A drill-mill cutter and a drill-mill method for machining a waist hole of a thin-walled shell

Abstract

The application provides a drill-milling cutter for processing a waist-shaped hole of a thin-walled shell, which comprises a drill tip, a cutter body front section, a cutter body middle section and a cutter body handle, and is characterized in that: the blade diameter d1 of the cutter body handle is greater than the blade diameter d2 of the cutter body front section, the blade diameter d2 of the cutter body front section is greater than the blade diameter d3 of the cutter body middle section, the length a2 of the cutter body front section is less than the wall thickness L of the thin-walled shell, the length a3 of the cutter body middle section is greater than the wall thickness L of the thin-walled shell, the drill tip and the cutting tooth of the cutter body front section form a W-shaped structure, the difference a4 between the height of the drill tip in the axial direction of the drill-milling cutter and the height of the highest point of the cutting tooth of the cutter body front section in the axial direction of the drill-milling cutter is less than the wall thickness L of the thin-walled shell, and the top angle of the drill tip is 90 DEG <= alpha <= 140 DEG. The drill-milling cutter provided by the application can efficiently maintain the consistency of the thin-walled part during processing and improve the qualified rate of part processing.

Description

Technical Field

[0001] This invention relates to the field of cutting tools, and more particularly to a drilling and milling cutter for machining waist-shaped holes in thin-walled shells, as well as a drilling and milling method. Background Technology

[0002] With the rapid development of the automotive industry, the requirements for the quality and performance of automotive parts are becoming increasingly stringent. Among automotive parts, battery housings and transmission housings are two crucial components, requiring advantages such as light weight, high strength, good tensile strength, and high corrosion resistance. To meet these requirements, high-performance cast aluminum materials are widely used in the manufacture of these parts.

[0003] Among these parts, the oblong hole is a common structural form, characterized by high surface roughness on both the inner and outer walls, as well as dimensional and positional tolerances such as parallelism between the upper and lower walls. To meet these requirements, traditional machining processes typically employ tools such as drills, roughing and finishing milling cutters, finishing milling cutters, chamfering cutters, and back scrapers.

[0004] In the process of developing the existing technology, the inventors discovered that:

[0005] Because the same tool needs to be used to machine the same position multiple times, the consistency of the machining cannot be guaranteed. Furthermore, deformation is easily generated when machining the waist-shaped hole of the thin-walled shell, which affects the final pass rate of the parts.

[0006] Therefore, there is a need to provide a drilling and milling cutter with a higher yield rate for machining waist-shaped holes in thin-walled shells, in order to solve the technical problem of low yield rate of existing drilling and milling cutters for machining waist-shaped holes in thin-walled shells. Summary of the Invention

[0007] The main technical problem solved by this invention is to address the low yield rate of existing drilling and milling cutters used for machining oblong holes in thin-walled shells. This application provides a drilling and milling cutter for machining oblong holes in thin-walled shells, comprising:

[0008] A drill tip, a front section of the cutter body, a middle section of the cutter body, and a shank of the cutter body, characterized in that: the cutting diameter d1 of the shank of the cutter body is greater than the cutting diameter d2 of the front section of the cutter body; the cutting diameter d2 of the front section of the cutter body is greater than the cutting diameter d3 of the middle section of the cutter body; the length a2 of the front section of the cutter body is less than the wall thickness L of the thin-walled shell being machined; the length a3 of the middle section of the cutter body is greater than the wall thickness L of the thin-walled shell being machined; the drill tip and the cutting teeth of the front section of the cutter body form a W-shaped structure; the difference a4 between the height of the drill tip along the axis of the drill-milling cutter and the height of the highest point of the cutting teeth of the front section of the cutter body along the axis of the drill-milling cutter is less than the wall thickness L of the thin-walled shell being machined; and the apex angle of the drill tip is 90°≤α≤140°.

[0009] Furthermore, the difference a4 between the height of the drill tip along the axis of the drill-and-mill cutter and the height of the highest point of the cutting teeth at the front section of the cutter body along the axis of the drill-and-mill cutter is less than the wall thickness L of the thin-walled shell being machined, specifically including:

[0010] 1 / 4L≤a4≤1 / 3L.

[0011] Furthermore, the length a2 of the front section of the cutter body is less than the wall thickness L of the thin-walled shell being machined, specifically including:

[0012] 2 / 3L≤a2≤L.

[0013] Furthermore, the length a3 of the middle section of the cutter body is greater than the wall thickness L of the thin-walled shell being machined, specifically including:

[0014] a3-L≥5mm.

[0015] Furthermore, the front section of the cutter body has at least two helical cutting teeth evenly distributed along the axis of the drill and milling cutter. The helical cutting teeth are connected to the cutter body shank through the middle section of the cutter body. A helical chip removal groove is provided between the helical cutting teeth. The helical chip removal groove extends to the cutter body shank through the middle section of the cutter body.

[0016] The front section of the blade, the handle of the blade, and the middle section of the blade are provided with chamfers.

[0017] Furthermore, the helical cutting teeth at the front section of the cutter body have helical cutting edges on their sidewalls that are close to the cutting edge of the cutting teeth.

[0018] Furthermore, the spiral cutting teeth in the middle section of the cutter body have a double rear angle structure, specifically including a first rear angle end face and a second rear angle end face that connects to the first rear angle end face;

[0019] The angle between the first rear corner end face and the tangent direction of the rotating cutting edge of the spiral cutting tooth in the middle section of the tool body is A, and the angle between the second rear corner end face and the tangent direction of the rotating cutting edge of the spiral cutting tooth in the middle section of the tool body is B.

[0020] The BA=12°.

[0021] In addition, this application also provides a drilling and milling method for machining waist-shaped holes in thin-walled shells, comprising the following steps:

[0022] A drill bit is used to rough-drill a waist-shaped hole in a thin-walled shell, employing the drill tip and the front section of the cutter body of a drill-milling cutter.

[0023] The contour milling of the waist-shaped hole in the thin-walled shell, roughened by the drill bit, is performed by the middle section of the drill cutter body.

[0024] Furthermore, the process of contour milling of the thin-walled shell oblong hole roughened by the drill bit through the middle section of the drill cutter body also includes:

[0025] The burr removal of the waist-shaped hole is achieved by chamfering the middle section of the blade body and the handle of the blade body;

[0026] The waist-shaped hole is deburred by chamfering the middle section and the front section of the blade body.

[0027] Furthermore, the cutting diameter d2 of the front section of the drill-milling cutter is smaller than the diameter D of the waist-shaped hole, and the difference between the cutting diameter d2 of the front section of the drill-milling cutter and the diameter D of the waist-shaped hole is greater than 2mm.

[0028] Furthermore, the cutting diameter d3 of the middle section of the drill-milling cutter body is smaller than the diameter D of the waist-shaped hole, and the difference between the cutting diameter d2 of the front section of the drill-milling cutter body and the diameter D of the waist-shaped hole is greater than 3mm.

[0029] The embodiments provided in this application have at least the following beneficial effects: The drilling and milling cutter and method for machining waist-shaped holes in thin-walled shells provided in this application can achieve a centering effect during machining through a special drill tip design, efficiently maintaining the consistency of thin-walled parts during machining. This drill tip design can also distribute the force on the thin-walled parts during machining, ensuring the positional accuracy of the rough-machined hole without deformation. The front section of the cutter body ensures stability during machining and provides significant finishing effects through extrusion machining, excellently guaranteeing the surface quality of the hole wall. The milling cutter design in the middle section of the cutter effectively ensures the contour accuracy, positional correction, and surface quality of the waist-shaped hole. The composite positive and negative chamfers of the cutter body can also efficiently remove burrs generated on the inner and outer sides of the shell during machining. In other words, the thin-walled shells machined by the drilling and milling cutter provided in this application can maintain the consistency of thin-walled parts during machining, are less prone to deformation, and improve the pass rate of part machining. Attached Figure Description

[0030] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0031] Figure 1 A schematic diagram of the drill and milling cutter structure for machining waist-shaped holes in thin-walled shells provided in this application;

[0032] Figure 2 Another schematic diagram of the drill and milling cutter for machining waist-shaped holes in thin-walled shells provided in this application;

[0033] Figure 3 A schematic diagram of the cross-sectional structure of the drill and milling cutter for machining the waist-shaped hole of a thin-walled shell provided in this application;

[0034] Figure 4 This is a schematic diagram of the drilling and milling method for machining waist-shaped holes in thin-walled shells provided in this application.

[0035] Figure Labels

[0036] A drill and milling cutter for machining waist-shaped holes in thin-walled shells - 100; drill tip - 1; front section of cutter body - 2; middle section of cutter body - 3; cutter body shank - 4; helical cutting teeth - 20; helical cutting edge - 201; helical chip groove - 21; double back angle structure - 30; first back angle end face - 301; second back angle end face - 302. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0038] Please refer to Figures 1 to 3 This application provides a drilling and milling cutter for machining waist-shaped holes in thin-walled shells, comprising: a drill tip, a front section of the cutter body, a middle section of the cutter body, and a cutter body shank. The cutter body shank has a cutting diameter d1 greater than the cutting diameter d2 of the front section, a cutting diameter d2 greater than the cutting diameter d3 of the middle section, a length a2 of the front section that is less than the wall thickness L of the thin-walled shell being machined, a length a3 of the middle section that is greater than the wall thickness L, a W-shaped structure between the drill tip and the cutting teeth of the front section, a difference a4 between the height of the drill tip along the axis of the drilling and milling cutter and the height of the highest point of the cutting teeth of the front section along the axis of the drilling and milling cutter that is less than the wall thickness L of the thin-walled shell being machined, and a apex angle of the drill tip that is 90° ≤ α ≤ 140°.

[0039] Specifically, the drill tip and the cutting teeth of the front section of the cutter body form a W-shaped structure, so that when the drill and milling cutter is cutting, it no longer only processes the part in the axial direction with the drill tip, but also fully disperses the axial force received by the thin-walled part through the cutting teeth of the drill tip and the front section of the cutter body while ensuring centering.

[0040] Meanwhile, the difference a4 between the height of the drill tip along the axis of the drill-end mill and the height of the highest point of the cutting teeth at the front section of the cutter body along the axis of the drill-end mill is less than the wall thickness L of the thin-walled shell being machined. This is to ensure that the sharp corner of the drill tip does not penetrate the thin wall of the part while cutting into it, thus achieving a good centering effect. It should be noted that, before satisfying that the distance a4 provided in this application is less than the wall thickness L of the thin-walled shell being machined, it should also satisfy d1 / 30≤a4≤d1 / 20, so that the drill tip can exert its stable centering performance during the drilling and milling process.

[0041] Regarding the aforementioned difference a4 between the height of the drill tip along the axis of the drill-end mill and the height of the highest point of the cutting teeth at the front section of the cutter body along the axis of the drill-end mill, which is less than the wall thickness L of the thin-walled shell being machined, this application preferably specifies: 1 / 4L ≤ a4 ≤ 1 / 3L. That is, a4 is less than one-third of the wall thickness L of the thin-walled shell being machined, and greater than or less than one-quarter of the wall thickness L of the thin-walled shell being machined. This setting is mainly based on the consideration that when the drill-end mill is machining a thin-walled shell, both the drill tip and the front section of the cutter body perform cutting operations without penetrating the thin wall of the part before the drill tip has machined through two-thirds of the wall thickness L of the thin-walled shell. Only when the drill tip has machined through two-thirds of the wall thickness L of the thin-walled shell will it penetrate the thin wall of the part. It can be seen that the drill-end mill does not penetrate the thin wall of the part during the cutting process, which can achieve a certain degree of centering effect.

[0042] Regarding the setting of the drill tip angle, after numerous experiments, it was found that when the drill tip apex angle is set to 90°≤α≤140°, the cutting ability of the drill tip is better. Compared to apex angles below 90°, the apex angle in this range is less prone to breakage. Compared to apex angles above 140°, the cutting ability in this range is better. Preferably, the drill tip apex angle is set to 125°.

[0043] Furthermore, the length a2 of the front section of the cutter body is less than the wall thickness L of the thin-walled shell being machined, specifically including:

[0044] 2 / 3L≤a2≤L.

[0045] Specifically, the length of the tool body's front section is primarily determined by the final shaping of the thin-walled shell. Through numerous experiments, it was found that when the length of the tool body's front section is less than 2 / 3L, its strength decreases during machining. Conversely, when it exceeds L, machining efficiency declines. Therefore, the designed length range for the tool body's front section is less than 2 / 3L and greater than L.

[0046] Furthermore, the length a3 of the middle section of the cutter body is greater than the wall thickness L of the thin-walled shell being machined, specifically including:

[0047] a3-L≥5mm.

[0048] Specifically, the length range of the middle section of the cutter body, a3, is mainly for milling the contour of thin-walled shells through the middle section. Setting a length of a3-L greater than 5mm is primarily to facilitate milling in the middle section. It's understandable that if a3-L is less than 5mm, the machined metal chips will scrape against the inner and outer walls of the hole, causing surface scratches and affecting machining quality. If a3-L is greater than 5mm, the strength of the drill-milling cutter and machining efficiency will be affected. In other words, the cutting diameter of the middle section of the cutter body is smaller than that of the front section and the shank; if the middle section is too long, it is prone to breakage during machining.

[0049] Furthermore, the front section of the cutter body has at least two helical cutting teeth evenly distributed along the axis of the drill and milling cutter. The helical cutting teeth are connected to the cutter body shank through the middle section of the cutter body. A helical chip removal groove is provided between the helical cutting teeth. The helical chip removal groove extends to the cutter body shank through the middle section of the cutter body. A chamfer is provided between the front section of the cutter body, the cutter body shank, and the middle section of the cutter body.

[0050] Specifically, the drill and milling cutter may have two or more helical cutting teeth. In a preferred embodiment provided in this application, four helical cutting teeth are preferably evenly distributed, and helical chip removal grooves are provided between the corresponding helical cutting teeth. It should be understood that the drill and milling cutter also has features such as chip-receiving grooves between the helical cutting teeth and the helical chip removal grooves. Since these are not the main technical improvements of this application, they will not be described in detail.

[0051] A chamfer is provided between the front section of the cutter body, the cutter shank, and the middle section of the cutter body. The chamfer is mainly designed to efficiently remove burrs generated on the inner and outer sides of the part during machining. The back angle of the chamfer is machined together with the peripheral cutting edge of the milling cutter, which can effectively eliminate stress concentration at the root of the chamfer and ensure the rigidity of the tool and the stability of machining.

[0052] Furthermore, the helical cutting teeth at the front section of the cutter body have helical cutting edges on their sidewalls that are close to the cutting edge of the cutting teeth.

[0053] Specifically, a spiral cutting edge is provided on the spiral cutting tooth near the cutting edge of the cutting tooth. This spiral cutting edge ensures the stability of the drilling and milling cutter during processing and the extrusion process during processing, resulting in a significant finishing effect and excellent guarantee of the surface quality of the hole wall.

[0054] Furthermore, the helical cutting teeth in the middle section of the cutter body have a double rear angle structure. The double rear angle structure specifically includes a first rear angle end face and a second rear angle end face that connects to the first rear angle end face. The angle between the first rear angle end face and the tangent direction of the cutting edge of the helical cutting teeth in the middle section of the cutter body is A, and the angle between the second rear angle end face and the tangent direction of the cutting edge of the helical cutting teeth in the middle section of the cutter body is B. The angle BA = 12°.

[0055] Specifically, in the double clearance angle structure, the angle between the first clearance angle end face and the tangent direction of the rotating cutting edge of the spiral cutting tooth in the middle section of the cutter body is set to A. The purpose is to ensure the sharpness of the tool while not making the clearance angle too large to ensure the finishing properties of the milling cutter. The angle between the second clearance angle end face and the tangent direction of the rotating cutting edge of the spiral cutting tooth in the middle section of the cutter body is set to B. This is to ensure the machining clearance on the basis of A, but it is also necessary to appropriately ensure the rigidity of the tool back.

[0056] In a preferred embodiment provided in this application, A = 3-6° and BA = 12°. That is, the included angle A is set to a smaller angle to ensure sharpness while achieving finishing with the milling cutter. The included angle B is to ensure the machining clearance of the milling cutter and to guarantee the rigidity of the tool back. The design of the double back angle structure mainly considers the strength of the milling cutter's contour while also taking into account the machining of positive and negative chamfers.

[0057] It should be noted that the drilling and milling cutter provided in this application can replace the previous method of using multiple cutters to machine thin-walled shell oblong holes, which could not guarantee the consistency of machining and the easy deformation of thin-walled shaped holes. Based on this, this application also improves the structure of the drill tip, the front section of the cutter body, and the middle section of the cutter body, ensuring that when machining oblong holes in thin-walled shells, the machined oblong holes do not suffer from inconsistent machining or easy deformation, thereby improving the final part yield.

[0058] In addition, this application also provides a drilling and milling method for machining waist-shaped holes in thin-walled shells, comprising the following steps:

[0059] S110: A drill bit used for roughing thin-walled shell waist-shaped holes, employing the drill tip and the front section of the cutter body of a drill-milling cutter;

[0060] S120: The contour milling of the waist-shaped hole of the thin-walled shell roughened by the drill bit is performed by the middle section of the drill cutter body.

[0061] Specifically, the drill tip and the front section of the cutter body first rough the waist-shaped hole of the thin-walled shell, and then the middle section of the cutter body performs contour milling of the waist-shaped hole.

[0062] In the above processing, the method for processing the waist-shaped hole of the thin-walled shell further includes: using the chamfer of the middle section of the drill-milling cutter body and the chamfer of the cutter body shank to perform positive chamfering and deburring of the waist-shaped hole, and using the chamfer of the middle section of the cutter body and the chamfer of the front section of the cutter body to perform reverse chamfering and deburring of the waist-shaped hole.

[0063] It is understood that the positive chamfering and deburring can be performed after step S120 or simultaneously during the S120 machining process. In a preferred embodiment provided in this application, they are preferably performed during the S120 contour milling process.

[0064] Specifically, such as Figure 4 The image shows one method for machining a waist-shaped hole in a thin-walled shell, as provided in this application. It includes: roughing the waist-shaped hole in the thin-walled shell using the drill tip and the front section of the drill-milling cutter; then contour milling the waist-shaped hole in the thin-walled shell using the middle section of the drill-milling cutter. During the milling process, the chamfers on the front and middle sections of the cutter body, and the chamfers on the front and middle sections of the cutter body, are used for positive and negative chamfering deburring when they contact the end face of the waist-shaped hole. Figure 4 S1201 is for deburring with a positive chamfer, and S1202 is for deburring with a negative chamfer.

[0065] Furthermore, the cutting diameter d2 of the front section of the drill-milling cutter is smaller than the diameter D of the waist-shaped hole, and the difference between the cutting diameter d2 of the front section of the drill-milling cutter and the diameter D of the waist-shaped hole is greater than 2mm.

[0066] Specifically, by setting the cutting diameter to be smaller than the finished hole size, the cutting diameter is fully inserted, resulting in the significant removal of excess material from the part. The difference between the cutting diameter d2 of the front section of the drill-milling cutter and the diameter D of the waist-shaped hole is greater than 2 mm. In a preferred embodiment provided in this application, d1 is preferably (D-2) mm.

[0067] Furthermore, the cutting diameter d3 of the middle section of the drill-milling cutter body is smaller than the diameter D of the waist-shaped hole, and the difference between the cutting diameter d2 of the front section of the drill-milling cutter body and the diameter D of the waist-shaped hole is greater than 3mm.

[0068] Specifically, the cutting diameter d3 of the middle section of the drill-end mill cutter body is smaller than the cutting diameter d2 of the front section of the drill-end mill cutter body. Obviously, the cutting diameter d3 of the middle section of the drill-end mill cutter body is smaller than the diameter D of the waist-shaped hole. In a preferred embodiment provided in this application, d3 is preferably (D-3) mm.

[0069] In one practical application scenario provided in this application, the aforementioned drill-and-mill cutter is used to machine a waist-shaped hole in a thin-walled shell. The thickness L of the thin-walled shell is selected within the range of 4mm ≤ L ≤ 8mm, and the diameter of the waist-shaped hole is selected within the range of 10mm ≤ D ≤ 15mm. This application sets the thickness L of the thin-walled shell to 4mm and the diameter of the waist-shaped hole to 10mm. Accordingly, based on the thickness of the thin-walled shell and the diameter of the waist-shaped hole, this application selects the cutting diameter d2 of the front section of the cutter body to be 8mm, the cutting diameter d3 of the middle section of the cutter body to be 7mm, and the cutting diameter d1 of the cutter body shank to be 9mm. The length a3 of the middle section of the cutter body is 9mm, the length a2 of the front section of the cutter body is 4mm, the difference a4 between the height of the drill tip along the axis of the drill-and-mill cutter and the height of the highest point of the cutting tooth in the front section of the cutter body along the axis of the drill-and-mill cutter is 1.5mm, and the drill tip angle is 120°.

[0070] It should also be noted that, compared to the previous method of roughing with a drill, then machining with a rough milling cutter, then machining with a finish milling cutter, and finally removing burrs from the previous processes with chamfering and reverse chamfering cutters, the drilling and milling cutters provided in this application have lower tooling costs and do not require multiple tools to repeatedly machine the same location, ensuring machining consistency. Furthermore, because the wall thickness of thin-walled shells is relatively thin, the original machining method is prone to deformation, making it impossible to guarantee flatness. The improved tooling in this application avoids this problem and improves the final pass rate of the parts.

[0071] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A drill and milling cutter for machining waist-shaped holes in thin-walled shells, comprising: A drill tip, a front section of the cutter body, a middle section of the cutter body, and a shank of the cutter body, characterized in that: the cutting diameter d1 of the shank of the cutter body is greater than the cutting diameter d2 of the front section of the cutter body; the cutting diameter d2 of the front section of the cutter body is greater than the cutting diameter d3 of the middle section of the cutter body; the length a2 of the front section of the cutter body is less than the wall thickness L of the thin-walled shell being machined; the length a3 of the middle section of the cutter body is greater than the wall thickness L of the thin-walled shell being machined; the cutting teeth of the drill tip and the front section of the cutter body form a W-shaped structure; the difference a4 between the height of the drill tip along the axis of the drill-milling cutter and the height of the highest point of the cutting teeth of the front section of the cutter body along the axis of the drill-milling cutter is less than the wall thickness L of the thin-walled shell being machined; and the apex angle of the drill tip is 90°≤α≤140°. The difference a4 between the height of the drill tip along the axis of the drill and milling cutter and the height of the highest point of the cutting teeth at the front section of the cutter body along the axis of the drill and milling cutter is less than the wall thickness L of the thin-walled shell being machined, specifically including: 1 / 4L≤a4≤1 / 3L; The length a2 of the front section of the cutter body is less than the wall thickness L of the thin-walled shell being processed, specifically including: 2 / 3L≤a2≤L; The length a3 of the middle section of the cutter body is greater than the wall thickness L of the thin-walled shell being processed, specifically including: a3-L≥5mm; The spiral cutting teeth in the middle section of the cutter body have a double rear angle structure. The double rear angle structure specifically includes a first rear angle end face and a second rear angle end face that is connected to the first rear angle end face. The angle between the first rear corner end face and the tangent direction of the rotating cutting edge of the spiral cutting tooth in the middle section of the tool body is A, and the angle between the second rear corner end face and the tangent direction of the rotating cutting edge of the spiral cutting tooth in the middle section of the tool body is B. The BA=12°.

2. The drill and milling cutter as described in claim 1, characterized in that, The front section of the cutter body has at least two helical cutting teeth evenly distributed along the axis of the drill and milling cutter. The helical cutting teeth of the front section of the cutter body are connected to the cutter body shank through the middle section of the cutter body. A helical chip removal groove is provided between the helical cutting teeth of the front section of the cutter body. The helical chip removal groove extends to the cutter body shank through the middle section of the cutter body. The front section of the blade, the handle of the blade, and the middle section of the blade are provided with chamfers.

3. The drilling and milling cutter as described in claim 2, characterized in that, The helical cutting teeth at the front section of the cutter body have helical cutting edges on their sidewalls, close to the cutting edge of the cutting teeth.

4. A drilling and milling method for machining waist-shaped holes in thin-walled shells, characterized in that, Includes the following steps: A drill bit is used to rough-drill a thin-walled shell waist-shaped hole using the drill tip and the front section of the drill and milling cutter as described in any one of claims 1-3; The contour milling of the waist-shaped hole in the thin-walled shell, roughened by the drill bit, is performed by the middle section of the drill cutter body.

5. The drilling and milling method for machining waist-shaped holes in thin-walled shells as described in claim 4, characterized in that, The process further includes using the middle section of the drill cutter body to perform contour milling of the thin-walled shell waist-shaped hole roughened by the drill bit, and also includes: The burr removal of the waist-shaped hole is achieved by chamfering the middle section of the blade body and the handle of the blade body; The waist-shaped hole is deburred by chamfering the middle section and the front section of the blade body.

6. The drilling and milling method for machining waist-shaped holes in thin-walled shells as described in claim 4, characterized in that, The cutting diameter d2 of the front section of the drill and milling cutter is smaller than the diameter D of the waist-shaped hole, and the difference between the cutting diameter d2 of the front section of the drill and milling cutter and the diameter D of the waist-shaped hole is greater than 2mm.

7. The drilling and milling method for machining waist-shaped holes in thin-walled shells as described in claim 4, characterized in that, The cutting diameter d3 of the middle section of the drill-and-mill cutter body is smaller than the diameter D of the waist-shaped hole, and the difference between the cutting diameter d3 of the middle section of the drill-and-mill cutter body and the diameter D of the waist-shaped hole is greater than 3mm.

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