Protective machining tool suitable for drilling laminated materials

Abstract

The invention provides a protective machining tool suitable for drilling laminated materials, and belongs to the technical field of machining. The protective machining tool comprises four areas, namely a drilling area, a cuttings flow guide area, a discharged cuttings discharging area and a tool handle clamping area. The cutting flow guide area comprises a sleeve body and a part of cutter body. The tool takes a twist drill as a basic configuration, and cuttings are guided into a sleeve from a front tool face through the design of a fillet at the bottom end of the sleeve; the coaxiality and the positioning precision of the cutter and the sleeve are ensured by matching the pin with the pin holes of the holes in the cutter and the sleeve; the two symmetrical keys on the cutter are matched with the key grooves of the grooves in the sleeve, so that the influence of vibration on matching during cutting is reduced, and the matching stability is enhanced; and it is guaranteed that through cooperation of the sleeve and the cutter structure, scratches of lower-layer hard metal cuttings to an upper-layer soft rubber layer in the hole forming process are reduced, and finally the hole wall quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical processing and relates to a protective processing tool suitable for drilling laminated materials. Background Art

[0002] Laminated materials are usually made of two or more materials with different properties. Currently, the more common ones include laminated materials composed of soft materials and hard metals. They are lightweight, high-strength, shock-absorbing and energy-absorbing, and are widely used in precision equipment, aerospace and impact-resistant structures. Parts made of this material often require a large number of hole-making operations during the assembly and connection process. In the process of drilling a composite material of a heterogeneous laminated structure of a soft adhesive layer and a hard metal, the chips generated by the metal base layer are discharged axially. Because the upper layer of adhesive is soft and the lower layer of metal is hard, the chips and the adhesive layer hole wall are subjected to intense friction, which is prone to composite damage such as interface delamination and hole wall scratches, significantly reducing the integrity of the hole surface and resulting in poor processing quality of the composite material. At present, hole wall damage is very likely to occur during the drilling and hole-making process of laminated composite materials, resulting in a significant decrease in the load-bearing performance and service life of the workpiece, posing a major safety hazard. Therefore, there is an urgent need to develop protective processing tools that can effectively reduce drilling damage to laminated materials.

[0003] In order to solve the problem of low-damage hole making in laminated composite materials, scholars have studied the structure of the tool. For example, Liu Huaqiu and others from the Jinan Special Structure Research Institute of China Aviation Industry Corporation invented the "reamer for improving the quality of hole making in aluminum alloy-composite material-titanium alloy laminates", with patent number CN202410856236.9. This tool improves the problem of composite hole diameter deviation and composite entrance and exit damage during the hole making process by adding a guide section and a straight groove structure. However, its complex structure leads to strong application limitations and is difficult to adapt to laminated structural materials with different thickness ratios; Sun Jie and others from Shandong University invented the "integrated tool for hole making in laminated structures with variable spiral grooves and double-cone angles", with patent number CN201720341716.7. This tool has a double-cone angle drill tip, a spiral peripheral blade, Characteristic structures such as variable spiral grooves ensure hole-making accuracy and coaxiality, but the variable spiral groove design makes it difficult to effectively control the secondary damage to the upper soft material hole wall caused by long chips generated by the hard material when processing soft and hard laminated materials. Jia Zhenyuan and others from Dalian University of Technology invented a "multi-step multi-edge tool for integral hole-making of laminated structural parts," patented as CN201610010005.1. This tool uses a stepped ligament structure to isolate the tool, chips, and hole wall, preventing long chips from scratching the composite hole wall, thereby suppressing damage such as delamination and tearing at the composite material entrance. However, fiber-reinforced composite materials and titanium alloys are both hard materials, and the viscoelastic properties of the soft rubber layer can easily cause the tool to stick. This tool structure is not suitable for hole-making in laminated composite materials with a soft upper layer and a hard lower layer. It can be seen that existing tools have difficulty in achieving protective processing in the drilling of laminated composite materials, and there is an urgent need to develop a protective processing tool suitable for drilling laminated materials. Summary of the Invention

[0004] The present invention aims to solve the problem that when drilling holes in laminated composite materials, metal substrate chips are easily generated, which scratch the adhesive layer hole wall and lead to poor processing quality. The present invention has invented an integrated hole-making tool sleeve structure suitable for composite materials with a soft adhesive layer and a hard metal heterogeneous laminate structure. The tool has a tool body structure, a sleeve structure, a pin hole structure, a keyway structure, and a rounded corner structure. The sleeve structure is combined with a traditional tool with a twist drill as the basic configuration to establish a closed cutting field, isolate the chips from the hole wall of the final hole, and allow the chips generated during the processing to be directed into the internal space of the sleeve through the outside of the hole wall, thereby effectively avoiding the contact friction between the chips and the hole wall surface and significantly reducing the hole The risk of wall scratching is reduced, and protective processing of laminated materials is achieved; the pin hole structure realizes the connection between the tool and the sleeve by matching the pin with the holes on the tool and the sleeve to ensure the coaxiality and circumferential positioning accuracy of the two; the keyway structure cooperates with the key at the bottom end of the tool and the keyway of the bottom end groove of the sleeve, and the two together realize the fastening connection between the sleeve structure and the tool; the rounded corner structure located on the inner side of the bottom end of the sleeve is used to guide the chips and realize the transportation and discharge of the chips along the inner wall of the sleeve; the tool sleeve integrated structure formed by the above structures can effectively reduce the damage to the hole wall during the drilling process of soft rubber layer and hard metal laminate, and realize low-damage and high-quality protective processing of laminated materials.

[0005] The technical solution of the present invention:

[0006] A protective machining tool suitable for drilling laminated materials, comprising four areas: a drilling area A, a chip guide area B, a chip discharge area C, and a tool holder clamping area D; the chip guide area B comprises a sleeve body 2 and a portion of a tool body 1.

[0007] The drilling area A includes the tool top angle N, the main cutting edge 109, the positioning plane 106, the flank 107, and the rake 108. The main structure of the protective machining tool is based on a twist drill. The ultimate goal is to machine a final hole with a diameter of D3, wherein the inner diameter of the necking part is D4, and the outer diameter of the necking part is D3. To ensure that the necking part can withstand torque and axial force to avoid fracture, the ratio of D3 and D4 is calculated according to the torsional stress verification ratio formula:

[0008]

[0009] where τ load is the actual shear stress borne by the necking part during drilling, τ allow is the allowable shear stress of the tool material.

[0010] Two main cutting edges 109 are ground outward from the center of the end of the protective machining tool. The side where the chips flow out is the front cutting edge 108, and the side of the front cutting edge 108 away from the main cutting edge 109 is the back cutting edge 107. The tool top angle N realizes the functions of heat dissipation and chip breaking. The part between the outer circle of the necking part of the protective machining tool drill bit and the inner circle of the necking part constitutes a positioning plane 106. The width of the positioning plane 106 is (D3-D4) / 2, which is used for surface contact positioning with the annular plane 206 formed between the outer circle and the inner circle of the bottom end of the sleeve body 2.

[0011] In the chip guide area B 1, the sleeve body 2 includes a sleeve body hole 202, a groove 205, a pin body 3, and a fillet structure 204. Part of the tool body 1 includes a tool body hole 102 and a key 105. The length of the tool body 1 is h1, and the distance between the bottom end of the tool body hole 102 and the bottom end of the tool is h2; the sleeve body 2 is used to isolate the chips from the wall of the final hole drilled by the protective processing tool to form a closed structure, preventing metal chips from scratching the glue layer hole wall, thereby playing a protective role. The fillet structure 204 at the bottom end of the sleeve body 2 is two symmetrical concave arcs. In order to ensure that a channel is formed to guide the chips into the interior of the sleeve body 2, the length of the concave arc should be greater than the transverse cross-sectional length of the chip groove 101. The length of the sleeve body 2 is h3, and the distance between the bottom end of the sleeve body hole 202 and the bottom end of the sleeve is h4. In order to ensure that the sleeve body 2 and the tool are symmetrical, the fillet structure 204 at the bottom end of the sleeve body 2 is h3. The tool body 1 has a stable fit, h1 is greater than h3, the outer diameter of the sleeve is D6, and the inner diameter of the sleeve is D7. The sleeve body 2 and the tool body 1 adopt a base shaft system, with a basic size of D3, forming a clearance fit to ensure assembly and retain appropriate lubrication clearance. After determining the fit accuracy, the proportional relationship between D4 and D7 can be calculated, and the D7 size can be further obtained; the grooves 205 are symmetrically distributed on both sides of the bottom end of the sleeve body 2, and are used to form a keyway structure with the raised key 105 on the tool body 1. The grooves 205 are inserted into the upper key 105 of the drill bit until the upper side surface 203 of the groove is tightly fitted with the upper side surface 104 of the key to achieve a positioning effect, so that the grooves 2 05 is clearance-fitted with the key 105, and the annular plane 206 at the bottom end of the sleeve is in surface contact with the upper positioning plane 106 of the drilling area A of the tool body 1, which enhances the matching stability; the thickness of the groove 205 is the same as the thickness of the sleeve body 2, that is, (D6-D7) / 2; in the keyway structure composed of the groove 205 and the key 105, in order to ensure accurate and stable positioning, the circumference C1 of the outer arc of the cross section of the groove 205 should not be too large; the pin body 3 is used to connect the upper hole 102 of the tool body and the upper hole 202 of the sleeve body, and the two ends of the pin body 3 are rounded to play an assembly guide role, so that the pin body 3 is inserted into the upper hole 102 of the tool body and the upper hole of the sleeve body In 202, by rotating the pin until it passes through the upper hole 102 of the tool body and the upper hole 202 of the sleeve body, the outer surface 301 of the pin is tightly fitted with the inner surface 103 of the upper hole of the tool body and the inner surface 201 of the upper hole of the sleeve body to form a pin hole structure. The pin body 3 cannot rotate or slide relative to the upper hole 102 of the tool body and the upper hole 202 of the sleeve body. The diameter of the upper hole 102 of the tool body is D2, the diameter of the upper hole 202 of the sleeve body is D5, and the diameter of the cross-section circle of the pin body 3 is D8, where D2=D5. According to the theory of internal pressure on thin-walled cylinders, the pin diameter D8 and the tool core diameter D9 should satisfy the proportional relationship:

[0012]

[0013] The axial tensile force is F, and the allowable tensile stress of the pin material is σallow , determine the pin diameter according to the processing requirements and workpiece material;

[0014] To ensure the coaxial positioning accuracy of the tool and sleeve, the tool body hole 102, the sleeve body hole 202, and the pin body 3 are mated using a base axis system with a basic dimension of D2 (D5), forming a clearance fit to ensure assembly and maintain an appropriate lubrication gap. After determining the fit accuracy, the proportional relationship between D2 (D5) and D8 is calculated, and the D8 dimension is further determined. To ensure the stable fit of the pin body 3 with the tool body 1 and sleeve body 2, the length h5 of the pin body 3 must be no less than the sleeve outer diameter D6, and the horizontal plane containing the pin hole structure must form a certain angle with the longitudinal plane containing the groove 205 structure. After the keyway and pin hole fit is completed, the tool body 1 and sleeve body 2 cannot rotate or slide relative to each other. At this point, the assembly of the tool body and sleeve body 2 in the chip guide area B is complete.

[0015] The chip discharge area C includes a chip groove 101. The two chip grooves 101 are formed by two main cutting edges 109 spiraling downward. The chips are discharged from the chip groove 101 inside the sleeve body 2. To ensure smooth chip discharge, the axial length of the spiral groove is less than the total length of the tool. To ensure smooth chip discharge and prevent chip blockage, reduce the chip path in the hole, and ensure the rigidity of each structure of the tool, the tool helix angle β should not be too large and is within the range of 0° to 30.

[0016] The tool shank clamping area D is set to a straight shank clamping mode, and the diameter of the tool shank clamping part is D1, which is the same as the inner diameter of the drill bit, that is, D1 = D3, and the length is set according to the specific clamping requirements.

[0017] Beneficial effects of the present invention: The present invention proposes a protective machining tool for drilling laminated materials, which uses a twist drill as its basic configuration. The rounded corner design at the bottom end of the sleeve guides the chips from the front cutting edge to the inside of the sleeve; the pin cooperates with the pin hole on the tool and the sleeve to ensure the coaxiality and positioning accuracy of the tool and the sleeve; the two symmetrical keys on the tool cooperate with the keyway of the sleeve to reduce the impact of vibration during cutting on the cooperation and enhance the stability of the cooperation; the closed overall structure formed by the cooperation between the sleeve and the tool structure is ensured to isolate the chips from the final hole obtained by drilling, reduce the scratching of the upper soft rubber layer by the lower hard metal chips during the hole making process, and ultimately improve the quality of the hole wall. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Front view of protective tool assembly structure for drilling laminated materials.

[0019] Figure 2 The main view of the protective machining tool body structure for drilling laminated materials.

[0020] Figure 3 This is the end view of the drill tip position.

[0021] Figure 4 This is a partial enlarged view of the drill tip position.

[0022] Figure 5 This is the main view of the sleeve body structure.

[0023] Figure 6 This is a partial enlarged view of the bottom of the sleeve.

[0024] Figure 7 This is a three-dimensional view of the pin body structure.

[0025] In the figure: A-drilling area, B-chip guide area, C-chip discharge area, D-shank clamping area; 1-tool body, 101-chip groove, 102-tool body upper hole, 103-inner surface of tool body upper hole, 104-upper side surface of key, 105-key, 106-positioning plane, 107-flank face, 108-rake face, 109-main cutting edge; 2-sleeve body, 201-inner surface of sleeve body upper hole, 202-sleeve body upper hole, 203-upper side surface of groove, 204-radius structure, 205-groove, 206-annular plane at sleeve bottom end; 3-pin body, 301-outer side surface of pin; D1-diameter of the tool holder clamping part, D2-diameter of the hole 102 on the tool body, D3-outer diameter of the necked part, D4-inner diameter of the necked part, D5-diameter of the hole on the sleeve body, D6-outer diameter of the sleeve, D7-inner diameter of the sleeve, D8-diameter of the cross-section circle of the pin body, D9-core diameter of the tool; C1-circumference of the outer arc of the groove section; h1-length of the tool body, h2-distance from the bottom end of the hole 102 on the tool body to the bottom end of the tool, h3-length of the sleeve body, h4-distance from the bottom end of the hole 202 on the sleeve body to the bottom end of the sleeve, h5-length of the pin body; N-tool top angle, β-tool helix angle. DETAILED DESCRIPTION

[0026] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings and technical solutions.

[0027] Protective machining tool for drilling laminated materials, the specific embodiment of the tool is as follows Figure 1As shown, this tool includes four functional areas: drilling zone A, chip diversion zone B, chip removal zone C, and toolholder clamping zone D. The main cutting edge 109, positioning plane 106, rake face 108, and flank face 109 are contained within drilling zone A. The sleeve body 2 and tool body 1 are integrated into a keyway structure, a hole-shaft structure, and a flat surface that assists positioning. The key 105 and groove 205 of the keyway structure, as well as the tool body hole 102, sleeve body hole 202, pin body 3, sleeve body 2, and fillet structure 204 of the hole-shaft structure, are all contained within chip protection zone B. The chip flute 101 is contained within chip removal zone C. In this example, the ultimate goal is to machine a final hole with a diameter of 7.5 mm, i.e., D3 = 7.50 mm.

[0028] The drilling area A is located at the front end of the tool, and two main cutting edges 109 extend outward from the center of the drill tip. Two chip grooves 101 are formed spirally along the two main cutting edges 109. The side of the main cutting edge 109 where chips flow out is the rake face 108, and the side of the rake face 108 away from the main cutting edge 109 is the flank face 107. In this embodiment, the drill tip apex angle N = 100°, which is convenient for balancing the cutting force and chip removal ability, D3 / D4 = 1.12, that is, D4 = 6.70 mm, and the width of the positioning plane 106 is (D3-D4) / 2 = 0.4 mm.

[0029] The chip protection zone B is located at the upper part of the drill bit, and includes the sleeve body 2, the rounded corner structure 204 at the bottom of the sleeve, and the keyway structure and hole axis structure of the sleeve and the tool. In this embodiment, the tool length h1 = 110mm, the sleeve length h3 = 53mm, the distance h2 from the bottom end of the tool to the bottom end of the hole 102 on the tool body = 55.5mm, and the distance h4 from the bottom end of the sleeve to the bottom end of the hole 202 on the sleeve body = 50mm. In order to ensure that the sleeve and the tool are accurately positioned and sufficient chips can enter, the sleeve and the tool in this embodiment adopt the H7 / g6 matching with the basic axis system of 7.50mm, taking D4 / D7 = 1.00, and the ratio of the outer circle and inner circle diameter of the sleeve D6 / D7 = 1.10, that is, D6 = 7.37mm, D7 = 6.70mm; in the keyway structure composed of the groove 205 and the key 105, the ratio of the outer circle circumference of the tool section to the outer circle arc of the groove section is ΠD 3 / C1=36.23, that is, the outer arc of the groove cross section C1=0.65mm. In this embodiment, the pin diameter D8=1.50mm, the tool core diameter D9=1.48mm, the hole 102 on the tool body (the hole 202 on the sleeve body) and the pin body 3 adopt the H7 / g6 hole axis with a basic axis system and a basic size of 1.50mm. D5(D2) / D8=1.00, the hole 102 on the tool body and the hole 202 on the sleeve body have the same diameter, that is, D2=D5=1.50mm, the ratio of the length h5 of the pin body 3 to the outer diameter D6 of the sleeve is h5 / D6=1.0, that is, h5=7.37mm, and the angle between the transverse plane where the center of the pin hole structure is located and the longitudinal plane where the groove structure is located is 90°.

[0030] The chip discharge area C is located between the sleeve and the straight shank of the tool. In order to ensure a smooth chip discharge process and prevent chip blockage, reduce the chip path in the hole, and ensure the rigidity of each tool structure, in this embodiment, the helix angle β is taken as 17°, and the axial length of the spiral groove is 67% of the total length of the tool.

[0031] The diameter D of the tool holder clamping area is the same as the inner diameter of the drill bit, both of which are D4, namely 6.70 mm. The clamping length is determined according to the actual clamping requirements.

[0032] The present invention is used for protective machining during drilling of laminated materials. The combination of the sleeve and tool isolates the chips from the final hole wall, directing them from the hole wall through the rounded corner structure and then discharging them into the sleeve, minimizing scratches on the adhesive layer caused by the metal chips. The keyway structure and the hole axis structure achieve accurate coordination and stable positioning. The small helix angle facilitates smooth chip discharge and shortens the path of the chips within the hole wall, minimizing damage to the adhesive layer caused by the metal chips. The integrated tool sleeve structure formed by the above structures reduces damage to the hole wall, such as delamination and scratches, during the drilling of soft adhesive layers and hard metal laminates, ultimately achieving protective machining during drilling of laminated composite materials.

Claims

1. A protective machining tool suitable for drilling laminated materials, characterized in that: The protective machining tool comprises four areas: a drilling area (A), a chip guide area (B), a chip discharge area (C), and a tool holder clamping area (D); the chip guide area (B) comprises a sleeve body (2) and a part of the tool body (1).

2. A protective machining tool suitable for drilling laminated materials according to claim 1, characterized in that: The drilling area (A) includes the tool top angle N, the main cutting edge (109), the positioning plane (106), the back face (107) and the front face (108). The main structure of the protective processing tool is based on the twist drill. The ultimate goal is to process a final hole with a diameter of D3, wherein the inner diameter of the necking part is D4 and the outer diameter of the necking part is D3. In order to ensure that the necking part can withstand torque and axial force to avoid fracture, the proportional relationship between D3 and D4 is calculated according to the torsional stress verification ratio formula: where τ load is the actual shear stress borne by the necking part during drilling, τ allow is the allowable shear stress of the tool material; Two main cutting edges (109) are ground outward from the center of the end of the protective machining tool, the side where the chips flow out is the front cutting edge (108), and the side of the front cutting edge (108) away from the main cutting edge (109) is the back cutting edge (107). The tool top angle N realizes the functions of heat dissipation and chip breaking. The part between the outer circle and the inner circle of the necking part of the protective machining tool drill bit forms a positioning plane (106). The width of the positioning plane (106) is (D3-D4) / 2, and is used for surface contact positioning with the annular plane (206) formed between the outer circle and the inner circle of the bottom end of the sleeve body (2).

3. A protective machining tool suitable for drilling laminated materials according to claim 1, characterized in that: In the chip guide area (B), the sleeve body (2) includes a sleeve body hole (202), a groove (205), a pin body (3), and a fillet structure (204), and part of the tool body (1) includes a tool body hole (102) and a key (105); the length of the tool body (1) is h1, and the distance between the bottom end of the tool body hole (102) and the bottom end of the tool is h2; the sleeve body (2) is used to isolate the chips from the end hole wall drilled by the protective processing tool to prevent the metal chips from scratching the glue layer hole wall. The fillet structure (204) at the bottom end of the sleeve body (2) is two symmetrical concave arcs. In order to ensure the formation of a channel for guiding the chips into the sleeve body (2), the inner The length of the concave arc should be greater than the transverse cross-sectional length of the chip removal groove (101), the length of the sleeve body (2) is h3, and the distance between the bottom end of the hole (202) on the sleeve body and the bottom end of the sleeve is h4. In order to ensure the stable fit between the sleeve body (2) and the tool body (1), h1 is greater than h3, the outer diameter of the sleeve is D6, and the inner diameter of the sleeve is D7. The sleeve body (2) and the tool body (1) are matched with the base shaft system, and the basic size is D3, forming a clearance fit to ensure assembly and retain appropriate lubrication clearance. After determining the fit accuracy, the proportional relationship between D4 and D7 can be calculated, and the D7 size can be further obtained; the grooves (205) are symmetrically distributed on both sides of the bottom end of the sleeve body (2) and are used to fit with the tool body (1) The raised key (105) forms a keyway structure, and the groove (205) is inserted into the key (105) on the upper part of the drill bit until the upper side surface (203) of the groove is tightly fitted with the upper side surface (104) of the key to achieve a positioning effect, so that the groove (205) and the key (105) are clearance-matched, and the annular plane (206) at the bottom end of the sleeve is in surface contact with the upper positioning plane (106) of the drilling area (A) of the tool body (1), thereby enhancing the matching stability; the thickness of the groove (205) is the same as the thickness of the sleeve body (2), i.e. (D6-D7) / 2; in the keyway structure composed of the groove (205) and the key (105), in order to ensure accurate and stable positioning, the circumference of the outer arc of the groove (205) cross section is C1 It should not be too large; the pin body (3) is used to connect the hole (102) on the tool body and the hole (202) on the sleeve body, and both ends of the pin body (3) are rounded to play an assembly guide role, so that the pin body (3) is inserted into the hole (102) on the tool body and the hole (202) on the sleeve body, and the pin is rotated until it passes through the hole (102) on the tool body and the hole (202) on the sleeve body, and the outer surface (301) of the pin is tightly fitted with the inner surface (103) of the hole on the tool body and the inner surface (201) of the hole on the sleeve body to form a pin hole structure, and the pin body (3) cannot rotate or slide relative to the hole (102) on the tool body and the hole (202) on the sleeve body;The diameter of the hole (102) on the tool body is D2, the diameter of the hole (202) on the sleeve body is D5, and the diameter of the cross-section circle of the pin body (3) is D8, wherein D2=D5. According to the theory of internal pressure on a thin-walled cylinder, the pin diameter D8 and the tool core diameter D9 should satisfy the proportional relationship: The axial tensile force is F, and the allowable tensile stress of the pin material is σ allow , determine the pin diameter according to the processing requirements and workpiece material; In order to ensure the positioning accuracy of the coaxiality of the tool and the sleeve, the hole (102) on the tool body, the hole (202) on the sleeve body and the pin body (3) are matched with the basic axis system, and the basic size is D2 or D5, forming a clearance match to ensure assembly and retain appropriate lubrication clearance. After determining the matching accuracy, the proportional relationship between D2 or D5 and D8 is calculated, and the D8 size is further obtained; in order to ensure the stable matching of the hole-axis structure of the pin body (3) and the tool body (1) and the sleeve body (2), the length h5 of the pin body (3) should not be less than the outer diameter D6 of the sleeve, and the horizontal plane where the center of the pin hole structure is located and the longitudinal plane where the groove (205) structure is located form a certain angle; after completing the keyway matching and the pin hole matching, the tool body (1) and the sleeve body (2) cannot rotate or slide relative to each other, and the assembly of the part of the tool body and the sleeve body (2) in the chip guide area (B) is completed.

4. A protective machining tool suitable for drilling laminated materials according to claim 1, characterized in that: The chip discharge area (C) includes a chip groove (101), and the two chip grooves (101) are formed by two main cutting edges (109) spirally downward. The chips are discharged from the chip groove (101) in the sleeve body (2). In order to ensure smooth chip discharge, the axial length of the spiral groove is less than the total length of the tool. In order to ensure smooth chip discharge and prevent chip blockage, reduce the path of the chips in the hole, and ensure the rigidity of each structure of the tool, the tool helix angle β should not be too large and is within the range of 0° to 30.

5. The protective machining tool suitable for drilling laminated materials according to claim 1, characterized in that: The tool shank clamping area (D) is set to a straight shank clamping mode, and the diameter of the tool shank clamping part is D1, which is the same as the inner diameter of the aforementioned drill bit, that is, D1 = D3, and the length is set according to specific clamping requirements.

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