Fluctuation ultrasonic brittle-plastic composite cross-scale cutting enhanced processing method for ceramic matrix composite material

Abstract

The invention relates to a ceramic matrix composite material fluctuation ultrasonic brittle-plastic composite cross-scale cutting enhanced processing method, which comprises the following steps that a workpiece is fixed on an ultrasonic vibration processing platform, and a cutter of the ultrasonic vibration processing platform can generate axial ultrasonic vibration; the amplitude, the frequency, the rotating speed and the axial cutting depth of an ultrasonic vibration machining platform are set according to the material brittle-plastic transformation critical cutting thickness of a workpiece, plastic cutting and brittle cutting are alternately carried out in the one-time cutting process through phase difference control of tool movement track waveforms, and brittle-plastic composite cutting is achieved. According to the method, micro-adjustment of the single removal amount is achieved through phase difference control of ultrasonic machining track waveforms, micro-texture cutting is achieved, a specific vibration machining track is formed in the cutting process, and variable-thickness cross-scale cutting is formed. According to the manufacturing process, the final surface area in the cutting process is overlapped in a microscale through control over the feeding parameters, the plastic final surface is formed, and the surface quality and the machining efficiency of the ceramic matrix composite are improved.

Description

Technical Field

[0001] The invention relates to the technical field of ceramic matrix composite material processing, and in particular to a wave ultrasonic brittle-plastic composite cross-scale cutting enhanced processing method for ceramic matrix composite materials. Background Art

[0002] The extensive application of ceramic-based composites is an important development trend in the field of aerospace manufacturing. Due to the excellent properties of ceramic-based composites such as light weight, high strength, high modulus, wear resistance or high and low temperature resistance, the demand for ceramic-based composites in the aerospace field is growing, and the proportion of ceramic-based composites in the total amount of materials used in the aerospace field is gradually increasing. However, ceramic-based composites are difficult to process, and mechanical damage such as material breakage and tearing is easily caused during the cutting process. Macroscopic defects caused by fiber delamination and shedding often occur, which reduces the quality of the processed surface, makes it difficult to ensure product accuracy, and affects product performance. According to the material removal mechanism of ceramic-based composites, removing materials in the micro-brittle fracture domain can achieve high-quality surface processing, but it is difficult to determine the optimal cutting conditions for complex multivariable optimization problems, and the optimal way to improve cutting efficiency is not easy to determine. Therefore, at present, in order to achieve high surface quality processing of parts, it is usually chosen to sacrifice processing efficiency to ensure surface quality, which is difficult to balance processing efficiency and processing surface quality. Summary of the invention

[0003] The purpose of the present invention is to provide a wave ultrasonic brittle-plastic composite cross-scale cutting enhanced processing method for ceramic-based composite materials, so as to improve the processing efficiency of ceramic-based composite materials and take into account the processing surface quality.

[0004] In order to achieve the above object, the present invention provides a wave ultrasonic brittle-plastic composite cross-scale cutting and enhanced processing method for ceramic matrix composite materials, comprising the following steps:

[0005] The workpiece is fixed on an ultrasonic vibration processing platform, and the tool of the ultrasonic vibration processing platform can generate axial ultrasonic vibration;

[0006] The amplitude, frequency, rotation speed and axial cutting depth of the ultrasonic vibration machining platform are set according to the critical cutting thickness of the brittle-to-plastic transition of the workpiece material. By controlling the phase difference of the tool motion trajectory waveform, plastic cutting and brittle cutting are performed alternately in one cutting process to achieve brittle-plastic composite cutting.

[0007] Optionally, the tool motion trajectory is:

[0008]

[0009] Where f is the feed rate, A is the amplitude, k is the vibration frequency, and θ is the radian of tool rotation;

[0010] Dynamic cutting thickness H1 is:

[0011]

[0012] Among them, x(θ-m2π) is the maximum value of the first m trajectories, and the ratio of frequency to speed ξ in brittle-plastic composite cutting is defined as:

[0013]

[0014] Where n is the rotation speed;

[0015] Then, the phase difference ψ between the two trajectory waveforms can be expressed as:

[0016] ψ=2π(ξ-[ξ])

[0017] Among them, [ξ] is the integer of ξ, and its physical meaning is explained as follows: the ultrasonic frequency is generally higher than 20kHz, n / 60 represents the rotation frequency and is generally below 100Hz, so the two are not always divisible. When they are exactly divisible, the phase difference is zero. When they are not divisible, the ratio of frequency to rotation speed consists of an integer part and a decimal part. The decimal part determines the positional relationship between two adjacent rotations, and the phase angle can be calculated from the decimal part.

[0018] Optionally, the control unit of the ultrasonic machining control platform adjusts the phase difference ψ between the waveforms Λn and Λn+1 of the two trajectories to meet the following conditions, and plastic cutting occurs:

[0019] The minimum value of waveform Λn is x n (θ1), the corresponding tool rotation angle is θ1,

[0020] Then x n (θ1+ψ)≥x n+1 (θ1), H1=x n (θ1+ψ)-x n+1 (θ1) and H1(θ)≤H;

[0021] Among them, H is the critical cutting thickness of the brittle-ductile transition of the material.

[0022] Optionally, the ratio of plastic cutting to brittle cutting in one cutting process is adjusted as follows:

[0023] First, adjust the cutting thickness at the lowest point of the waveform to be less than the critical cutting thickness of the material's brittle-ductile transition;

[0024] Then, the ratio of plastic cutting and brittle cutting in one cutting process is adjusted by adjusting the phase difference and duty cycle.

[0025] Optionally, the cutting duty cycle DC is adjusted based on the condition of separation between the tool and the cutting surface during the machining process. When the separation condition is met, the ratio of the cutting segment to one vibration cycle within one vibration cycle is defined as the duty cycle of the wave cutting. The definition and calculation formula of the duty cycle DC is:

[0026]

[0027] Among them, T and t1 represent the total time and contact time between tool and workpiece in one vibration cycle, respectively;

[0028] The conditions for separation between the tool and the cutting surface during machining are as follows:

[0029]

[0030] Among them, f is the feed rate, A is the amplitude, and ap is the axial cutting depth.

[0031] Optionally, the ratio η between plastic cutting and brittle cutting is adjusted based on the following relationship:

[0032]

[0033] when

[0034] Among them, ts is the plastic cutting time and tc is the brittle cutting time.

[0035] Optionally, one cutting process includes:

[0036] one or more plastic cutting segments; and

[0037] One or more brittle cutting segments.

[0038] The above technical solution of the present invention has the following advantages:

[0039] The present invention provides a method for enhanced processing of ceramic-based composite materials by ultrasonic brittle-plastic composite cross-scale cutting, comprising the following steps: fixing a workpiece on an ultrasonic vibration processing platform, wherein the tool of the ultrasonic vibration processing platform is capable of axial ultrasonic vibration. The amplitude, frequency, rotation speed and axial cutting depth of the ultrasonic vibration processing platform are set according to the critical cutting thickness of the brittle-plastic transition of the material of the workpiece, and the phase difference control of the tool motion trajectory waveform is used to alternately perform plastic cutting and brittle cutting in a single cutting process to achieve brittle-plastic composite cutting. The method utilizes the phase difference control of the ultrasonic processing trajectory waveform to achieve micro-adjustment of the single removal amount and realize micro-texture cutting. The cutting process forms a unique vibration processing trajectory to form variable thickness cross-scale cutting. The manufacturing process, through the control of the feed parameters, overlaps the final surface area of ​​the cutting process at the microscale to form a plastic final surface, thereby improving the surface quality and processing efficiency of ceramic-based composite materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The drawings of the present invention are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not necessarily be consistent with the actual products.

[0041] Figure 1 is a schematic structural diagram of an ultrasonic vibration processing platform used in an embodiment of the present invention;

[0042] Figure 2 It is a schematic diagram of the trajectory changes of two cutting edges of a tool during ultrasonic machining of ceramic-based composite materials in the prior art;

[0043] Figure 3 It is a schematic diagram of the tool motion trajectory during the machining process of the wave ultrasonic brittle-plastic composite cross-scale cutting enhancement machining method for ceramic-based composite materials in an embodiment of the present invention;

[0044] Figure 4 It is a schematic diagram of the control flow of the ultrasonic vibration processing platform used in the wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing method for ceramic-based composite materials in an embodiment of the present invention;

[0045] Figure 5 It is a schematic diagram of the spatial distribution of the brittle-plastic composite processing trajectory of the ceramic-based composite material using the wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing method in an embodiment of the present invention.

[0046] In the figure:

[0047] 1: Workpiece;

[0048] 2: Cutting tools;

[0049] 3: Spindle and transducer;

[0050] 4: Driving motor;

[0051] 5. Vibration frequency regulator;

[0052] 6: Analog-to-digital converter;

[0053] 7: Computer;

[0054] 8: workbench;

[0055] 81: force measurement system;

[0056] 9: Tool motion trajectory;

[0057] 91: brittle removal zone;

[0058] 92: plastic removal zone;

[0059] 10: Brittle-plastic composite processing trajectory. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0061] See also Figure 1 The figure shows an ultrasonic vibration machining platform in the prior art, which mainly includes a tool 2, a spindle and a transducer 3, a spindle drive motor 4, a vibration frequency regulator 5, an analog-to-digital converter 6, a computer 7 and a workbench 8. The workbench 8 includes a force measuring system 81. The structure of the ultrasonic vibration machining platform is prior art and will not be described in detail here.

[0062] See also Figure 2 As shown in the figure, a schematic diagram of the trajectory of two cutting edges of a tool during ultrasonic processing of ceramic-based composite materials in the prior art is shown, wherein the horizontal axis is the radian and the vertical axis is the cutting depth. In the figure, A and B respectively refer to the two cutting edges of the tool, and the numbers after A and B represent the number of rotations of the tool. For example, A1 refers to the trajectory of cutting edge A when the tool rotates for the first circle, B1 refers to the trajectory of cutting edge B when the tool rotates for the first circle, A2 and B2 refer to the trajectories of cutting edge A and cutting edge B when the tool rotates for the second circle, respectively, and the rest are analogous, which will not be repeated here. As shown in the figure, this processing process is a general ultrasonic processing in the prior art, and its processing trajectory has a change in cutting thickness, and there is also a regular separation of the interface between the tool and the material, which can achieve cooling of the cutting process, but according to the change in its cutting thickness (the cutting thickness is large), there is no plastic cutting, and the process shown in the figure is brittle removal.

[0063] The ceramic matrix composite material wave ultrasonic brittle plastic composite cross-scale cutting enhancement processing method provided by the embodiment of the present invention adopts the following method: Figure 1 The ultrasonic vibration processing platform shown in the figure is used for processing, and the processing includes the following steps:

[0064] The workpiece is fixed on an ultrasonic vibration processing platform, and during processing, the tool of the ultrasonic vibration processing platform can generate axial ultrasonic vibration.

[0065] The amplitude, frequency, rotation speed and axial cutting depth of the ultrasonic vibration machining platform are set according to the critical cutting thickness of the brittle-to-plastic transition of the workpiece material. By controlling the phase difference of the tool motion trajectory waveform, plastic cutting and brittle cutting are performed alternately in one cutting process to achieve brittle-plastic composite cutting.

[0066] See also Figure 3As shown, a workpiece is processed by the wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing method for ceramic-based composite materials in an embodiment of the present invention. The curve with an arrow in the figure is a schematic diagram of the tool motion trajectory 9. The tool generates ultrasonic vibration in the vertical direction, which causes the tool to cut the material surface cyclically. The cutting thickness changes periodically, and the cutting part presents a narrow and long shape, and one end is relatively thick and gradually decreases toward the other end. This cutting area is a brittle cutting area 91. When the cutting thickness is reduced to a certain extent (brittle-plastic transition thickness), the tool cuts the material for plastic removal, and this section of the cutting area is a plastic cutting area 92.

[0067] See also Figure 4 The figure shows a control flow diagram of the ultrasonic vibration machining platform used in the wave ultrasonic brittle-plastic composite cross-scale cutting enhancement machining method for ceramic matrix composite materials in an embodiment of the present invention. The amplitude, frequency, rotation speed and axial cutting depth of the ultrasonic vibration machining platform are set according to the critical cutting thickness of the brittle-plastic transition of the material of the workpiece, and the ratio of cutting and brittle cutting (brittle-plastic ratio) η is determined by controlling the phase difference of the waveform of the tool motion trajectory, so that plastic cutting and brittle cutting are alternately performed in one cutting process to achieve brittle-plastic composite cutting.

[0068] See also Figure 5 As shown, it is a schematic diagram of the spatial distribution of the brittle-plastic composite machining trajectory of the wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing method for ceramic-based composite materials in an embodiment of the present invention. The red line in the figure is the vibration trajectory, and the dashed box is the cutting shape of one-time cutting. The different color blocks in the figure represent the cutting of a single removal, and the cutting area is distributed up and down, that is, the tool is fed from a high place (cutting into the material) and the material is cut out from a low place. The cutting thickness (cut thickness) is large when cutting in, and the cutting thickness when cutting out (low point) is less than the critical thickness of the brittle-plastic transition of the material. At this time, the cutting low point is plastic cutting, the material is removed by plasticity, and the processing surface quality is better. The curve on the surface of the workpiece in the figure is a schematic diagram of the brittle-plastic composite machining trajectory 10.

[0069] The processing method of this embodiment uses the phase difference control of the ultrasonic processing trajectory waveform to achieve micro-adjustment of the single removal amount and realize micro-texture cutting. The cutting process forms a unique vibration processing trajectory and forms variable thickness cross-scale cutting. This manufacturing process, through the control of feed parameters, overlaps the final surface area of ​​the cutting process at the microscale to form a plastic final surface, thereby improving the surface quality and processing efficiency of ceramic matrix composite materials.

[0070] It should be noted that "cross-scale" in the present invention refers to the simultaneous realization of cutting at the microscopic (10-100 microns) and fine (meso) (0.1-10 mm) levels.

[0071] In this embodiment, the ratio of plastic cutting to brittle cutting is related to the amplitude, frequency, feed speed and cutting depth.

[0072] In one implementation of this embodiment, the tool motion trajectory is:

[0073]

[0074] Where f is the feed rate, A is the amplitude, k is the vibration frequency, and θ is the radian of tool rotation;

[0075] Dynamic cutting thickness H1 is:

[0076]

[0077] Among them, x(θ-m2π) is the maximum value of the first m trajectories, and the ratio of frequency to speed ξ in brittle-plastic composite cutting is defined as:

[0078]

[0079] Where n is the rotation speed;

[0080] Then, the phase difference ψ between the two trajectory waveforms can be expressed as:

[0081] ψ=2π(ξ-[ξ])

[0082] Among them, [ξ] is the integer of ξ, and its physical meaning is explained as follows: the ultrasonic frequency is generally higher than 20kHz, and n / 60 represents the rotation frequency and is generally below 100Hz, so the two are not always divisible. When they are exactly divisible, it means that the angles corresponding to the adjacent rotation trajectories at the initial phase (or peak and trough) are the same, also known as zero phase difference. When they are not divisible, the ratio of frequency to rotation speed consists of an integer part and a decimal part. The decimal part determines the positional relationship between the two adjacent rotations, and the phase angle can be calculated from the decimal part.

[0083] In this embodiment, the control unit of the ultrasonic machining control platform adjusts the phase difference ψ between the waveforms Λn and Λn+1 of the two trajectories to meet the following conditions, and plastic cutting occurs:

[0084] The minimum value of waveform Λn is x n (θ1), the corresponding tool rotation angle is θ1,

[0085] Then x n (θ1+ψ)≥x n+1 (θ1), H1=x n (θ1+ψ)-x n+1 (θ1) and H1(θ)≤H;

[0086] Among them, H is the critical cutting thickness of the brittle-ductile transition of the material.

[0087] In this embodiment, optionally, the ratio η of plastic cutting to brittle cutting in one cutting process is adjusted as follows:

[0088] First, adjust the cutting thickness at the lowest point of the waveform to be less than the critical cutting thickness of the material's brittle-ductile transition;

[0089] Then, the ratio η of plastic cutting and brittle cutting in one cutting process is adjusted by adjusting the phase difference ψ and the duty cycle DC.

[0090] In one example, the cutting duty cycle DC is adjusted based on the condition of separation between the tool and the cutting surface during the machining process. When the separation condition is met, the ratio of the cutting segment to one vibration cycle within one vibration cycle is defined as the duty cycle of the wave cutting. The definition and calculation formula of the duty cycle DC is:

[0091]

[0092] Among them, T and t1 represent the total time and contact time between tool and workpiece in one vibration cycle, respectively;

[0093] The conditions for separation between the tool and the cutting surface during machining are as follows:

[0094]

[0095] Among them, f is the feed rate, A is the amplitude, and ap is the axial cutting depth.

[0096] In one example, the ratio η between plastic cutting and brittle cutting is adjusted based on the following relationship:

[0097]

[0098] when

[0099] Among them, ts is the plastic cutting time and tc is the brittle cutting time.

[0100] In this embodiment, a cutting process may include one plastic cutting segment and one brittle cutting segment; may include one plastic cutting segment and multiple brittle cutting segments; may include multiple plastic cutting segments and one brittle cutting segment; may also include multiple plastic cutting segments and multiple brittle cutting segments.

[0101] Parts not described in detail in the present invention are common knowledge or prior art.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that not every embodiment contains only one independent technical solution. In the absence of a conflict of solutions, the various technical features mentioned in each embodiment can be combined in any manner to form other implementation methods that can be understood by those skilled in the art.

[0103] In addition, without departing from the scope of the present invention, the technical solutions described in the aforementioned embodiments may be modified, or some of the technical features may be replaced by equivalents, without causing the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing of ceramic matrix composite materials, characterized in that: The following steps are involved: Fixing the workpiece on an ultrasonic vibration processing platform, wherein a tool of the ultrasonic vibration processing platform can generate axial ultrasonic vibration; The amplitude, frequency, rotation speed and axial cutting depth of the ultrasonic vibration machining platform are set according to the critical cutting thickness of the brittle-to-plastic transition of the workpiece material. By controlling the phase difference of the tool motion trajectory waveform, plastic cutting and brittle cutting are performed alternately in one cutting process to achieve brittle-plastic composite cutting.

2. The method for wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing of ceramic matrix composite materials according to claim 1 is characterized in that: The tool motion trajectory is: Among them, f is the feed speed, A is the amplitude, k is the vibration frequency, and λ is the radian of tool rotation; Dynamic cutting thickness H1 is: Among them, x(θ-m2π) is the maximum value of the first m trajectories, and the ratio of frequency to speed ξ in brittle-plastic composite cutting is defined as: Where n is the rotation speed; Then, the phase difference ψ between the two trajectory waveforms can be expressed as: ψ=2π(ξ-[ξ]) Among them, [ξ] is the integer of ξ, and its physical meaning is explained as follows: the ultrasonic frequency is generally higher than 20kHz, n / 60 represents the rotation frequency and is generally below 100Hz, so the two are not always divisible. When they are exactly divisible, the phase difference is zero. When they are not divisible, the ratio of frequency to rotation speed consists of an integer part and a decimal part. The decimal part determines the positional relationship between two adjacent rotations, and the phase angle can be calculated from the decimal part.

3. The method for wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing of ceramic matrix composite materials according to claim 2 is characterized in that: The control unit of the ultrasonic machining control platform adjusts the phase difference ψ between the waveforms Λn and Λn+1 of the two trajectories to meet the following conditions, and plastic cutting occurs: The minimum value of waveform Λn is x n (θ1), the corresponding tool rotation angle is θ1, Sox n (θ1+ψ)≥x n+1 (θ1), H1=x n (θ1+ψ)-x n+1 (θ1) and H1(θ)≤H; Among them, H is the critical cutting thickness of the brittle-ductile transition of the material.

4. The method for wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing of ceramic matrix composite materials according to claim 2, characterized in that: The ratio of plastic cutting and brittle cutting in one cutting process is adjusted as follows: First, adjust the cutting thickness at the lowest point of the waveform to be less than the critical cutting thickness of the material's brittle-ductile transition; Then, the ratio of plastic cutting and brittle cutting in one cutting process is adjusted by adjusting the phase difference and duty cycle.

5. The method for wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing of ceramic matrix composite materials according to claim 4, characterized in that: The cutting duty cycle DC is adjusted based on the condition of separation between the tool and the cutting surface during the machining process. When the separation condition is met, the ratio of the cutting segment to a vibration cycle within a vibration cycle is defined as the duty cycle of the wave cutting. The definition and calculation formula of the duty cycle DC is: Among them, T and t1 represent the total time and contact time between tool and workpiece in one vibration cycle, respectively; The conditions for separation between the tool and the cutting surface produced by the machining process are as follows: Among them, f is the feed rate, A is the amplitude, and ap is the cutting depth.

6. The method for wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing of ceramic matrix composite materials according to claim 4, characterized in that: The ratio η between plastic cutting and brittle cutting is adjusted based on the following relationship: when Among them, ts is the plastic cutting time and tc is the brittle cutting time.

7. The method for wave ultrasonic brittle-plastic composite cross-scale cutting enhancement processing of ceramic matrix composite materials according to claim 1, characterized in that: One cutting process includes: one or more plastic cutting segments; and One or more brittle cutting segments.

Images