Device and method for machining annular prefabricated fragment micro groove

Abstract

The invention discloses a device and method for machining annular prefabricated fragment micro grooves, the device comprises a combined broach and a positioning assembly, the combined broach comprises a center shaft and an annular tool apron, m axial installation grooves are formed in the outer circle face of the annular tool apron, a blade and a pressing block used for pressing the blade are installed in the axial installation grooves, and the positioning assembly is connected with the center shaft. The positioning assembly comprises a limiting sleeve, a shaft sleeve, a pressing ring and a tool setting ring, m tool setting grooves are formed in the tool setting ring, a cylindrical pin is arranged between the tool setting ring and the pressing ring, and a plurality of pin holes for installing the cylindrical pin are formed in the pressing ring. The purpose of fixing a plurality of stacked annular prefabricated fragment blanks on the broaching machine workbench can be achieved through the positioning assembly, a plurality of micro grooves are formed in the annular prefabricated fragment blanks through broaching at the same time through the combined broaching tool, and the machining efficiency of machining the micro grooves of the annular prefabricated fragments through the device is high; and the requirement for rapid and large-batch production of the annular prefabricated fragments can be met.

Description

Technical Field

[0001] The invention belongs to the technical field of annular prefabricated fragment processing, and particularly relates to a device and method for processing micro grooves of annular prefabricated fragments. Background Art

[0002] Annular prefabricated fragments are a type of killing component used in ammunition such as mines and grenades. They use their high density and high strength to form high-speed fragments during explosion to kill targets. Typically, annular prefabricated fragments are prefabricated with microgrooves (groove depth of 2 mm, groove width ≤ 0.5 mm). Currently, the microgrooving method is to first produce a blank using powder metallurgy injection molding or compression molding, and then produce an annular or tubular tungsten alloy semi-finished product without microgrooves through degreasing, sintering, heat treatment, and subsequent processing such as turning and grinding. The microgrooves are then processed using laser cutting or water jet cutting. However, because laser cutting easily causes alloy ablation at the laser contact point, it is difficult or even impossible to effectively cut microgrooves with a width of less than 0.5 mm. Water jet cutting is also difficult or even impossible to effectively cut microgrooves with a width of less than 0.5 mm due to the limitations of current water jet technology. Although wire cutting can achieve uniform microgrooves in width and depth, the processing speed is very slow, making it difficult to achieve rapid and large-scale production requirements. Therefore, a device and method for processing microgrooves in annular prefabricated fragments should be provided. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a device and method for processing micro-grooves in annular prefabricated fragments. The device and method have a simple structure and a reasonable design. A positioning component can be used to fix multiple stacked annular prefabricated fragment blanks on a broaching table. A combined broach is used to simultaneously broach multiple micro-grooves on multiple annular prefabricated fragment blanks. The device has high processing efficiency for processing micro-grooves in annular prefabricated fragments, can meet the requirements of rapid and large-scale production of annular prefabricated fragments, and has low processing costs, making it easy to promote and apply.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is: a device for processing micro-grooves of annular prefabricated fragments, characterized in that it includes a combined broach for broaching multiple micro-grooves at one time and a positioning assembly arranged on a broaching machine workbench and used to stack multiple annular prefabricated fragment blanks, the combined broach includes a central axis and an annular tool holder coaxially mounted on the central axis, the outer circumferential surface of the annular tool holder is provided with m axial mounting grooves arranged at equal intervals along the circumferential direction, wherein m is a positive integer, and the axial mounting grooves are arranged at equal intervals along the circumferential direction. A blade and a pressure block for pressing the blade are installed in the groove, and both ends of the annular tool holder are provided with limit rings for limiting the axial positions of multiple blades. The positioning assembly includes a limit sleeve installed on the workbench of the broaching machine, a shaft sleeve coaxially installed in the limit sleeve, a pressure ring installed on the top of the limit sleeve and a tool setting ring installed on the pressure ring. The tool setting ring is provided with m tool setting grooves, a cylindrical pin is provided between the tool setting ring and the pressure ring, and the pressure ring is provided with multiple pin holes for installing the cylindrical pin.

[0005] The above-mentioned device for processing micro-grooves of annular prefabricated fragments is characterized in that: N cutting teeth are provided on the blade edge, and the height difference t between two adjacent cutting teeth satisfies t=h / N, wherein h is the groove depth of the micro-groove of the annular prefabricated fragment, h and N are both positive integers, and the thickness of the cutting teeth is equal to the groove width of the micro-groove.

[0006] The above-mentioned device for processing annular prefabricated fragment micro-grooves is characterized in that: the central axis includes an annular tool holder mounting section, a top connecting section and a bottom connecting section coaxially arranged at both ends of the annular tool holder mounting section, and the top end of the top connecting section and the bottom end of the bottom connecting section are both provided with a connecting head for connecting to a broach fixture.

[0007] The above-mentioned device for processing annular prefabricated fragment micro-grooves is characterized in that: the number of the annular tool holders is three, the three annular tool holders are coaxially installed on the annular tool holder mounting section, and the cutting depth of the three blades located on the same plane is equal to the groove depth of the micro-groove.

[0008] The above-mentioned device for processing annular prefabricated fragment micro-grooves is characterized in that: the annular tool holder mounting section is connected to the annular tool holder by a flat key, and the annular tool holder mounting section is provided with a first axial end retaining ring located at the top end of the annular tool holder and a second axial end retaining ring located at the bottom end of the annular tool holder.

[0009] The above-mentioned device for processing annular prefabricated fragment micro-grooves is characterized in that: the pressure block is fixedly installed in the axial mounting groove by a first fastening bolt, and the limiting ring is fixedly installed on the end face of the annular knife seat by a second fastening bolt; both ends of the blade have adjacent clamping grooves and clamping protrusions, and the limiting ring is provided with a clearance hole that cooperates with the clamping protrusion.

[0010] The above-mentioned device for processing annular prefabricated fragment micro-grooves is characterized in that an external thread section is provided at the bottom end of the annular tool holder mounting section, and a locking nut for tightening the second shaft end retaining ring is mounted on the external thread section.

[0011] The present invention also provides a method for machining annular prefabricated fragment microgrooves using the above-mentioned device for machining annular prefabricated fragment microgrooves, characterized in that it comprises the following steps: Step 1: Install multiple annular prefabricated fragment blanks on the broaching machine workbench: The limiting sleeve is installed on the broaching machine workbench, a shaft sleeve is installed in the limiting sleeve, a plurality of annular prefabricated fragment blanks are stacked and arranged in the shaft sleeve, and a clamping ring is installed on the top of the limiting sleeve; Step 2: determining the number of broaching times and the number of pin holes according to the number of micro grooves of the annular prefabricated fragment and the number of tool setting grooves on the tool setting ring; The number of broaching times is equal to the number of pin holes, and both the number of broaching times n and the number of pin holes n satisfy n=M / m, where M is the number of microgrooves of the annular prefabricated fragment, and m is the number of tool grooves. That is, the combined broach can machine m microgrooves per broaching operation, and therefore, the combined broach needs to be broached n times to broach M microgrooves. Step 3: Install a knife ring on the top surface of the clamping ring and insert a cylindrical pin into the first pin hole; In order to ensure that the M micro grooves are evenly divided in the circumferential direction of the annular prefabricated fragment after n broaching, the hole position A1 of the first pin hole is set to 0°, and the hole position An of the nth pin hole is the angle An between the straight line connecting the center of the nth pin hole and the center of the tool ring and the straight line connecting the center of the first pin hole and the center of the tool ring, wherein the hole position An of the nth pin hole satisfies the formula An=360°(n-1) / M; Step 4: Install the combined broach on the broaching machine; Step 5: After the combined broach moves downward and is aligned with the tool setting ring, the combined broach is used to perform a first broaching on a plurality of annular prefabricated fragment blanks; Step 6: After the combined broach moves upward and returns to its original position, the tool setting ring is rotated to insert the cylindrical pin into the n-1th pin hole. After that, the combined broach moves downward and is aligned with the tool setting ring, and then the n-1th broaching is performed; Step 7: After the combined broach moves upward and returns to its original position, the tool setting ring is rotated to insert the cylindrical pin into the nth pin hole. After that, the combined broach moves downward and aligns with the tool setting ring to perform the nth broaching.

[0012] Compared with the prior art, the present invention has the following advantages: 1. The device of the present invention includes a combined broach and a positioning assembly. In actual use, the positioning assembly can be used to fix multiple stacked annular prefabricated fragment blanks on the broaching table, and the combined broach is used to simultaneously broach multiple micro-grooves on the multiple annular prefabricated fragment blanks. Compared with the prior art method of using laser cutting or water jet cutting to process micro-grooves, the device for processing micro-grooves in annular prefabricated fragments has high processing efficiency, can meet the requirements of rapid and large-scale production of annular prefabricated fragments, and has low processing costs, which is easy to promote and apply.

[0013] 2. The combined broach of the present invention includes a center shaft, an annular tool holder, a blade, a pressure block and a limit ring. In actual use, the annular tool holder is coaxially mounted on the center shaft, and both ends of the center shaft are mounted on the broaching machine. By opening m axial mounting grooves arranged in the circumferential direction and at equal intervals on the outer circular surface of the annular tool holder, a blade is fixedly mounted in each axial mounting groove by a pressure block. When the broaching machine drives the combined broach to move a working stroke from top to bottom, the m blades can achieve the purpose of cutting out m micro grooves at the same time. Under the joint action of the pressure block and the limit ring, the reliability of the installation of the blade on the annular tool holder can be guaranteed.

[0014] 3. The positioning assembly of the present invention includes a limit sleeve, a shaft sleeve, a clamping ring and a knife ring. With the joint action of the limit sleeve, the shaft sleeve and the clamping ring, multiple annular prefabricated fragment blanks can be fixedly installed on the broaching machine workbench. During the broaching process, multiple annular prefabricated fragment blanks will not shift or deform. By providing m knife grooves on the knife ring, during actual installation, the knife ring and the clamping ring are positioned and connected by a cylindrical pin. One end of the cylindrical pin is fixedly installed on the knife ring, and the clamping ring is provided with multiple pin holes for inserting the other end of the cylindrical pin. During actual use, the purpose of rotating the knife ring installation direction can be achieved by selecting pin holes in different positions to insert the cylindrical pins. Through multiple knife settings and multiple cutting, more dense micro-grooves can be cut in multiple annular prefabricated fragment blanks. There is no need for secondary clamping of the combined broach, which helps to improve cutting efficiency and cutting accuracy and is convenient for promotion and application.

[0015] 4. The processing method of the present invention is reasonably designed, easy to operate, and convenient to promote and apply.

[0016] In summary, the present invention utilizes a positioning component to achieve the purpose of fixing multiple stacked annular prefabricated fragment blanks on a broaching table, and utilizes a combined broach to simultaneously broach multiple micro-grooves on multiple annular prefabricated fragment blanks. The micro-grooves of annular prefabricated fragments processed by this device are highly efficient, can meet the requirements of rapid and large-scale production of annular prefabricated fragments, and have low processing costs, making it easy to promote and apply.

[0017] The present invention is further described in detail below through the accompanying drawings and examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the structure of the annular prefabricated fragment of the present invention.

[0019] Figure 2 It is a structural schematic diagram of the combined broach of the present invention.

[0020] Figure 3 The figure is a schematic diagram of the installation structure of the annular knife seat, the blade, the pressing block and the limiting ring of the present invention.

[0021] Figure 4 It is a structural schematic diagram of the blade of the present invention.

[0022] Figure 5 It is a schematic diagram of the installation structure of the broaching machine workbench, positioning assembly and multiple annular prefabricated fragment blanks of the present invention.

[0023] Figure 6 for Figure 5 AA cross-sectional view.

[0024] Figure 7 Flowchart of the method of the present invention.

[0025] Description of the accompanying drawings: 1—Center axis; 1-1—Annular knife seat installation section; 1-2—Top connection section; 1-3—Bottom connecting section; 2—Annular knife seat; 2-1—Axial mounting groove; 2-2—radial mounting slot; 3—blade; 3-1—cutting tooth; 3-2—card-mounting groove; 3-2—card-mounting protrusion; 4—pressing block; 5—first fastening bolt; 6—limiting ring; 7—second fastening bolt; 8—first shaft end retaining ring; 9—second shaft end retaining ring; 10—locking nut; 11—Flat key; 12—Shaft sleeve; 13—Connector; 14—Broaching machine workbench; 15—Limiting sleeve; 16—Pressure ring; 16-1—pin hole; 17—tool setting ring; 17-1—tool setting groove; 18—cylindrical pin; 19—annular prefabricated fragment blank; 20—annular prefabricated fragment; 20-1—Micro slot. DETAILED DESCRIPTION

[0026] like Figures 1 to 6 As shown, a device for processing micro-grooves of annular prefabricated fragments includes a combined broach for broaching multiple micro-grooves 20-1 at one time and a positioning assembly arranged on a broaching machine workbench 14 and for stacking multiple annular prefabricated fragment blanks 19. The combined broach includes a central shaft 1 and an annular tool holder 2 coaxially mounted on the central shaft 1. The outer circumferential surface of the annular tool holder 2 is provided with m axial mounting grooves 2-1 arranged in a circumferential direction and at equal intervals, wherein m is a positive integer. A blade 3 and a pressure block for pressing the blade 3 are installed in the axial mounting groove 2-1. 4. Both ends of the annular tool holder 2 are provided with a limit ring 6 for limiting the axial position of the multiple blades 3. The positioning assembly includes a limit sleeve 15 installed on the broaching machine workbench 14, a shaft sleeve 12 coaxially installed in the limit sleeve 15, a clamping ring 16 installed on the top of the limit sleeve 15 and a tool setting ring 17 installed on the clamping ring 16. The tool setting ring 17 is provided with m tool setting grooves 17-1, a cylindrical pin 18 is provided between the tool setting ring 17 and the clamping ring 16, and the clamping ring 16 is provided with a plurality of pin holes 16-1 for installing the cylindrical pin 18.

[0027] In this embodiment, the device includes a combined broach and a positioning assembly. In actual use, the positioning assembly can be used to fix multiple stacked annular prefabricated fragment blanks 19 on the broaching table 14, and the combined broach is used to simultaneously broach multiple micro-grooves 20-1 on the multiple annular prefabricated fragment blanks 19. Compared with the method of using laser cutting or water cutting to process the micro-grooves 20-1 in the prior art, the micro-grooves of the annular prefabricated fragments processed by this device are highly efficient, can meet the requirements of rapid and large-scale production of annular prefabricated fragments, and have low processing costs, making it easy to promote and apply.

[0028] like Figure 2 and Figure 3As shown, in this embodiment, the combined broach includes a central shaft 1, an annular tool holder 2, a blade 3, a pressure block 4 and a limit ring 6. In actual use, the annular tool holder 2 is coaxially mounted on the central shaft 1, and both ends of the central shaft 1 are mounted on the broaching machine. By opening m axial mounting grooves 2-1 along the circumferential direction and at equal intervals on the outer circular surface of the annular tool holder 2, a blade 3 is fixedly mounted in each axial mounting groove 2-1 through a pressure block 4. When the broaching machine drives the combined broach to move a working stroke from top to bottom, the m blades 3 can achieve the purpose of simultaneously cutting out m micro grooves 20-1. Under the joint action of the pressure block 4 and the limit ring 6, the reliability of the installation of the blade 3 on the annular tool holder 2 can be guaranteed.

[0029] like Figure 5 and Figure 6 As shown, in this embodiment, the positioning assembly includes a limit sleeve 15, a shaft sleeve 12, a clamping ring 16 and a tool ring 17. It should be noted that the center hole of the shaft sleeve 12 is a stepped hole, and the stepped hole includes a large-diameter hole section and a small-diameter hole section located at the bottom end of the large-diameter hole section. The diameter of the large-diameter hole section is equal to the diameter of the annular prefabricated fragment blank 19, and the top surface of the small-diameter hole section forms an annular boss for supporting multiple annular prefabricated fragment blanks 19. The diameter of the small-diameter hole section is larger than the diameter of the center circle where the bottoms of multiple micro grooves 20-1 are located. When the combined broach moves from top to bottom to cut multiple When a micro groove 20-1 is formed, the small-diameter hole section needs to avoid contact with multiple blades 3; the center hole of the clamping ring 16 is also a stepped hole, and the stepped hole of the clamping ring 16 can simultaneously play the role of clamping the shaft sleeve 12 and multiple annular prefabricated fragment blanks 19, and the clamping ring 16 also needs to avoid contact with multiple blades 3. Under the joint action of the limit sleeve 15, the shaft sleeve 12 and the clamping ring 16, the multiple annular prefabricated fragment blanks 19 can be fixedly installed on the broaching table 14. During the broaching process, the multiple annular prefabricated fragment blanks 19 will not be displaced or deformed.

[0030] In this embodiment, m tool setting grooves 17-1 are provided on the tool setting ring 17. During actual installation, the tool setting ring 17 and the clamping ring 16 are positioned and connected by a cylindrical pin 18. One end of the cylindrical pin 18 is fixedly installed on the tool setting ring 17. The clamping ring 16 is provided with a plurality of pin holes 16-1 for inserting the other end of the cylindrical pin 18. During actual use, the installation direction of the tool setting ring 17 can be rotated by selecting pin holes 16-1 at different positions to insert the cylindrical pin 18. Through multiple tool setting and multiple cutting, more dense micro grooves 20-1 can be cut in multiple annular prefabricated fragment blanks 19. No secondary clamping of the combined broach is required, which helps to improve cutting efficiency and cutting accuracy and facilitates popularization and application.

[0031] In this embodiment, N cutting teeth 3-1 are provided on the blade edge of the blade 3, and the height difference t between two adjacent cutting teeth 3-1 satisfies t=h / N, wherein h is the groove depth of the micro groove 20-1 of the annular prefabricated fragment 20, h and N are both positive integers, and the thickness of the cutting tooth 3-1 is equal to the groove width of the micro groove 20-1.

[0032] In this embodiment, the central shaft 1 includes an annular tool holder mounting section 1-1, a top connecting section 1-2 and a bottom connecting section 1-3 coaxially arranged at both ends of the annular tool holder mounting section 1-1, and the top end of the top connecting section 1-2 and the bottom end of the bottom connecting section 1-3 are both provided with a connecting head 13 for connecting to the broach fixture.

[0033] In this embodiment, there are three annular tool holders 2, and the three annular tool holders 2 are coaxially mounted on the annular tool holder mounting section 1-1. The cutting depths of the three blades 3 located on the same plane are equal to the groove depth of the micro groove 20-1.

[0034] In this embodiment, the annular tool holder mounting section 1-1 is connected to the annular tool holder 2 by a flat key 11, and the annular tool holder mounting section 1-1 is provided with a first axial end retaining ring 8 located at the top end of the annular tool holder 2 and a second axial end retaining ring 9 located at the bottom end of the annular tool holder 2.

[0035] like Figure 3 and Figure 4 As shown, in this embodiment, the pressure block 4 is fixedly installed in the axial mounting groove 2-1 by a first fastening bolt 5, and the limiting ring 6 is fixedly installed on the end face of the annular knife seat 2 by a second fastening bolt 7; both ends of the blade 3 have adjacent clamping grooves 3-2 and clamping protrusions 3-3, and the limiting ring 6 is provided with a clearance hole 6-1 that cooperates with the clamping protrusion 3-3.

[0036] In this embodiment, the blade 3 can be pressed against a side wall of the axial mounting groove 2-1 by using the pressure block 4 and the first fastening bolt 5. By providing a clamping groove 3-2 at both ends of the blade 3, during actual installation, the limit ring 6 is clamped in the clamping groove 3-2, and the clamping protrusion 3-3 is passed through the clearance hole 6-1, which can limit the axial installation position of the blade 3 and avoid displacement of the blade 3 in the axial direction.

[0037] like Figure 2 As shown, in this embodiment, an external thread section is provided at the bottom end of the annular tool holder mounting section 1 - 1 , and a locking nut 10 for tightening the second shaft end retaining ring 9 is sleeved on the external thread section.

[0038] In actual use, when the combined broach moves downward, the locking nut 10 can buffer the impact force of the three annular tool seats 2 and the second shaft end retaining ring 9 moving downward.

[0039] like Figure 7 A method for machining annular prefabricated fragment micro-grooves is shown, comprising the following steps: Step 1: Install multiple annular prefabricated fragment blanks 19 on the broaching machine workbench 14: The limiting sleeve 15 is installed on the broaching table 14, the shaft sleeve 12 is installed in the limiting sleeve 15, a plurality of annular prefabricated fragment blanks 19 are stacked and arranged in the shaft sleeve 12, and a clamping ring 16 is installed on the top of the limiting sleeve 15; Step 2: Determine the number of broaching times and the number of pin holes 16 - 1 according to the number of micro grooves 20 - 1 of the annular prefabricated fragment 20 and the number of tool grooves 17 - 1 on the tool ring 17 ; The number of broaching times is equal to the number of the pin holes 16 - 1 . The number of broaching times n and the number n of the pin holes 16 - 1 both satisfy n=M / m, where M is the number of microgrooves 20 - 1 of the annular prefabricated fragment 20 , and m is the number of tool grooves 17 - 1 . That is, the combined broach can machine m microgrooves 20 - 1 per broaching operation. Therefore, the combined broach needs to be broached n times to broach M microgrooves 20 - 1 . Step 3: Install the knife ring 17 on the top surface of the clamping ring 16, and insert the cylindrical pin 18 into the first pin hole 16-1; In order to ensure that the M micro grooves (20-1) are evenly divided in the circumferential direction of the annular prefabricated fragment (20) after n times of broaching, the hole position A1 of the first pin hole (16-1) is set to 0°, and the hole position An of the nth pin hole (16-1) is the angle An between the straight line connecting the center of the nth pin hole (16-1) and the center of the tool ring (17) and the straight line connecting the center of the first pin hole (16-1) and the center of the tool ring (17), wherein the hole position An of the nth pin hole (16-1) satisfies the formula An=360°(n-1) / M; In this embodiment, the number of micro grooves 20-1 is 45, the number of tool grooves 17-1 is 15, the number of pin holes 16-1 is 3, the hole position A1 of the first pin hole (16-1) is 0°, the hole position A2 of the second pin hole (16-1) is 8°, and the hole position A3 of the third pin hole (16-1) is 16°. In the actual processing process, since the distance between the three pin holes (16-1) processed according to this rule is relatively close, according to the optimization formula An 优 =360°(n-1)(1 / M+1 / m), the optimized hole position A of the second pin hole (16-1)2优 The optimized hole position A of the third pin hole (16-1) is 32°. 3优 It is 72°.

[0040] Step 4: Install the combined broach on the broaching machine; Step 5: After the combined broach moves downward and is aligned with the tool setting ring 17, the combined broach is used to perform the first broaching on the plurality of annular prefabricated fragment blanks 19; Step 6: After the combined broach moves upward and returns to its original position, the tool setting ring 17 is rotated to insert the cylindrical pin 18 into the n-1th pin hole 16-1. After that, the combined broach moves downward and is aligned with the tool setting ring 17, and then the n-1th broaching is performed; Step 7: After the combined broach moves upward and returns to its original position, the tool setting ring 17 is rotated to insert the cylindrical pin 18 into the nth pin hole 16-1. After that, the combined broach moves downward and aligns with the tool setting ring 17 to perform the nth broaching.

[0041] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent structural change made to the above embodiment based on the technical essence of the present invention shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A device for machining micro-grooves in annular prefabricated fragments, characterized by: The invention relates to a combined broach for broaching a plurality of micro grooves (20-1) at one time and a positioning assembly arranged on a broaching machine workbench (14) and used for stacking a plurality of annular prefabricated fragment blanks (19), wherein the combined broach comprises a central axis (1) and an annular tool holder (2) coaxially mounted on the central axis (1), wherein the outer circumferential surface of the annular tool holder (2) is provided with m axial mounting grooves (2-1) arranged in a circumferential direction and at equal intervals, wherein m is a positive integer, wherein a blade (3) and a pressing block (4) for pressing the blade (3) are mounted in the axial mounting groove (2-1), and both ends of the annular tool holder (2) are provided with A limiting ring (6) for limiting the axial positions of a plurality of blades (3), the positioning assembly comprising a limiting sleeve (15) mounted on a broaching machine workbench (14), a shaft sleeve (12) coaxially mounted in the limiting sleeve (15), a clamping ring (16) mounted on the top of the limiting sleeve (15), and a tool setting ring (17) mounted on the clamping ring (16), the tool setting ring (17) being provided with m tool setting grooves (17-1), a cylindrical pin (18) being provided between the tool setting ring (17) and the clamping ring (16), and the clamping ring (16) being provided with a plurality of pin holes (16-1) for mounting the cylindrical pin (18).

2. The device for machining micro-grooves in annular preformed fragments according to claim 1, characterized in that: The blade (3) is provided with N cutting teeth (3-1), and the height difference t between two adjacent cutting teeth (3-1) satisfies t=h / N, wherein h is the groove depth of the micro groove (20-1) of the annular prefabricated fragment (20), h and N are both positive integers, and the thickness of the cutting teeth (3-1) is equal to the groove width of the micro groove (20-1).

3. The device for machining micro-grooves in annular preformed fragments according to claim 1, characterized in that: The central shaft (1) comprises an annular tool holder mounting section (1-1), a top connecting section (1-2) and a bottom connecting section (1-3) coaxially arranged at both ends of the annular tool holder mounting section (1-1), and a connecting head (13) for connecting to a broach fixture is provided at the top end of the top connecting section (1-2) and the bottom end of the bottom connecting section (1-3).

4. The device for machining micro-grooves in annular preformed fragments according to claim 3, characterized in that: The number of the annular tool seats (2) is three, and the three annular tool seats (2) are coaxially mounted on the annular tool seat mounting section (1-1), and the cutting depths of the three blades (3) located on the same plane are equal to the groove depth of the micro groove (20-1).

5. The device for machining micro-grooves in annular preformed fragments according to claim 3, characterized in that: The annular knife seat mounting section (1-1) is connected to the annular knife seat (2) via a flat key (11), and the annular knife seat mounting section (1-1) is provided with a first axial end retaining ring (8) located at the top end of the annular knife seat (2) and a second axial end retaining ring (9) located at the bottom end of the annular knife seat (2).

6. The device for machining micro-grooves in annular preformed fragments according to claim 2, characterized in that: The pressure block (4) is fixedly mounted in the axial mounting groove (2-1) by a first fastening bolt (5), and the limiting ring (6) is fixedly mounted on the end face of the annular blade seat (2) by a second fastening bolt (7); both ends of the blade (3) have adjacent clamping grooves (3-2) and clamping protrusions (3-3), and the limiting ring (6) is provided with a clearance hole (6-1) that matches the clamping protrusion (3-3).

7. The device for machining micro-grooves in annular preformed fragments according to claim 3, characterized in that: An external thread section is provided at the bottom end of the annular tool holder mounting section (1-1), and a locking nut (10) for tightening the second shaft end retaining ring (9) is sleeved on the external thread section.

8. A method for machining annular preformed fragment microgrooves using the apparatus for machining annular preformed fragment microgrooves according to claim 1, characterized in that: The following steps are involved: Step 1: Install multiple annular prefabricated fragment blanks (19) on the broaching machine workbench (14): The limiting sleeve (15) is installed on the broaching machine workbench (14), the shaft sleeve (12) is installed in the limiting sleeve (15), a plurality of annular prefabricated fragment blanks (19) are stacked and arranged in the shaft sleeve (12), and a clamping ring (16) is installed on the top of the limiting sleeve (15); Step 2: determining the number of broaching times and the number of pin holes (16-1) based on the number of micro grooves (20-1) of the annular prefabricated fragment (20) and the number of tool grooves (17-1) on the tool ring (17); The number of broaching times is equal to the number of the pin holes (16-1), and the number of broaching times n and the number n of the pin holes (16-1) both satisfy n=M / m, wherein M is the number of micro grooves (20-1) of the annular prefabricated fragment (20), and m is the number of tool grooves (17-1), that is, the combined broach can process m micro grooves (20-1) each time it completes broaching. Therefore, broaching M micro grooves (20-1) requires using the combined broach to broach n times; Step 3: Install the knife ring (17) on the top surface of the clamping ring (16), and insert the cylindrical pin (18) into the first pin hole (16-1); In order to ensure that the M micro grooves (20-1) are evenly divided in the circumferential direction of the annular prefabricated fragment (20) after n times of broaching, the hole position A1 of the first pin hole (16-1) is set to 0°, and the hole position An of the nth pin hole (16-1) is the angle An between the straight line connecting the center of the nth pin hole (16-1) and the center of the tool ring (17) and the straight line connecting the center of the first pin hole (16-1) and the center of the tool ring (17), wherein the hole position An of the nth pin hole (16-1) satisfies the formula An=360°(n-1) / M; Step 4: Install the combined broach on the broaching machine; Step 5: After the combined broach is moved downward and aligned with the tool setting ring (17), the combined broach is used to perform a first broaching on a plurality of annular prefabricated fragment blanks (19); Step 6: After the combined broach moves upward and returns to its original position, the tool setting ring (17) is rotated to insert the cylindrical pin (18) into the n-1th pin hole (16-1). After that, the combined broach moves downward and is aligned with the tool setting ring (17), and then the n-1th broaching is performed; Step 7: After the combined broach moves upward and returns to its original position, the tool setting ring (17) is rotated to insert the cylindrical pin (18) into the nth pin hole (16-1). After that, the combined broach moves downward and is aligned with the tool setting ring (17) to perform the nth broaching.

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