Externally embedded flocking broach

Abstract

The invention discloses an externally embedded flocked broach; the externally embedded flocked broach comprises a broach body, and a plurality of flocked blade teeth arranged in sequence along the length direction of the broach body. A fluff area is provided on the front cutting surface of the flocking blade teeth; a plurality of fluff fibers are provided in the fluff area. The diameter of a single fiber fluff is 0.8 μm to 10 μm, and the length is 0.6 mm to 1 mm; the invention provides a fluff area on the front cutting surface of the broach blade teeth, so that the front cutting surface of the broach has good lipophilicity, and significantly reduces the friction force and friction coefficient of the blade interface during processing. In the invention, different fluff areas are provided in the rough drawing section, the semi-finishing drawing section and the finishing drawing section; a connected whole fluff area is provided in the rough drawing section to maximize the heat dissipation effect during the rough drawing process; a plurality of mutually isolated partitions are provided in the semi-finishing drawing section and the finishing drawing section, and the channels between the partitions are used to improve the chip removal effect, thereby improving the surface quality of the processed surface of the workpiece.

Description

Technical Field

[0001] The invention relates to the field of high-performance manufacturing technology of broaches with functional surfaces based on physics, and in particular to a high-performance, high-precision and high-efficiency externally embedded flocking broach. Technical Background

[0002] In order to improve the broaching performance of broaches, the improvement and optimization of broaches have been very common. However, most of the existing improvement methods are only changes in morphology and structure, and have not achieved qualitative improvement and demonstrated higher performance. In addition, many existing broaches are one-piece broaches, which not only have high cost and manufacturing cost, but also have a short service life and cannot be recycled. Once local damage occurs, the whole broach cannot be used again. Therefore, based on the existing technology and problems, an externally embedded flocking broach is proposed to achieve a significant improvement in the comprehensive performance of the broach.

[0003] At present, for example, the patent with application number CN202121943352.2 discloses a spline broach assembly and broach arbor. The spline broach changes the installation and positioning method of the traditional spline broach assembly. The diameter of the shank section at the tail end of the spline broach arbor is increased to increase the force contact area of ​​the entire broach. The tail end shank section is used as the positioning reference to increase the stability of the positioning surface. The leading external spline is set on an independent spline leading sleeve. The spline leading sleeve is short and has good processability. It is easy to process the leading external spline and improve the positioning accuracy. However, the spline broach does not improve the broaching performance of the tool, such as broaching load, friction coefficient, and surface quality of the workpiece. For example, the patent with application number CN202110258842.7 discloses a single section and a complete set of internally cooled carbide blade broaches. The single section and the complete set of internally cooled carbide blade broaches of the present invention can inject broaching oil into the blade edge to reduce the broaching temperature of the broach, thereby indirectly improving the service life of the tool. However, the broach fails to optimize the problems of tool wear and tool vibration caused by grinding chips during the broaching process.

[0004] The service performance of broaches has always been affected by the inherent problems such as the physical structure of the broaches and the wear caused by the broaching process, which leads to various problems when the broaches are used, and has an unpredictable impact on the actual use of structures such as mortise and tenon, spline, etc. Therefore, an externally embedded flocked broach is proposed to solve the problems of broach cooling, load reduction, lubrication and micro-chip processing. Summary of the invention

[0005] The purpose of the present invention is to propose an externally embedded flocked broach to address the problems of poor workpiece precision, low quality and severe wear when processing important core aerospace components such as turbine disc tenons and grooves, due to the influence of temperature and the physical structure of the tool when the integrated broach is put into use, as well as large cutting load, high cutting temperature and short service life of the tool.

[0006] An externally embedded flocking broach comprises a broach body and a plurality of flocking blade teeth arranged in sequence along the length direction of the broach body. A fluff area is provided on the front blade surface of the flocking blade teeth; a plurality of fluff fibers are provided in the fluff area. The diameter of a single fluff fiber is 0.8 μm to 10 μm, and the length is 0.6 mm to 1 mm;

[0007] Preferably, the broach body is divided into a roughing section, a semi-finishing section, and a finishing section arranged in sequence along the broaching feed direction. The roughing section, the semi-finishing section, and the finishing section each contain a plurality of flocking teeth. The fluff area on the flocking teeth is composed of a plurality of flocking partitions arranged in sequence along the width direction of the flocking teeth; the number of flocking partitions of the flocking teeth of the roughing section, the semi-finishing section, and the finishing section increases in sequence, and the width of a single flocking partition and the spacing between two adjacent flocking partitions decrease in sequence.

[0008] Preferably, the fluff area of ​​the flocking teeth of the rough drawing section is a rectangular area; the length of the rectangular area is equal to the width of the flocking teeth. The fluff area of ​​the flocking teeth of the semi-fine drawing section is composed of three first rectangular partitions arranged in sequence along the width direction of the flocking teeth; the spacing between two adjacent first rectangular partitions is 2.5mm to 2.7mm. The fluff area of ​​the flocking teeth of the fine drawing section is composed of four second rectangular partitions arranged in sequence along the width direction of the flocking teeth; the spacing between two adjacent second rectangular partitions is 1.8mm to 1.9mm.

[0009] Preferably, the material of the fluff fibers is nylon or carbon fiber; the fluff fibers are fixed to the fluff area by electrostatic flocking; the flocking density of the fluff area is 0.175 mg / mm 2 ~0.183mg / mm 2 The corresponding flocking voltage is 15kV~17kV.

[0010] Preferably, the flocking blade has a length c=14 mm, a width k=13 mm, and a front angle γ=13°-15°. The width of the first rectangular partition is 2.6 mm; the width of the second rectangular partition is 1.86 mm. The width of the fluff area is 3-5 mm.

[0011] Preferably, the broach body is provided with a plurality of blade limiting parts arranged in sequence in the length direction of the broach; the flocking teeth correspond to the blade limiting parts one by one. A limiting groove is provided on the blade limiting part. Two limiting surfaces perpendicular to each other are provided on the limiting groove. A positioning hole in the shape of 3 / 4 circle is provided at the connection of the two limiting surfaces; each flocking tooth is respectively arranged in the limiting groove of the corresponding blade limiting part.

[0012] Preferably, the back angles of the blade limiting parts in the rough drawing section, the semi-finishing drawing section, and the finishing drawing section are α1, α2, and α3, respectively, wherein α1=4°-6°, α2=5°-7°, α3=6°-8°, and α3>α2>α1.

[0013] Preferably, a countersunk hole is provided in the middle of each flocking blade, and a threaded hole is provided on the bottom surface of each limiting groove. The countersunk hole of the flocking blade is fixed to the threaded hole of the corresponding limiting groove by bolts.

[0014] Preferably, the center distance between any two adjacent blade limiting portions is h2 = 30 mm to 33 mm.

[0015] Preferably, the distance between the blade limiting portion at the head end and the front end of the broach body is h1=17 mm to 20 mm.

[0016] Preferably, the rough drawing section, the semi-finishing drawing section and the finishing drawing section all comprise three flocking teeth.

[0017] The beneficial effects of the present invention are:

[0018] 1. The present invention provides a fuzzy area on the front cutting surface of the broach teeth, so that the front cutting surface of the broach has good lipophilicity, significantly reduces the friction force and friction coefficient of the blade interface during processing, and further reduces the cutting force Fc and the positive pressure Ft.

[0019] 2. In the present invention, different fluff areas are arranged in the rough drawing section, semi-finishing drawing section and finishing drawing section; a connected whole fluff area is arranged in the rough drawing section to maximize the heat dissipation effect during the rough drawing process; a plurality of mutually isolated partitions are arranged in the semi-finishing drawing section and the finishing drawing section, and the channels between the partitions are utilized to improve the chip removal effect and improve the surface quality of the processed surface of the workpiece.

[0020] 3. The present invention attaches a layer of fluff with high elastic self-recovery ability on the rake face of the broach teeth, which can suppress the coupled chatter phenomenon of the tool during the processing, thereby suppressing the deformation caused by chatter and reducing the thermal deformation of the workpiece caused by the cutting temperature, and further suppressing the vibration marks and ablation of the workpiece.

[0021] 4. The layer of fluff attached to the front cutting edge of the broach tooth of the present invention has a certain height, so that the tiny grinding chips generated during the broaching process can be stored in the gaps between the fluffs, so that they flow away with the lubricating fluid, thereby reducing the stress between the tool and the chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0023] Figure 2 It is a side view of the present invention.

[0024] Figure 3 It is a top view of the present invention.

[0025] Figure 4 It is a schematic diagram of a single flocking knife tooth in the present invention.

[0026] Figure 5 It is a schematic diagram of the installation positions of different flocking blade teeth in the present invention.

[0027] Figure 6 Schematic diagram of the design structure and corresponding surface morphology of the experimental groups 1-4 and the control group in the broaching force and normal pressure comparison test.

[0028] Figure 7 This is a comparison chart of the results of the broaching force and positive pressure comparison test.

[0029] Figure 8 Comparison of wettability between flocked surface and non-flocked surface.

[0030] Fig. 9 This is a comparison chart of lubricant spreading on flocked surface and non-flocked surface.

[0031] Fig.10 Schematic diagram for comparison of the cutting process of experimental groups 1-4.

[0032] Fig.11 This is a comparison chart of the vibration suppression effects between the experimental groups 1-4 and the control group.

[0033] Fig.12 Schematic diagram of the broaching process of flocked broaches and non-flocked broaches. DETAILED DESCRIPTION

[0034] The present invention is further described below in conjunction with the accompanying drawings.

[0035] like Figure 1As shown, an externally embedded flocking broach comprises a broach body 1 and nine flocking teeth 3. The broach body 1 is provided with nine blade limiting parts 2 arranged in sequence in the length direction of the broach; the blade limiting part 2 is provided with a limiting groove. The limiting groove is provided with two mutually perpendicular limiting surfaces. A 3 / 4 circular positioning hole 2-5 is provided at the connection of the two limiting surfaces to facilitate the installation of the flocking teeth; the nine flocking teeth 3 are respectively arranged in the limiting grooves of the nine blade limiting parts 2. A countersunk hole 2-4 is provided in the middle of each flocking tooth; a threaded hole is provided on the bottom surface of each limiting groove. The countersunk hole of the flocking tooth and the threaded hole of the corresponding limiting groove are fixed by bolts.

[0036] The broach body 1 is provided with a roughing section 2-1, a semi-finishing section 2-2, and a finishing section 2-3 arranged in sequence along the broaching feed direction. The roughing section 2-1, the semi-finishing section 2-2, and the finishing section 2-3 each include three blade limiting parts 2. The back angles of the blade limiting parts 2 in the roughing section 2-1, the semi-finishing section 2-2, and the finishing section 2-3 are α i , i = 1, 2, 3. Among them, α1 = 4° ~ 6°, α2 = 5° ~ 7°, α3 = 6° ~ 8°, and α3> α2> α1. The distance between the first blade stopper 2 and the front end of the broach body is h1 = 17mm ~ 20mm; the center distance between any two adjacent blade stoppers 2 is h2 = 30mm ~ 33mm, and the distance is uniform.

[0037] like Figure 2 , Figure 4 and Figure 5 As shown, the length c of the flocking tooth 3 is 14 mm, the width k is 13 mm, and the front angle γ is 13°-15°; a fluff area is provided on the front blade surface of the flocking tooth 3; a plurality of densely arranged fluff fibers 4 are implanted or bonded in the fluff area. The diameter of a single fluff fiber 4 is 0.8 μm to 10 μm, and the length is 0.6 mm to 1 mm; the length of the fluff fiber 4 is preferably 0.8 mm. The material of the fluff fiber 4 is nylon or carbon fiber (nylon is used in subsequent comparative tests); the fluff fiber is fixed to the fluff area by electrostatic flocking; the flocking voltage is 16 kV; and the final flocking density is 0.18 mg / mm 2 .

[0038] The shapes of the pile areas of the flocking blade teeth 3 in the rough drawing section, the semi-finishing drawing section and the finishing drawing section are different from each other.

[0039] The flocking blade teeth 3 of the rough drawing section adopt the first flocking method: the flock area of ​​the flocking blade teeth 3 of the rough drawing section is a rectangular area; the length x1 of the rectangular area is 13 mm, and the width y1 is 5 mm.

[0040] The flocking teeth 3 of the semi-finishing drawing section adopt the second flocking method: the flock area of ​​the flocking teeth 3 of the semi-finishing drawing section is composed of three first rectangular partitions; the length x2=2.6mm, the width y2=5mm of the first rectangular partition; each first rectangular partition is arranged in sequence along the width direction of the flocking teeth 3 (that is, the direction of the cutting edge axis); the distance between two adjacent first rectangular partitions is t1=2.6mm.

[0041] The flocking teeth 3 of the fine drawing section adopt the third flocking method: the flock area of ​​the flocking teeth 3 of the fine drawing section is composed of four second rectangular partitions; the length x3=1.86mm, the width y3=5mm of the second rectangular partition; each second rectangular partition is arranged in sequence along the width direction of the flocking teeth 3 (that is, the direction of the cutting edge axis); the distance between two adjacent second rectangular partitions is t2=1.86mm.

[0042] The flocking teeth 3 of the roughing section 2-1, the semi-finishing section 2-2 and the finishing section 2-3 are respectively roughing teeth 3-1, semi-finishing teeth 3-2 and finishing teeth 3-3. In a broaching stage, the roughing teeth 3-1, semi-finishing teeth 3-2 and finishing teeth 3-3 broach the workpiece in sequence.

[0043] Since the rough broaching tooth 3-1 that first contacts the workpiece during broaching has the largest amount of metal material broached, a large amount of heat and large debris will be generated during the broaching process. In order to better reduce the heat generated by broaching and clean up the large debris, a flocking method of a single complete rectangular area is adopted. In addition, since the rough broaching tooth 3-1 has to remove thicker metal material, the wear between the metal material and the tool is more serious, and a larger flocking area helps to improve the adsorption capacity of the tooth to the lubricant, thereby providing a better lubrication effect, reducing the wear of the workpiece, and improving the surface quality of the workpiece.

[0044] When the workpiece contacts the semi-finishing broach tooth 3-2, due to the buffering of the rough broach tooth 3-1, the temperature will be reduced and the debris will be reduced, mainly small-volume grinding chips. In order to prevent the grinding chips from accumulating on the front cutting face of the semi-finishing broach tooth 3-2 during the broaching process, the interval flocking method composed of three first rectangular partitions is selected; this flocking method can not only store a certain amount of lubricating fluid by capillary force, but also play the role of quickly flushing away the grinding chips from the gaps between adjacent first rectangular partitions.

[0045] The finishing broach teeth 3-3 are used to process high dimensional accuracy and high-quality surfaces; and the abrasive chips formed by broaching are an important reason affecting the surface quality of the workpiece; therefore, the finishing broach teeth 3-3 are selected to adopt an interval flocking method consisting of four second rectangular partitions. This flocking method can not only maximize the effect of washing away the abrasive chips, but also use capillary force and Laplace pressure difference to ensure that a sufficient amount of lubricating fluid is retained on the front cutting edge of the finishing broach teeth 3-3.

[0046] To summarize, the present invention provides a method for comprehensively improving the physical and chemical properties of the broach by changing a plurality of rows of teeth into an externally embedded broach consisting of blade limiting grooves and flocking teeth that increase and change sequentially from the cutting entry end to the cutting exit end based on a processing method of a broach; a method for realizing convenient disassembly and installation by using self-designed flocking teeth; a method for a broach having regularly distributed fluff fibers to ensure that the tool has the functions of load reduction, cooling, lubrication, vibration suppression, and chip storage when in service; a method for fixing flocking teeth by regularly arranging blade limiting grooves on a broach body to realize the transformation into an integrated broach having a plurality of rows of teeth after the flocking teeth are combined; a method for improving and optimizing the problems and challenges of traditional broaches by using a flocking broach with a multi-functional, multi-responsive, and intelligent design; and an externally embedded flocking broach that integrates fluff fibers, flocking teeth, and a broach body.

[0047] In order to evaluate the cutting performance of flocking cutters with different flocking methods, comparative tests were conducted at different broaching speeds. The specific test process is as follows:

[0048] The tested tooth was installed on a single-tooth broaching test bench, and the tested tooth was used to broach the cemented carbide YG8 workpiece at different broaching speeds. The broaching depth was 0.05 mm; the broaching speeds were 20 mm / s, 40 mm / s, and 60 mm / s, respectively. During the broaching process, a three-dimensional force sensor (model: KISTLER9119AA2) with a collection frequency of 1024 Hz was used to collect the broaching load. After broaching, a high-speed digital camera (type: KEYENCE VW-9000) was used to observe the morphology of the chips and workpiece.

[0049] like Figure 6 As shown, four experimental groups and one control group are set up. The four experimental groups are respectively denoted as FB1-FB4; the control group is denoted as (NB); in experimental group 1 (FB1), the tested blade teeth are flocked broaches using the first flocking method; in experimental group 2 (FB2), the tested blade teeth are flocked broaches using the third flocking method; in experimental group 3 (FB3), the tested blade teeth are flocked broaches using the second flocking method; in the control group (NB), no flocking is performed on the tested blade teeth.

[0050] The specific dimensions of the flocking areas in the four experimental groups and one control group are shown in Table 1 .

[0051] Table 1 Dimensional parameters of five types of broach flocking

[0052]

[0053] The test results are as follows Figure 7 shown; from Figure 7It can be seen from part (a) that with the increase of cutting speed, the cutting force (Fc) of all broaches increases to varying degrees. Compared with the control group (NB), the flocking broach presents a smaller cutting force. In addition, the cutting force of experimental group 2 (FB2) decreases the most. At a cutting speed of 20-60 mm / s, the cutting force of experimental group 2 (FB2) is reduced by 16.52%, 16.81% and 5.35% compared with that of control group 1 (NB), respectively. The maximum reduction of the broaching force of experimental group 2 (FB2) is 59.73N at 40 mm / s. The reductions of experimental group 1 (FB1), experimental group 3 (FB3) and experimental group 4 (FB4) at 40 mm / s are 16.25N, 48.79N and 23.33N, respectively.

[0054] The influence of different surface broaches on the normal pressure (Ft) is as follows Figure 7 (b). The changing trends of normal pressure and cutting force are very similar at different broaching speeds. Experimental group 2 (FB2) shows the best cutting performance due to the smallest cutting force. At cutting speeds of 20 mm / s, 40 mm / s and 60 mm / s, the normal pressure of experimental group 2 (FB2) is reduced by 23.95%, 24.41% and 11.37% respectively compared with control group 1 (NB). Therefore, it can be concluded that at a speed of 40 mm / s, the flocking broach can show the best broaching effect, and the processing performance of the flocking teeth may be reduced when the cutting speed is too high.

[0055] It can be seen that flocking teeth have good lipophilicity, which can reduce the friction force and friction coefficient of the blade interface during processing. The lubricant can absorb the high temperature generated by friction, limit the abrasive wear caused by high temperature and the adhesive wear of the tool-chip interface, thereby reducing the cutting force Fc and the positive pressure Ft.

[0056] Cutting fluid plays an important role in lubrication and friction improvement, so wettability experiments were conducted to evaluate the lipophilicity of the flocked surface (FB) and the non-flocked surface (NB). The test results are shown in Figure 2. Figure 8 As shown. It can be seen that at 1 second, the contact angles of both surfaces are less than 90°, indicating that all broaches have good lipophilicity; the contact angle of the unflocked surface (NB) reaches a relatively stable state within 1 second; but the contact angle of the flocked surface (FB) continues to decrease to zero after 1 second, showing good lipophilicity. The reason for this phenomenon is that when the oil droplet contacts the fluff surface, the density of the fluff is quite large, which exerts a thrust on the oil droplet. This is attributed to the presence of an air cushion between the fiber and the oil droplet, which prevents the oil droplet from entering the fiber smoothly. In addition, when the droplet enters the fluff, due to the capillary action between the fluff, the droplet quickly diffuses between the fluff, causing the contact angle of the droplet to decrease rapidly.

[0057] In order to further verify the effectiveness of flocking, a spreading experiment was carried out on the front cutting edge. The results are as follows: Fig. 9 As shown. Fig. 9 In part (a) of the figure, we can see the actual (OD) and analytical (AD) images of the oil spreading on the tooth surface. It can be seen that the droplets spread steadily on the non-flocked surface (NB). However, the droplets spread rapidly on the flocked surface (FB) in an irregular manner. Fig. 9 As shown in part (b), the droplets on the non-flocked surface (NB) spread within 1 second, and then slowly entered a stable state after 1 second. However, the droplets on the flocked surface (FB) continued to spread rapidly throughout the process due to the Laplace pressure difference. Therefore, it can be shown that the flocked surface has a good lubrication effect.

[0058] like Fig.10 As shown, in Fig.10 In part (a), the advantages and disadvantages of the flocking area and flocking interval on the tool surface are summarized to show the advantages of various flocking tools; in part (b), the different cutting performances of various flocking tools caused by the difference in flocking area and surface are explained mechanistically.

[0059] The flocking teeth (FB) changed the contact area between the rake face and the chips, reducing the friction coefficient during broaching. More importantly, due to the good lipophilicity of the flocking teeth (FB), the micro-chip removal capacity (CMR) and the ability to store lubricating fluid were effectively guaranteed compared with the control group 1 (NB), thereby reducing Fc and Ft.

[0060] like Fig.10 As shown in part (b) of Figure 1, experimental group 1 (FB1) can only guarantee good oil storage capacity. Therefore, after a period of broaching, too many micro-chips are generated on the tool surface due to the lack of flock spacing. When the micro-chips cannot be discharged in time, the fibers of experimental group 1 (FB1) can no longer continuously support the micro-chips, which will increase the contact stress of the micro-chips, thereby increasing Fc and Ft. However, compared with experimental group 1 (FB1), experimental group 3 (FB3) and experimental group 4 (FB4), experimental group 2 (FB2) has a reasonable flocking area and spacing, so that the flocks have good adsorption capacity for lubricants and store sufficient lubricants in the gaps. Based on the thickness of the lubricant, experimental group 2 (FB2) also shows excellent CMR in the un-flocking position. Therefore, experimental group 2 (FB2) presents the smallest Fc and Ft. For experimental group 3 (FB3) and experimental group 4 (FB4), since the flocking spacing is larger than that of experimental group 2 (FB2), the lubricity and CMR cannot be guaranteed, resulting in relatively large Fc and Ft.

[0061] In summary, it can be found that the lubrication performance of the tool increases with the increase of the flocking area, and the CMR of the tool increases with the increase of the flocking area, such as Fig.10 Therefore, it can be concluded that there is a certain threshold for the area and spacing of the flocking surface, and exceeding or falling below this threshold will seriously affect the tool broaching performance.

[0062] In order to evaluate the vibration reduction effect of the broach, the cutting forces of the five broaches were analyzed by converting the time domain data (Fc) into the frequency domain through Fourier transform under the conditions of cutting speed of 40 mm / s and time window of 1.57 seconds. Fig.11 As shown, the peak value appears due to the vibration caused by the cutting force and positive cutting force generated by the experimental system when the broach passes through the workpiece. Small peaks can be observed near the broach passing frequency. These small peaks are caused by broach jumping and cutting thickness changes. The maximum average amplitude occurs at control group 1 (NB), indicating that control group 1 (NB) vibrates severely during processing. However, the average amplitude of FB is relatively small compared with control group 1 (NB). Therefore, it can be explained that the flocking broach plays a beneficial role in suppressing vibration. And the average amplitude fluctuation of experimental group 2 (FB2) is the smallest.

[0063] The deformation caused by chatter and the thermal deformation of the workpiece caused by cutting temperature can increase the average friction coefficient on the tool-workpiece interface, thereby affecting the surface quality of the workpiece and reducing the surface roughness. In addition, due to the coupled chatter during the machining process, there are obvious vibration pits and ablation on the workpiece surface. Since the fiber material on the surface of the broach has elastic recovery ability, it can suppress vibration and make the surface quality of the workpiece closer to the ideal surface, such as Fig.12 As shown. For experimental group 1 (FB1), due to the large flocking area, the micro-chips cannot be processed in time, so the micro-chips accumulate on the front cutting edge, causing chatter similar to control group 1 (NB). Experimental groups 3 (FB3) and 4 (FB4) have relatively poor lubricant storage capacity due to the large flocking spacing, resulting in inferior processing quality compared to experimental group 2 (FB2). Due to the balanced flock distribution, experimental group 2 (FB2) has excellent ability in improving broaching stability.

Claims

1. An externally embedded flocking broach, comprising a broach body (1), characterized in that: It also includes a plurality of flocking teeth (3) arranged in sequence along the length direction of the broach body (1); a fluff region is provided on the front blade surface of the flocking teeth (3); a plurality of fluff fibers (4) are provided in the fluff region; a single fluff fiber (4) has a diameter of 0.8 μm to 10 μm and a length of 0.6 mm to 1 mm; The broach body (1) is divided into a rough drawing section (2-1), a semi-finishing drawing section (2-2), and a fine drawing section (2-3) which are arranged in sequence along the broaching feed direction; the rough drawing section (2-1), the semi-finishing drawing section (2-2), and the fine drawing section (2-3) each comprise a plurality of flocking teeth (3); the fluff area on the flocking teeth (3) is composed of a plurality of flocking partitions which are arranged in sequence along the width direction of the flocking teeth (3); the number of flocking partitions of the flocking teeth (3) of the rough drawing section (2-1), the semi-finishing drawing section (2-2), and the fine drawing section (2-3) increases in sequence, and the width of a single flocking partition and the distance between two adjacent flocking partitions decrease in sequence; The fluff area of ​​the flocking teeth (3) of the rough drawing section is a rectangular area; the length of the rectangular area is equal to the width of the flocking teeth (3); the fluff area of ​​the flocking teeth (3) of the semi-fine drawing section is composed of three first rectangular partitions arranged in sequence along the width direction of the flocking teeth (3); the spacing between two adjacent first rectangular partitions is 2.5mm to 2.7mm; the fluff area of ​​the flocking teeth (3) of the fine drawing section is composed of four second rectangular partitions arranged in sequence along the width direction of the flocking teeth (3); the spacing between two adjacent second rectangular partitions is 1.8mm to 1.9mm.

2. The externally embedded flocking broach according to claim 1, characterized in that: The material of the fluff fiber is nylon or carbon fiber; the fluff fiber is fixed to the fluff area by electrostatic flocking; the flocking density of the fluff area is 0.175 mg / mm 2 ~0.183mg / mm 2 .

3. The externally embedded flocking broach according to claim 1 or 2, characterized in that: The length of the flocking blade (3) =14mm, width =13mm, front angle =13°~15°; the width of the first rectangular partition is 2.6mm; the width of the second rectangular partition is 1.86mm; the width of the fluff area is 3~5mm.

4. The externally embedded flocking broach according to claim 1 or 2, characterized in that: The broach body (1) is provided with a plurality of blade limiting parts (2) arranged in sequence in the length direction of the broach; the flocked blade teeth (3) correspond to the blade limiting parts (2) one by one; a limiting groove is provided on the blade limiting part (2); two limiting surfaces perpendicular to each other are provided on the limiting groove; a positioning hole (2-5) in the shape of a 3 / 4 circle is provided at the connection between the two limiting surfaces; and each flocked blade tooth (3) is respectively arranged in the limiting groove of the corresponding blade limiting part (2).

5. The externally embedded flocking broach according to claim 4, characterized in that: The back angles of the blade limiting portion (2) in the rough drawing section (2-1), the semi-finishing drawing section (2-2), and the finishing drawing section (2-3) are respectively , , ;in, , , ,and .

6. The externally embedded flocking broach according to claim 4, characterized in that: A countersunk hole (2-4) is provided in the middle of each flocking knife tooth; a threaded hole is provided on the bottom surface of each limiting groove; and the countersunk hole of the flocking knife tooth and the threaded hole of the corresponding limiting groove are fixed by bolts.

7. The externally embedded flocking broach according to claim 4, characterized in that: The center distance between any two adjacent blade limiting parts (2) 30mm~33mm.

8. The externally embedded flocking broach according to claim 4, characterized in that: The distance between the blade stopper (2) at the head end and the front end of the broach body 17mm~20mm.

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