Throttle pipe hole machining method for small-diameter pipe

Abstract

The invention discloses a throttle pipe hole machining method for a small-diameter pipe, and relates to the field of throttle pipe hole machining of small-diameter pipes in the fields of boilers, chemical engineering and the like. The problem that the throttle pipe hole machining difficulty is large is solved. The method comprises the following steps: firstly, supporting and fixing a pipe by adopting a pipe supporting tool; then, the highest point of the pipe is determined through a highest point positioning tool; further, a plurality of vertically-arranged middle through holes are sequentially and evenly machined in the length direction of the pipe from front to back through a twist drill; further, two first groove arcs and two second groove arcs are machined on the upper surface of the pipe through a split machining tool; and finally, pipe hole inner wall chamfering is conducted on the connecting positions of the middle through holes and the inner wall of the pipe through a pipe hole inner wall chamfering tool, so that throttling pipe hole machining of the small-diameter pipe is completed. The method is used for machining the throttle pipe hole of the full penetration welding structure, and the subsequent welding quality is guaranteed.

Description

Technical Field

[0001] The invention relates to the field of throttling tube hole processing of small-diameter tubes in the fields of boilers, chemical industry, etc., and in particular to a throttling tube hole processing method for small-diameter tubes. Background Art

[0002] With the continuous expansion of product types and the improvement of product technical parameters, our company has adopted a full-penetration throttling tube hole in many projects. The tube diameter is Φ89×13.5, the length is 2500mm, and there are 20 throttling tube holes. The throttling tube hole is a double groove structure. Figure 1 As shown, the middle through hole d is Φ8mm, the two groove arcs are R2.5 and R5 respectively, and the maximum cutting length is 32.5mm. Due to the small diameter, long length and poor rigidity of the tube, the tube vibrates during processing, affecting the processing quality; the middle through hole d is Φ8mm, the cutting force is large, and the guide column is easy to break, so how to process the throttling tube hole becomes a key process.

[0003] In summary, the main reasons for the difficulty in processing the throttling tube hole are: the tube has a small diameter and poor rigidity, and it vibrates under force during processing; it is difficult to align the highest point and the positioning is inaccurate; the diameter of the middle through hole is small, the amount of cutting is large during processing, and the guide column is easy to break; the through hole diameter is small and it is difficult to chamfer the inner wall. Summary of the invention

[0004] The purpose of the present invention is to solve the problem that it is difficult to process a throttling tube hole, and further provide a throttling tube hole processing method for a small diameter tube.

[0005] The technical solution of the present invention is:

[0006] A method for machining a throttling hole for a small diameter pipe is implemented by the following steps:

[0007] Step 1: Fix the pipe 5:

[0008] First, the pipe support fixture 1 is installed on the machine tool workbench; then, the pipe 5 is installed on the pipe support fixture 1, and the pipe support fixture 1 is used to support and fix the pipe 5;

[0009] Step 2: Determine the highest point of tube 5:

[0010] After the pipe 5 is fixed by the pipe supporting tool 1 described in step 1, the highest point positioning tool 2 is placed on the upper part of the pipe 5, and the highest point of the pipe 5 is determined by using the highest point positioning tool 2;

[0011] Step 3: Processing the middle through hole of tube 5:

[0012] Install the twist drill on the tool holder of the machine tool, determine the processing position of the throttling tube hole according to the highest point of the tube 5 determined in step 2, and use the twist drill to uniformly process multiple vertically arranged middle through holes from front to back along the length direction of the tube, and the axis of each middle through hole is located at the highest point of the tube 5;

[0013] Step 4: Processing the groove arc of pipe 5:

[0014] The split processing tool 3 is installed on the tool holder of the machine tool, and two first groove arcs and two second groove arcs are processed on the upper surface of the tube 5 by using the split processing tool 3, wherein the two first groove arcs are symmetrically arranged on the front and rear sides of the middle through hole with the axes of the multiple middle through holes processed in step 3 as the center, and the two second groove arcs are symmetrically arranged on the front and rear sides of the two first groove arcs with the axes of the multiple middle through holes processed in step 3 as the center;

[0015] Step 5: Process the inner wall chamfer of the tube hole:

[0016] The pipe hole inner wall chamfering tool 4 is installed on the hand electric drill, and the pipe hole inner wall chamfering tool 4 is used to chamfer the pipe hole inner wall connection points of the multiple intermediate through holes processed in step 3 and the pipe inner wall. At this point, the throttling pipe hole processing of the small diameter pipe is completed.

[0017] Furthermore, the pipe supporting tooling 1 described in step one includes a fixed platform 101, a channel steel 106 and a plurality of pipe clamping mechanisms, the fixed platform 101 is horizontally arranged on a machine tool worktable, the upper surface of the fixed platform 101 is provided with a horizontally arranged channel steel 106 along the length direction of the fixed platform, a horizontally arranged pipe 5 is placed at the upper opening of the channel steel 106, and a plurality of pipe clamping mechanisms are evenly arranged in sequence from front to back on the side of the channel steel 106 along the length direction of the fixed platform, the lower end of the pipe clamping mechanism is connected to the fixed platform 101, and the upper end of the pipe clamping mechanism is connected to the pipe 5.

[0018] Furthermore, each pipe clamping mechanism includes a pipe fixing bolt 102, a pipe fixing nut 103, a pad 104 and a support block 105. The upper surface of the fixed platform 101 is processed with a plurality of evenly arranged fixing platform connecting threaded holes from front to back along the length direction. The lower end of the pipe fixing bolt 102 is connected to the corresponding fixing platform connecting threaded hole. The pad 104 is horizontally arranged above the pipe 5. The lower surface of one end of the pad 104 contacts the upper surface of the pipe 5. The upper surface of the other end of the pad 104 is processed with a pad connecting hole, and the pad connecting hole corresponds to the fixing platform connecting threaded hole. The upper end of the pipe fixing bolt 102 passes through the pad connecting hole and is connected to the pipe fixing nut 103. A support block 105 is provided on the side of the pipe fixing bolt 102 away from the pipe 5. The lower end of the support block 105 contacts the upper surface of the fixed platform 101, and the upper end of the support block 105 contacts the lower surface of the pad 104.

[0019] Furthermore, the highest point positioning tool 2 described in step 2 includes a support frame 201, a spirit level 202 and a pointer 203. The cross-section of the support frame 201 is a U-shaped shape. The support frame 201 is buckled on the upper part of the pipe 5. A spirit level 202 is provided above the support frame 201. The spirit level 202 is connected to the upper surface of the support frame 201 by magnetic attraction. A vertically arranged pointer mounting hole is processed in the middle of the upper surface of the middle wing plate of the support frame 201. The pointer 203 is vertically inserted in the pointer mounting hole. The pointer 203 is gap-matched with the pointer mounting hole, and the lower end of the pointer 203 contacts the upper surface of the pipe 5.

[0020] Furthermore, the split processing tool 3 described in step three includes a guide column 301, a guide column fixing screw 303, a tool rod 305, two profiling blades 302 and four blade fixing bolts 304. Two blade mounting grooves are processed on the upper and lower sides of the head of the tool rod 305. The two blade mounting grooves are symmetrically arranged on the upper and lower sides of the center line of the tool rod. The two profiling blades 302 are respectively installed in the two blade mounting grooves. Each profiling blade 302 is connected to the tool rod 305 by two blade fixing bolts 304. A guide column disassembly hole 306 is opened in the center of the front surface of the head of the tool rod 305. The guide post disassembly hole 306 passes through the two end surfaces of the tool rod, and a guide post locking groove is provided at the center of the upper surface of the head of the tool rod 305. The guide post locking groove is connected to the guide post disassembly hole 306. Two coaxially arranged guide post locking threaded holes are provided on the left and right end surfaces of the head of the tool rod 305 respectively. The two guide post locking threaded holes are vertically connected to the guide post locking groove. The guide post 301 is inserted at the front end of the guide post disassembly hole 306, and the guide post fixing screw 303 is screwed in the two guide post locking threaded holes in turn. The guide post 301 is connected to the tool rod 305 through the guide post fixing screw 303.

[0021] Furthermore, the pipe hole inner wall chamfering tool 4 described in step 4 includes a tool rod 401, a chamfering blade 402, a spring 403, a spring stopper 404 and a stopper fixing screw 405, the tool rod 401 is a circular rod-shaped structure, the outer diameter of the tool rod 401 is smaller than the inner diameter of the middle through hole of the pipe 5, a blade mounting groove is radially provided on the lower side of the tool rod 401, and a blade through hole that penetrates the side of the guide rod is provided at the bottom of the blade mounting groove, the chamfering blade 402 has a T-shaped cross section, and the chamfering blade 402 has a T-shaped head end and a lower end. The sides are respectively processed into inclined surfaces, the chamfering blade 402 is installed in the blade installation groove, and the front end of the chamfering blade 402 passes through the blade through hole, and a spring 403 is provided at the end of the chamfering blade 402, and a spring stopper 404 is provided at the end of the spring 403 away from the chamfering blade 402, and two stopper connecting threaded holes are respectively provided on the sides of the spring stopper 404 and the tool rod 401, and the stopper fixing screw 405 is spirally installed in the two stopper connecting threaded holes, and the spring stopper 404 is connected to the tool rod 401 through the block fixing screw.

[0022] Furthermore, the diameter of the middle through hole on the tube 5 described in step three is 8 mm.

[0023] Furthermore, the radius of the first groove arc in step 4 is 2.5 mm, and the radius of the second groove arc is 5 mm.

[0024] Furthermore, the spacing between the two first groove arcs in step 4 is 30 mm, and the spacing between the two second groove arcs is 65 mm.

[0025] Compared with the prior art, the present invention has the following effects:

[0026] 1. The throttling tube hole processing method of the present invention can ensure the processing quality of the throttling tube hole with a full penetration structure. Through theoretical analysis and preliminary simulation tests, a tube support tool is designed to improve the overall rigidity of the tube and ensure processing stability; at the same time, a highest point positioning tool for the tube is also designed to ensure that the throttling tube hole is located at the highest point and the circumferential accuracy during processing; in addition, the present invention designs and manufactures a split processing tool, and adds a guide post disassembly hole on the tool rod for replacing the guide post, which reduces the production cost; the present invention also designs a tube hole inner wall chamfering tool, which can achieve chamfering of the inner wall of a small diameter through hole. The present invention ensures the processing quality of the throttling tube hole and reduces the production cycle through the above measures.

[0027] 2. The present invention successfully processes a throttling tube hole with a full penetration structure, ensures the subsequent welding quality, and provides a method for subsequent throttling tube hole processing with similar structures, especially providing ideas for processing throttling tube holes on small diameter pipes by drilling machines or boring machines. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1It is a structural schematic diagram of the throttling tube hole of the full penetration structure of the present invention;

[0029] Figure 2 It is a schematic diagram of processing the throttling hole of the small diameter pipe of the present invention;

[0030] Figure 3 is a front view of the pipe support tooling of the present invention;

[0031] Figure 4 is a side view of the pipe support tooling of the present invention;

[0032] Figure 5 It is a front view of the highest point positioning tool of the present invention;

[0033] Figure 6 is a side view of the highest point positioning tool of the present invention;

[0034] Figure 7 It is a front view of the split type machining tool of the present invention;

[0035] Figure 8 is a side view of the pipe hole inner wall chamfering tool of the present invention;

[0036] Fig. 9 It is a partial cross-sectional view of the pipe hole inner wall chamfering tool of the present invention.

[0037] In the figure: 1. pipe supporting tool; 101. fixing platform; 102. pipe fixing bolt; 103. pipe fixing nut; 104. pad; 105. support block; 106. channel steel; 2. highest point positioning tool; 201. support frame; 202. spirit level; 203. pointer; 3. split processing tool; 301. guide column; 302. contour blade; 303. guide column fixing screw; 304. blade fixing bolt; 305. tool bar; 306. hole for disassembling guide column; 4. chamfering tool for inner wall of pipe hole; 401. tool bar; 402. chamfering blade; 403. spring; 404. spring stopper; 405. stopper fixing screw; 5. pipe. DETAILED DESCRIPTION

[0038] Specific implementation method 1: Combination Figures 1 to 9 The present embodiment is described. The present embodiment is a method for machining a throttling hole for a small diameter pipe. The method is implemented by the following steps:

[0039] Step 1: Fix the pipe 5:

[0040] First, the pipe support fixture 1 is installed on the machine tool workbench; then, the pipe 5 is installed on the pipe support fixture 1, and the pipe support fixture 1 is used to support and fix the pipe 5;

[0041] Step 2: Determine the highest point of tube 5:

[0042] After the pipe 5 is fixed by the pipe supporting tool 1 described in step 1, the highest point positioning tool 2 is placed on the upper part of the pipe 5, and the highest point of the pipe 5 is determined by using the highest point positioning tool 2;

[0043] Step 3: Processing the middle through hole of tube 5:

[0044] Install the twist drill on the tool holder of the machine tool, determine the processing position of the throttling tube hole according to the highest point of the tube 5 determined in step 2, and use the twist drill to uniformly process multiple vertically arranged middle through holes from front to back along the length direction of the tube, and the axis of each middle through hole is located at the highest point of the tube 5;

[0045] Step 4: Processing the groove arc of pipe 5:

[0046] The split processing tool 3 is installed on the tool holder of the machine tool, and two first groove arcs and two second groove arcs are processed on the upper surface of the tube 5 by using the split processing tool 3, wherein the two first groove arcs are symmetrically arranged on the front and rear sides of the middle through hole with the axes of the multiple middle through holes processed in step 3 as the center, and the two second groove arcs are symmetrically arranged on the front and rear sides of the two first groove arcs with the axes of the multiple middle through holes processed in step 3 as the center;

[0047] Step 5: Process the inner wall chamfer of the tube hole:

[0048] The pipe hole inner wall chamfering tool 4 is installed on the hand electric drill, and the pipe hole inner wall chamfering tool 4 is used to chamfer the pipe hole inner wall connection points of the multiple intermediate through holes processed in step 3 and the pipe inner wall. At this point, the throttling pipe hole processing of the small diameter pipe is completed.

[0049] Specific implementation method 2: Combination Figures 1 to 4 To explain this embodiment, the pipe support tool 1 described in step 1 of this embodiment includes a fixed platform 101, a channel steel 106 and a plurality of pipe clamping mechanisms. The fixed platform 101 is horizontally arranged on the workbench of a machine tool. The upper surface of the fixed platform 101 is provided with a horizontally arranged channel steel 106 along the length direction of the fixed platform. A horizontally arranged pipe 5 is placed at the upper opening of the channel steel 106. The side of the channel steel 106 is provided with a plurality of pipe clamping mechanisms evenly arranged from front to back along the length direction of the fixed platform. The lower end of the pipe clamping mechanism is connected to the fixed platform 101, and the upper end of the pipe clamping mechanism is connected to the pipe 5. In this way, the pipe 5 is fixed to the channel steel 106 by a plurality of pipe clamping mechanisms, and the pipe 5 and the channel steel 106 are formed into a whole, which increases the overall rigidity, resists the cutting deformation force, and is simple and convenient to operate. Other components and connection relationships are the same as those in the specific embodiment 1.

[0050] Specific Embodiment 3: Combined with Figures 1 to 4 Describe this embodiment. Each pipe clamping mechanism in this embodiment includes a pipe fixing bolt 102, a pipe fixing nut 103, a backing plate 104, and a support block 105. A plurality of uniformly arranged fixing platform connection threaded holes are machined on the upper surface of the fixing platform 101 in the length direction from front to back. The lower end of the pipe fixing bolt 102 is connected to the corresponding fixing platform connection threaded hole. The backing plate 104 is horizontally arranged above the pipe 5. One end of the lower surface of the backing plate 104 is in contact with the upper surface of the pipe 5. A backing plate connection hole is machined on the upper surface of the other end of the backing plate 104. The backing plate connection hole corresponds to the fixing platform connection threaded hole. The upper end of the pipe fixing bolt 102 passes through the backing plate connection hole and is connected to the pipe fixing nut 103. A support block 105 is arranged on the side of the pipe fixing bolt 102 away from the pipe 5. The lower end of the support block 105 is in contact with the upper surface of the fixing platform 101, and the upper end of the support block 105 is in contact with the lower surface of the backing plate 104. With such a setting, a detachable support block 105 is arranged on the other side of the pipe 5. By replacing the support blocks 105 with different heights, the support for pipes 5 with different apertures can be adapted, ensuring the horizontal accuracy of the backing plate 104. Finally, the positioning of the pipe 5 in the vertical direction is achieved through the pipe fixing bolt 102 and the pipe fixing nut 103. In addition, the positioning of the pipe 5 in the horizontal direction can be achieved through the two web plates of the channel steel 106. Other compositions and connection relationships are the same as those in Specific Embodiment 1 or 2.

[0051] Specific Embodiment 4: Combined with Figure 1 、 Figure 2 、 Figure 5 和 Figure 6 Describe this embodiment. The highest point positioning tooling 2 in step 2 of this embodiment includes a support frame 201, a level 202, and a pointer 203. The cross-section of the support frame 201 is U-shaped. The support frame 201 is buckled on the upper part of the pipe 5. A level 202 is arranged above the support frame 201. The level 202 is connected to the upper surface of the support frame 201 by magnetic attraction. A vertically arranged pointer installation hole is machined in the middle of the upper surface of the middle web plate of the support frame 201. The pointer 203 is vertically inserted into the pointer installation hole. The pointer 203 has a clearance fit with the pointer installation hole. The lower end of the pointer 203 is in contact with the upper surface of the pipe 5. With such a setting, the level 202 is magnetically attracted to the surface of the support frame 201, and the pointer 203 is located in the middle of the support frame 201. When placing, by adjusting the support frame 201, when the level 202 is in a horizontal position, tap the pointer 203 to determine the highest point of the pipe 5. Other compositions and connection relationships are the same as those in Specific Embodiments 1, 2, or 3.

[0052] Specific Embodiment 5: Combined with Figure 1 、 Figure 2 和 Figure 7The present embodiment is described. The split processing tool 3 described in step 3 of the present embodiment includes a guide post 301, a guide post fixing screw 303, a tool rod 305, two profiling blades 302 and four blade fixing bolts 304. Two blade mounting grooves are processed on the upper and lower sides of the head of the tool rod 305. The two blade mounting grooves are symmetrically arranged on the upper and lower sides of the center line of the tool rod. The two profiling blades 302 are respectively installed in the two blade mounting grooves. Each profiling blade 302 is connected to the tool rod 305 by two blade fixing bolts 304. A guide post disassembly hole is opened in the center of the front surface of the head of the tool rod 305. 306, the guide post disassembly hole 306 penetrates the two end surfaces of the knife bar, the center of the upper surface of the knife bar 305 is provided with a guide post locking groove, the guide post locking groove is connected with the guide post disassembly hole 306, the left and right side end surfaces of the knife bar 305 are respectively provided with two coaxially arranged guide post locking threaded holes, the two guide post locking threaded holes are vertically connected with the guide post locking groove, the guide post 301 is inserted into the front end of the guide post disassembly hole 306, the guide post fixing screw 303 is screwed in the two guide post locking threaded holes in turn, and the guide post 301 is connected to the knife bar 305 through the guide post fixing screw 303. In this way, the profiling blade 302 is designed according to the throttling tube hole structure for throttling tube hole processing. In order to ensure uniform force during processing, a symmetrical profiling blade 302 is designed, and the profiling blade 302 is fixed to the knife bar 305 by a blade fixing bolt 304. The guide post 301 is fixed on the tool bar 305 by using the guide post fixing screw 303. Since the profiling blade 302 is subjected to a large force during the processing and the guide post 301 is thin, it is easy for the guide post 301 to break. A guide post disassembly hole 306 is designed on the tool bar 305. When the guide post 301 breaks, the guide post 301 is knocked out from one end of the tool bar 305 with round steel. By designing the split processing tool 3 and the guide post disassembly hole 306, the replaceability of the profiling blade 302 and the guide post 301, which are consumable parts, is guaranteed, and the manufacturing cost is reduced. The other components and connection relationships are the same as those of the specific embodiments one, two, three or four.

[0053] Specific implementation method six: Combination Figure 1 , Figure 2 , Figure 8 and Fig. 9The present embodiment is described. The pipe hole inner wall chamfering tool 4 described in step 4 of the present embodiment comprises a tool bar 401, a chamfering blade 402, a spring 403, a spring stopper 404 and a stopper fixing screw 405. The tool bar 401 is a circular rod-shaped structure. The outer diameter of the tool bar 401 is smaller than the inner diameter of the middle through hole of the pipe 5. A blade mounting groove is radially provided on the side surface of the lower part of the tool bar 401. A blade through hole that penetrates the side surface of the guide rod is provided at the bottom of the blade mounting groove. The chamfering blade 402 has a T-shaped cross section. The chamfering blade 402 The upper and lower sides of the head end are processed into inclined surfaces respectively, the chamfering blade 402 is installed in the blade installation groove, and the head end of the chamfering blade 402 passes through the blade through hole, and a spring 403 is provided at the end of the chamfering blade 402, and a spring stopper 404 is provided at the end of the spring 403 away from the chamfering blade 402, and two stopper connection threaded holes are respectively provided on the side of the spring stopper 404 and the knife rod 401, and the stopper fixing screw 405 is screwed on the two stopper connection threaded holes, and the spring stopper 404 is connected to the knife rod 401 through the block fixing screw. With such a configuration, in view of the small diameter of the pipe hole, a pipe hole inner wall chamfering tool 4 is designed, and the pipe hole inner wall chamfering tool 4 is used to process the inner wall of the pipe hole to ensure that it does not affect the flow. When the pipe hole inner wall chamfering tool 4 enters the pipe hole, the chamfering blade 402 is directly retracted into the tool rod 401 due to the pressure of the chamfering blade 402. When passing through the pipe hole, the chamfering blade 402 is automatically ejected by the pressure of the spring 403 and close to the inner wall of the pipe hole. The tool rod 401 is installed on a hand drill. When rotating, the chamfering blade 402 performs chamfering. When exiting the pipe hole, it is subjected to the pressure of the pipe hole, so that the chamfering blade 402 retracts into the tool rod 401 until it exits the pipe hole. Other components and connection relationships are the same as those of the specific embodiments one, two, three, four or five.

[0054] Specific implementation method seven: Combination Figure 1 To illustrate this embodiment, the diameter of the middle through hole on the tube 5 described in step 3 of this embodiment is 8 mm. Other components and connection relationships are the same as those of the specific embodiments 1, 2, 3, 4, 5 or 6.

[0055] Specific implementation method eight: Combination Figure 1 To illustrate this embodiment, the radius of the first groove arc in step 4 of this embodiment is 2.5 mm, and the radius of the second groove arc is 5 mm. Other components and connection relationships are the same as those of specific embodiments 1, 2, 3, 4, 5, 6 or 7.

[0056] Specific implementation method nine: Combination Figure 1 To illustrate this embodiment, the spacing between the two first groove arcs in step 4 of this embodiment is 30 mm, and the spacing between the two second groove arcs is 65 mm. Other components and connection relationships are the same as those of the specific embodiments 1, 2, 3, 4, 5, 6, 7 or 8.

[0057] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for machining a throttling hole for a small diameter pipe, characterized in that: The method is implemented by the following steps: Step 1: Fix the pipe (5): First, the pipe support fixture (1) is installed on the machine tool workbench; then, the pipe (5) is installed on the pipe support fixture (1), and the pipe (5) is supported and fixed by the pipe support fixture (1); Step 2: Determine the highest point of the tube (5): After the pipe (5) is fixed by the pipe supporting tool (1) described in step 1, the highest point positioning tool 2 is placed on the upper part of the pipe (5), and the highest point of the pipe (5) is determined by using the highest point positioning tool 2; Step 3: Processing the middle through hole of the tube (5): The twist drill is mounted on the tool holder of the machine tool, and the processing position of the throttling tube hole is determined according to the highest point of the tube (5) determined in step 2. The twist drill is used to uniformly process a plurality of vertically arranged middle through holes in sequence from front to back along the length direction of the tube, and the axis of each middle through hole is located at the highest point of the tube (5); Step 4: Processing the arc of the groove of the pipe (5): The split processing tool (3) is mounted on a tool holder of a machine tool, and two first groove arcs and two second groove arcs are processed on the upper surface of the tube (5) using the split processing tool (3), wherein the two first groove arcs are symmetrically arranged on the front and rear sides of the middle through hole with the axes of the multiple middle through holes processed in step 3 as the center, and the two second groove arcs are symmetrically arranged on the front and rear sides of the two first groove arcs with the axes of the multiple middle through holes processed in step 3 as the center; Step 5: Process the inner wall chamfer of the tube hole: The pipe hole inner wall chamfering tool (4) is mounted on a hand electric drill, and the pipe hole inner wall chamfering tool (4) is used to chamfer the pipe hole inner wall at the connection points between the plurality of intermediate through holes processed in step 3 and the pipe inner wall. Thus, the throttling pipe hole processing of the small diameter pipe is completed.

2. A method for machining a throttling hole for a small diameter pipe according to claim 1, characterized in that: The pipe supporting tool (1) described in step 1 comprises a fixed platform (101), a channel steel (106) and a plurality of pipe clamping mechanisms. The fixed platform (101) is horizontally arranged on a machine tool workbench. The upper surface of the fixed platform (101) is provided with a horizontally arranged channel steel (106) along the length direction of the fixed platform. A horizontally arranged pipe (5) is placed at the upper opening of the channel steel (106). The side of the channel steel (106) is provided with a plurality of pipe clamping mechanisms evenly arranged in sequence from front to back along the length direction of the fixed platform. The lower end of the pipe clamping mechanism is connected to the fixed platform (101), and the upper end of the pipe clamping mechanism is connected to the pipe (5).

3. A method for machining a throttling hole for a small diameter pipe according to claim 2, characterized in that: Each pipe clamping mechanism includes a pipe fixing bolt (102), a pipe fixing nut (103), a backing plate (104) and a support block (105). A plurality of uniformly arranged fixing platform connection threaded holes are machined on the upper surface of the fixing platform (101) in the length direction from front to back. The lower end of the pipe fixing bolt (102) is connected to the corresponding fixing platform connection threaded hole. The backing plate (104) is horizontally arranged above the pipe (5). One end of the lower surface of the backing plate (104) is in contact with the upper surface of the pipe (5). A backing plate connection hole is machined on the upper surface of the other end of the backing plate (104). The backing plate connection hole corresponds to the fixing platform connection threaded hole. The upper end of the pipe fixing bolt (102) passes through the backing plate connection hole and is connected to the pipe fixing nut (103). A support block (105) is arranged on the side of the pipe fixing bolt (102) away from the pipe (5). The lower end of the support block (105) is in contact with the upper surface of the fixing platform (101). The upper end of the support block (105) is in contact with the lower surface of the backing plate (104).

4. A method for machining a throttling hole for a small diameter pipe according to claim 3, characterized in that: The highest point positioning tooling 2 described in step two includes a support frame (201), a level (202) and a pointer (203). The cross-section of the support frame (201) is U-shaped. The support frame (201) is buckled on the upper part of the pipe (5). A level (202) is arranged above the support frame (201). The level (202) is connected to the upper surface of the support frame (201) by magnetic attraction. A vertically arranged pointer mounting hole is machined in the middle of the upper surface of the middle wing plate of the support frame (201). The pointer (203) is vertically inserted into the pointer mounting hole. The pointer (203) has a clearance fit with the pointer mounting hole. The lower end of the pointer (203) is in contact with the upper surface of the pipe (5).

5. A method for machining a throttling hole for a small diameter pipe according to claim 4, characterized in that: The split-type machining tool (3) described in step three includes a guide post (301), a guide post fixing screw (303), a tool rod (305), two profiling blades (302) and four blade fixing bolts (304). Two blade mounting grooves are machined on the upper and lower sides of the head of the tool rod (305). The two blade mounting grooves are symmetrically arranged on the upper and lower sides of the center line of the tool rod. The two profiling blades (302) are respectively installed in the two blade mounting grooves. Each profiling blade (302) is connected to the tool rod (305) by two blade fixing bolts (304). A guide post disassembly hole (306) is opened at the center of the front surface of the head of the tool rod (305). The guide post disassembly hole (306) runs through the front and rear end faces of the tool rod head. A guide post locking groove is opened at the center of the upper surface of the head of the tool rod (305). The guide post locking groove communicates with the guide post disassembly hole (306). Two coaxially arranged guide post locking threaded holes are respectively opened on the left and right side end faces of the head of the tool rod (305). The two guide post locking threaded holes are both vertically and perpendicularly penetrated with the guide post locking groove. The guide post (301) is inserted into the front end of the guide post disassembly hole (306). The guide post fixing screw (303) is sequentially screwed into the two guide post locking threaded holes. The guide post (301) is connected to the tool rod (305) by the guide post fixing screw (303).

6. A method for machining a throttling hole for a small diameter pipe according to claim 5, characterized in that: The pipe hole inner wall chamfering tool (4) described in step 4 comprises a tool rod (401), a chamfering blade (402), a spring (403), a spring stopper (404) and a stopper fixing screw (405), wherein the tool rod (401) is a circular rod-shaped structure, the outer diameter of the tool rod (401) is smaller than the inner diameter of the middle through hole of the pipe (5), a blade mounting groove is radially provided on the lower side of the tool rod (401), a blade through hole is provided at the bottom of the blade mounting groove and is connected to the side of the guide rod, the chamfering blade (402) has a T-shaped cross section, and the upper and lower sides of the head end of the chamfering blade (402) are respectively The chamfering blade (402) is processed into an inclined surface, and is installed in the blade installation groove. The front end of the chamfering blade (402) passes through the blade through hole. A spring (403) is provided at the end of the chamfering blade (402). A spring stopper (404) is provided at one end of the spring (403) away from the chamfering blade (402). Two stopper connection threaded holes are respectively provided on the sides of the spring stopper (404) and the tool rod (401). A stopper fixing screw (405) is spirally installed on the two stopper connection threaded holes. The spring stopper (404) is connected to the tool rod (401) through the block fixing screw.

7. A method for machining a throttling hole for a small diameter pipe according to claim 1 or 6, characterized in that: The diameter of the middle through hole on the tube (5) described in step 3 is 8 mm.

8. A method for machining a throttling hole for a small diameter pipe according to claim 7, characterized in that: The radius of the first groove arc described in step 4 is 2.5 mm, and the radius of the second groove arc described is 5 mm.

9. A method for machining a throttling hole for a small diameter pipe according to claim 8, characterized in that: The distance between the two first groove arcs described in step 4 is 30 mm, and the distance between the two second groove arcs is 65 mm.

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