A twist drill for finish boring

Abstract

The utility model relates to the technical field of machining, especially relates to a twist drill for final hole. It includes horizontal blade, main cutting edge and vice cutting edge, the horizontal blade protrudes in the middle part of drill bit, the main cutting edge is extended to the edge on the circumference of drill bit from the end of horizontal blade, the upper and lower ends of main cutting edge are connected with horizontal blade and vice cutting edge respectively and are integrated, the vice cutting edge is round blade, and the vice cutting edge is used for rounding the hole wall.

Description

Technical Field

[0001] This utility model relates to the field of machining technology, and in particular to a twist drill for final hole drilling. Background Technology

[0002] During aircraft assembly or rework, it is necessary to position and clamp all components to ensure that they cannot shift relative to each other, and then use a drill bit to prepare the final hole. Therefore, conventional drill bits for final holes are mainly used for components with small-diameter initial holes or no holes at all. The drilling efficiency can be improved by the synergistic action of the drill bit's chisel edge, main cutting edge, and secondary cutting edge.

[0003] However, when components that are already in the final hole stage are involved in the assembly, using conventional drill bits may cause the secondary cutting edge to damage the hole wall of the final hole component under the eccentric force of hole making, resulting in out-of-tolerance hole diameter and affecting the assembly quality of the component. Utility Model Content

[0004] This utility model provides a twist drill for final drilling to avoid out-of-tolerance hole diameter, which includes a chisel edge, a main cutting edge and a secondary cutting edge. The chisel edge protrudes from the middle of the drill bit, and the main cutting edge extends from the end of the chisel edge to the circumferential edge of the drill bit. The upper and lower ends of the main cutting edge are respectively connected to the chisel edge and the secondary cutting edge. The secondary cutting edge is a rounded edge and is used to round the corners on the hole wall.

[0005] Furthermore, the drill bit is also provided with a secondary rake face, the secondary cutting edge being the cutting edge of the secondary rake face, and the surface of the secondary rake face being rounded.

[0006] Furthermore, the secondary rake face intersects with the main rake face of the drill bit and the chip removal groove of the drill bit, respectively.

[0007] Furthermore, it also includes a cutting edge that is spirally formed at the back angle of the secondary cutting edge along the length direction of the drill bit.

[0008] Furthermore, the rake angle of the transverse blade can be in the range of -54° to -60°.

[0009] Furthermore, the bevel angle of the transverse blade can be in the range of 50°-55°.

[0010] Furthermore, the length of the transverse blade can be in the range of 1.2mm-1.5mm.

[0011] Furthermore, the apex angle of the main cutting edge can be in the range of 118°-120°.

[0012] Furthermore, the clearance angle of the main cutting edge can be in the range of 8°-14°.

[0013] Furthermore, the helix angle of the main cutting edge can be in the range of 18°-30°.

[0014] This invention provides a twist drill for final drilling, suitable for aircraft components with or without pre-drilled holes, especially those with pre-drilled holes. It addresses the crucial need to prevent damage to the hole wall from the secondary cutting edge under eccentric force during final drilling. When the twist drill is in operation, the rounded secondary cutting edge creates a chamfer on the hole wall during cutting, reducing damage and mitigating the risk of out-of-tolerance hole diameter. This is particularly suitable for aircraft assembly or rework. Furthermore, this invention utilizes a small-sized, low-rake-angle chisel edge to minimize drill bit eccentricity during final drilling, further preventing damage to the hole wall. Attached Figure Description

[0015] Figure 1 An isometric view of a twist drill for final hole drilling provided by this utility model.

[0016] Figure 2 This is another isometric view of the twist drill used for final hole drilling in this utility model.

[0017] Figure 3 This is a top view of the twist drill used for final drilling in this utility model.

[0018] Figure 4 This is a front view of the twist drill used for final drilling in this utility model.

[0019] Figure 5 This is a left view of the twist drill used for final drilling in this utility model. Detailed Implementation To further illustrate the technical means and effects adopted by this utility model in order to achieve the intended purpose of the invention, the present utility model will be described in detail below with reference to the accompanying drawings and preferred embodiments.

[0020] It should be noted that the terms "first," "second," "third," "fourth," etc., in the specification and claims of this utility model are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence.

[0021] Please see Figures 1 to 5The twist drill for final drilling provided by this utility model includes a chisel edge 3, a main cutting edge 4, and a secondary cutting edge 5. Specifically, the twist drill for final drilling in this utility model includes a drill bit 1 and a drill body, i.e., the cutting part and the guiding part of the twist drill. The drill bit 1 is provided with a chisel edge 3, a main cutting edge 4, and a secondary cutting edge 5. The chisel edge 3 protrudes from the middle of the drill bit 1. The main cutting edge 4 extends from both ends of the chisel edge 3 to the circumferential edge of the drill bit 1. The secondary cutting edge 5 extends from the main cutting edge 4 in the circumferential edge of the drill bit 1 towards the drill body. In this utility model, the secondary cutting edge 5 is a rounded edge, used to round the corners on the hole wall. Please refer to the following for details. Figure 3 Specifically, in this embodiment, the drill bit 1 is a centrally symmetrical twist drill, meaning that the cutting edge of the chisel edge 3 is located at the center of the drill bit 1, and the chisel edge 3 is connected between two main cutting edges 4 symmetrically arranged around the central axis of the drill bit 1. The upper and lower ends of the main cutting edges 4 are respectively integrated with the chisel edge 3 and the secondary cutting edge 5. The twist drill for final hole preparation in this invention can be applied to components with or without pre-drilled holes, but it is more suitable for pre-drilled components. This is because pre-drilled components already have holes smaller than the target hole diameter, and during the final hole preparation process, it is more necessary to avoid damage to the hole wall by the secondary cutting edge 5 under the action of eccentric force. When the twist drill for final hole preparation in this invention is working, the secondary cutting edge 5, which has a rounded edge shape, can round the corners on the hole wall during cutting, reducing the damage to the hole wall caused by the secondary cutting edge 5 during the final hole preparation, and mitigating the risk of hole diameter deviation. It is particularly suitable for aircraft assembly or rework.

[0022] Please refer to this carefully. Figure 3 Furthermore, the twist drill for final hole preparation in this invention also includes a secondary relief face 7, a secondary cutting edge 5 which is the cutting edge of the secondary relief face 7, and a rounded surface on the secondary relief face 7. The secondary relief face 7 intersects with the main relief face 6 of the drill bit 1 and the chip removal groove 8 of the drill bit 1. Specifically, in this embodiment, the secondary relief face 7 is positioned below the main relief face 6 and above the chip removal groove 8. The edge of the secondary relief face 7 in the cutting direction is connected to the secondary cutting edge 5 and the cutting edge band. The cutting edge band is spirally formed at the relief angle of the secondary cutting edge 5 along the length direction of the drill bit 1. The edge of the secondary relief face 7 in the guiding direction is connected to the chip removal groove 8. This invention, by using a secondary relief face 7 with a rounded surface and a secondary cutting edge 5 with a rounded cutting edge, avoids additional scratching of the hole wall during final hole preparation, thus preventing hole diameter deviations and achieving good economic benefits. In a preferred embodiment of this invention, the secondary relief angle of the secondary cutting edge 5 is preferably negative to form a rounded edge.

[0023] Furthermore, in a preferred embodiment of this utility model, the rake angle of the chisel edge 3 can be in the range of -54° to -60°; the bevel angle of the chisel edge 3 can be in the range of 50° to 55°; and the length of the chisel edge 3 can be in the range of 1.2mm to 1.5mm. Specifically, since the chisel edge 3 is located at the intersection of the two main cutting edges 4, that is, two main cutting edges 4 are provided at both ends of the chisel edge 3, as is well known to those skilled in the art, the chisel edge 3 is located at the center of gravity of the drill bit 1 and bears a large axial pressure during cutting. Therefore, the centering ability of the chisel edge 3 is particularly important. However, as mentioned above, the twist drill for final hole preparation in this utility model is suitable for components with pre-drilled holes. Therefore, the chisel edge 3 does not need to participate in positioning and cutting most of the time. When designing the chisel edge 3, a small size and a small rake angle are selected to minimize the eccentric force during final hole preparation and further avoid damage to the hole wall.

[0024] Furthermore, in a preferred embodiment of this utility model, the apex angle of the main cutting edge 4 can be in the range of 118°-120°; the clearance angle of the main cutting edge 4 can be in the range of 8°-14°; and the helix angle of the main cutting edge 4 can be in the range of 18°-30°. Specifically, the apex angle of the main cutting edge 4 can affect the torque of the drill bit 1, the clearance angle of the main cutting edge 4 can affect the friction between the drill bit 1 and the component, and the helix angle of the main cutting edge 4 can affect the chip removal of the drill body 2. As mentioned above, the twist drill for final hole drilling in this utility model is suitable for components with pre-drilled holes. For pre-drilled components, the torque of the drill bit 1 is not the most important parameter, but the friction between the drill bit 1 and the component and the chip removal capability of the drill body 2 are important. Therefore, a smaller helix angle and a larger clearance angle are selected when designing the main cutting edge 4 to improve the cutting capability of the main cutting edge 4 and the chip removal capability of the drill body 2, and to assist the secondary cutting edge 5 in rounding the corners on the hole wall.

[0025] In summary, the twist drill for final hole preparation provided by this invention is suitable for aircraft components with or without pre-drilled holes, especially those with pre-drilled holes. It effectively mitigates damage to the hole wall caused by eccentric forces on the secondary cutting edge during the final hole preparation process. When the twist drill for final hole preparation of this invention is in operation, the rounded secondary cutting edge can round off the corners on the hole wall during cutting, reducing damage to the hole wall caused by the secondary cutting edge during final hole preparation and mitigating the risk of out-of-tolerance hole diameter. This is particularly suitable for aircraft assembly or rework. Furthermore, this invention uses a small-sized, low-rake-angle chisel edge to minimize drill bit eccentricity during final hole preparation, further preventing damage to the hole wall.

[0026] The above are merely specific embodiments of this utility model, but the protection scope of this utility model is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this utility model should be included within the protection scope of this utility model. Therefore, the protection scope of this utility model should be determined by the scope of the claims.

Claims

1. A twist drill for final hole drilling, comprising a chisel edge (3), a main cutting edge (4), and a secondary cutting edge (5), characterized in that: The transverse cutting edge (3) protrudes from the middle of the drill bit (1). The main cutting edge (4) extends from the end of the transverse cutting edge (3) to the circumferential edge of the drill bit (1). The upper and lower ends of the main cutting edge (4) are connected to the transverse cutting edge (3) and the secondary cutting edge (5) respectively. The secondary cutting edge (5) is a rounded edge and is used to round the corners on the hole wall.

2. A twist drill for finish boring as claimed in claim 1 wherein: The drill bit (1) is also provided with a secondary rake face (7), the secondary cutting edge (5) is the cutting edge of the secondary rake face (7), and the surface of the secondary rake face (7) is rounded.

3. A twist drill for finish boring as claimed in claim 2 wherein: The secondary rake face (7) intersects with the main rake face (6) of the drill bit (1) and the chip removal groove (8) of the drill bit (1), respectively.

4. A twist drill for finish boring as defined in claim 1 wherein: It also includes a cutting edge that is spirally formed along the length of the drill bit (1) at the back angle of the secondary cutting edge (5).

5. The twist drill for final hole drilling as described in claim 1, characterized in that: The rake angle of the transverse blade (3) can be in the range of -54° to -60°.

6. The twist drill for final hole drilling as described in claim 1, characterized in that: The oblique angle of the transverse blade (3) can be in the range of 50°-55°.

7. A twist drill for finish boring as claimed in claim 1 wherein: The length of the transverse blade (3) can be in the range of 1.2mm-1.5mm.

8. The twist drill for final hole drilling as described in claim 1, characterized in that: The apex angle of the main cutting edge (4) can be in the range of 118°-120°.

9. The twist drill for final hole drilling as described in claim 1, characterized in that: The back angle of the main cutting edge (4) can be in the range of 8°-14°.

10. The twist drill for final hole drilling as described in claim 1, characterized in that: The helix angle of the main cutting edge (4) can be in the range of 18°-30°.

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