Cutting drill with replaceable tooth crown

Abstract

The utility model discloses a cutting drill with a replaceable tooth crown, which belongs to the technical field of metal cutting tools and comprises a drill bit and a cutter body. The drill bit comprises a cutting blade, a middle section clearance area and a mounting part which are sequentially arranged from top to bottom. The cutter body comprises a base and two clamping arms arranged in a rotational symmetry mode, and each clamping arm comprises an inner curved surface, a supporting platform and a boss. The eccentric circular arc on the mounting part and the inner curved surface are eccentrically arranged, the eccentric distance is less than or equal to 0.05 mm, and the diameter of the circular arc section on the mounting part and the diameter of the circular arc section on the inner curved surface are less than or equal to 0.02 mm. At least two sections of non-concentric arcs are arranged at the bottom of the drill bit, interference fit is completed by screwing the drill bit into the corresponding inner curved surfaces, and the drill bit and the cutter body base are locked. The anti-separation effect of the cutting blade and the base is guaranteed, meanwhile, the eccentric structure locking mode is utilized, unnecessary deformation is reduced, and the cutter body still has the long service life after the drill bit and the cutter body are installed and detached for many times.

Description

Technical Field

[0001] The utility model belongs to the technical field of metal cutting tools, in particular to a replaceable tooth crown type cutting drill. 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. Traditional one-piece drill bits, while offering good rigidity and stability, require complete replacement when worn, increasing processing costs and impacting production efficiency. To address these issues, the cutting portion of the drill bit has been gradually optimized, with the cutter body (for chip breaking and guiding) and the drill tip (for machining) separated into two parts. This has led to the development of replaceable head drill bits.

[0003] Interchangeable-tip drills are similar to modular drills, but feature a simpler structure. By separating the drill tip (which performs cutting) from the toolholder (which holds it), worn drill bits can be replaced independently without replacing the entire tool. To ensure ease of assembly and stability during machining, the design of the connection between the toolholder and drill is crucial.

[0004] Currently, the main locking methods for crown drills fall into two categories: fastener locking and self-locking. Fastener locking is relatively simple, but requires additional tools for assembly and removal, resulting in inefficient assembly and removal. Furthermore, under high-frequency vibration or impact, the fasteners may gradually loosen, affecting the securement of the drill bit and the toolholder, and even posing a safety hazard. Self-locking locking relies on an interference fit between the drill tip and the toolholder, achieving self-locking through precise dimensional matching. The advantage of this self-locking design is that it assembles quickly without the need for additional fasteners and tools. However, this design also has significant disadvantages. During machining, the axial locking force generated by the crown drill is only sufficient to prevent the drill bit from falling when it exits the workpiece. The interference fit between the drill bit and toolholder typically evenly distributes force across the entire surface, resulting in extensive, unnecessary deformation and relatively laborious installation. With increased use, the toolholder's rigidity and stability may decrease, affecting the overall life of the tool. Utility Model Content

[0005] The purpose of the utility model is to provide a replaceable tooth crown type cutting drill to solve the problems raised in the above-mentioned prior art.

[0006] Provided is a replaceable crown type cutting drill, comprising:

[0007] The drill bit includes a cutting blade, a middle section clearance area, and a mounting portion arranged in sequence from top to bottom. The bottom of the cutting blade is recessed inward to form two groove areas, and the two groove areas are rotationally symmetrically arranged. There are at least two arc segments in the length direction of the mounting portion that are eccentric arcs with respect to each other.

[0008] The tool body includes a base and two clamping arms arranged in a rotationally symmetric manner. The clamping arm includes an inner curved surface, a support platform, and a boss arranged in sequence from bottom to top.

[0009] When the drill bit is assembled with the tool body, the mounting portion cooperates with the inner curved surface, the middle section clearance area cooperates with the support platform, and the two groove areas respectively cooperate with the corresponding bosses.

[0010] The eccentric arc on the mounting portion is eccentric with respect to the inner curved surface, and the eccentricity is ≤ 0.05 mm. The difference in the diameters of the arc segments on the mounting portion and the arc segments on the inner curved surface is ≤ 0.02 mm.

[0011] As a further embodiment of the present invention: The groove area is provided with a bottom plane and a raised plane in sequence along the radial inner wall of the drill bit axis in the fitting order. The boss is provided with a transition platform and a support plane in sequence along the radial outer wall of the tool body axis in the fitting order. The raised plane extends outward axially relative to the bottom plane to form a stepped structure, and the support plane extends outward axially relative to the transition platform to form a stepped structure.

[0012] When the drill bit is screwed into the tool body, the bottom plane first contacts the transition platform. During the continuous entry of the bottom plane, the bottom plane rises to the support plane, and the transition platform contacts the raised plane. The entire drill bit is jacked up in the axial direction through the stepped structure to form axial positioning.

[0013] As a further embodiment of the present invention: The height difference between the bottom plane and the raised plane in the axial direction is 0.05 mm to 0.1 mm, and the height difference between the transition platform and the support plane in the axial direction is 0.05 mm to 0.1 mm. By limiting the height difference of the stepped structure, the fitting strength between the mounting portion and the support platform is controlled, while ensuring the pressing force between the mounting portion and the support platform and preventing excessive deformation from reducing the service life of the tool body.

[0014] As a further embodiment of the present invention: After the drill bit and the tool body are assembled, a gap of 0.02 mm to 0.06 mm is formed between the side wall of the middle section clearance area and the relative side wall of the support platform. The support platform only serves to support the drill bit and does not participate in clamping the drill bit.

[0015] As a further embodiment of the present utility model: An outer curved surface that smoothly transitions with the spiral groove on the tool body is formed on the drill bit. The outer curved surface and the spiral groove cooperate to form a complete spiral transition structure, which facilitates the discharge of chips from the spiral groove during the cutting process of the drill bit.

[0016] Compared with the prior art, the beneficial effects of the present utility model are as follows:

[0017] The crown-type drill bit adopts a tower-type design structure. After the two bosses on the tool body cooperate with the two groove areas at the bottom of the cutting blade, torque can be transmitted to the cutting blade. The middle section of the drill bit is a middle-section clearance area, which plays a guiding role during the rotation and screwing-in process of the drill bit, and at the same time cooperates with the support platform to form axial limitation. The bottom of the drill bit has a non-concentric arc design with at least two sections. Through screwing into the corresponding inner curved surface to complete the interference fit, the locking of the drill bit and the tool body base is realized. While ensuring the anti-detachment effect of the cutting blade and the base, the form of eccentric structure locking is utilized, reducing unnecessary deformation. After the drill bit and the tool body are installed and disassembled multiple times, the tool body still has a long service life. Description of the Drawings

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present drawings or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following-described drawings are only some embodiments of the present drawings. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0019] Figure 1 It is one of the schematic diagrams of the state of the cooperation between the drill bit and the tool body provided by the present utility model;

[0020] Figure 2 It is the second schematic diagram of the state of the cooperation between the drill bit and the tool body provided by the present utility model;

[0021] Figure 3 It is the third schematic diagram of the state of the cooperation between the drill bit and the tool body provided by the present utility model;

[0022] Figure 4 It is a partial structural schematic diagram of the tool body provided by the present utility model;

[0023] Figure 5 It is a structural schematic diagram of the drill bit provided by the present utility model.

[0024] In the figure: 1. Drill bit; 11. Cutting blade; 12. Middle section clearance area; 13. Mounting part; 14. Groove area; 141. Bottom plane; 142. Raised plane; 143. Stopping plane; 15. Outer curved surface; 2. Tool body; 21. Base; 22. Clamping arm; 221. Inner curved surface; 222. Support platform; 223. Boss; 2231. Transition platform; 2232. Support plane; 2233. Pushing surface. Detailed implementation manners

[0025] In order to make the objectives, technical solutions and advantages of the present application clearer and more understandable, the present application will be described and explained below in combination with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application. All other embodiments obtained by those of ordinary skill in the art based on the embodiments provided in the present application without creative efforts fall within the scope of protection of the present application.

[0026] Obviously, the accompanying drawings in the following description are only some examples or embodiments of the present application. For those of ordinary skill in the art, without creative efforts, the present application can also be applied to other similar scenarios based on these drawings. In addition, it can also be understood that although the efforts made in this development process may be complex and time-consuming, for those of ordinary skill in the art related to the content disclosed in the present application, some design, manufacturing or production changes made based on the technical content disclosed in the present application are only conventional technical means and should not be understood as the content disclosed in the present application being insufficient.

[0027] However, there will be cases where unnecessary detailed descriptions are omitted. For example, there are cases where detailed descriptions of well-known matters are omitted and repeated descriptions of actually identical structures are omitted. This is to avoid the following description from becoming unnecessarily lengthy and to facilitate the understanding of those skilled in the art. In addition, the accompanying drawings and the following description are provided for those skilled in the art to fully understand the present application and are not intended to limit the subject matter recited in the claims.

[0028] Please refer to Figures 1-5As shown in the figure, the replaceable crown type cutting drill in the embodiment of the present utility model includes a drill bit 1 and a tool body 2. The drill bit 1 includes a cutting blade 11, a middle section clearance area 12, and a mounting portion 13 arranged in sequence from top to bottom. The bottom of the cutting blade 11 is recessed inward to form two groove areas 14, and the two groove areas 14 are rotationally symmetrically arranged. There are at least two arc segments on the mounting portion 13 that are eccentric arcs with respect to each other in the length direction. The tool body 2 includes a base 21 and two clamping arms 22 arranged in a rotationally symmetric manner. The clamping arm 22 includes an inner curved surface 221, a support platform 222, and a boss 223 arranged in sequence from bottom to top. When the drill bit 1 and the tool body 2 are assembled, the mounting portion 13 cooperates with the inner curved surface 221, the middle section clearance area 12 cooperates with the support platform 222, and the two groove areas 14 respectively cooperate with the corresponding bosses 223. The eccentric arc on the mounting portion 13 is eccentric with respect to the inner curved surface 221, and the eccentricity is ≤ 0.05 mm. The difference between the diameters of the arc segments on the mounting portion 13 and the arc segments on the inner curved surface 221 is ≤ 0.02 mm.

[0029] Except for several eccentric arcs provided on the mounting portion 13, the central axis of the entire drill bit 1 coincides with the central axis of the tool body 2. The drill bit 1 includes a cutting blade 11 that participates in machining in the upper section, a middle section clearance area 12 for structural transition in the middle, and a mounting portion 13 for locking in the lower section. When the drill bit 1 cooperates with the tool body 2, the drill bit 1 enters vertically between the two clamping arms 22 relative to the base 21. Then the drill bit 1 is rotated relative to the tool body 2. During the rotation process, the mounting portion 13 contacts the inner curved surfaces 221 on the two clamping arms 22 and is limited and blocked under the action of the eccentric arcs on the mounting portion 13. During the continuous advancement process, the two clamping arms 22 deform and complete the interference fit with the mounting portion 13 to achieve locking; a partial cylindrical shape of the middle section clearance area 12 is adapted to the arc-shaped side wall of the support platform 222; the two groove areas 14 on the cutting blade 11 respectively cooperate with the two bosses 223, and the stop plane 143 in the groove area 14 contacts the pushing surface 2233 on the boss 223 to form a limiting relationship. During the process of the tool body 2 driving the drill bit 1 to rotate, the boss 223 transmits a thrust to the stop plane 143 in the groove area 14 through the pushing surface 2233.

[0030] By restricting the eccentricity between several eccentric arcs, the clamping force between the clamping arm 22 and the mounting portion 13 is controlled, avoiding the problem that the excessive deformation of the tool body 2 caused by too large an eccentricity leads to a decrease in the service life of the tool body 2, and avoiding the problem of unsmooth assembly caused by too large an interference blocking effect. The diameters of the mounting portion 13 and the inner curved surface 221 should theoretically be the same. Introducing a tolerance value of 0.02 mm is to avoid dimensional deviations caused by machining.

[0031] The groove area 14 is provided with a bottom plane 141 and a raised plane 142, and the boss 223 is provided with a transition platform 2231 and a support plane 2232. When the mounting portion 13 rotates within the tool body 2, the bottom plane 141 is located at the front end of rotation and first contacts the transition platform 2231, and then leaps onto the support plane 2232 under the stepped structure of the transition platform 2231 and the support plane 2232, so that the mounting portion 13 is integrally pulled up in the axial direction to contact and press against the bottom surface of the support platform 222, realizing the axial positioning and fixing of the drill bit 1. Finally, the raised plane 142 contacts the transition platform 2231 to balance the acting force between the cutting blade 11 and the boss 223.

[0032] Furthermore, the height difference between the bottom plane 141 and the raised plane 142 in the axial direction is 0.05 mm to 0.1 mm, and the height difference between the transition platform 2231 and the support plane 2232 in the axial direction is 0.05 mm to 0.1 mm. By restricting the height difference of the stepped structure, the mating strength between the mounting portion 13 and the support platform 222 is controlled, while ensuring the pressing force between the mounting portion 13 and the support platform 222 and preventing excessive deformation of the support platform 222 from reducing the service life of the tool body 2.

[0033] An outer curved surface 15 is formed on the drill bit 1, which smoothly transitions with the spiral groove on the tool body 2. After the outer curved surface 15 cooperates with the tool body 2, it has the same chip fluting, extending at a certain spiral angle along the central axis, facilitating chip evacuation during the drilling process of the drill bit 1.

[0034] After the drill bit 1 and the tool body 2 are assembled, a gap of 0.02 mm to 0.06 mm is formed between the side wall of the middle clearance area 12 and the relative side wall of the support platform 222. The locking force between the drill bit 1 and the tool body 2 is mainly provided by the interference fit between the mounting portion 13 and the inner curved surface 221, and the pressing force between the mounting portion 13 and the bottom surface of the support platform 222. The support platform 222 only serves to support the drill bit 1 and does not participate in clamping the drill bit 1.

[0035] It should be noted that the present application is not limited to the above embodiments. The above embodiments are only examples, and embodiments having the same composition and achieving the same effects as the technical idea within the scope of the technical solution of the present application are included in the technical scope of the present application. In addition, within the scope of not departing from the gist of the present application, various deformations that can be conceived by those skilled in the art are applied to the embodiments, and other ways constructed by combining some constituent elements of the embodiments are also included in the scope of the present application.

Claims

1. A replaceable crown type cutting drill, characterized in that, Comprising: A drill bit (1), which includes a cutting blade (11), a middle section clearance area (12), and a mounting portion (13) arranged in sequence from top to bottom. The bottom of the cutting blade (11) is recessed inward to form two groove areas (14), and the two groove areas (14) are rotationally symmetrically arranged. At least two arc segments of the mounting portion (13) are eccentric arcs with respect to each other in the length direction; A tool body (2), which includes a base (21) and two clamping arms (22) arranged in a rotationally symmetric manner. The clamping arm (22) includes an inner curved surface (221), a support platform (222), and a boss (223) arranged in sequence from bottom to top; When the drill bit (1) is assembled with the tool body (2), the mounting portion (13) cooperates with the inner curved surface (221), the middle section clearance area (12) cooperates with the support platform (222), and the two groove areas (14) respectively cooperate with the corresponding bosses (223); The eccentric arc on the mounting portion (13) is eccentric with respect to the inner curved surface (221), and the eccentricity is ≤ 0.05 mm. The diameter difference between the arc segments on the mounting portion (13) and the arc segments on the inner curved surface (221) is ≤ 0.02 mm.

2. The replaceable crown type cutting drill according to claim 1, characterized in that, On the radial inner wall of the drill bit (1) along the axis, the groove area (14) is sequentially provided with a bottom plane (141) and a raised plane (142) in the fitting order. On the radial outer wall of the tool body (2) along the axis, the boss (223) is sequentially provided with a transition platform (2231) and a support plane (2232) in the fitting order. The raised plane (142) extends outward axially relative to the bottom plane (141) to form a stepped structure. The support plane (2232) extends outward axially relative to the transition platform (2231) to form a stepped structure.

3. The replaceable crown type cutting drill according to claim 2, wherein The height difference between the bottom plane (141) and the raised plane (142) in the axial direction is 0.05 mm to 0.1 mm. The height difference between the transition platform (2231) and the support plane (2232) in the axial direction is 0.05 mm to 0.1 mm.

4. The replaceable crown type cutting drill according to claim 1, characterized in that, After the drill bit (1) is assembled with the tool body (2), a gap of 0.02 mm to 0.06 mm is formed between the side wall of the middle section clearance area (12) and the relative side wall of the support platform (222).

5. The replaceable crown type cutting drill according to claim 1, characterized in that, An outer curved surface (15) is formed on the drill bit (1) that smoothly transitions with the spiral groove on the tool body (2).

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