阅读说明：本技术 一种防止复合材料制孔表面纤维劈裂的方法 (Method for preventing fiber splitting on surface of composite material hole ) 是由 谢辉 卢大伟 周欣康 王佳鑫 冯绍红 苟德森 肖红亮 赵康雄 于 2021-09-24 设计创作，主要内容包括：本发明公开了一种防止复合材料制孔表面纤维劈裂的方法,属于航空复合材料加工技术领域,其特征在于,包括以下步骤：a、在复合材料制件上先制出初孔,初孔直径为D1；b、然后用带限位器的锪窝钻对初孔入口处进行倒角处理,锪窝直径为D2,再用扩孔钻头进行扩孔,扩孔直径为D3；c、最后用精铰铰刀对扩孔后的孔进行精铰制成终孔。本发明能够有效避免扩孔时扩孔钻头产生轴线偏移,保证扩孔质量,有效降低复合材料制孔表面劈裂的风险,能够增加扩孔钻头的切削接触面积,减小复合材料制件单位面积的切削力,有效避免复合材料制件表面纤维因切削力太大而产生的纤维劈裂,且能够极大的提升复合材料大直径孔的制孔效率。(The invention discloses a method for preventing fiber splitting on the surface of a composite material hole, which belongs to the technical field of aviation composite material processing and is characterized by comprising the following steps of: a. firstly, making a primary hole on the composite material workpiece, wherein the diameter of the primary hole is D1; b. then, chamfering the inlet of the primary hole by using a counter bit with a limiter, wherein the diameter of the counter bit is D2, and then reaming by using a reaming bit, wherein the diameter of the reaming is D3; c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer to obtain a final hole. The invention can effectively avoid the axial deviation of the reaming bit during reaming, ensure the reaming quality, effectively reduce the risk of the splitting of the surface of the composite material hole, increase the cutting contact area of the reaming bit, reduce the cutting force of the unit area of the composite material part, effectively avoid the fiber splitting of the surface fiber of the composite material part caused by too large cutting force, and greatly improve the hole-making efficiency of the composite material large-diameter hole.)

1. A method for preventing fiber splitting on the surface of a hole made of a composite material is characterized by comprising the following steps:

a. firstly, a primary hole (4) is formed in the composite material part (1), and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole (4) by using a counter bit (5) with a limiter, the diameter of the counter bit is D2, and then reaming is carried out by using a reaming bit (6) under the condition of chamfering, and the reaming diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer (7) to obtain a final hole (8).

2. A method of preventing fibre splitting at the surface of a composite material bore according to claim 1, wherein: and a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using a dimple drill (5) with a limiter, the chamfering angle is 120 degrees, and the chamfered dimple diameter D2 is 0.1mm larger than the reaming diameter D3.

3. A method of preventing fibre splitting at the surface of a composite material bore according to claim 1, wherein: and in the step b, chamfering the inlet of the primary hole (4) by using a counter bit drill (5) with a limiter, namely setting the chamfering angle to be 120 degrees for chamfering, wherein the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the counter bit.

4. A method of preventing fibre splitting at the surface of a composite material bore according to claim 1, wherein: in the step b, reaming by using the reaming bit (6) specifically means that the cutting angle of the reaming bit (6) is set to 118 degrees for cutting and reaming.

5. A method of preventing fibre splitting at the surface of a composite material bore according to claim 1, wherein: in the step c, finish reaming is carried out on the reamed hole by using a finish reaming reamer (7) to prepare a final hole (8), specifically, finish reaming is carried out according to the condition that the cutting amount of a single side of each reaming is not more than 0.05mm, and finish reaming is carried out for multiple times until the hole diameter reaches the final hole diameter D4.

6. A method of preventing fibre splitting at the surface of a composite material bore according to claim 1, wherein: the initial hole diameter D1 is more than the reaming diameter D3 is more than the dimple diameter D2 is less than or equal to the final hole diameter D4.

7. A method of preventing fibre splitting at the surface of a composite material bore according to claim 1, wherein: in the step a, the primary hole (4) is prepared according to the condition that the unilateral cutting amount of each reaming is not more than 0.25 mm.

8. A method of preventing fibre splitting at the surface of a composite material bore according to claim 1, wherein: in the step a, preparing a primary hole (4) at the composite material hole-making inlet end (2) of the composite material part (1) by adopting a primary hole drill (3) with the size of phi 3.1 mm.

Technical Field

The invention relates to the technical field of aviation composite material processing, in particular to a method for preventing fiber splitting on the surface of a composite material hole.

Background

Currently, fiber-reinforced composite materials have been widely used in the fields of aviation, aerospace, chemical engineering, automobiles, etc. due to their many superior mechanical properties, such as high specific strength and high specific modulus. The fabrication of holes in composite parts has become an important task, particularly in the assembly of aircraft. The composite material has the following material characteristics:

1. the composite material part is formed by bonding a plurality of layers of fiber cloth, and the interlayer bonding force is low;

2. the composite material is an anisotropic material, each layer of the composite material has a fixed fiber direction, and stress concentration is easy to generate during hole making;

3. the composite material has higher hardness and higher cutting heat during hole making.

Due to the characteristics, the composite material becomes a typical difficult-to-process material, and the defect of fiber splitting is easily generated in hole making. The traditional composite material hole making method adopts a method of reducing cutting amount to prevent the problem of surface fiber splitting, but the small cutting amount causes a large amount of tool changing operation. Therefore, it is necessary to find an efficient hole-making method and effectively prevent fiber splitting on the surface of the hole-making hole. At present, in the known literature, most of common methods for preventing fiber splitting on the surface of a composite material hole are methods for optimizing a cutter structure and hole making technological parameters, and the optimization and improvement of the composite material hole making technological method are rarely researched.

Chinese patent literature with publication number CN 103231415A and publication date of 2013, 08 and 07 discloses a method for making holes in a composite material unidirectional tape, which is characterized by comprising the following steps:

step one, manufacturing a test piece: forming by using a carbon fiber one-way belt by using a vacuum bag-autoclave method, and then cutting into test pieces with regular shapes, wherein the shapes are determined according to actual requirements and are rhombus, rectangular or circular; the test piece is used as a test plate;

step two, using a cutter and a universal force clamp to fix the test plate, and drilling the test piece under the following parameter conditions: the rotating speed of the air drill on the cutter is 3000 plus 4500rpm/min, and the feeding speed is 45-225 mm/min; and (3) removing dust by using a dust collector during hole making.

The method for making holes in the composite material unidirectional tape disclosed in the patent document is used for making holes in a test plate made of the composite material unidirectional tape by selecting a proper cutter material, a proper edge shape and corresponding process parameters, and the obtained holes are uniform in diameter and smooth in hole wall. However, the generation of fiber splitting cannot be effectively avoided, and the hole forming quality and the hole forming efficiency are influenced.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provides a method for preventing fiber splitting on the surface of a composite material hole, which can effectively avoid the axial deviation of a hole expanding drill bit during hole expanding, ensure the hole expanding quality, effectively reduce the risk of the fiber splitting on the surface of the composite material hole, increase the cutting contact area of the hole expanding drill bit, reduce the cutting force of a unit area of a composite material part, effectively avoid the fiber splitting on the surface of the composite material part caused by too large cutting force, and greatly improve the hole forming efficiency of a large-diameter hole of the composite material.

The invention is realized by the following technical scheme:

a method for preventing fiber splitting on the surface of a hole made of a composite material is characterized by comprising the following steps:

a. firstly, making a primary hole on the composite material workpiece, wherein the diameter of the primary hole is D1;

b. then chamfering the initial hole entrance by using a counter bit with a limiter, wherein the diameter of the counter bit is D2, and then reaming by using a reaming bit under the condition of chamfering, and the reaming diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer to obtain a final hole.

And a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using a dimple drill with a limiter, the chamfering angle is 120 degrees, and the chamfered dimple diameter D2 is 0.1mm larger than the reaming diameter D3.

And in the step b, chamfering the inlet of the initial hole by using a counter bit with a limiter specifically means that the chamfering angle is set to 120 degrees for chamfering, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole.

In the step b, reaming by using the reamer bit specifically means that the cutting angle of the reamer bit is set to 118 ° for cutting and reaming.

And c, performing finish reaming on the reamed hole by using a finish reaming reamer to prepare a final hole, namely performing finish reaming according to the condition that the cutting amount of a single side of each reaming is not more than 0.05mm, and performing finish reaming for multiple times until the hole diameter reaches the final hole diameter D4.

The initial hole diameter D1 is more than the reaming diameter D3 is more than the dimple diameter D2 is less than or equal to the final hole diameter D4.

In the step a, the primary hole is prepared according to the condition that the unilateral cutting amount of each reaming is not more than 0.25 mm.

In the step a, a primary hole drill with the size of phi 3.1mm is adopted to carry out primary hole preparation at the composite material hole-making inlet end of the composite material part.

The beneficial effects of the invention are mainly shown in the following aspects:

firstly, manufacturing a primary hole on a composite material workpiece, wherein the diameter of the primary hole is D1; b. then chamfering the initial hole entrance by using a counter bit with a limiter, wherein the diameter of the counter bit is D2, and then reaming by using a reaming bit under the condition of chamfering, and the reaming diameter is D3; c. finally, the hole after reaming is finely reamed by using a fine reaming reamer to form a final hole, as a complete technical scheme, compared with the prior art, the method can effectively avoid the axial deviation of the reaming bit during reaming, ensure the reaming quality, effectively reduce the risk of surface splitting of the composite material hole, increase the cutting contact area of the reaming bit, reduce the cutting force of the unit area of the composite material part, effectively avoid the fiber splitting of the surface fiber of the composite material part caused by too large cutting force, and greatly improve the hole-making efficiency of the large-diameter hole of the composite material.

And step two, secondary chamfering treatment, specifically, after hole expansion in step b, chamfering treatment is carried out on the hole expansion inlet again by using a dimple drill with a limiter, the chamfering angle is 120 degrees, the diameter D2 of the chamfered dimple is 0.1mm larger than the hole expansion diameter D3, the cutting contact area of the reamer bit is increased, the cutting force of the unit area of the composite material part is reduced, and fiber splitting caused by too large cutting force of the surface fiber of the composite material part is avoided.

In the step b, chamfering treatment is carried out on the inlet of the primary hole by using the counter bit with the limiter, specifically, the chamfering angle is set to be 120 degrees for chamfering, the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole, the chamfer made by the primary hole has a guiding effect on the reamer head, the axial deviation of the reamer head during reaming can be avoided, and the reaming quality is effectively ensured.

In the step b, reaming by using the reaming bit specifically means that the cutting angle of the reaming bit is set to 118 degrees for cutting and reaming, and the cutting angle of the reaming bit of 118 degrees is effectively matched with the chamfering angle of 120 degrees, so that the cutting contact area of the reaming bit can be further increased, and the cutting force of the unit area of the composite material part is reduced.

And fifthly, in the step c, finish reaming is carried out on the reamed hole by using a finish reaming reamer to prepare the final hole, specifically, finish reaming is carried out according to the cutting amount of a single side of each reaming is not more than 0.05mm, and finish reaming is carried out for multiple times until the hole diameter reaches the diameter D4 of the final hole, so that the quality of the finally prepared final hole is guaranteed.

Sixthly, in the invention, the initial hole diameter D1 is larger than the reaming diameter D3 is larger than the dimple diameter D2 is smaller than or equal to the final hole diameter D4, and the chamfering exists in the reaming process, so that the cutting contact area of the reaming bit is increased, the cutting force of the unit area of the composite material part is reduced, the fiber splitting on the surface of the composite material part can be effectively avoided, and the hole making quality is improved.

Seventhly, in the step a, the primary hole is prepared according to the condition that the unilateral cutting amount of each reaming is not more than 0.25mm, so that the risk of splitting of the fiber on the surface of the composite material part can be reduced.

Eighthly, in the step a, the initial hole is prepared by adopting the initial hole drill bit with the size of phi 3.1mm, so that the cutting material at the inlet end of the drill bit can be effectively reduced, the variation range of the cutting amount is reduced, the cutting force is stabilized, the axial force during cutting is reduced, the cutting heat is reduced, and better cutting conditions are provided.

Drawings

The invention will be further described in detail with reference to the drawings and the detailed description, wherein:

FIG. 1 is a schematic structural view of primary pores made of the composite material of the present invention;

FIG. 2 is a schematic structural view of a chamfer made of the composite material of the present invention;

FIG. 3 is a schematic diagram of reaming a composite drill bit of the present invention;

FIG. 4 is a schematic diagram of a composite material finish-reaming of the present invention;

the labels in the figure are: 1. a composite material part 2, a composite material hole-making inlet end 3, a primary hole drill bit 4, a primary hole 5, a counter boring drill with a limiter 6, a hole-expanding drill bit 7, a finish reaming reamer 8 and a final hole; d1 is the initial hole diameter, D2 is the dimple diameter, D3 is the counterbore diameter, and D4 is the final hole diameter.

Detailed Description

Example 1

Referring to fig. 1-4, a method for preventing fiber splitting on the surface of a composite material hole comprises the following steps:

a. firstly, a primary hole 4 is formed in the composite material product 1, and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer 7 to obtain a final hole 8.

In this embodiment, a primary hole 4 is first formed in the composite material product 1, and the diameter of the primary hole is D1; b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3; c. finally, the hole after reaming is finely reamed by the fine reaming reamer 7 to form a final hole 8, and as a complete technical scheme, compared with the prior art, the method can effectively avoid the axial deviation of the reaming bit 6 during reaming, ensure the reaming quality, effectively reduce the risk of surface splitting of the composite material hole, increase the cutting contact area of the reaming bit 6, reduce the cutting force of the unit area of the composite material part 1, effectively avoid the fiber splitting of the surface fiber of the composite material part 1 caused by too large cutting force, and greatly improve the hole-making efficiency of the large-diameter hole of the composite material.

Example 2

Referring to fig. 1-4, a method for preventing fiber splitting on the surface of a composite material hole comprises the following steps:

a. firstly, a primary hole 4 is formed in the composite material product 1, and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer 7 to obtain a final hole 8.

And a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using the counter bit drill 5 with the limiter, the chamfering angle is 120 degrees, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reaming hole.

The embodiment is a preferred embodiment, and the secondary chamfering step specifically includes performing chamfering again on the reaming entrance by using the counter bit 5 with the stopper after reaming in the step b, where the chamfering angle is 120 °, and the chamfer diameter D2 is 0.1mm larger than the reaming diameter D3, so that the cutting contact area of the reaming bit 6 is increased, the cutting force per unit area of the composite material part 1 is reduced, and fiber splitting caused by too large cutting force on the surface fiber of the composite material part 1 is avoided.

Example 3

Referring to fig. 1-4, a method for preventing fiber splitting on the surface of a composite material hole comprises the following steps:

a. firstly, a primary hole 4 is formed in the composite material product 1, and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer 7 to obtain a final hole 8.

And a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using the counter bit drill 5 with the limiter, the chamfering angle is 120 degrees, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reaming hole.

In the step b, chamfering the inlet of the initial hole 4 by using the counter bit drill 5 with the limiter specifically means that the chamfering angle is set to 120 degrees for chamfering, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole.

In the step b, the chamfering treatment of the entrance of the primary hole 4 by the counter bit 5 with the stopper specifically includes setting the chamfering angle to 120 ° for chamfering, wherein the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole, and the chamfer made on the primary hole 4 has a guiding effect on the head of the reamer bit 6, so that the axial deviation of the reamer bit 6 during reaming can be avoided, and the reaming quality is effectively ensured.

Example 4

Referring to fig. 1-4, a method for preventing fiber splitting on the surface of a composite material hole comprises the following steps:

a. firstly, a primary hole 4 is formed in the composite material product 1, and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer 7 to obtain a final hole 8.

And a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using the counter bit drill 5 with the limiter, the chamfering angle is 120 degrees, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reaming hole.

In the step b, chamfering the inlet of the initial hole 4 by using the counter bit drill 5 with the limiter specifically means that the chamfering angle is set to 120 degrees for chamfering, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole.

In the step b, reaming by the reamer bit 6 specifically means cutting and reaming by setting the cutting angle of the reamer bit 6 to 118 °.

In this embodiment, as a further preferred embodiment, in the step b, reaming with the reamer bit 6 specifically means that the cutting angle of the reamer bit 6 is set to 118 ° for cutting and reaming, and the cutting angle of 118 ° of the reamer bit 6 is effectively matched with the chamfer angle of 120 °, so that the cutting contact area of the reamer bit 6 can be further increased, and the cutting force per unit area of the composite material part 1 can be reduced.

Example 5

Referring to fig. 1-4, a method for preventing fiber splitting on the surface of a composite material hole comprises the following steps:

a. firstly, a primary hole 4 is formed in the composite material product 1, and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer 7 to obtain a final hole 8.

And a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using the counter bit drill 5 with the limiter, the chamfering angle is 120 degrees, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reaming hole.

In the step b, chamfering the inlet of the initial hole 4 by using the counter bit drill 5 with the limiter specifically means that the chamfering angle is set to 120 degrees for chamfering, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole.

In the step b, reaming by the reamer bit 6 specifically means cutting and reaming by setting the cutting angle of the reamer bit 6 to 118 °.

In the step c, finish reaming is carried out on the reamed hole by using a finish reaming reamer 7 to prepare a final hole 8, specifically, finish reaming is carried out according to the fact that the cutting amount of a single side of each reaming is not more than 0.05mm, and finish reaming is carried out for multiple times until the hole diameter reaches the final hole diameter D4.

In this embodiment, which is another preferred embodiment, in step c, the finish reaming of the reamed hole by the finish reaming reamer 7 to form the final hole 8 specifically means that finish reaming is performed according to the single-side cutting amount of each reaming being not more than 0.05mm, and finish reaming is performed for multiple times until the hole diameter reaches the final hole diameter D4, so that the quality of the final hole 8 is ensured.

Example 6

Referring to fig. 1-4, a method for preventing fiber splitting on the surface of a composite material hole comprises the following steps:

a. firstly, a primary hole 4 is formed in the composite material product 1, and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer 7 to obtain a final hole 8.

And a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using the counter bit drill 5 with the limiter, the chamfering angle is 120 degrees, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reaming hole.

In the step b, chamfering the inlet of the initial hole 4 by using the counter bit drill 5 with the limiter specifically means that the chamfering angle is set to 120 degrees for chamfering, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole.

In the step b, reaming by the reamer bit 6 specifically means cutting and reaming by setting the cutting angle of the reamer bit 6 to 118 °.

In the step c, finish reaming is carried out on the reamed hole by using a finish reaming reamer 7 to prepare a final hole 8, specifically, finish reaming is carried out according to the fact that the cutting amount of a single side of each reaming is not more than 0.05mm, and finish reaming is carried out for multiple times until the hole diameter reaches the final hole diameter D4.

The initial hole diameter D1 is more than the reaming diameter D3 is more than the dimple diameter D2 is less than or equal to the final hole diameter D4.

In the embodiment, a preferred embodiment is provided, the initial hole diameter D1 is greater than the reaming diameter D3 is greater than the dimple diameter D2 is less than or equal to the final hole diameter D4, and in the reaming process, due to the existence of the chamfer, the cutting contact area of the reaming bit 6 is increased, the cutting force per unit area of the composite material part 1 is reduced, the fiber splitting on the surface of the composite material part 1 can be effectively avoided, and the hole making quality is improved.

Example 7

Referring to fig. 1-4, a method for preventing fiber splitting on the surface of a composite material hole comprises the following steps:

a. firstly, a primary hole 4 is formed in the composite material product 1, and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer 7 to obtain a final hole 8.

And a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using the counter bit drill 5 with the limiter, the chamfering angle is 120 degrees, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reaming hole.

In the step b, chamfering the inlet of the initial hole 4 by using the counter bit drill 5 with the limiter specifically means that the chamfering angle is set to 120 degrees for chamfering, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole.

In the step b, reaming by the reamer bit 6 specifically means cutting and reaming by setting the cutting angle of the reamer bit 6 to 118 °.

In the step c, finish reaming is carried out on the reamed hole by using a finish reaming reamer 7 to prepare a final hole 8, specifically, finish reaming is carried out according to the fact that the cutting amount of a single side of each reaming is not more than 0.05mm, and finish reaming is carried out for multiple times until the hole diameter reaches the final hole diameter D4.

The initial hole diameter D1 is more than the reaming diameter D3 is more than the dimple diameter D2 is less than or equal to the final hole diameter D4.

In the step a, the primary hole 4 is prepared according to the condition that the unilateral cutting amount of each reaming is not more than 0.25 mm.

In this embodiment, which is a further preferred embodiment, in step a, the primary holes 4 are prepared according to the single-edge cutting amount per reaming which is not more than 0.25mm, so that the risk of fiber splitting on the surface of the composite material part 1 can be reduced.

Example 8

Referring to fig. 1-4, a method for preventing fiber splitting on the surface of a composite material hole comprises the following steps:

a. firstly, a primary hole 4 is formed in the composite material product 1, and the diameter of the primary hole is D1;

b. then, chamfering treatment is carried out on the inlet of the primary hole 4 by using a counter bit drill 5 with a limiter, the diameter of the counter bit is D2, and then hole expansion is carried out by using a hole expansion drill 6 under the condition of chamfering, and the hole expansion diameter is D3;

c. and finally, performing finish reaming on the reamed hole by using a finish reaming reamer 7 to obtain a final hole 8.

And a secondary chamfering treatment step, specifically, after reaming in the step b, chamfering treatment is carried out on the reaming inlet again by using the counter bit drill 5 with the limiter, the chamfering angle is 120 degrees, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reaming hole.

In the step b, chamfering the inlet of the initial hole 4 by using the counter bit drill 5 with the limiter specifically means that the chamfering angle is set to 120 degrees for chamfering, and the diameter D2 of the chamfered counter bit is 0.1mm larger than the diameter D3 of the reamed hole.

In the step b, reaming by the reamer bit 6 specifically means cutting and reaming by setting the cutting angle of the reamer bit 6 to 118 °.

In the step c, finish reaming is carried out on the reamed hole by using a finish reaming reamer 7 to prepare a final hole 8, specifically, finish reaming is carried out according to the fact that the cutting amount of a single side of each reaming is not more than 0.05mm, and finish reaming is carried out for multiple times until the hole diameter reaches the final hole diameter D4.

The initial hole diameter D1 is more than the reaming diameter D3 is more than the dimple diameter D2 is less than or equal to the final hole diameter D4.

In the step a, the primary hole 4 is prepared according to the condition that the unilateral cutting amount of each reaming is not more than 0.25 mm.

In the step a, a primary hole 4 is prepared at the composite material hole-making inlet end 2 of the composite material part 1 by adopting a primary hole drill 3 with the size of phi 3.1 mm.

In the embodiment, which is the best implementation mode, in the step a, the primary hole 4 is prepared by using the primary hole drill 3 with the size of phi 3.1mm, so that the cutting material at the inlet end of the drill can be effectively reduced, the variation range of the cutting amount is reduced, the cutting force is stabilized, the axial force during cutting is reduced, the cutting heat is reduced, and better cutting conditions are provided.

The following hole making processes for 4.2mm, 5mm, 6.6mm, 8mm, 10mm and 12mm holes were compared with the prior art using the basic embodiment of the present invention:

4.2mm holes: in the prior art, the cutting frequency is 5 times in the basic implementation mode, and the processing efficiency is improved by 0 percent;

5mm of holes: in the prior art, the cutting frequency is 7 times, the cutting frequency of the basic embodiment is 6 times, and the processing efficiency is improved by 14 percent;

6.6mm holes: in the prior art, the cutting frequency is 10 times, the cutting frequency of the basic embodiment is 8 times, and the processing efficiency is improved by 20 percent;

8mm holes: in the prior art, the cutting frequency is 14 times, the cutting frequency of the basic embodiment is 10 times, and the processing efficiency is improved by 29 percent;

10mm holes: in the prior art, the cutting frequency is 18 times, the cutting frequency of the basic embodiment is 12 times, and the processing efficiency is improved by 33 percent;

12mm holes: in the prior art, the cutting frequency is 22, the cutting frequency of the basic embodiment is 15, and the processing efficiency is improved by 32%.

Table 1 shows the prior art for composite hole making;

table 2 shows the composite material was perforated using the basic embodiment of the present invention;

TABLE 1

TABLE 2

As can be seen from tables 1 and 2, the composite material hole forming efficiency is significantly improved by the basic embodiment of the present invention on the premise of ensuring the hole forming quality.

The following best mode of carrying out the invention is adopted to compare the hole making processes of 4.2mm, 5mm, 6.6mm, 8mm, 10mm and 12mm holes with the prior art respectively:

4.2mm holes: in the prior art, the cutting frequency is 5 times, the cutting frequency of the best implementation mode is 5 times, and the processing efficiency is improved by 0 percent;

5mm of holes: in the prior art, the cutting frequency is 7 times, the cutting frequency of the best embodiment is 6 times, and the processing efficiency is improved by 14 percent;

6.6mm holes: in the prior art, the cutting frequency is 10 times, the cutting frequency of the best embodiment is 8 times, and the processing efficiency is improved by 20 percent;

8mm holes: in the prior art, the cutting frequency is 14 times, the cutting frequency of the best embodiment is 8 times, and the processing efficiency is improved by 43 percent;

10mm holes: in the prior art, the cutting frequency is 18 times, the cutting frequency of the best embodiment is 10 times, and the processing efficiency is improved by 44%;

12mm holes: in the prior art, the cutting frequency is 22 times, the cutting frequency of the best mode is 11 times, and the processing efficiency is improved by 50%.

Table 3 shows the composite material holes made using the best mode of the invention;

TABLE 3

As can be seen from table 3, on the premise of ensuring the hole drilling quality, the hole expanding times are optimized in the basic embodiment of the present invention by using the best embodiment of the present invention, and the hole drilling efficiency of the composite material is further improved compared with that in the basic embodiment of the present invention.