Polishing equipment for tubular workpieces

Abstract

The application discloses a kind of pipe workpiece polishing equipment, belong to pipe workpiece polishing field.The device includes rotary clamping tool, for clamping and driving U-shaped pipe around its own axis rotation;Polishing member is oppositely arranged with rotary clamping tool, for polishing U-shaped pipe polishing, and when polishing polishing, the inner and outer wall of U-shaped pipe is cooled synchronously;The application is arranged vertically by U-shaped pipe and cooperates with internal and external double-way cooling, and synchronous continuous cooling is implemented to inner wall polishing arc area in the whole polishing process, effectively reduces the temperature difference and additional thermal stress of inner and outer wall;Simultaneously, the discharge rate is limited by the gap between polishing roller and pipe wall, so that local fluid accumulation is formed at the bending part to realize immersion cooling, and high-temperature tissue damage is avoided;In addition, chamfer is arranged at the end of polishing roller, and the upper end is blocked and the liquid supply flow is increased, so that the pipe cavity forms controllable high pressure, the passive discharge is converted into active high-pressure directional jet, stubborn debris is removed powerfully, and the cleanliness and processing quality of pipe are ensured.

Description

Technical Field

[0001] This invention relates to the field of tubular workpiece grinding technology, specifically to a tubular workpiece grinding and polishing equipment.

[0002] In the field of pipeline system processing, thin-walled stainless steel U-shaped pipe fittings can be used in automotive air conditioning pipelines, hydraulic power steering pipelines, and heat exchanger core connection pipes, etc. In order to ensure the fitting accuracy of the U-shaped pipe fitting port with the quick coupling, welding sleeve or O-ring sealing surface, its port finishing usually includes grinding the pipe end face and micro-grinding the inner wall of the pipe end (i.e. the inner side wall and inner chamfer surface of the port) to remove cutting burrs and spiral marks or micro-burrs left by the inner hole processing, and ensure the perpendicularity of the end face and the smoothness of the inner wall.

[0003] Currently, in order to save equipment space and adapt to automated loading and unloading robots, the above-mentioned grinding process is often carried out in a sequential manner when the stainless steel U-shaped pipe is in a vertical position (i.e., both ends are located on the same vertical axis). That is, the end face and inner wall of the first end of the pipe are ground in sequence, and after completion, the workpiece is immediately turned around and switched to the second end for grinding.

[0004] However, the above-mentioned grinding of the inner wall of the pipe has the following defects in actual production: When grinding the inner wall of a stainless steel U-shaped tube, the grinding head extends into the port, and the heating point is surrounded by the tube wall. The existing external spray cooling method cannot allow the coolant to reach the grinding arc area of ​​the inner wall. The grinding heat generated on the inner wall can only be slowly conducted through the tube wall. Due to the low thermal conductivity of stainless steel, the heat conduction in the tube wall thickness direction is delayed, resulting in the temperature on the inner wall side being higher than that on the outer wall side. This creates a temperature difference between the inside and outside and uneven thermal expansion, thereby introducing additional thermal stress inside the tube wall and weakening the structural stability of the tube. Summary of the Invention

[0005] The purpose of this invention is to provide a grinding and polishing equipment for tubular workpieces, in order to solve the problem in the prior art that when stainless steel U-shaped tubes are ground vertically in sequence, the grinding heat on the inner wall is conducted along the tube wall and accumulates at the bottom of the bend, and the heat is difficult to dissipate sufficiently during the switching interval between the two ends, resulting in heat superposition and excessive temperature rise at the bottom of the bend, which causes the tube to oxidize, discolor and deteriorate in its structural properties.

[0006] The technical problem to be solved by this invention can be achieved through the following technical solution: a grinding and polishing device for tubular workpieces, comprising: A rotary clamping fixture is used to clamp and drive a U-shaped tube to rotate about its own axis; The grinding component is arranged opposite to the rotating clamping fixture and is used to grind and polish the U-shaped tube, and to simultaneously cool the inner and outer walls of the U-shaped tube during grinding and polishing. The grinding component includes two sets of longitudinally parallel moving parts. A cylinder is mounted on the upper moving part, and an internal cooling component is mounted on the extended end of the cylinder.

[0007] Preferably, a second cylinder is installed on the moving part below, and a drive motor is provided at the extended end of the second cylinder. A polishing roller for polishing the inner wall of the U-shaped tube port is installed on the drive shaft of the drive motor. The polishing roller is arranged opposite to the lower port of the thin-walled U-shaped tube. The grinding roller is equipped with a corresponding external cooling nozzle.

[0008] Preferably, an external delivery pipe is installed above the external cooling nozzle, and a second solenoid valve is provided on the outer wall of the external delivery pipe. The external delivery pipe is fixedly connected to the internal cooling component through a connecting plate and moves as a whole with the internal cooling component.

[0009] Preferably, the internal cooling component includes a mounting post fixedly connected to one protruding end of the cylinder, a mounting plate is mounted on the side wall of the mounting post, and an internal cooling nozzle is embedded at the end of the mounting plate.

[0010] Preferably, an inner conveying pipe is vertically inserted into the top of the mounting column, and a conveying groove for connecting the inner cooling nozzle and the inner conveying pipe is opened in the mounting column and the mounting plate. A solenoid valve is provided on the outer wall of the inner conveying pipe.

[0011] Preferably, the first solenoid valve, the first cylinder, the second cylinder, the drive motor, and the second solenoid valve are all electrically connected to the CNC system of the machine tool.

[0012] Preferably, the output side of the internal cooling nozzle is positioned facing the upper port of the U-shaped tube.

[0013] Preferably, the outer diameter of the internal cooling nozzle gradually decreases from the side closest to the mounting plate to the side furthest from the mounting plate.

[0014] Preferably, the outer circumference of the grinding roller opposite to the lower port is chamfered.

[0015] One method for grinding and polishing tubular workpieces includes the following steps: Process: Control cylinder one inserts the inner cooling nozzle into the upper port of the U-shaped tube, and open solenoid valve one and solenoid valve two. The cutting fluid is sprayed into the inner cavity of the U-shaped tube through the inner cooling nozzle and flows down the inner wall under the action of gravity and is discharged from the lower port. At the same time, the outer cooling nozzle sprays and cools the outer wall of the lower port. Process: Control cylinder two to insert the grinding roller into the inner wall of the lower port of the U-shaped tube for grinding, and the internal cooling nozzle continuously supplies liquid so that the cutting fluid accumulates at the bend of the U-shaped tube and submerges the area. Process: After grinding is completed, control the drive motor to stop rotating, control cylinder two to retract so that the chamfered part of the grinding roller and the inner wall of the lower port form an enlarged channel. At the same time, control cylinder one to drive the inner cooling nozzle to block the upper port and increase the liquid supply flow of solenoid valve one, so that the cutting fluid carrying the debris is discharged outward under high pressure through the enlarged channel, and simultaneously washes the surface of the grinding roller.

[0016] Compared with the prior art, the beneficial effects of this application are as follows: 1. This invention arranges the U-shaped tube vertically, with the inner cooling nozzle guiding the coolant into the inner cavity from the upper port and allowing it to flow naturally through the inner wall of the U-shaped tube by gravity and exit from the lower port; at the same time, the outer cooling nozzle sprays the outer wall of the lower port. The dual-path synergy of the inner wall gravity-guided cooling and the outer wall spray cooling enables synchronous and continuous cooling of the inner and outer walls of the U-shaped tube before the grinding roller intervenes and throughout the grinding process, so that the coolant reaches the inner wall grinding arc area, reduces the temperature difference between the inner and outer walls, and reduces the additional thermal stress caused by the thermal gradient inside the tube wall.

[0017] 2. The present invention utilizes the gap between the grinding roller and the wall of the U-shaped tube, and under the condition of continuous liquid supply from the internal cooling nozzle, to limit the rate of cutting fluid discharge, so that the cutting fluid forms a local accumulation at the bend of the U-shaped tube, and performs immersion cooling on that area.

[0018] 3. The present invention provides a chamfered structure at the end of the grinding roller, so that when it is withdrawn a certain distance after grinding, the chamfered bevel and the inner wall of the port can form a discharge channel larger than the original grinding gap; at the same time, the internal cooling nozzle moves up to block the upper port and actively increases the liquid supply flow, so that a controllable high pressure environment is formed inside the tube. Using this enlarged channel as the only pressure relief outlet, the natural passive discharge is transformed into an active high pressure directional jet, thereby stripping away the stubborn attached debris on the surface of the grinding roller and the inner wall of the port with a strong scouring force. Attached Figure Description

[0019] Figure 1 This is a perspective view of the overall structure of the present invention.

[0020] Figure 2 This is a perspective view of the overall structure of the grinding component in this invention.

[0021] Figure 3 This is a perspective view of the overall structure of the cooling component inside the tube in this invention.

[0022] Figure 4 This is a front view of the structure of process 1 in this invention.

[0023] Figure 5 yes Figure 4 A magnified front view of the structure of region a in the middle.

[0024] Figure 6 This is a front view of the structure of process 2 in this invention.

[0025] Figure 7 This is a front view of the structure of process 3 in this invention. Figure 8 yes Figure 7 Enlarged front view of the structure in region b.

[0026] Figure 9 yes Figure 7 A magnified front view of the structure in region c.

[0027] Explanation of reference numerals in the attached figures: 1. Rotary clamping fixture; 2. Grinding component; 21. Moving part; 22. Cylinder 1; 23. Cylinder 2; 24. Drive motor; 241. Grinding roller; 25. External cooling nozzle; 26. External conveying pipe; 27. Mounting column; 28. Mounting plate; 29. ​​Internal cooling nozzle; 30. Internal conveying pipe. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0029] Example 1 In the prior art, when grinding the inner wall of a thin-walled stainless steel U-shaped tube, the grinding head extends into the port, and the heating point is surrounded by the tube wall. The existing external spray cooling method cannot allow the coolant to reach the grinding arc area of ​​the inner wall. The grinding heat generated on the inner wall can only be slowly conducted through the tube wall. Due to the low thermal conductivity of stainless steel, the heat conduction in the tube wall thickness direction is delayed, resulting in the temperature on the inner wall side being higher than that on the outer wall side. This creates a temperature difference between the inside and outside and uneven thermal expansion, thereby introducing additional thermal stress inside the tube wall and weakening the structural stability of the tube.

[0030] like Figures 1 to 5 In this embodiment, a grinding and polishing device for tubular workpieces includes: a machine tool worktable, which is prior art and is not drawn or labeled in the figure; a rotary clamping fixture 1, which is prior art and is fixedly installed on the machine tool worktable for clamping and driving the thin-walled U-shaped tube to rotate around its own axis; and a grinding component 2, which is arranged opposite to the rotary clamping fixture 1 for grinding and polishing the thin-walled U-shaped tube and for simultaneously cooling the inner and outer walls of the tube during grinding and polishing.

[0031] The grinding component 2 includes two sets of longitudinally parallel moving parts 21. A cylinder 22 is mounted on the upper moving part 21, and an internal cooling component is mounted on the extended end of the cylinder 22.

[0032] A cylinder 23 is installed on the lower moving part 21. A drive motor 24 is provided at the extended end of the cylinder 23. A polishing roller 241 for polishing the inner wall of the U-shaped tube is installed on the drive shaft of the drive motor 24. The polishing roller 241 is positioned opposite to the lower port of the U-shaped tube. Above the grinding roller 241 is a corresponding external cooling nozzle 25, and above the external cooling nozzle 25 is an external conveying pipe 26. The outer wall of the external conveying pipe 26 is equipped with a solenoid valve 2.

[0033] The internal cooling component includes a mounting post 27 fixedly connected to the protruding end of cylinder 22. A mounting plate 28 is mounted on the side wall of the mounting post 27. An internal cooling nozzle 29 is embedded at the end of the mounting plate 28. An internal delivery pipe 30 is vertically inserted into the top of the mounting post 27. Delivery grooves for connecting the internal cooling nozzle 29 and the internal delivery pipe 30 are opened in the mounting post 27 and the mounting plate 28. A solenoid valve is provided on the outer wall of the internal delivery pipe 30.

[0034] The outer diameter of the internal cooling nozzle 29 gradually decreases from the side closest to the mounting plate 28 to the side furthest from the mounting plate 28, and the output side of the internal cooling nozzle 29 is positioned facing the upper port of the thin-walled U-shaped tube.

[0035] Electromagnetic valve 1, cylinder 1 22, cylinder 2 23, drive motor 24, and electromagnetic valve 2 are all electrically connected to the machine tool CNC system; the machine tool CNC system is a conventional industrial CNC system.

[0036] Working principle: such as Figure 4 , Figure 5 The thin-walled U-shaped tube is vertically clamped on the rotating clamping fixture 1; the telescopic end of the control cylinder 22 extends outward, inserting the inner cooling nozzle 29 into the upper port of the U-shaped tube; the solenoid valve 1 and solenoid valve 2 are opened, and the cutting fluid is sprayed into the inner cavity of the U-shaped tube through the inner delivery pipe 30, the delivery groove, and the inner cooling nozzle 29. Under the action of gravity, the cutting fluid flows downward along the inner wall of the U-shaped tube and is discharged from the lower port; at the same time, the cutting fluid is sprayed out from the outer cooling nozzle 25 through the outer delivery pipe 26 to spray and cool the outer wall of the lower port of the U-shaped tube. At this time, the grinding roller 241 has not yet entered the lower port of the U-shaped tube. The lower port of the U-shaped tube is in a fully open state, and the coolant on the inner wall can be discharged without obstruction, thereby achieving dual pre-cooling of the inner and outer walls of the lower port of the U-shaped tube and completing process 1. Furthermore, during the subsequent actual polishing process, the inner and outer walls of the U-shaped tube end are continuously cooled synchronously to reduce the temperature difference between the inside and outside of the U-shaped tube during polishing and to avoid uneven thermal expansion at the end of the U-shaped tube wall.

[0037] It should be emphasized that the core improvement of this embodiment is that by arranging the U-shaped tube vertically, the inner cooling nozzle 29 introduces the coolant into the inner cavity from the upper port, and uses gravity to flow naturally through the inner wall of the U-shaped tube and discharge it from the lower port; at the same time, the outer cooling nozzle 25 sprays the outer wall of the lower port. The dual-path synergy of the inner wall gravity-guided cooling and the outer wall spray cooling can synchronously and continuously cool the inner and outer walls of the U-shaped tube before the grinding roller 241 intervenes and throughout the grinding process, so that the coolant reaches the inner wall grinding arc area, reduces the temperature difference between the inner and outer walls, and reduces the additional thermal stress caused by the thermal gradient inside the tube wall.

[0038] It should be noted that the moving part 21 has the function of driving the second cylinder 23 and the first cylinder 22 to move back and forth. The rotating clamping fixture 1 has multiple clamping stations and can clamp multiple U-shaped tubes. The processing of U-shaped tubes on multiple stations is achieved through the moving part 21. This is conventional prior art in this field. Its specific structure and control method will not be described here. It should be noted that the machine tool CNC system is a conventional industrial CNC system known in the art; in addition, in order to further ensure the cooling effect and processing stability, the spray flow rate and spray angle of the inner cooling nozzle 29 and the outer cooling nozzle 25 can be adaptively adjusted according to the specifications of the U-shaped pipe and the grinding parameters. The specific adjustment method is conventionally set by those skilled in the art based on the actual working conditions, and will not be elaborated here, so as to take into account the cooling needs under different working conditions.

[0039] It should be noted that, such as Figure 3 The external delivery pipe 26 is fixedly connected to the internal cooling component through a connecting plate and moves as a whole with the internal cooling component.

[0040] Example 2 Understandably, in the existing technology, due to the extremely short interval between the two processes, the heat from the first processed end has not been fully dissipated, and the U-shaped tube is already in a high temperature state. When the other end is immediately turned around to grind, the newly generated grinding heat continues to be conducted inward along the tube wall, and accumulates with the residual heat at the bend of the U-shaped tube. The bend is the part of the U-shaped tube with the smallest bending radius and the most concentrated stress. Heat is continuously input and difficult to dissipate effectively, resulting in a significant increase in temperature in this area. Stainless steel is prone to turning blue or discoloring under these high-temperature conditions, and may even experience localized deterioration of its properties, reducing the strength and corrosion resistance of pipe fittings and affecting sealing reliability.

[0041] like Figure 6To solve the above problems, the CNC system of the machine tool controls the extension of cylinder 23. Cylinder 23 drives the grinding roller 241 to extend into the inner wall of the lower port of the U-shaped tube. There is a gap between the grinding roller 241 and the inner wall of the lower port. When the grinding roller 241 is working, due to the limited size of the gap, the discharge rate of the cutting fluid is restricted. Some cutting fluid splashes outward through the gap. As the internal cooling nozzle 29 continues to deliver cutting fluid, the cutting fluid gradually accumulates at the bend of the U-shaped tube and submerges the area until the grinding is completed, thus completing process 2.

[0042] It should be emphasized that the core improvement of this embodiment is: by using the gap between the grinding roller 241 and the wall of the U-shaped tube, and under the condition of continuous liquid supply from the internal cooling nozzle 29, the cutting fluid outflow rate is limited by the gap, so that the cutting fluid forms a local accumulation at the bend of the U-shaped tube, and immersion cooling is implemented in this area.

[0043] It should be noted that the speed at which the cutting fluid injected into the U-shaped tube by the internal cooling nozzle 29 is greater than the discharge speed of the gap at the lower end of the U-shaped tube.

[0044] It should be noted that during the polishing process in step 2, the external cooling nozzle 25 continues to spray, simultaneously cooling the outer wall. It is independent of the internal coolant and does not interfere with it. The internal and external dual-path cooling is implemented in coordination.

[0045] Example 3 It is understandable that in Embodiment 2, after the grinding process is completed, during the process of the grinding roller 241 being withdrawn from the lower end of the U-shaped tube, the channel formed by the natural movement of the grinding roller 241 and the passive flow of coolant cannot generate sufficient directional scouring force. As a result, the stubborn debris on the surface of the grinding roller 241 and the inner wall of the port cannot be effectively peeled off and removed, thereby affecting the subsequent processing quality and the cleanliness of the U-shaped tube.

[0046] like Figures 7 to 9 To address the aforementioned issues, a chamfer is provided on the outer circumference of the grinding roller 241 opposite to the lower port.

[0047] Working principle: After completing step 2, the extended end of cylinder 23 is first controlled to retract, driving the grinding roller 241 to move away from the lower port, so that the chamfer position is opposite to the circumferential side wall of the lower port, increasing the circumferential gap between the grinding roller 241 and the inner wall of the port, i.e., the channel; at the same time, cylinder 22 drives the inner cooling nozzle 29 to move further towards the upper port, so that the outer wall of the inner cooling nozzle 29 forms a blockage against the inner wall of the upper port, and increases the flow rate of cutting fluid in the inner delivery pipe 30. Under the blocked state, the pressure inside the pipe cavity rises rapidly, and the cutting fluid carrying the debris is discharged outward under high pressure through the enlarged channel between the lower port and the chamfer, and simultaneously washes the surface of the grinding roller 241, completing the cleaning of the residual debris from this end of the grinding. After cleaning is completed, control cylinder 1 22 retracts, completely retracting the internal cooling nozzle 29 from the upper port and resetting it; control cylinder 2 23 continues to retract, completely moving the grinding roller 241 out of the lower port area and resetting it; close solenoid valve 1 and solenoid valve 2 to complete process 3.

[0048] Subsequently, the rotating clamping fixture 1 rotates the U-shaped pipe 180° around its axis, so that the original upper port becomes the lower port (the end to be processed) and the original lower port becomes the upper port (the processed end). Then, the process is carried out in sequence according to process 1, process 2 and process 3. At this point, the grinding and cleaning of both ends of the U-shaped pipe are completed.

[0049] It should be emphasized that the core improvement of this embodiment is that a chamfer structure is provided at the end of the grinding roller 241, so that when it is withdrawn a certain distance after grinding, the chamfered surface and the inner wall of the port can form a discharge channel with a larger gap than the original grinding gap; at the same time, the internal cooling nozzle 29 moves up to block the upper port and actively increases the liquid supply flow, so that a controllable high pressure environment is formed inside the tube. The enlarged channel is used as the only pressure relief outlet, and the natural passive discharge is transformed into an active high pressure directional jet, thereby stripping the stubborn attached debris from the surface of the grinding roller 241 and the inner wall of the port with a strong scouring force.

[0050] It should be noted that increasing the cutting fluid delivery flow rate of the inner delivery pipe 30 means adjusting the opening of the solenoid valve to be greater than the fluid supply flow rate during normal operation of process 2. Preferably, the fluid supply flow rate can be adjusted to 1.5 to 2 times the working flow rate of process 2, so that the liquid level in the pipe cavity rises rapidly and forms sufficient flushing pressure under the blocked state. The specific flow rate and pressure value can be determined by those skilled in the art through conventional experiments based on the pipe diameter, wall thickness and the specifications of the grinding roller 241, and no specific limitation is made here.

[0051] It should be noted that when transitioning from process 2 to process 3, the machine tool CNC system controls the drive motor 24 to stop rotating, and the grinding roller 241 stops rotating.

[0052] The basic principles, main features, and advantages of this application have been described above. Those skilled in the art should understand that this application is not limited to the above embodiments. The embodiments and descriptions in the specification are merely the principles of this application. Various changes and modifications can be made to this application without departing from its spirit and scope, and all such changes and modifications fall within the scope of the claimed application.

Claims

1. A grinding and polishing equipment for tubular workpieces, characterized in that, include: Rotary clamping fixture (1) is used to clamp and drive the U-shaped tube to rotate around its own axis; The grinding component (2) is arranged opposite to the rotary clamping fixture (1) and is used to grind and polish the U-shaped tube. During grinding and polishing, the inner and outer walls of the U-shaped tube are cooled simultaneously. The grinding component (2) includes two sets of longitudinally parallel moving parts (21), with a cylinder (22) mounted on the upper moving part (21), and an internal cooling component mounted on the extended end of the cylinder (22).

2. The grinding and polishing equipment for tubular workpieces as described in claim 1, characterized in that, A cylinder two (23) is installed on the moving part (21) below. A drive motor (24) is provided at the extended end of the cylinder two (23). A polishing roller (241) for polishing the inner wall of the U-shaped tube is installed on the drive shaft of the drive motor (24). The polishing roller (241) is arranged opposite to the lower port of the thin-walled U-shaped tube. The grinding roller (241) is provided with a corresponding external cooling nozzle (25).

3. The grinding and polishing equipment for tubular workpieces as described in claim 2, characterized in that, An external delivery pipe (26) is installed above the external cooling nozzle (25). A solenoid valve is provided on the outer wall of the external delivery pipe (26). The external delivery pipe (26) is fixedly connected to the internal cooling component through a connecting plate and moves as a whole with the internal cooling component.

4. The grinding and polishing equipment for tubular workpieces as described in claim 3, characterized in that, The tube cooling component includes a mounting post (27) fixedly connected to the protruding end of cylinder (22), and a mounting plate (28) is mounted on the side wall of the mounting post (27). An internal cooling nozzle (29) is embedded at the end of the mounting plate (28).

5. The grinding and polishing equipment for tubular workpieces as described in claim 4, characterized in that, An inner conveying pipe (30) is vertically inserted into the top of the mounting column (27). The mounting column (27) and the mounting plate (28) are provided with a conveying groove for connecting the inner cooling nozzle (29) and the inner conveying pipe (30). A solenoid valve is provided on the outer wall of the inner conveying pipe (30).

6. The grinding and polishing equipment for tubular workpieces as described in claim 5, characterized in that, The solenoid valve one, cylinder one (22), cylinder two (23), drive motor (24), and solenoid valve two are all electrically connected to the machine tool CNC system.

7. The grinding and polishing equipment for tubular workpieces as described in claim 4, characterized in that, The output side of the internal cooling nozzle (29) is positioned facing the upper port of the U-shaped tube.

8. The grinding and polishing equipment for tubular workpieces as described in claim 4, characterized in that, The outer diameter of the internal cooling nozzle (29) gradually decreases from the side closer to the mounting plate (28) to the side farther away from the mounting plate (28).

9. The grinding and polishing equipment for tubular workpieces as described in claim 4, characterized in that, The grinding roller (241) has a chamfer on the outer circumference of the side opposite to the lower port.

10. A method for grinding and polishing tubular workpieces, using the grinding and polishing equipment for tubular workpieces as described in any one of claims 1-9, characterized in that, Includes the following steps: Process 1: Control cylinder 1 (22) inserts the inner cooling nozzle (29) into the upper port of the U-shaped pipe, and opens solenoid valve 1 and solenoid valve 2. The cutting fluid is sprayed into the inner cavity of the U-shaped pipe through the inner cooling nozzle (29) and flows down along the inner wall under the action of gravity and is discharged from the lower port. At the same time, the outer cooling nozzle (25) sprays and cools the outer wall of the lower port. Process 2: Control cylinder 2 (23) to insert the grinding roller (241) into the inner wall of the lower port of the U-shaped tube for grinding, and the internal cooling nozzle (29) continuously supplies liquid so that the cutting fluid accumulates at the bend of the U-shaped tube and immerses the area; Step 3: After grinding is completed, control the drive motor (24) to stop rotating, control cylinder two (23) to contract so that the chamfered part of the grinding roller (241) and the inner wall of the lower port form an enlarged channel. At the same time, control cylinder one (22) to drive the inner cooling nozzle (29) to block the upper port and increase the liquid supply flow of solenoid valve one, so that the cutting fluid carries the debris out through the enlarged channel and is discharged under high pressure, and simultaneously washes the surface of the grinding roller (241).

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