CN203245429U - Helical end milling cutter used for carbon fiber reinforced composite material - Google Patents

Abstract

The utility model relates to a pineapple end mill used for carbon fiber reinforced composite materials. In general, when milling and processing such composite plates and laminated plates, defects such as delamination, splitting, and burns are prone to occur, among which delamination and splitting have the greatest impact on processing quality. A pineapple end mill for carbon fiber reinforced composite materials, which consists of: a tool handle (1), the tool handle is connected to a knife neck (2) made of alloy material, and the knife neck has a right-handed tooth belt (3) and right-handed knife teeth (4), the right-handed knife tooth belt has left-handed teeth (5) and left-handed tooth grooves, and the right-handed knife teeth and the left-handed teeth have nanocomposite coatings . The method can be widely used in the processing of aerospace, racing car shell manufacturing, mold plate making, advertising decoration, precision electronic parts and the like.

Description

Pineapple End Mills for Carbon Fiber Reinforced Composites

Technical field:

The utility model provides an end milling cutter for carbon fiber reinforced composite materials used in aerospace and automobile competitions and circuit boards.

Background technique:

Carbon fiber reinforced composite materials have the advantages of high specific strength, high specific modulus, and good vibration damping. They have been widely used in the aerospace field, and their applications in automobile competitions, sports equipment and other industries are also increasing. Fighters in service after the 1980s all use a large number of carbon fiber reinforced composite materials, and the amount of composite materials has become one of the important indicators to measure the performance of aircraft. For example, the French Rafale fighter accounted for 40% of composite materials, the Swedish JAS39 fighter accounted for 30%, the European "Typhoon" fighter accounted for more than 40%, the U.S. killer weapon B-2 strategic bomber accounted for 50%, and the U.S. Air Force's latest F-22 The amount of composite materials used in the "Raptor" fighter jet reached 35%. In 1984, Toray Corporation of Japan successfully developed carbon fiber T800H with high strength and large elongation. In 1986, it successfully developed T1000. Subsequently, Toho of Japan, Mitsubishi Rayon and Hexcel of the United States successively developed similar high-performance carbon fibers, providing new composite materials for the manufacture of large aircraft. Since then, the use of carbon fiber reinforced composite materials in large aircraft has skyrocketed.

With the expansion of the application field of composite materials, it is increasingly urgent to solve the problem of high-precision and high-efficiency processing of composite materials. Under normal circumstances, when milling and processing such composite plates and laminated plates, defects such as delamination, splitting, and burns are prone to occur, among which delamination and splitting have the greatest impact on processing quality. According to reports, in the manufacture of AV-8B aircraft, the failure rate of parts caused by delamination and splitting caused by processing accounts for more than 60% of the failure rate of CFRP parts in the whole aircraft.

The main reasons for delamination and splitting are: (1) The composite panel is made of carbon fiber layers, and the layers are bonded with resin. Since carbon fiber reinforced composite is an anisotropic material, its mechanical properties are different in different directions, and the strength of the material along the direction of fiber layup is higher, while the strength perpendicular to the direction of fiber layup depends on the resin bond strength, generally In this case, the interlayer bonding strength is only 2.2% of the fiber direction strength. (2) During processing, there is an axial force Fz perpendicular to the direction of fiber layup, thereby generating normal stress in the laminate. When the normal stress generated by the cutting force exceeds the resin bonding strength, resin fracture and fiber layer separation will occur. Delamination or splitting and other phenomena, the greater the axial force, the more serious the delamination and splitting phenomenon.

Invention content:

The utility model provides a cutting tool for milling on a carbon fiber composite laminated plate to overcome the existing problems of resin fracture, delamination or splitting of fiber layers.

The purpose of this utility model is achieved in that:

A pineapple end mill for carbon fiber-reinforced composite materials, comprising: a handle, the handle is connected to a knife neck of an alloy material, and the knife neck has a right-handed knife tooth belt and a right-handed knife The right-handed tooth belt has left-handed teeth and left-handed tooth grooves, and the right-handed knife teeth and the left-handed teeth have nanocomposite coatings.

In the pineapple end mill for carbon fiber reinforced composite materials, the number of right-handed teeth on the right-handed tooth belt is 2-8, and the helix angle is 30°-60°.

For the pineapple end mill for carbon fiber reinforced composite materials, the helix angle is 40°-45°, and the change of the helix angle of a single cutter is not more than 5°.

For the pineapple end mill for carbon fiber reinforced composite materials, the cutter diameter is 0.80mm to 3.175mm, and the cutter neck with a shank diameter of 3.175mm adopts carbide rods and tungsten steel rods. The right-handed cutter teeth and the left-handed teeth use ultra-fine grain cemented carbide materials.

Beneficial effect:

Carbon fiber reinforced composite materials are often connected with other structures in the application process, and the connection is the weak link of the composite material structure. According to statistics, 60% to 80% of the damage in aerospace vehicles occurs at the joints. The most commonly used mechanical connection in the connection requires the processing of the mechanical connection part first. For example, a Boeing 747 aircraft has more than 3 million connecting holes, while the most advanced F-22 fighter jet in the United States requires 14,000 fine holes for each wing to be milled. Composite materials are typical difficult-to-machine materials, and their processing technology is complex, which requires higher requirements on cutting tools and process parameters. Therefore, the pore-making process of composite materials has become one of the key processes in the application of composite materials. The utility model effectively solves the problem of splitting and delamination in fine hole machining.

Carbon fiber reinforced composite material is a two-phase or multi-phase structure composed of a soft and viscous matrix material and a high-strength, high-hardness carbon fiber reinforced material. Its mechanical properties are anisotropic, and the interlayer strength is low. Under the action of cutting force, defects such as delamination and splitting are easy to occur.

Due to the high hardness of the material in the existing drilling process of carbon fiber reinforced composite materials, its hardness HRC value can reach 53~65, which is equivalent to the hardness of general high-speed steel, so the cutting edge wears quickly during milling. Due to the strength of the connection value, the interlayer strength is low, and defects such as delamination are easy to occur during processing; and the composite material is an anisotropic material, and when the stress concentration is large, it is easy to cause defects such as burrs and splits. The utility model adopts a specific cutting angle and helix angle, and increasing the number of left-handed blades can effectively offset the axial cutting force generated during cutting, and reduce burrs and delamination as much as possible. Delamination is a major defect in the processing of carbon fiber composites. The size of delamination defects can be expressed by delamination factor (Fd). The delamination factor can be expressed by the following formula: Fd =Dmax/D, where Dmax represents the diameter of the maximum damaged area, and D represents the actual diameter of the hole, as shown in Figure 2. There is a linear or piecewise linear relationship between the delamination factor Fd and the average axial force Fz: the greater the average axial force Fz, the greater the delamination factor Fd, and the more serious the delamination. The utility model effectively overcomes the delamination resistance through the design of a specific helix angle, and obtains a precise hole shape.

The utility model adopts more left-handed teeth, presses down the material, provides tooling rigidity, and obtains better surface quality. The specific parameters of this product are specially used for processing composite materials such as carbon fiber, glass fiber, honeycomb material, MMC metal matrix, etc., 0-degree edge angle end mill: suitable for a variety of composite materials (including plastic matrix composite materials) for most applications , metal matrix composites and ceramic matrix composites); more than positive 3 degrees (right-handed) and upper edge inclination end mills: the material is pressed down during processing to obtain the best surface quality of the upper surface; negative 3 degrees or more ( Left-handed) rake end mills: push the material up during machining to get the best surface quality on the upper surface.

The knife neck of the utility model adopts cemented carbide rods and tungsten steel rods, which have high hardness, high wear resistance, high strength, bending resistance, and breakage resistance. Long tool life is preferred, and the knife teeth use ultra-fine grain Granular carbide material, with good milling performance to ensure high work efficiency; sufficient bending strength and wear resistance; milling slots, holes and board edges, the surface is clean, tidy, and burr-free. The method can be widely used in the processing of aerospace, racing car shell manufacturing, mold plate making, advertising decoration, precision electronic parts and the like.

Description of drawings:

Accompanying drawing 1 is the structural representation of the utility model.

Accompanying drawing 2 is the stress distribution diagram of delamination resistance.

Detailed ways

Example 1:

A pineapple end mill for carbon fiber reinforced composite materials, which consists of: a handle 1, the handle is connected to a knife neck 2 of an alloy material, and the knife neck has a right-handed knife tooth belt 3 and Right-handed knife teeth 4, said right-handed knife-tooth belt has left-handed teeth 5 and left-handed tooth grooves, said right-handed knife teeth and said left-handed teeth have nanocomposite coatings.

Example 2:

Example 1 For the pineapple end mill for carbon fiber reinforced composite materials, the number of right-handed teeth is 2-8, and the helix angle is 30°-60°. The conventional tooth shapes of spiral edge end mills are straight and helical. Compared with the straight edge, the spiral edge end mill has the advantages of light cutting, smooth cutting, high efficiency and wide application range, so it has been widely used in milling. According to the different requirements of processing equipment and processing objects, helical edge end mills have four different combinations of left edge, right edge, and left helix and right helix. The axial cutting resistance has a tendency to pull the end mill out of the toolholder, so tension bolts are needed to overcome the axial cutting resistance. However, the axial cutting resistance of the left helix and the right helix just press the end mill to the chuck, so a tapered shank and a flat tail are often used to adapt to high-power cutting. Because the right-edged and right-helical end mill can let the chips discharge to the handle along the chip flute, it is easy to ensure the smooth cutting, conforms to the standard of the rotation direction of the machine tool spindle, and is easy to load and unload with the support of the high-performance chuck. The utility model is used The helix angle is better between 30° and 45°.

Example 3:

For the pineapple end mill for carbon fiber reinforced composite materials described in Embodiment 1 or 2, the cutter diameter is 0.80mm to 3.175mm, and the shank diameter is 3.175mm. Most suitable for processing thin-layer composite materials.

Example 4:

In the pineapple end mill for carbon fiber reinforced composite materials described in embodiment 1 or 2 or 3, the helix angle is 35°-55°, and the helix angle of a single cutter is changed by no more than 5° . The helix angle β of the helical edge end mill is the blade inclination angle λs. A larger helix angle can increase the number of teeth working at the same time, reduce the impact during milling and increase its stability, and make the edge of the end mill sharp and the actual rake angle increased. big. In addition, overcut always occurs on the up-cut milling side, and on the contrary, miss cut always occurs on the down-milling side, and the maximum point of overcut and miss cut is at the farthest point where the end mill protrudes. This is in line with the deformation law of the tool and the deformation law of the protruding length of the tool during up milling and down milling. The utility model adopts unequal (or different) helix angles, which include two meanings, one is that the length of each cutting edge is the same, and the other design is that the helix angle is changed along the length of the cutting edge of. For example, the helix angle of the rake face of a tool is 30°, the angle at a certain point in the middle is 37.5°, and the helix angle of the flank face can reach 45°. The helix angle can likewise vary from 37° to 30°. During cutting, the tool is affected by damping as the end mill cuts along the same helix at different angles. End mills have different helical flute pitches (or different tooth pitches), so they can produce a cutting motion that is out of phase (out of phase) to prevent resonance. For example, the tooth pitch of a 4-groove end mill (or a variable displacement end mill) is 89° between the 1st and 2nd grooves, 91° between the 2nd and 3rd grooves, and so on. Add up to 360°. When processing with an ordinary end mill, there will be continuous harmonic vibration, which is based on the premise that the helix angle of the milling cutter is the same and the cutting edges are evenly distributed. For a set of end mills with a given geometry, when you look at it from all directions, the helix angle cannot vary by more than 5°, otherwise it will cause stability problems. The result is a clear sound pattern from each cutting edge of a tool as it contacts and moves along the workpiece surface. Since the cutting edges produce different sound modes, the potential for resonance may be overlooked. Although variable helix end mills have the same geometry along each cutting edge, rake angles, undercuts, helixes, and even rake to flank of complete changes. While machining a workpiece with this milling cutter, the tool will constantly change its sound pattern.

Before the helix angle of the end mill is less than 30°, whether it is the down milling side or the up milling side, the squareness error value increases with the increase of the helix angle. After the helix angle is greater than 40°, it becomes smaller with the increase of the helix angle. When the end mill has a small helix angle or a large helix angle, the shape accuracy of the milling groove is high.

Example 5:

The pineapple end mill for carbon fiber reinforced composite materials described in embodiment 1 or 2 or 3 or 4 has been proved by practice. The precision is the highest when the helix angle is 0°, that is, the cutting edge is straight. However, from the basic characteristics of the helix angle of the end mill, it can be seen that the cutting is completely intermittent at this time, the cutting impact is large, and the requirements for the production accuracy of the tool itself are high. The machining accuracy is very dependent on the accuracy of the tool itself, and the service life of the tool Short, helix angle and 4-flute end milling side milling experiment On the vertical machining center, 4-flute end mills with helix angles of 30° and 55° were used to mill the side, and the two end mills were compared with the cutting width ( The influence of the change of the radial cutting amount) on the machining accuracy. The diameter of the end mill is 25mm, and the material to be cut is No. 45 steel with a hardness of 94HRB. All cutting adopts down milling and dry cutting. The cutting parameters are unified as follows: feed rate 100mm/min, cutting speed 26m/min, cutting depth 38mm. The verticality error measured after machining, when the cutting width is not particularly large, the machining accuracy of the end mill with a large helix angle of 55° is higher than that of the end mill with a helix angle of 30°. This is because when the cutting width is small, the actual rake angle of the end mill with a large helix angle is large, the cutting edge is sharp, and the penetration is good; the tangential cutting resistance is small, which reduces energy consumption and tool deformation, and the cutting is brisk; the cutting edge and There are many contact points on the cut surface, so that the cutting in and out of the end mill is relatively stable, the fluctuation of cutting resistance is small, and the combined effect of the vibration excitation of the end mill during processing is weakened.

Through the application of the utility model, the helix angle can be determined: (1) Helix angle and cutting resistance: the tangential cutting resistance decreases with the increase of the helix angle, and the axial cutting resistance increases with the increase of the helix angle. (2) Helix angle and rake angle: The increase of the helix angle increases the actual rake angle of the end mill and makes the cutting edge sharper. (3) Helix angle and the accuracy of the machined surface: Generally, the tolerance value of verticality and flatness of the machined surface increases with the increase of the helix angle, but when the helix angle is greater than 40°, it decreases with the increase of the helix angle. small trend. (4) Helix angle and tool life: the wear rate of the peripheral edge zone is basically proportional to the size of the helix angle; on the other hand, when the helix angle is small, slight tool wear will also significantly reduce the cutting performance of the tool and cause vibration. Make the tool unusable. When the helix angle is too large, the rigidity of the tool is deteriorated and the life is shortened. (5) Helix angle and the material to be cut: when processing soft materials with low hardness, use a large helix angle to increase the rake angle and improve the sharpness of the cutting edge; when processing hard materials with high hardness, use a small helix angle , to reduce the rake angle and improve the rigidity of the cutting edge.

The helix angle is one of the main parameters of the helical edge end mill, and the change of the helix angle has a great influence on the cutting performance of the tool. With the development of CNC machining technology and flexible manufacturing technology, if we further study the various effects of the helix angle on the cutting performance of helical edge end mills, when manufacturing and selecting helical edge end mills, combined with machine tools and fixtures Performance, according to the performance of the processed material, processing accuracy, processing efficiency, tool material and tool life and other factors, optimizing the size of the helix angle will undoubtedly play an important role in promoting high-efficiency and high-precision milling.

The pineapple-shaped milling cutter of the utility model is used for processing various composite materials such as carbon fiber, glass fiber, metal matrix composite material and glass. When the length of the cutting edge has a certain requirement, it can also be used to process the plate, and the cutting edge of the milling cutter is divided into several sections for use. Undoubtedly, it is a cost-effective and suitable for almost all solid carbide milling cutters on the market. This utility model adopts DURA nano-composite coating, which can greatly improve the wear resistance and the relationship between the coating and the substrate compared with ordinary diamond coatings. Bonding force, thereby increasing the life of the tool.

Claims (4)

1. A pineapple end mill for carbon fiber reinforced composite materials, which consists of: a handle, the handle is connected to the neck of an alloy material, and it is characterized in that: the neck of a knife has a right-handed knife A toothed belt and a right-handed knife tooth. The right-handed knife tooth belt has left-handed teeth and left-handed tooth grooves, and the right-handed knife tooth and the left-handed tooth have a nanocomposite coating. 2. The pineapple end mill for carbon fiber reinforced composite materials according to claim 1, characterized in that: the number of right-handed teeth on the right-handed toothed belt is 2-8, and the helix angle is 30°-60° °. 3. The pineapple end mill for carbon fiber reinforced composite materials according to claim 2, characterized in that: the helix angle is 40°-45°, and the change of the helix angle of a single cutter does not exceed 5°. 4. The pineapple end mill for carbon fiber reinforced composite materials according to claim 1, 2 or 3, characterized in that: the blade diameter is 0.80mm to 3.175mm, and the blade neck with a shank diameter of 3.175mm Carbide rods and tungsten steel rods are used, and the right-handed cutter teeth and the left-handed teeth use ultra-fine-grained hard alloy materials.

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