AU2020101554A4

AU2020101554A4 - A composite vibration drilling method suitable for CFRP / titanium (aluminum) alloy laminate materials

Info

Publication number: AU2020101554A4
Application number: AU2020101554A
Authority: AU
Inventors: Feng JIAO; Xiangshan Mao; Ying NIU; Jialiang QI; Dong Wang; Xiaobo Wang; Xiaoliang Wang; Bo Zhao
Original assignee: Henan University of Technology
Current assignee: Henan University of Technology
Priority date: 2020-07-29
Filing date: 2020-07-29
Publication date: 2020-09-03
Anticipated expiration: 2028-07-29

Abstract

The invention provides a composite vibration drilling method suitable for CFRP / titanium (aluminum) alloy laminate materials. In this method, ultrasonic vibration is applied to the drill bit 4 by the ultrasonic handle 3, low-frequency vibration is applied to the material to be processed by the low frequency vibration box 7, Optimum drilling effect of each layer is obtained by restraining machining defects of each layer by different vibration machining methods. The present method reduces the machining damage at the interface by simultaneously using a high and low frequency vibration compound assisted drilling method at the junction of the two materials of the laminated materials 5 and 6. In this method, the program of the CNC control panel of the vertical machining cent 1 can simultaneously control the machining parameters of the ultrasonic power supply 8 and the servo motor 9 and the position and speed of the spindle box of the machine center 1, further, the machining parameters and vibration modes of the drill bit 4 and the stage 17 are controlled to realize the automatic operation of the high-low frequency compound vibration drilling. 1/4 Frequency Curen 10 .- 11 12 13 13-1 15 13-2 -/1 15 3 Figure 1

Description

1/4

Frequency Curen

10 .- 11 12 13 13-1 15 13-2 -/1 15 3

Figure 1

AUSTRALIA

PATENTS ACT 1990

PATENT SPECIFICATION FOR THE INVENTION ENTITLED:

A composite vibration drilling method suitable for CFRP / titanium (aluminum) alloy laminate materials

The invention is described in the following statement:-

TECHNICAL FIELD

[0001] The present invention belongs to the technical field of precision machining, in particular to a method for precision machining of holes of carbon fiber / titanium alloy laminated materials.

BACKGROUND

[0002] With the development of China's aviation industry, the aircraft manufacturing sector has a growing demand for high-performance aviation materials. Aeronautical laminated material is a new type of aeronautical material which is a composite material composed of carbon fiber and titanium alloy. The carbon fiber has the characteristics of high specific strength, high specific modulus, good fatiue resistance and excellent heat resistance. Titanium alloy is an important aviation metal with high mechanical strength and light weight.

[0003] In practice, Riveting is the main method of Aeronautical laminated composites, so it is necessary to process the holes of laminated composites. Carbon fiber has high hardness and titanium alloy has active chemical properties. They will cause serious wear to the cutting tools. The worn cutting tools will increase the cutting force and cutting heat. When the temperature exceeds 200 °C, the resin will melt and the knife will stick. When the temperature continues to rise, chips may be ignited, causing safety accidents. When the temperature continues to rise, it may also ignite the chips, causing a safety accident. In addition, after the two materials are combined to form a laminated material, the mechanical characteristics and thermal conductivity at the material joint face will change step by step, so that the tool is subjected to step force and thermal shock, which is very easy to cause the tool chipped and broken. In addition, the stacking sequence of the carbon fibers and the titanium alloy also has an influence on the working procedure, and when the carbon fiber is on top of the titanium alloys, when drilling carbon fibers, titanium alloys can be used as carbon fiber backing plates, in this case, the carbon fiber are not easily delaminated. When the carbon fiber is under the titanium alloy, the rigidity of carbon fiber itself is small, the inter-laminar shear strength is low, and the delamination defect is easy to occur without support.

[0004] Hole processing methods such as waterjet, high-energy particle beam and electric spark are not suitable for the processing of holes of carbon fiber / titanium alloy aviation laminated materials, because the carbon fiber will have poor performance after absorbing liquid. Therefore, in practice, dry cutting is adopted; high-energy particle beam and electric spark will cause thermal damage to the hole wall, so the hole processing of carbon fiber / titanium alloy laminated material is still mainly mechanical processing.

[0005] Vibration drilling is intermittent cutting, which is favorable for chip breaking, and vibration drilling can reduce axial force and tool wear. Ultrasonic vibration drilling is suitable for machining difficult-to-machine materials, and for carbon fiber materials, it is favorable for cutting burr, reducing roughness and improving hole wall quality. However, ultrasonic vibration drilling of titanium alloy will cause the increase of cutting heat, so low-frequency axial vibration drilling is generally used for titanium alloy.

When the drill is located at the joint surface of the carbon fiber board and the titanium alloy, the high-low frequency compound vibration assisted drilling is adopted to further reduce the damage of joint surface through parameter optimization. In addition, in the vibration process, the parameters that influence the process quality include frequency, amplitude and vibration mode, and the conventional vibration drilling adopts a single vibration mode and cannot cope with the characteristics of various type of materials, which is not conducive to good processing quality.

SUMMARY

[0006] The object of the present invention is to provide a method for precisely machining holes in a carbon fiber / titanium alloy aeronautical laminated material in order to solve the disadvantages of the existing drilling technology for laminated composite materials.

[0007] The present invention is realized such that a precision machining process for a hole of a carbon fiber / titanium alloy aeronautical laminated material comprises the following steps:

First, the laminated material is fixed to the stage 17 of the low-frequency vibration box 7.

[0008] (2) Low-frequency vibration is generated by the low-frequency vibrating box 7 through the mechanical structure: The cam 19 and the ram 18 constitute a cam ram mechanism, and the high-precision servo motor 9 drives the cams 19 inside the lower-frequency oscillating box 7 to rotate. Each time the cam 19 rotates, the ram 18 reciprocates up and down once. The ends of the ejector pins 18 are connected to the stage 17, which then transmits low-frequency vibrations to the laminated material to be processed. The frequency of the low-frequency vibration is the speed per second of the servo motor 9, which can be controlled by the servo motor 9, and the amplitude is adjusted by the elongation of the ejector pin 18 in contact with the cam 19. Adjust the required amplitude and frequency to complete the low frequency vibration parameter setting.

[0009] (3) The ultrasonic vibration is generated by the ultrasonic transducer 12 and the ultrasonic horn 13. In order to power the transducer 12, the method employs a wireless power supply. The wireless power supply system is realized by the principle of electromagnetic induction between the main coil 10 inside the wireless transmission device 2 and the sub-coil 11 inside the handle 3. The side wall of the wireless transmission device 2 is mounted on the spindle head 1 of the machining center by means of screws, and the coil 10 inside the device is connected to the ultrasonic power supply 8, so that the device 2 does not rotate during machining. The ultrasonic transducer 12 and the ultrasonic horn 13 are assembled together by stud bolts. There are two modes of ultrasonic vibration: Longitudinal and torsional compound vibration and axial vibration, and each mode of vibration has multiple resonance frequencies and amplitudes. The amplitude and mode of vibration are determined by the shape of the ultrasonic horn 13 and the resonant frequency is selected by the transducer 12. The front end of each ultrasonic horn 13 clamps the drill bit 4 by a colletting chuck 14. During machining, the setting of ultrasonic vibration parameters is accomplished by selecting the form of ultrasonic horn 13, setting the resonance frequency and power of ultrasonic power supply 8, and setting the low-frequency vibration according to the required amplitude, resonance frequency, and vibration mode.

[0010] (4) The ultrasonic power supply 8 and the controller of the low frequency vibration box 7 are equipped with the universal standard type I / 0 interface, through which they can be connected with the PLC controller in the CNC control panel of the machining center 1. After the connection is completed, the ultrasonic power supply 8, the low-frequency vibration box 7 and the machining center 1 can be simultaneously operated by inputting a program on the panel. According to the thickness and material characteristics of the laminated material to be processed, the rotational speed and feed are selected and programmed on the CNC control panel of the machining center 1.

According to the low-frequency vibration of metal layer and the ultrasonic vibration of carbon fiber layer, the hybrid vibration drilling method is selected at the joint of two materials according to their stacking sequence.

[0011] The present invention overcomes the disadvantages of the prior art, and utilizes the composite vibration mode to process the hole of the carbon fiber / titanium alloy laminated material, which can reduce the material delamination area, cutting temperature and reduce the tool wear to achieve high quality processing. In this method, the ultrasonic pow source 8, the low-frequency vibration box 7 and the machining cent 1 can be simultaneously operated through an input program, so that the machining efficiency can be improved.

BRIEF DESCRIPTION OF THE FIGURES

[0012] FIG. 1 is a schematic diagram of a low-frequency vibration box 7 of the present invention;

[0013] FIG. 2 is a schematic view of the ultrasonic holder 3 of the present invention;

[0014] FIG. 3 is a schematic view of the depth of progress of the drill bit 4 during the laminated material processing of the present invention;

DESCRIPTION OF THE INVENTION

[0015] In order to make the objects, technical solutions and advantages of the present invention more clear, the invention is further described in detail below in conjunction with the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the invention.

[0016] A method for machining holes in a carbon fiber / titanium alloy laminate composite material, comprising the steps:

First, the low-frequency axial vibration box 7 is mounted on the table of the universal vertical machining center 1, and the carbon fiber / titanium alloy laminated material is mounted and clamped on the stage 17.

The servo motor controller of the low-frequency axial vibration box 7 is connected with the PLC controller inside the CNC control panel of the vertical machining center 1 through the I / 0 connection port, The vertical machining center 1 can adjust the parameters of the low-frequency axial vibration box 7 by programming on the CNC control panel.

[0017] (2) The servo motor 9 rotates the cam 19, and the rotation speed of the motor 9 per second is the frequency of low-frequency vibration in the range of 0-200 Hz, which can be modulated steplessly. The amplitude is set by adjusting the stroke of the ram 18 to a maximum amplitude of 0.5 mm, which can be adjusted steplessly between 0 and 0.5 mm

(3) As shown in FIG. 2, three kinds of resonance frequencies of ultrasonic vibration machining are selected: 20000, 28,000, and 35,000 Hz, and the wireless transmission device 2 is fixed to the spindle box of the machine tool 1 through side-wall screws. The ultrasonic power supply 8 is connected to the internal coil 10 of the wireless transmission device 2 through a wire.

The controller of the ultrasonic power supply 8 is connected to the PLC inside the vertical machining center 1 through the I / 0 connection port, and the vertical manufacturing center 1 can adjust the parameters of ultrasonic power 8 by programming on the CNC control panel.

The main coil 10 inside the wireless transmission device 2 and the sub-coil 11 inside the handle 3 realize energy transmission by electromagnetic induction. The tool holder 3 is divided into two types in terms of structure: A stepped horn 13-1 for generating axial vibration and a helical groove 13-2. In order to generate that combined longitudinal and torsional vibration; there are three amplitude of the ultrasonic horn 13: 5pm, 10pm and pm,respectively. Considering the previous 3 amplitudes, 3 frequencies and 2 vibration forms, there are 18 vibration processing modes in total, and there is a wide range of options. After the vibration mode is selected, the drill bit 4 is selected properly, and the drill head 4 and the tool shank 3 are assembled together by using the colletion of chuck 14 and the pressure cap

, and then the tool stem 3 is inserted into the spindle 16.

[0018] (4) As shown in Figure 3, the stroke of the drill bit 4 is from 0 to D. Assuming that the thicknesses of the carbon fiber and the titanium alloy are

each lcm, and the thickness parameter of the material has been input into the

machining program through the CNC control panel of the machining center

1 before machining. The program will automatically process according to

the programmed program based on the feed depth of the drill bit. When the

upper material of the laminate is the carbon fiber layer 5 and the lower

material is the titanium alloy layer 6, in this order of lamination, the titanium

oxide layer 6 has a supporting effect on the carbon fib layer 5, so when

drilling the carbon fabric layer 5, carbon fibers do not delaminate easily. In

the process of feeding the drill bit 4 from 0 to B, the machine tool

automatically switches to the preset machining parameters. The processing

speed may be selected as 15mm / min, and the rotating speed as 6000r / min.

And in the process from 0 to B, the material will be processed is carbon

fiber. in this process, ultrasonic vibration drilling shall be adopted, and the

axial vibration mode can be selected, with the frequency of 35000 Hz and

the amplitude of 5pm. When the drill bit 4 cuts two materials simultaneously

in the process from B to C, the process shall adopt ultrasonic frequency and

low-frequency vibration processing at the same time, and the low frequency

amplitude may be selected as 0.1mm and the frequency as 100Hz. After the drill 4 has passed through the section C, only the titanium alloy is drilled, and the ultrasonic power supply 8 is turned off, and only the low-frequency vibration is used.

[0019] (5) When the titanium alloy layer 6 is on the top and the carbon fiber layer 5 is at the bottom, the lower portion of the carbon fibers layer 5 loses support and is easily delaminated. When processing the titanium alloy layer 6, the machine tool is automatically switched to the preset processing parameters from 0 to B, and the rotating speed can be set at 6000 r / min, the feed speed is selected as 15 mm / min, as the section from 0 to B is made of titanium alloy material, low frequency vibration drilling should be adopted, and the low frequency amplitude can be selected as 0.1 mm and the frequency as 100 Hz. In the interval of B to C, the drill bit 4 processes two materials at the same time, at this time, ultrasonic vibration and low frequency vibration are simultaneously apply, and the ultrasonic vibration mode can be selected as the axial vibration mode, the frequency is 35000 Hz, the amplitude is 5pm, However, since that carbon fib is easy to delaminate, in order to reduce delamination, the fee rate should be decreased, and the feed rate may be selected as 5mm / min, and in order that the material removal rate can be improved, the rotation rate is increased to 15000r / min. When the drill is in the section from C to D, the rotation speed and the feed speed are unchanged, the low-frequency vibration is turned off, and only the ultrasonic vibration is used for drilling.

[0020] Compared with the disadvantages and disadvantages of the prior art, the present invention has the following beneficial effects:

In this method, the process mode of ultrasonic frequency and low frequency vibration can be freely switched, so that the defect that the single vibration mode is difficult to take into account when process the carbon fiber and the titanium alloy laminated material simultaneously is avoided, In this method, different process modes are adopt for different materials, and a mixed vibration processing mode is used at the interface of the material, so that the cutting heat and the delamination are reduced, and the processing quality is improved.

[0021] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. any modification, equivalent substitution, improvement, etc., which is made within the spirit and principles of the invention, and should be included in the scope of the present invention.

Claims

THE CLAIMS DEFINING THE INVENTION ARE AS FOLLOWS:

The invention relates to a compound vibration drilling method for carbon fiber / titanium (aluminum) alloy laminated material hole, which is characterized in that laminated material is subjected to composite auxiliary effects of ultrasonic frequency vibration and low frequency vibration in a machining process. According to the drilling position of the drill, the vibration application mode is adjusted reasonably, and the optimum processing parameters are adopted to realize the precise drilling of the carbon fiber / titanium (aluminum) alloy laminated material.
2. The composite vibration drilling method for laminated materials as claimed in claim 1 is characterized in that the laminated material metal layer adopts a low-frequency vibration-assisted drilling mode, which can effectively reduce the axial drilling force and the drilling temperature, the chip length is reduced to realize the hole precision machining while reducing the influence on the carbon fiber layer.
3. The composite vibration drilling method for laminated materials as claimed in claim 1 is characterized in that the carbon fiber layer of the laminated materials adopts an ultrasonic frequency vibration assisted drilling mode, which can effectively reduce the drilling force, reducing delamination defects and tool wear, and achieve precision and efficient hole processing.
4. The composite vibration drilling method for laminated materials as claimed in claim 1, characterized in that a composite vibration-assisted drilling method with ultrasonic and low-frequency vibration is simultaneously adopted at the bonding surfaces of two materials of the laminated materials, which can reduce the cutting force and cutting thermal damage at the joint surface.
5. The laminated material composite vibration drilling method as claimed in claim 1, characterized in that by adjusting the object to which the vibration is applied, the different forms of compound vibration drilling methods are as follows: (1) a composite vibration drilling method in which ultrasonic vibration is applied to the tool and low frequency vibration is applied to the workpiece; (2) a composite vibration drilling method in which low frequency vibration is applied to the tool and ultrasonic frequency vibration is applied to the workpiece; and (3) a composite vibration drilling method in which both ultrasonic vibration and low frequency vibration are applied to the tool.(4)A composite vibration drilling method that simultaneously applies ultrasonic vibration and low frequency vibration to the workpiece.
6. A laminated material composite vibration drilling method as claimed in claim 1, characterized in that an ultrasonic power supply and a low frequency vibration switch can be controlled by programming, in order to realize that automatic operation of high and low frequency compound vibration drilling, only by inputting the dimension parameter, drilling and vibration parameters of the laminate material.