opening (8) is a blind hole, first install the arrow-shaped grinding head, and after fixing the assembly limit fixture (4), grind the blind hole to the through hole state, and then replace the ball grinding head. S4: Grinding the inner wall of the opening: After completing step S3, use the grinding pen (3) to drive the grinding head (2) to move the small hole axially and radially inside the opening (8); S5: Cleaning after grinding. After completing step S4, remove the limiting fixture (4) and grinding head (2), and use compressed air to remove grinding debris inside the opening (8). S6: Endoscopic inspection. After completing step S5, the welding and grinding position of the thin-walled bend (9) is magnified and visually inspected through an endoscope to ensure that there are no burrs or sharp residues in the fusion area between the filler metal and the pipe wall, and that the transition between the thin-walled bend (9) and the opening (8) is uniform and smooth. S7: Passability check. After completing step S6, place steel balls with a diameter of 60% of the inner diameter of the thin-walled bend (9) at both ends. Through gravity, ensure that the steel balls can pass smoothly and obtain qualified products.

9. The grinding method of the aperture inner wall grinding device according to claim 1, characterized in that: In step S1, the drilling depth is fixed at 7 mm.

10. The grinding method of the aperture inner wall grinding device according to claim 1, characterized in that: In step S1, compressed air and a wire brush are used to clean the inside, outside and surrounding areas of the hole.

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