Replaceable drill bit

Abstract

The utility model discloses a replaceable drill bit blade and a cutter body thereof, which belong to the technical field of metal cutting tools and comprise a blade, a cutter body and a screw. A screw through hole penetrates through the side wall of the blade, and a concave positioning face is formed at the bottom of the blade. The end of the cutter body extends outwards to form two clamping arms, threaded holes are formed in the two clamping arms in a penetrating mode, and the bottom face part of the assembling groove of the cutter body extends outwards to form an outwards-protruding positioning face. The screw can sequentially penetrate through the screw through hole and the threaded hole. The blade is clamped between the two clamping arms, the positioning function is achieved, and meanwhile the cutter body stably transmits torque to the blade through the two clamping arms. Meanwhile, in the assembly groove, the bottom of the blade is matched with the convex positioning surface on the cutter body through the concave positioning surface, so that the blade can be quickly aligned with the center of the cutter body, the overall assembly precision of the drill bit is ensured, and the situation that the performance and the service life of the blade are affected due to reduction of the overall strength and precision of the drill bit caused by eccentric load on the drill bit is avoided.

Description

Technical Field

[0001] The utility model belongs to the technical field of metal cutting tools, in particular to a replaceable drill bit. Background Art

[0002] Metal cutting drill bits are tools used to drill holes in metal materials. They are typically made of high-strength, high-hardness materials to ensure effective cutting of hard metals. Carbide drills have seen rapid development in recent years. To achieve higher efficiency, lower costs, and conserve carbide material, new replaceable-tip drill designs have emerged. Compared to solid carbide drills, replaceable-tip drills require only the drill head to be replaced in the event of damage. This not only improves production efficiency but also reduces inventory and saves costs.

[0003] The head of a replaceable drill bit is generally made of cemented carbide, and the connected cutter body is made of a relatively elastic material. The connection between the drill head and the cutter body requires sufficient precision and strength to ensure the product's processing accuracy and stability, so the design of the connection part is particularly important. Currently, the replaceable drill bit blades on the market are mainly divided into crown-type and single-piece types. The crown-type drill bit blade and the cutter body have higher installation and matching precision, and relatively good processing precision and lifespan, but they require high manufacturing difficulty and greatly increase production costs. For single-piece drill bit blades, the manufacturing difficulty requirements are relatively low and the cost-effectiveness is high, but the structure of the single-piece drill bit blade is relatively thin. The method of matching with the cutter body is usually to squeeze and lock the blade through the center hole of the blade or to squeeze the side of a round pin by screws. The overall accuracy of the blade and the cutter body after locking is not as good as that of the crown-type drill bit blade.

[0004] Utility model patent application number 201510252190.0 discloses a drill bit with a replaceable cutter head structure. The drill bit features a cutter head fixing hole and a locking groove in the cutter head. The cutter head and cutter body are secured together by a retaining screw that engages the locking groove. However, this method of engagement generates subtle, high-frequency vibrations between the fixing post and the fixing screw, generating significant localized stress between the two, which can easily lead to loosening of the fixing screw. Furthermore, eccentric loading negatively impacts the cutter head's strength, significantly reducing its service life. Utility Model Content

[0005] The purpose of the present invention is to provide a replaceable drill bit to solve the problems raised in the above-mentioned prior art.

[0006] A replaceable drill bit is provided, comprising:

[0007] A blade, wherein a screw through hole is passed through the side wall of the blade, and the bottom assembly surface of the blade is recessed inward to form a concave positioning surface;

[0008] A blade body, wherein the end of the blade body extends outwardly to form two clamping arms, an assembly groove is formed between the assembly surfaces of the two clamping arms, and the two clamping arms are penetrated by a threaded hole coaxially arranged with the screw through hole, and the bottom surface of the blade body located in the assembly groove extends outward to form a convex positioning surface that can be affixed to the concave positioning surface;

[0009] The screw can pass through the screw through hole and the threaded hole in sequence.

[0010] As a further embodiment of the present invention, the mating surfaces of the concave and convex positioning surfaces are two smooth surfaces extending in opposite directions. These smooth surfaces allow the blade to slide naturally into the blade body when inserted into the assembly slot, allowing the concave and convex positioning surfaces to engage with each other without the need for external force. Furthermore, the smooth surfaces ensure that the structural strength of the blade and the blade body is evenly distributed, preventing one from being too strong while the other is too weak.

[0011] As a further embodiment of the present invention, the angle between the two smooth surfaces is α, and the angle α is 140°~165°, so as to ensure that the convex positioning surface of the cutter body has sufficient supporting strength.

[0012] As a further embodiment of the present invention, the two side mounting surfaces of the blade respectively form, from top to bottom, a positioning and clamping surface and a clearance surface. The clearance surface is formed by being recessed inwardly relative to the positioning and clamping surface on the side wall of the blade. The clearance surface serves to reduce the contact area between the side wall of the lower half of the blade and the clamping arm of the blade body. This not only reduces the manufacturing difficulty of the blade body and the grinding cost of the blade, but also improves the fitting precision of the connection between the blade and the blade body.

[0013] As a further embodiment of the present invention, the recessed distance of the clearance surface relative to the positioning and clamping surface is 0.15 mm to 0.3 mm, thereby ensuring the structural strength of the blade while meeting the requirement of reducing the processing accuracy.

[0014] As a further embodiment of the present invention, the distance between the two positioning and clamping surfaces of the blade is 0.01 mm to 0.08 mm smaller than the distance between the two assembly surfaces of the assembly slot, thereby ensuring smooth insertion of the blade while preventing excessive positioning errors caused by excessive clearance.

[0015] As a further embodiment of the present invention, the central axis of the screw hole forms an angle of β degrees with the normal to the sidewall mounting surface of the blade, and the angle β is between 25° and 40°. The inclined arrangement of the screw hole is to allow the screw to avoid the spiral groove on the blade, ensuring that the screw hole and the threaded hole have sufficient apertures, thereby ensuring the assembly strength between the blade and the blade body.

[0016] Compared with the prior art, the beneficial effects of the present invention are:

[0017] The blade is clamped between two clamping arms, providing a positioning function while the cutter body, through the two clamping arms, stably transmits torque to the blade. Simultaneously, within the assembly slot, the blade's bottom, via a concave positioning surface, mates with the convex positioning surface on the cutter body, enabling the blade to quickly align with the center of the cutter body. This ensures the overall assembly accuracy of the drill bit and prevents eccentric loading on the drill bit, which could reduce overall strength and precision, thereby impacting the blade's performance and service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present drawings or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present drawings. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0019] Figure 1 This is an exploded structural diagram of a replaceable drill bit;

[0020] Figure 2 This is the assembly drawing of the replaceable drill bit;

[0021] Figure 3 This is one of the structural diagrams of the blade provided by the utility model;

[0022] Figure 4 This is the second structural diagram of the blade provided by the utility model;

[0023] Figure 5 This is the third structural diagram of the blade provided by the utility model.

[0024] In the figure: 1. Blade; 11. Screw through hole; 12. Concave positioning surface; 13. Positioning and clamping surface; 14. Air-avoiding surface; 2. Blade body; 21. Clamping arm; 22. Assembly groove; 23. Threaded hole; 24. Convex positioning surface; 3. Screw. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is described and illustrated below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are merely used to explain this application and are not intended to limit this application. Based on the embodiments provided in this application, all other embodiments obtained by those of ordinary skill in the art without making any creative efforts are within the scope of protection of this application.

[0026] Obviously, the drawings described below are merely examples or embodiments of the present application. Those skilled in the art can, without inventive effort, apply the present application to other similar scenarios based on these drawings. Furthermore, it is also understood that, although the effort involved in such a development process may be complex and lengthy, for those skilled in the art related to the content disclosed in this application, changes in design, manufacturing, or production based on the technical content disclosed in this application are merely conventional technical means and should not be construed as an insufficiency of the content disclosed in this application.

[0027] However, unnecessary detailed descriptions may be omitted. For example, detailed descriptions of well-known matters and repetitive descriptions of substantially identical structures may be omitted. This is to avoid unnecessary redundancy in the following description and to facilitate understanding by those skilled in the art. Furthermore, the drawings and the following description are provided to facilitate a thorough understanding of this application by those skilled in the art and are not intended to limit the subject matter recited in the claims.

[0028] See also Figure 1-3 As shown, the replaceable drill bit in the embodiment of the present invention includes a blade 1, a cutter body 2, and a screw 3. The side wall of the blade 1 is penetrated by a screw through hole 11, and the bottom assembly surface of the blade 1 is recessed inward to form an inner concave positioning surface 12. The end of the cutter body 2 extends outward to form two clamping arms 21, and an assembly groove 22 is formed between the assembly surfaces of the two clamping arms 21. Both clamping arms 21 are penetrated by a threaded hole 23 arranged coaxially with the screw through hole 11. The bottom surface of the cutter body 2 located in the assembly groove 22 extends outward to form a convex positioning surface 24 that can fit with the inner concave positioning surface 12. The screw 3 can pass through the screw through hole 11 and the threaded hole 23 in sequence.

[0029] The replaceable drill bit blade 1 as a whole adopts a sheet-like centrally symmetrical structure. The top of the blade 1 is provided with a drill tip and cutting edge, and spiral chip grooves are provided on both sides, which smoothly transition to the spiral chip groove structure on the cutter body 2. The mating surfaces between the blade 1 and the two clamping arms 21 are the two side assembly surfaces, and the mating surface between the blade 1 and the bottom of the assembly groove 22 of the cutter body 2 is the bottom assembly surface. The concave positioning surface 12 at the bottom of the blade 1 is concave inward and has the same shape as the convex positioning surface 24 extending from the bottom of the assembly groove 22. This enables the blade 1 to be quickly aligned with the center of the cutter body 2, avoiding assembly errors caused by manual assembly and alignment. At the same time, the bottom mating surface plays a supporting role for the entire blade 1, bearing the axial force transmitted from the drill tip during drilling.

[0030] After the blade 1 and the cutter body 2 are positioned, screws 3 are threadedly connected to the two threaded holes 23 and pass through screw holes 11, securing the blade 1 to the cutter body 2. The diameter of screw holes 11 should be 0.2mm to 0.6mm larger than the diameter of screw 3 to ensure that screw 3 can pass through the blade 1 and lock it without interference. The restraining fit between the concave positioning surface 12 and the convex positioning surface 24 can greatly eliminate vibration of the blade 1 caused by this clearance.

[0031] The concave positioning surface 12 and the convex positioning surface 24 are two smooth surfaces extending in opposite directions, forming a V-shaped positioning surface. When inserting the blade 1 into the assembly slot 22 from top to bottom, the blade 1 quickly and accurately lands on the convex positioning surface 24 and is clamped and positioned by the two clamping arms 21 on the blade body 2, achieving efficient and precise positioning.

[0032] The included angle α between the two smooth surfaces of the "V"-shaped positioning surface is 140° to 165°. When the bottom mounting surface of insert 1 is fully in contact with the mounting surface of cutter body 2, gravity quickly aligns the center of insert 1 with the center of cutter body 2, preventing deviations in overall accuracy caused by manual factors during installation. To ensure structural strength, the included angle should not be too small to prevent the area around the concave positioning surface 12 of insert 1 from breaking due to excessive lateral forces.

[0033] See also Figure 1 and Figure 4 As shown, the two side assembly surfaces of the blade 1 form a positioning clamping surface 13 and an air avoidance surface 14 from top to bottom, respectively. If the entire surface of the side assembly surface of the blade 1 is in a horizontal plane, assembly interference may occur between a certain part of the side assembly surface of the blade 1 and the assembly surface of the clamping arm 21 due to processing accuracy issues, especially the bottom area of ​​the side assembly surface of the blade 1 and the bottom area of ​​the side wall of the assembly groove 22 of the cutter body 2, thereby causing local interference and stress to affect the assembly process and the structural strength of the drill bit. The air avoidance surface 14 can reduce the contact area between the blade 1 and the cutter body 2, prevent the bottom of the side assembly surface of the blade 1 from interfering with the bottom part of the side wall of the assembly groove 22 of the cutter body 2, improve the force uniformity of the clamping surface of the blade 1, and improve the clamping effect of the clamping arm 21.

[0034] The clearance surface 14 is recessed by 0.15mm to 0.3mm relative to the positioning and clamping surface 13. This provides a margin for machining accuracy issues at the bottom of the assembly slot 22 of the blade body 2. Even if this portion extends outward, the clearance surface 14 still has sufficient space to prevent interference. However, the recessed distance should be limited to prevent the bottom of the blade 1 from being weakened and impacting its strength.

[0035] The distance between the two positioning and clamping surfaces 13 of the blade 1 is 0.01mm to 0.08mm smaller than the distance between the two mounting surfaces of the assembly slot 22. This ensures smooth insertion of the blade 1 while preventing excessive clearance that could lead to significant positioning errors. After the blade 1 is inserted into the assembly slot 22 and assembled with the cutter body 2, the two clamping arms 21 are connected using screws 3. The clamping surfaces of the two clamping arms 21 are brought closer together, causing a slight deformation to clamp the blade 1, achieving a stable fixation.

[0036] See also Figure 1 and Figure 5 As shown, the central axis of screw hole 11 forms an angle of β degrees with the normal to the sidewall mounting surface of blade 1, with β being between 25° and 40°. The inclined arrangement of screw hole 11 is intended to allow screw 3 to avoid the spiral groove on blade 1, ensuring sufficient apertures for screw hole 11 and threaded hole 23, and ensuring the assembly strength between blade 1 and blade body 2. Too large an angle would affect the overall rigidity of blade 1, while too small an angle would not provide sufficient avoidance.

[0037] Spiral cooling water channels 4 are provided on the outer diameter surfaces on both sides of the spiral groove of the cutter body 2. The spiral direction is consistent with the direction of the chip groove. Its function is to increase the flow rate and flow velocity of the coolant outside the cutter body 2. It can not only prevent large circles of iron chips from being entangled on the side walls of the cutter body 2, but also effectively solve the problem of small debris being involved in the repeated friction between the outer side walls of the cutter body 2 and the hole wall, thereby avoiding affecting the smoothness of the processed hole wall.

[0038] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are merely examples, and any embodiments having substantially the same structure and effect as the technical concept within the scope of the present application are all included in the technical scope of the present application. In addition, without departing from the scope of the present application, any other embodiments that can be conceived by those skilled in the art and that combine some of the constituent elements in the embodiments are also included in the scope of the present application.

Claims

1. A replaceable drill bit, characterized in that: include: A blade (1), wherein a screw through hole (11) is passed through a side wall of the blade (1), a bottom assembly surface of the blade (1) is recessed inwardly to form an inwardly recessed positioning surface (12), and two side assembly surfaces of the blade (1) are formed from top to bottom to form a positioning clamping surface (13) and a clearance surface (14), respectively, wherein the clearance surface (14) is formed on the side wall of the blade (1) to be recessed inwardly relative to the positioning clamping surface (13); A blade body (2), wherein the end of the blade body (2) extends outward to form two clamping arms (21), an assembly groove (22) is formed between the assembly surfaces of the two clamping arms (21), and the two clamping arms (21) are penetrated by a threaded hole (23) coaxially arranged with the screw through hole (11), and the bottom surface of the blade body (2) located in the assembly groove (22) extends outward to form a convex positioning surface (24) that can be fitted with the concave positioning surface (12); A screw (3) is provided, wherein the screw (3) can sequentially pass through the screw through hole (11) and the threaded hole (23), wherein an angle of β degrees is formed between the central axis of the screw through hole (11) and the normal to the side wall assembly surface of the blade (1), and the angle β is 25° to 40°.

2. The replaceable drill bit according to claim 1, characterized in that: The fitting surfaces of the inner concave positioning surface (12) and the outer convex positioning surface (24) are two smooth surfaces extending to both sides respectively.

3. The replaceable drill bit according to claim 2, characterized in that: The angle between the two smooth surfaces is α, and the angle α is 140°~165°.

4. The replaceable drill bit according to claim 1, characterized in that: The indentation distance of the air-avoiding surface (14) relative to the positioning clamping surface (13) is 0.15 mm to 0.3 mm.

5. The replaceable drill bit according to claim 1, characterized in that: The distance between the two positioning clamping surfaces (13) of the blade (1) is 0.01 mm to 0.08 mm smaller than the distance between the two assembly surfaces of the assembly groove (22).

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