Machining device and machining method for thin-walled tube guide groove

Abstract

The invention discloses a machining device and a machining method for a thin-walled tube guide groove, and aims to solve the problem that precision and surface quality do not reach the standard due to the fact that machining of a thin-walled deep hole of a control rod guide tube is easily affected by cutting force, vibration and thermal deformation. The device comprises a cutter bar, a slotting motor and a milling cutter, the cutter bar is provided with a limiting guide structure and comprises a ring sleeve and a limiting sleeve which are in clearance fit with the inner wall of a guide pipe, the limiting sleeve is provided with a chip groove, and a cooling liquid pipeline is arranged in the cutter bar; the two ends of the ring sleeve are transition slopes, the diameter of the middle is larger, and the limiting sleeve is attached to the installation head through the limiting protrusion. According to the machining method, layered milling is adopted, rough machining, semi-finish machining and finish machining are conducted through milling cutters with the diameters of 8 mm, 9.8 mm and 10 + / -0.005 mm in sequence, and high-pressure cutting fluid is used for flushing during machining. Through rigid supporting and an optimized machining process, high-precision machining of the guide groove is ensured, the strict requirements of nuclear reactor components are met, and the machining efficiency and quality are improved.

Description

Technical Field

[0001] The invention relates to the technical field of thin-walled tube processing devices, in particular to a processing device and a processing method for a thin-walled tube guide groove. Background Art

[0002] Control rod guide tubes (such as Figure 1 The core component of a nuclear reactor's internals (shown in Figure 1) provides precise guidance for the control rod drive wires. Its machining quality directly impacts the reactor's safety and operational reliability, thus placing extremely stringent demands on dimensional accuracy, geometric tolerances, and surface quality.

[0003] The guide tube is a slender structure, with a total length of approximately 3400mm, a maximum outer diameter of 110mm, an inner diameter of only 95mm, and a wall thickness of 7.5mm. It is a typical thin-walled, deep-hole component. Two symmetrically distributed square keyways, 1300mm long and 10mm wide, must be machined into its inner wall. After keyway machining, the local wall thickness is reduced to only 0.96mm, further increasing the structural fragility. Due to the confined inner hole, poor tool accessibility, and susceptibility to cutting forces, vibration, and thermal deformation during machining, the component can suffer from bending, excessive ovality, and substandard surface quality, making its machining extremely challenging.

[0004] Furthermore, due to tight testing cycles, guide tube processing often faces tight delivery deadlines. Optimizing the process and improving efficiency while ensuring high precision and quality becomes a key challenge in the manufacturing process. Therefore, it is essential to use highly rigid cutting tools, optimize cutting parameters, and incorporate appropriate support and clamping solutions to minimize deformation and ensure that the guide groove's dimensional accuracy, straightness, and surface finish meet stringent technical requirements. Summary of the Invention

[0005] The technical problem to be solved by the present invention is that long guide rods are easily affected by cutting forces, vibrations and thermal deformation during the grooving process of thin-walled tubes, resulting in bending of parts, excessive ovality or substandard surface quality.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: a processing device for thin-walled tube guide grooves, including a tool rod, a slotting motor fixed at one end of the tool rod and a milling cutter installed at the output end of the slotting motor. The slotting motor is arranged perpendicular to the tool rod, and the tool rod is provided with a limiting guide structure adapted to the inner wall of the control rod guide tube.

[0007] Preferably, the limiting guide structure includes a ring sleeve and a limiting sleeve respectively sleeved on the tool rod and the slotting motor, the ring sleeve and the limiting sleeve are both clearance-matched with the inner side wall of the control rod guide tube, and the side wall of the limiting sleeve is provided with a chip removal groove.

[0008] Preferably, a mounting head is provided at the end of the tool rod, the slotting motor is arranged in the mounting head, the ring sleeve is located on the connecting end of the tool rod and the mounting head, and the ring sleeve is fixed by bolts.

[0009] Preferably, both ends of the outer wall of the ring sleeve are provided with transition slopes, and the diameter of the middle portion of the outer wall of the ring sleeve is larger than the diameters of the two ends of the outer wall.

[0010] Preferably, a mounting groove is provided inside the limiting sleeve, and an accommodating groove for the entire slotting motor to pass through along the radial direction of the knife rod is provided at the end of the limiting sleeve.

[0011] Preferably, limiting protrusions are provided on both sides of the interior of the installation groove, the limiting protrusions are located below the installation groove, and the limiting protrusions are in contact with the side walls of the installation head.

[0012] Preferably, the chip removal grooves are distributed directly below and on both sides of the mounting groove.

[0013] Preferably, the tool rod has a built-in coolant pipeline, the heat exchanger in the coolant pipeline is located on one side of the mounting head, and the end of the tool rod away from the slotting motor is provided with a liquid inlet pipe and a liquid return pipe connected to the coolant pipeline.

[0014] Preferably, one end of the cutter bar away from the slotting motor is coaxially fixedly connected to a fixed flange, and is connected to the output end of the planer through the fixed flange.

[0015] A method for processing a thin-walled tube guide groove processing device comprises the following steps: Step 1: Pre-support installation: put the limit sleeve on the mounting head of the tool rod and fix the limit sleeve with bolts. Fix the mounting ring sleeve with bolts at the fixed end of the mounting head. Insert the slotted motor into the mounting head through the mounting slot of the limit sleeve in an inverted manner and fix the slotted motor in the mounting head. Step 2: Rough machining: Fix the cutter bar to the output end of the planer and install a φ8 milling cutter at the output end of the slotting motor. Leave 1mm in the depth direction to remove most of the excess of the guide groove in the control rod guide tube. When the milling cutter is machining, control the cutting fluid nozzle to flush the control rod guide tube with high-pressure cutting fluid and maintain the flushing state until the machining is completed. Step 2: Semi-finishing: Replace the milling cutter with a diameter of 9.8 mm and leave a 0.2 mm margin in the depth direction of the guide groove for semi-finishing. Step 3: Finishing: Replace the milling cutter with φ10±0.005mm and finish the guide groove.

[0016] The present invention provides a processing device and a processing method for a thin-walled tube guide groove, which have the following beneficial effects.

[0017] 1. By fixing the limit sleeve at the mounting head, the clearance between the limit sleeve and the inner wall of the control rod guide tube is matched to provide circumferential rigid support for the tool during machining, thereby ensuring machining accuracy.

[0018] 2. Use layered milling processing method and continuously replace higher precision tools during the processing process to ensure that the processing quality of the guide groove fully meets the application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The present invention will be further described below with reference to the accompanying drawings and examples: Figure 1 Schematic diagram of the structure of the control rod guide tube.

[0020] Figure 2 Schematic diagram of the structure of the knife bar in an embodiment of the present invention.

[0021] Figure 3 Schematic diagram of the structure of the tool arbor mounting head in an embodiment of the present invention.

[0022] Figure 4 This is the main structural view of the tool rod after the slotting motor is installed in the embodiment of the present invention.

[0023] Figure 5 Schematic diagram of the structure of the limiting sleeve in an embodiment of the present invention.

[0024] In the figure: 1. Control rod guide tube; 2. Guide groove; 3. Tool rod; 4. Fixed flange; 5. Mounting head; 6. Connecting seat; 7. Slotting motor; 8. Ring sleeve; 9. Milling cutter; 10. Limit sleeve; 11. Receiving groove; 12. Chip removal groove; 13. Mounting groove; 14. Limiting protrusion; 15. Liquid inlet pipe; 16. Liquid return pipe. DETAILED DESCRIPTION

[0025] like Figure 1-5 As shown, the present invention provides a processing device for thin-walled tube guide grooves, including a tool rod 3, a slotting motor 7 fixed to one end of the tool rod 3, and a milling cutter 9 installed at the output end of the slotting motor 7. The slotting motor 7 is arranged perpendicular to the tool rod 3, and a limiting guide structure adapted to the inner wall of the control rod guide tube 1 is provided on the tool rod 3.

[0026] By installing a limit guide structure on the tool rod 3, the limit guide structure and the control rod guide rod 1 are clearance-matched, using H7 / g6 dynamic fit clearance (0.02-0.05mm). The limit guide structure is made of brass, and the spacing has good wear resistance and adaptability.

[0027] like Figure 4 and Figure 5The limiting guide structure includes a collar 8 and a limiting sleeve 10, which are respectively mounted on the tool bar 3 and the slotting motor 7. Both the collar 8 and the limiting sleeve 10 are clearance-matched with the inner sidewall of the control rod guide tube 1. The sidewall of the limiting sleeve 10 is provided with a chip removal groove 12. The front end of the limiting sleeve 10 is provided with a tapered leading portion, which is machined to form a 5° taper angle, achieving a 30mm pre-guiding.

[0028] like Figure 4 and Figure 5 As shown. The end of the tool bar 3 is provided with a mounting head 5, within which the slotting motor 7 is mounted. The collar 8 is located at the connection between the tool bar 3 and the mounting head 5 and secured with bolts. The tool bar 3 is made of high-strength alloy steel, and a milling cutter clamping interface is provided at the end of the mounting head 5. After the slotting motor 7 is fixedly installed, a milling cutter 9 is mounted through the milling cutter clamping interface, and the milling cutter 9 is driven by the slotting motor 7 to rotate and perform milling processing.

[0029] like Figure 4 As shown. Both ends of the outer wall of the collar 8 are provided with transition bevels, and the diameter of the middle portion of the outer wall of the collar 8 is larger than the diameter of the outer wall at both ends. The collar 8 is mounted on the arbor 3, with annular bevels at both ends. While providing guidance, the collar 8, made of brass, has moderate elasticity, assisting the limiting sleeve 10 in guiding and damping. Furthermore, the positioning of the collar 8 enables effective positioning in conjunction with the limiting sleeve 10, ensuring coaxiality.

[0030] like Figure 3-5 As shown. The interior of the limiting sleeve 10 defines a mounting groove 13, and the end of the limiting sleeve 10 defines a receiving groove 11 for the entire slotting motor 7 to pass radially through the cutter bar 3. When installing the slotting motor 7, the limiting sleeve 10 is first fixedly mounted on the mounting head 5, and then the slotting motor 7 is inserted into the mounting head 5 through the receiving groove 11, so that the top end of the slotting motor 7 abuts the inner side wall of the limiting sleeve 10. The milling cutter 9 is then clamped.

[0031] like Figure 5 As shown. Limiting protrusions 14 are provided on both sides of the mounting groove 13. The limiting protrusions 14 are located below the mounting groove 13 and engage with the sidewalls of the mounting head 5. The limiting protrusions 14 are provided within the mounting groove 13. The two limiting protrusions 14 clamp the two sides of the mounting head 5, ensuring a secure connection between the limiting sleeve 10 and the mounting head 5.

[0032] like Figure 5As shown. The chip removal grooves 12 are distributed directly below and on both sides of the mounting groove 13. The chip removal grooves 12 are opened on the outer wall of the limiting sleeve 10, wherein the two chip removal grooves 12 on both sides are used to inject cutting fluid, and the chip removal groove 12 at the bottom is used to discharge cutting fluid and chips.

[0033] like Figure 2 As shown. The tool bar 3 has a built-in coolant pipeline. The heat exchanger in the coolant pipeline is located on one side of the mounting head 5. The end of the tool bar 3 away from the slotting motor 7 is provided with an inlet pipe 15 and a return pipe 16 connected to the coolant pipeline. The coolant pipeline is built into the tool bar 3, and coolant is input through the inlet pipe 15 and output through the return pipe 16. In conjunction with the heat exchanger, the slotting motor 7 is cooled, thereby extending the service life of the slotting motor 7.

[0034] like Figure 2 The end of the cutter bar 3 away from the slotting motor 7 is coaxially fixedly connected to a fixed flange 4, and is connected to the output end of the planer through the fixed flange 4. The fixed flange 4 ensures the stable installation of the cutter bar 3 and the coaxiality between the cutter bar 3 and the limit sleeve 10.

[0035] A method for processing a thin-walled tube guide groove processing device comprises the following steps: Step 1: Pre-support installation: put the limit sleeve 10 on the mounting head 5 of the tool rod 3, and use bolts to fix the limit sleeve 10, and fix the mounting ring sleeve 8 with bolts at the fixed end of the mounting head 5, insert the slotting motor 7 into the mounting head 5 through the mounting groove 13 of the limit sleeve 10 in an inverted manner, and fix the slotting motor 7 in the mounting head 5; Step 2: Rough machining: Fix the cutter bar 3 to the output end of the planer, install a φ8 milling cutter 9 at the output end of the slotting motor 7, and reserve 1mm in the depth direction to remove most of the excess of the guide groove 2 in the control rod guide tube 1. While the milling cutter 9 is machining, control the cutting fluid nozzle to flush the control rod guide tube 1 with high-pressure cutting fluid, and maintain the flushing state until the machining is completed; Step 2: Semi-finishing: Replace the milling cutter 9 with a diameter of 9.8 mm and leave a 0.2 mm margin in the depth direction of the guide groove 2 for semi-finishing. Step 3: Finishing: Replace the milling cutter 9 with a diameter of φ10±0.005 mm and perform finish machining on the guide groove 2 .

Claims

1. A processing device for a thin-walled tube guide groove, characterized in that: The invention comprises a tool rod (3), a slotting motor (7) fixed at one end of the tool rod (3), and a milling cutter (9) installed at the output end of the slotting motor (7). The slotting motor (7) is arranged perpendicular to the tool rod (3). The tool rod (3) is provided with a limiting guide structure adapted to the inner side wall of the control rod guide tube (1).

2. A processing device for a thin-walled tube guide groove according to claim 1, characterized in that: The limiting guide structure comprises a ring sleeve (8) and a limiting sleeve (10) respectively mounted on the tool rod (3) and the slotting motor (7); the ring sleeve (8) and the limiting sleeve (10) are both clearance-matched with the inner side wall of the control rod guide tube (1); and a chip removal groove (12) is provided on the side wall of the limiting sleeve (10).

3. A processing device for a thin-walled tube guide groove according to claim 2, characterized in that: The end of the knife rod (3) is provided with a mounting head (5), the slotting motor (7) is arranged in the mounting head (5), the ring sleeve (8) is located on the connecting end of the knife rod (3) and the mounting head (5), and the ring sleeve (8) is fixed by bolts.

4. A processing device for a thin-walled tube guide groove according to claim 3, characterized in that: Both ends of the outer wall of the ring sleeve (8) are provided with transition slopes, and the diameter of the middle portion of the outer wall of the ring sleeve (8) is larger than the diameters of the two ends of the outer wall.

5. A processing device for a thin-walled tube guide groove according to claim 3, characterized in that: The limiting sleeve (10) is provided with a mounting groove (13) inside, and the end of the limiting sleeve (10) is provided with a receiving groove (11) for the slotting motor (7) to pass through as a whole along the radial direction of the knife rod (3).

6. A processing device for a thin-walled tube guide groove according to claim 5, characterized in that: Limiting protrusions (14) are provided on both sides of the interior of the installation groove (13), the limiting protrusions (14) are located below the installation groove (13), and the limiting protrusions (14) are in contact with the side walls of the installation head (5).

7. A processing device for a thin-walled tube guide groove according to claim 6, characterized in that: The chip removal grooves (12) are distributed directly below the installation groove (13) and on both sides below it.

8. A processing device for a thin-walled tube guide groove according to claim 1, characterized in that: The tool rod (3) has a built-in coolant pipeline, and a heat exchanger in the coolant pipeline is located on one side of the mounting head (5). The end of the tool rod (3) away from the slotting motor (7) is provided with a liquid inlet pipe (15) and a liquid return pipe (16) connected to the coolant pipeline.

9. A processing device for a thin-walled tube guide groove according to claim 1, characterized in that: One end of the cutter bar (3) away from the slotting motor (7) is coaxially fixedly connected to a fixed flange (4), and is connected to the output end of the planer through the fixed flange (4).

10. A processing method for a thin-walled tube guide groove processing device as claimed in claim 1, characterized in that: The steps include: Step 1: Pre-support installation: put the limit sleeve (10) on the mounting head (5) of the tool rod (3), and use bolts to fix the limit sleeve (10), and fix the mounting ring sleeve (8) at the fixed end of the mounting head (5) through bolts, insert the slotting motor (7) into the mounting head (5) through the mounting groove (13) of the limit sleeve (10) in an inverted manner, and fix the slotting motor (7) in the mounting head (5); Step 2: Rough machining, fix the cutter bar (3) on the output end of the planer, install a φ8 milling cutter (9) on the output end of the slotting motor (7), reserve 1mm in the depth direction to remove most of the remaining amount of the guide groove (2) in the control rod guide tube (1), and when the milling cutter (9) is machining, control the cutting fluid nozzle toward the control rod guide tube (1) to flush the high-pressure cutting fluid, and maintain the flushing state until the machining is completed; Step 2: Semi-finishing: Replace the milling cutter (9) with a diameter of 9.8 mm and leave a 0.2 mm margin in the depth direction of the guide groove (2) for semi-finishing; Step 3: Finishing: Replace the milling cutter (9) with a diameter of φ10±0.005 mm and perform finishing of the guide groove (2).

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