Small-angle and small-diameter stainless steel elbow inner hole grinding method and tool for nuclear power

Abstract

The present invention discloses a method and a tool for polishing the inner hole of a small-angle and small-diameter stainless steel elbow for nuclear power, which solves the problem of difficult polishing of high-strength, large-diameter, and thick-wall stainless steel elbows. The polishing tool of the present invention includes a polishing machine, and further includes a connecting rod, a handle, and a power device for driving the polishing machine, which are sequentially connected to the polishing machine. A support disc is sleeved on the connecting rod through a universal ball joint bearing. A plurality of support holes are evenly formed in the support disc, and support rods are inserted into the support holes. The method for polishing the inner hole of a small-angle and small-diameter stainless steel elbow for nuclear power of the present invention uses the above tool to polish the outer arc area and the inner arc blind area of the inner hole of the elbow in sequence. The process of the present invention is simple, easy to operate, can conveniently polish the inner hole of a small-angle and small-diameter stainless steel elbow for nuclear power, has a high surface quality of the inner hole after processing, and is applicable to the inner holes of stainless steel elbows with different bending angles. The tool of the present invention has a simple structure, is easy to disassemble, assemble, and maintain, and has good flexible adaptability.

Description

Technical Field

[0001] The present invention relates to the field of bent pipe processing, and specifically to a method and tool for grinding the inner hole of a small-angle and small-diameter stainless steel bent pipe for nuclear power plants. Background Art

[0002] High-strength, large-diameter, and thick-wall stainless steel bent pipes are important components of industrial equipment, especially widely used in the fields of petrochemical and nuclear power. The existing bent pipe processes mainly include press bending, push bending, roll bending, etc. The pipe blanks bent by these bent pipe process schemes inevitably have large biaxial compressive stresses in the bent pipe section, so it is easy to cause uneven wall thickness in the bent pipe section, and even wrinkling phenomenon in the inner arc section. According to the design requirements of the pipeline, there are high requirements for the wall thickness of the pipeline, and the inner wall is required to be smooth. In order to meet these requirements, it is necessary to perform secondary processing on the inner hole of the pipeline after bending. However, it is very difficult to achieve by mechanical processing of the inner hole, especially for small-diameter and small-angle bent pipes with an inner hole diameter of less than 300 mm and a bending angle of less than 120 degrees.

[0003] The main reason is that the straight pipe sections on the left and right sides of the bent pipe are relatively long, generally more than 2000 mm. The tool bar has too long a cantilever and is restricted by the inner wall of the bent pipe, so the inner hole processing in the bent pipe area cannot be completed. Only manual grinding can be adopted.

[0004] Difficulties in manual grinding: (1) After bending the pipe, the straight pipe sections on the left and right sides are relatively long, greater than 2000 mm, and the inner hole diameter of the bent pipe is less than 300, and ordinary pneumatic grinders cannot reach this depth. (2) As the bending angle of the bent pipe becomes smaller, the grinding difficulty increases, and there are visual blind spots in the inner arc area of the bent pipe (as shown in Figure 1 and 4 ). (3) When the bending angle of the bent pipe is less than 120 degrees, it is difficult to visually inspect the bent pipe area. (4) High requirements are imposed on the surface quality of the inner hole of the bent pipe, and the wall thickness difference should be controlled within 1 mm and the surface roughness should be Ra3.2. When manually operating, it is very easy to cause secondary damage to the surface of the bent pipe, and it is difficult to meet the requirements for the surface processing of the inner hole of the stainless steel bent pipe. Summary of the Invention

[0005] The purpose of the present invention is to solve the above technical problems, and provide a method for grinding the inner hole of a small-angle and small-diameter stainless steel bent pipe for nuclear power plants, which has a simple process, is easy to operate, can conveniently grind the inner hole of the small-angle and small-diameter stainless steel bent pipe for nuclear power plants, has high surface quality of the inner hole after processing, and is applicable to small-angle and small-diameter stainless steel bent pipes for nuclear power plants with different bending angles.

[0006] The present invention also provides a tool for grinding the inner hole of a small-angle and small-diameter stainless steel bent pipe for nuclear power plants for the above grinding method.

[0007] The inner hole grinding tool for small-angle and small-caliber stainless steel elbows used in nuclear power plants of the present invention includes a grinding machine, and also includes a connecting rod, a handle, and a power device for driving the grinding machine that are sequentially connected to the grinding machine. A support disc is sleeved on the connecting rod through a universal ball joint bearing. A plurality of support holes are evenly formed in the support disc, and support rods are inserted into the support holes.

[0008] The thickness of the support disc is 0-30 mm greater than the thickness of the universal ball joint bearing.

[0009] The gap between the support disc and the pipe wall is controlled within 0.5 mm to 1 mm.

[0010] The grinding machine, the connecting rod, the handle, and the power device are all detachably connected.

[0011] The support disc and the support rods are made of nylon or bakelite.

[0012] The power device is an air compressor, the grinding machine is a pneumatic grinding machine, and the power outlet of the air compressor is communicated with the pneumatic grinding machine through a hollow handle, a connecting rod, and the pneumatic grinding machine.

[0013] A joint is also connected between the grinding machine and the connecting rod, and a ratchet mechanism is provided on the joint.

[0014] A joint is also detachably connected between the grinding machine and the connecting rod.

[0015] The inner hole grinding method for small-angle and small-caliber stainless steel elbows used in nuclear power plants of the present invention sequentially performs grinding on the outer arc area and the inner arc blind area of the inner hole of the elbow:

[0016] Among them, the following steps are adopted for grinding the outer arc area:

[0017] A1) Place an inner hole peephole at one end of the stainless steel elbow, and adjust the position of the inner hole peephole until the surface of the workpiece to be ground can be clearly seen.

[0018] A2) Rough grinding: Insert the inner hole grinding tool for the elbow without a joint into the inner hole of the stainless steel elbow from one end of the inner hole of the elbow, start the grinding machine to perform rough grinding on the outer arc area of the inner hole, and rough grind to half of the elbow section; at the same time, monitor through the inner hole peephole to adjust the grinding position of the grinding head. After rough grinding is completed, turn off the grinding machine and withdraw the inner hole grinding tool for the elbow.

[0019] A3) Fine grinding: Replace the grinding head of the grinding machine of the inner hole grinding tool for the elbow with a fine grinding head, insert it into the elbow section again, start the grinding machine to perform polishing and grinding on the outer arc area of the inner hole, and grind to half of the elbow section; at the same time, monitor through the inner hole peephole to adjust the grinding position of the grinding device, and at the same time use a wall thickness measuring instrument to control the pipe wall thickness. After grinding is completed, turn off the grinding machine and withdraw the inner hole grinding tool for the elbow.

[0020] A4) Polishing: Replace the grinding head of the grinding machine of the inner hole grinding tool of the elbow with a polishing grinding head, insert it into the elbow section again, start the grinding machine to polish the outer arc area of the inner hole, and polish until half of the elbow section is reached; at the same time, adjust the grinding position of the grinding device through the monitoring of the inner hole peephole, and use a wall thickness measuring instrument to control the pipe wall thickness. After the polishing is completed, turn off the grinding machine and withdraw the inner hole grinding tool of the elbow.

[0021] The inner arc blind area grinding adopts the following steps:

[0022] B1) Rough grinding: Insert the inner hole grinding tool of the elbow equipped with a joint into one end of the inner hole of the stainless steel elbow and into the elbow section, start the grinding machine to rough grind the inner arc blind area of the inner hole, and rough grind until half of the elbow section is reached; at the same time, adjust the grinding position of the grinding head through the monitoring of the inner hole peephole, and adjust the inclination angle of the grinding machine and the connecting rod through the ratchet mechanism on the joint so that the grinding head can completely contact the inner wall of the inner arc blind area of the inner hole of the elbow. After the rough grinding is completed, turn off the grinding machine and withdraw the inner hole grinding tool of the elbow;

[0023] B2) Fine grinding: Replace the grinding head of the grinding machine of the inner hole grinding tool of the elbow with a fine grinding head, insert it into the elbow section of the workpiece from one end of the inner hole of the workpiece, start the grinding machine to polish the inner arc blind area, and polish until half of the elbow section is reached; at the same time, adjust the grinding position of the grinding device through the monitoring of the inner hole peephole, control the pipe wall thickness through a wall thickness difference measuring instrument, and adjust the inclination angle of the grinding machine and the connecting rod through the ratchet mechanism on the joint so that the grinding head can completely contact the inner wall of the inner arc blind area of the inner hole of the elbow. After the grinding is completed, turn off the grinding machine and withdraw the inner hole grinding tool of the elbow;

[0024] B3) Polishing: Replace the grinding head of the grinding machine of the inner hole grinding tool of the elbow with a polishing grinding head, insert it into the elbow section of the workpiece from one end of the inner hole of the workpiece, start the grinding machine to polish the inner arc blind area, and polish until half of the elbow section is reached; at the same time, adjust the grinding position of the grinding device through the monitoring of the inner hole peephole, and adjust the inclination angle of the grinding machine and the connecting rod through the ratchet mechanism on the joint so that the grinding head can completely contact the inner wall of the inner arc blind area of the inner hole of the elbow. After the polishing is completed, turn off the grinding machine and withdraw the inner hole grinding tool of the elbow;

[0025] After completing the above steps, turn the stainless steel elbow around and repeat the steps of grinding the outer arc area and the inner arc blind area of the inner hole of the elbow to complete the grinding of the other half of the inner hole of the stainless steel elbow.

[0026] In the outer arc area grinding step, in A2), the grinding head of the grinding machine is equipped with a brown fused alumina grinding wheel; in A3), the grinding head of the grinding machine is equipped with an 80 - 120 grit flap wheel grinding head; in A4), the grinding head of the grinding machine is equipped with a 320 grit abrasive belt;

[0027] In the grinding step of the inner arc blind area, in B1), the grinding head of the grinding machine is equipped with a brown fused alumina grinding wheel; in B2), the grinding head of the grinding machine is equipped with a flap wheel grinding head with a grain size of 80-120; in B3), the grinding head of the grinding machine is equipped with a sand belt with a grain size of 320.

[0028] Beneficial effects:

[0029] 1) In the grinding tool of the present invention, a support disk is sleeved on the adapter rod through a universal ball joint bearing, the support disk is supported on the inner wall of the inner hole of the stainless steel elbow, and the adapter rod swings symmetrically on both sides of the support disk through a universal shaft. By controlling the installation position of the support disk and the lengths of the adapter rods on both sides of the support disk, the lever principle can be cleverly utilized to achieve the purpose of labor saving and easy operation.

[0030] 2) The thickness of the support disk should not be too thick, otherwise it is difficult to provide enough angular space for the support rod. Therefore, while reducing the thickness of the support disk, the inventor evenly opens a plurality of support holes on the support disk, and the support rods are inserted into the support holes. The support rods provide auxiliary support force for the support disk. The contact between the support rods and the inner wall of the variable pipe is line contact, which ensures the support strength and also gives enough movement space for the support rods to meet the requirements of different grinding angles. The adapter rod can rotate in any direction in the inner hole for circumferential grinding, greatly improving the grinding accuracy. Preferably, the support disk and the support rods are made of nylon or bakelite to avoid secondary damage to the hole wall caused by the direct action of rigid materials on the inner hole.

[0031] 3) Preferably, the gap between the support disk and the pipe wall is controlled within 0.5 mm - 1 mm, the thickness of the support disk is 0 - 30 mm greater than the thickness of the universal ball joint bearing, and the length of the support rod is preferably 300 mm. The shortest distance from the support hole to the edge of the support disk is 5 - 10 mm.

[0032] 4) The present invention is based on whether it is visible or not and uses area division for grinding, which is divided into an outer arc area and an inner arc blind area. When grinding in the outer arc area, a grinding tool without a joint is used; while in the inner arc blind area, since its bend angle exceeds the visible angle, a grinding tool with a joint is used in cooperation. Since a ratchet mechanism is provided on the joint, the turning angle of the joint can be adjusted through the ratchet device, so that the contact angle requirement between the grinding machine and the stainless steel elbow can also be met in the inner arc blind area.

[0033] 5) In the method of the present invention, the surface quality of the inner hole of the elbow is ensured through detection means such as a wall thickness measuring instrument and an ultrasonic flaw detector.

[0034] 6) The tool of the present invention has a simple structure, is easy to use, saves time and effort, and its components can be flexibly disassembled. It is easy to operate and can conveniently and quickly polish the inner hole of the stainless steel elbow for nuclear power. It is especially suitable for small-diameter and small-angle elbows with an inner hole diameter of less than 300 mm and a bending angle of less than 120 degrees. After being processed by the method of the present invention, the inner hole surface has high quality and uniform wall thickness, meeting the processing requirements for the inner hole surface, and is applicable to stainless steel elbows with different bending angles and longer straight pipe sections. Description of the Drawings

[0035] Figure 1 Schematic structural diagram of the stainless steel elbow.

[0036] Figure 2 Schematic diagram of the polishing state of the outer arc area of the present invention.

[0037] Figure 3 Schematic diagram of the polishing state of the blind area of the inner arc of the present invention.

[0038] Figure 4 Top view of the support plate.

[0039] Wherein: 1 - stainless steel elbow, 11 - outer arc area, 12 - blind area of the inner arc, 2 - polishing tool for the inner hole of the elbow, 21 - grinding head, 22 - grinding machine, 23 - joint, 24 - support rod, 25 - support plate, 26 - universal ball joint bearing, 27 - connecting rod, 28 - handle, 29 - switch, 30 - air compressor, 31 - support hole, 3 - inner hole peephole. Detailed Embodiment

[0040] The tool of the present invention will be further explained below with reference to the drawings:

[0041] See Figure 2 and Figure 3 The polishing tool 2 for the inner hole of the elbow of the present invention includes a joint 23, a connecting rod 27, a handle 28 and a power device for driving the grinding machine 22, which are sequentially connected to the grinding machine 22. In this embodiment, the grinding machine 22 is a pneumatic grinding machine, and the power device is an air compressor 30. When pneumatic polishing is adopted, the power outlet of the air compressor 30 is communicated with the pneumatic grinding machine 22 through the hollow handle 28, connecting rod 27, joint 23 and pneumatic grinding machine 22 to drive the pneumatic grinding machine 22 to work.

[0042] Those skilled in the art can also select electric or other power methods according to needs.

[0043] A support plate 25 is sleeved on the connecting rod 27 through a universal ball joint bearing 26. A plurality of support holes 31 are evenly formed on the support plate 25, and support rods 24 are inserted into the support holes 31.

[0044] Preferably, the thickness of the support disk 25 is 0 - 30 mm greater than that of the universal ball joint bearing 26. The diameter of the support disk 25 is slightly smaller than the aperture, and the gap is controlled within 0.5 mm to 1 mm. The shortest distance from the support hole 31 to the edge of the support disk 25 is 5 - 10 mm. The support disk 25 and the support rod 24 are preferably made of nylon or bakelite materials, which can not only ensure a certain support strength but also avoid damage to the inner wall surface.

[0045] The grinding machine 22, the joint 23, the connecting rod 27, the handle 28, and the air compressor 30 are all detachably connected (such as threaded connection or snap connection), and can be installed, maintained, or repaired as needed. Moreover, when grinding different regions, the joint 23 can be selectively installed or not installed as required (the joint 23 is not installed when grinding the outer arc region 11, and the joint 23 needs to be installed when grinding the inner arc blind region 12).

[0046] In the method of the present invention, the stainless steel bent pipe 1 is placed on the scribing platform, and the outer arc region 11 (corresponding to the outer arc section of the bent pipe) and the inner arc blind region 12 (corresponding to the inner arc section of the bent pipe) of the inner hole of the elbow are ground in sequence:

[0047] Among them, the outer arc region grinding adopts the following steps:

[0048] A1) One end of the stainless steel bent pipe 1 is placed into the inner hole peephole 3 of the universal head, and the position of the inner hole peephole 3 is adjusted until the surface of the workpiece to be ground (i.e., the outer arc region 11 of the inner hole) can be clearly seen.

[0049] A2) Rough grinding: The bent pipe inner hole grinding tool 2 without the joint 23 (see Figure 2 ) is inserted into the bent pipe section from one end of the inner hole of the stainless steel bent pipe 1, and the grinding machine 22 is started to perform rough grinding on the outer arc region 11 of the inner hole. Rough grinding to half of the bent pipe section is sufficient; at the same time, flaw detection can also be carried out in cooperation with a phased array ultrasonic flaw detector to ensure that the folding and wrinkling defects in the inner hole are completely removed. At the same time, the grinding position of the grinding head 21 is adjusted through the monitoring of the inner hole peephole 3. After rough grinding is completed, the grinding machine 22 is turned off, and the bent pipe inner hole grinding tool 2 is withdrawn; the grinding head 21 uses a brown fused alumina grinding wheel, which can remove the wrinkles, oxide scales, and burrs on the inner hole surface of the bent pipe section.

[0050] A3) Fine grinding: The grinding head of the grinding machine 22 of the bent pipe inner hole grinding tool 2 is replaced with a fine grinding head, and it is inserted into the bent pipe section again. The grinding machine 22 is started to perform polishing and grinding on the outer arc region 11 of the inner hole. Grinding to half of the bent pipe section is sufficient; at the same time, the pipe wall thickness is controlled by a wall thickness difference measuring instrument, and the grinding position of the grinding device is adjusted through the monitoring of the inner hole peephole 3. After polishing and grinding is completed, the grinding machine 22 is turned off, and the bent pipe inner hole grinding tool 2 is withdrawn. The grinding head 21 uses a 80 - 120 grit flap wheel grinding head, which can perform fine grinding on the inner hole and adjust the pipe wall thickness at the same time.

[0051] A4) Polishing: Replace the grinding head of the grinding machine 22 of the inner hole grinding tool 2 of the bent pipe with a polishing head, insert it into the bent pipe section again, start the grinding machine 22 to polish the outer arc area 11 of the inner hole, and polish until half of the bent pipe section; at the same time, adjust the grinding position of the grinding device through the monitoring of the inner hole endoscope 3. After the polishing is completed, turn off the grinding machine 22 and withdraw the inner hole grinding tool 2 of the bent pipe. The grinding head 21 uses a 320-grit abrasive belt, which can improve the roughness of the polished surface and polish the inner hole.

[0052] The inner arc blind area grinding adopts the following steps:

[0053] B1) Rough grinding: Insert the inner hole grinding tool 2 of the bent pipe equipped with the joint 23 into one end of the inner hole of the stainless steel bent pipe 1 and into the bent pipe section, start the grinding machine 22 to rough grind the inner arc blind area 12 of the inner hole, and rough grind until half of the bent pipe section; at the same time, it can also be cooperated with flaw detection by a phased array ultrasonic flaw detector to ensure that the folding and wrinkling defects in the inner hole are completely removed. At the same time, adjust the grinding position of the grinding head 21 through the monitoring of the inner hole endoscope 3, and adjust the inclination angle between the grinding machine 22 and the connecting rod 27 through the ratchet mechanism on the joint 23, so that the grinding head 21 can completely contact the inner wall of the inner arc blind area 12 of the inner hole of the bent pipe. After the rough grinding is completed, turn off the grinding machine 22 and withdraw the inner hole grinding tool 2 of the bent pipe; the grinding head 21 uses a brown fused alumina grinding wheel, which can remove the wrinkles, oxide scales and burrs on the inner hole surface of the bent pipe section.

[0054] B2) Fine grinding: Replace the grinding head 21 of the grinding machine 22 of the inner hole grinding tool 2 of the bent pipe (equipped with the joint 23, see Figure 3 ) with a polishing head, insert it into the bent pipe section from one end of the inner hole of the workpiece bent pipe, start the grinding machine 22 to polish the inner arc blind area 12, and polish until half of the bent pipe section; control the pipe wall thickness through a wall thickness difference measuring instrument, and at the same time, adjust the grinding position of the grinding device through the monitoring of the inner hole endoscope, and adjust the inclination angle between the grinding machine 22 and the connecting rod 27 through the ratchet mechanism on the joint 23, so that the grinding head 21 can completely contact the inner wall of the inner arc blind area 12 of the inner hole of the bent pipe. After the polishing is completed, turn off the grinding machine 22 and withdraw the inner hole grinding tool 2 of the bent pipe; the grinding head 21 uses an 80-120 grit flap disc grinding head, which can improve the roughness of the polished surface and at the same time adjust the pipe wall thickness.

[0055] B3) Polishing: The inner hole grinding tool 2 of the bent pipe (equipped with the joint 23, see Figure 3Replace the grinding head 21 of the grinding machine 22 with a polishing head, insert it from one end of the inner hole of the workpiece elbow pipe into the elbow pipe section, start the grinding machine 22 to polish and grind the inner arc blind area 12, and grind to half of the elbow pipe section; at the same time, adjust the grinding position of the grinding device through the monitoring of the inner hole peephole 3, and adjust the inclination angle of the grinding machine 22 and the connecting rod 27 through the ratchet mechanism on the joint 23, so that the grinding head 21 can completely contact the inner wall of the inner arc blind area 12 of the inner hole of the elbow pipe. After the polishing and grinding are completed, turn off the grinding machine 22 and withdraw the inner hole grinding tool 2 of the elbow pipe; the grinding head 21 uses a sand belt with a particle size of 320, which can improve the surface roughness of the polished surface and polish the inner hole.

[0056] After completing the above steps, turn the stainless steel elbow pipe 1 around and repeat the above steps of grinding the outer arc area 11 and the inner arc blind area 12 of the inner hole of the elbow to complete the grinding of the other half of the inner hole of the stainless steel elbow pipe 1.

[0057] After processing the stainless steel elbow pipe by the method of the present invention, the surface quality of the inner hole of the stainless steel elbow pipe meets the processing requirements of a surface with Ra 3.2, and it is particularly suitable for stainless steel elbow pipes with a straight pipe section greater than 2000 mm, an inner hole diameter of the elbow pipe less than 300 mm, and a bending angle less than 120 degrees. The wall thickness can be controlled to be uniform, and the wall thickness difference is guaranteed to be within 1 mm.

Claims

1. A polishing tool for the inner hole of a small-angle and small-caliber stainless steel elbow for nuclear power, comprising a polishing machine, characterized in that, It further includes a joint, a connecting rod, a handle, and a power device for driving the grinding machine, which are sequentially connected to the grinding machine. A ratchet mechanism is provided on the joint. A support disk is sleeved on the connecting rod through a universal ball joint bearing. A plurality of support holes are evenly formed in the support disk, and support rods are inserted into the support holes. The grinding machine, the joint, the connecting rod, the handle, and the power device are all detachably connected. The power device is an air compressor, the grinding machine is a pneumatic grinding machine, and the power outlet of the air compressor is communicated with the pneumatic grinding machine through the hollow handle, the connecting rod, and the pneumatic grinding machine.

2. The inner hole grinding tool for small-angle and small-caliber stainless steel elbows used in nuclear power as described in claim 1, characterized in that, The thickness of the support disk is 0 - 30 mm greater than the thickness of the universal ball joint bearing.

3. The inner hole grinding tool for small-angle and small-caliber stainless steel elbows used in nuclear power plants as described in claim 1, characterized in that, The gap between the support disk and the pipe wall is controlled within 0.5 mm to 1 mm.

4. The inner hole grinding tool for small-angle and small-caliber stainless steel elbows used in nuclear power as described in claim 1, wherein The support disk and the support rods are made of nylon or bakelite.

5. A method for grinding the inner hole of a small-angle and small-diameter stainless steel elbow for nuclear power, characterized in that, Using the grinding tool according to any one of claims 1 - 4, successively perform grinding on the outer arc area and the inner arc blind area of the inner hole of the elbow: Among them, the grinding of the outer arc area adopts the following steps: A1) Place an inner hole peephole at one end of the stainless steel elbow, and adjust the position of the inner hole peephole until the surface of the workpiece to be ground can be clearly seen. A2) Rough grinding: Insert the inner hole grinding tool of the elbow without the joint into the inner hole of the stainless steel elbow from one end of the inner hole of the elbow section, start the grinding machine to perform rough grinding on the outer arc area of the inner hole, and rough grind to half of the elbow section; at the same time, through the monitoring of the inner hole peephole, adjust the grinding position of the grinding head. After rough grinding is completed, turn off the grinding machine and withdraw the inner hole grinding tool of the elbow. A3) Fine grinding: Replace the grinding head of the grinding machine of the inner hole grinding tool of the elbow with a fine grinding head, insert it into the elbow section again, start the grinding machine to perform polishing and grinding on the outer arc area of the inner hole, and grind to half of the elbow section; at the same time, through the monitoring of the inner hole peephole, adjust the grinding position of the grinding device, and at the same time use a wall thickness measuring instrument to control the wall thickness of the pipe. After grinding is completed, turn off the grinding machine and withdraw the inner hole grinding tool of the elbow. A4) Polishing: Replace the grinding head of the grinding machine of the inner hole grinding tool of the elbow with a polishing head, insert it into the elbow section again, start the grinding machine to perform polishing and grinding on the outer arc area of the inner hole, and grind to half of the elbow section; at the same time, through the monitoring of the inner hole peephole, adjust the grinding position of the grinding device. After polishing and grinding is completed, turn off the grinding machine and withdraw the inner hole grinding tool of the elbow. The grinding of the inner arc blind area adopts the following steps: B1) Rough grinding: Insert the inner hole grinding tool of the elbow with the joint into the inner hole of the stainless steel elbow from one end of the inner hole of the elbow section, start the grinding machine to perform rough grinding on the inner arc blind area of the inner hole, and rough grind to half of the elbow section; at the same time, through the monitoring of the inner hole peephole, adjust the grinding position of the grinding head, and adjust the inclination angle between the grinding machine and the connecting rod through the ratchet mechanism on the joint, so that the grinding head can completely contact the inner wall of the inner arc blind area of the inner hole of the elbow. After rough grinding is completed, turn off the grinding machine and withdraw the inner hole grinding tool of the elbow. B2) Fine grinding: Replace the grinding head of the grinding machine of the inner hole grinding tool for the elbow with a fine grinding head. Insert it from one end of the inner hole of the workpiece elbow into the elbow section of the workpiece, start the grinding machine to polish and grind the blind area of the inner arc, and grind to half of the elbow section. At the same time, adjust the grinding position of the grinding device through the monitoring of the inner hole peephole, control the wall thickness of the pipe through the wall thickness measuring instrument, and adjust the inclination angle between the grinding machine and the connecting rod through the ratchet mechanism on the joint, so that the grinding head can completely contact the inner wall of the blind area of the inner arc of the inner hole of the elbow. After grinding, turn off the grinding machine and withdraw the inner hole grinding tool for the elbow. B3) Polishing: Replace the grinding head of the grinding machine of the inner hole grinding tool for the elbow with a polishing head. Insert it from one end of the inner hole of the workpiece elbow into the elbow section of the workpiece, start the grinding machine to polish and grind the blind area of the inner arc, and grind to half of the elbow section. At the same time, adjust the grinding position of the grinding device through the monitoring of the inner hole peephole, and adjust the inclination angle between the grinding machine and the connecting rod through the ratchet mechanism on the joint, so that the grinding head can completely contact the inner wall of the blind area of the inner arc of the inner hole of the elbow. After polishing and grinding, turn off the grinding machine and withdraw the inner hole grinding tool for the elbow. After completing the above steps, turn the stainless steel elbow around and repeat the steps of grinding the outer arc area and the blind area of the inner arc of the inner hole of the elbow to complete the grinding of the other half of the inner hole of the stainless steel elbow.

6. The method for grinding the inner hole of a small-angle and small-diameter stainless steel elbow for nuclear power as claimed in claim 5, wherein In the step of grinding the outer arc area, in A2), the grinding head of the grinding machine is equipped with a brown fused alumina grinding wheel; in A3), the grinding head of the grinding machine is equipped with a flap wheel grinding head with a grain size of 80 - 120; in A4), the grinding head of the grinding machine is equipped with a sand belt with a grain size of 320. In the step of grinding the blind area of the inner arc, in B1), the grinding head of the grinding machine is equipped with a brown fused alumina grinding wheel; in B2), the grinding head of the grinding machine is equipped with a flap wheel grinding head with a grain size of 80 - 120; in B3), the grinding head of the grinding machine is equipped with a sand belt with a grain size of 320.

Images