Semi-active damping vibration attenuation cutter bar based on piezoelectric ceramics

Abstract

The invention relates to a finish machining tool, in particular to a semi-active damping vibration attenuation tool bar based on piezoelectric ceramics. The invention aims to provide a semi-active damping vibration attenuation cutter bar based on piezoelectric ceramics. The cutter bar has the characteristics of good vibration attenuation effect and adjustable vibration attenuation frequency range. According to the technical scheme, the semi-active damping vibration attenuation cutter bar based on the piezoelectric ceramics comprises a center bar, the cutter bar is characterized by further comprising a left end cover, a right end cover, a balancing weight and an acceleration sensor, wherein the left end cover and the right end cover are positioned at the two ends of the center rod; the balancing weight is coaxially arranged on the center rod in a sleeving manner and is positioned between the left end cover and the right end cover; the piezoelectric ceramic stack is arranged in the right end cover; and the controller is electrically connected with the acceleration sensor and the piezoelectric ceramic stack.

Description

Technical Field

[0001] This invention relates to a finishing tool, and more particularly to a semi-active damping and vibration reduction tool holder based on piezoelectric ceramics. Background Technology

[0002] With the development of manufacturing technology, deep-hole parts are widely used in military and civilian fields, and boring is the main method for machining deep holes and cavities. However, during the boring process, especially when machining deep holes, the boring bar has a large length-to-diameter ratio, which leads to a sharp decrease in rigidity. In addition, the friction between the tool's flank face and the inner wall of the part is large, which intensifies the vibration of the boring bar. This can affect the accuracy of the machined parts, resulting in defective products, or even cause the cutting edge to break, thus posing a safety hazard.

[0003] Current vibration damping tools mainly consist of high-rigidity vibration damping tools and vibration damping tools with dynamic vibration absorbers. High-rigidity vibration damping tools reduce chatter generated by the tool during cutting by increasing the rigidity of the rod through inlaying, nesting, embedding of cemented carbide, or using cemented carbide rods. This type of tool has a relatively simple structure and is easy to manufacture.

[0004] Another type of vibration-damping tool uses a mass spring damping system attached to the tool shank near the tool tip. This system significantly reduces tool vibration through the principle of a dynamic vibration absorber. When tool chatter occurs, the mass spring damping system simultaneously resonates, absorbing the vibration energy of the tool shank and dissipating the energy through damping to reduce tool vibration. Due to its ease of use, relatively convenient maintenance, and significant vibration reduction effect, it has been widely used in actual production.

[0005] The two types of vibration-damping tools mentioned above can meet most of the requirements for deep hole and deep cavity machining. However, they have some problems in engineering applications:

[0006] (1) The vibration reduction effect of high stiffness damping tool cannot be adjusted, and when the length-to-diameter ratio is too large, the stiffness of the rod will still be greatly reduced, resulting in poor vibration reduction effect.

[0007] (2) The vibration damping tool with a dynamic vibration absorber is limited by the properties of the dynamic vibration absorber itself. The mass spring damping system does not have the function of adjusting the resonant frequency. The vibration absorption frequency range is fixed and the vibration absorption frequency band is narrow and cannot adapt to wide frequency vibration. When the excitation frequency is within the vibration absorption frequency range, the vibration absorber has a better effect and the vibration damping tool has higher machining accuracy. However, when the excitation frequency is not within the vibration absorption frequency band, the tool chatter is obvious and affects the machining quality of the workpiece.

[0008] Therefore, it is particularly important to design a vibration damping tool with adjustable vibration reduction effect. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings in the above-mentioned background technology and provide a semi-active damping vibration reduction tool holder based on piezoelectric ceramics, which has the characteristics of good vibration reduction effect and adjustable vibration reduction frequency range.

[0010] The technical solution of this invention is:

[0011] A semi-active damping vibration reduction tool holder based on piezoelectric ceramics includes a central rod, characterized in that: the tool holder further includes a left end cap and a right end cap positioned at both ends of the central rod, a counterweight coaxially sleeved on the central rod and positioned between the left end cap and the right end cap, an acceleration sensor installed on the left end cap, a piezoelectric ceramic stack installed in the right end cap, and a controller electrically connected to the acceleration sensor and the piezoelectric ceramic stack.

[0012] Rubber rings are installed between the counterweight and the left end cap, and between the counterweight and the right end cap. The central rod is inserted into the counterweight and maintains a radial gap with the tube hole wall of the counterweight.

[0013] The space enclosed by the left end cap, left rubber ring, counterweight, right rubber ring, right end cap and center rod is used to add damping fluid.

[0014] An annular mounting groove is provided on the end face of the right end cap facing the counterweight, and the piezoelectric ceramic stack is fixed in the mounting groove.

[0015] The left and right end caps are positioned at both ends of the central rod by a threaded structure. The left and right rubber rings and the counterweight are pressed together by the left end cap and the piezoelectric ceramic stack installed in the right end cap, thereby axially fixing the left and right rubber rings to the central rod.

[0016] The left and right rubber rings are axially compressed and radially expanded, which seals the damping fluid.

[0017] The acceleration sensor is arranged on the outer end face of the left end cover.

[0018] Both the left and right end caps are fitted with sealing rings on their outer circumferential surfaces to prevent cutting fluid from entering the vibration absorber.

[0019] The central rod is a tubular structure with coolant flowing inside.

[0020] The beneficial effects of this invention are:

[0021] The semi-active damping vibration reduction tool based on piezoelectric ceramics provided by this invention utilizes the inverse piezoelectric effect of piezoelectric ceramics. A driving voltage is applied to the piezoelectric ceramics to generate an output displacement. By changing the magnitude of the driving voltage of the piezoelectric ceramic stack, its output displacement is changed, which in turn changes the preload of the rubber ring, thereby changing the stiffness of the rubber ring, adjusting the vibration absorption frequency, and widening the vibration absorption bandwidth. The vibration absorption effect is best when the anti-resonance point is close to the excitation frequency. The vibration absorption capacity can be changed by changing the number of piezoelectric ceramic stack layers, the mass of the counterweight, and the preload of the rubber ring, so that the tool holder can be used in more types of tools and applied to more machining environments. Attached Figure Description

[0022] Figure 1 This is a three-dimensional structural diagram of the present invention.

[0023] Figure 2 This is a schematic diagram of the main structure of the present invention.

[0024] Figure 3 yes Figure 2 A schematic diagram of the AA cross-sectional structure.

[0025] Figure 4 This is a schematic diagram of the right end cap structure of the present invention.

[0026] Figure 5 yes Figure 4 A schematic diagram of the BB cross-sectional structure.

[0027] Figure label:

[0028] 1. Left end cap, 2. Left rubber ring, 3. Counterweight, 4. Center rod, 5. Right rubber ring, 6. Piezoelectric ceramic stack, 7. Right end cap, 8. Sealing ring, and 9. Accelerometer. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] Figure 1 The semi-active damping vibration reduction tool holder based on piezoelectric ceramics shown includes a left end cap 1, a left rubber ring 2, a counterweight 3, a center rod 4, a right rubber ring 5, a piezoelectric ceramic stack 6 (existing technology), a right end cap 7, a sealing ring 8, and an acceleration sensor 9; the left end of the tool holder is fixed with a tool head (omitted in the figure).

[0031] like Figure 2 , Figure 3As shown, a central rod 4 is provided at the axial position of the tool holder, and a tubular counterweight 3 is sleeved on the central rod 4. The left end cap 1 and the right end cap 7 are installed at both ends of the central rod 4. The left rubber ring 2 and the right rubber ring 5 are respectively provided between the left end cap 1 and the left end face of the counterweight 3 and between the right end cap 7 and the right end face of the counterweight 3. An annular mounting groove is formed on the end face of the right end cap facing the counterweight. The piezoelectric ceramic stack 6 is coaxially fixed in the mounting groove and contacts the right rubber ring 5. The two ends of the counterweight 3 abut against and are suspended on the left rubber ring 2 and the right rubber ring 5, and its tube hole wall maintains a radial clearance with the central rod 4. The axial portion of the left end cap 1 and the right end cap 7 are provided with internal threaded holes, which are respectively positioned at the two ends of the central rod 4 through the internal threaded holes and the external threads at the two ends of the central rod 4. The left end cap 1 and the piezoelectric ceramic stack 6 installed in the right end cap 7 press the left rubber ring 2, the right rubber ring 5 and the counterweight 3 together, and fix them axially on the central rod 4. The space enclosed by the left end cap 1, the left rubber ring 2, the counterweight 3, the right rubber ring 5, the right end cap 7 and the central rod 4 can be filled with damping fluid to improve the vibration reduction effect. The left rubber ring 1 and the right rubber ring 5 are axially pressed and radially expanded, which plays a sealing role for the damping fluid. When the tool is working, the positions of the center rod 4, left end cap 1, left rubber ring 2, right rubber ring 5, and right end cap 7 are fixed. The counterweight 3 undergoes radial vibration, which is provided by the left rubber ring 2 and right rubber ring 5. The left end cap 1 is connected to the tool head by screws and is coaxially fixed in the inner hole of the left end of the tool bar. Sealing rings are installed on the outer circumference of the end cap for sealing, preventing cutting fluid from entering the vibration absorber from the gap between the outer circumference of the end cap and the inner hole of the tool bar. The right end of the tool bar is fixed to the machine tool. The center rod 4 is hollow inside, and coolant flows through it.

[0032] like Figure 4 , Figure 5 As shown, an acceleration sensor 9 is installed on the outer end face of the left end cover; electronic circuits are arranged inside the piezoelectric ceramic stack; the acceleration sensor 9 and the electronic circuits are both connected to the controller through a transmission line.

[0033] Working principle of this invention:

[0034] The invention also includes a tool holder housing (omitted in the figure), with the left end cap 1, left rubber ring 2, counterweight 3, center rod 4, right rubber ring 5, piezoelectric ceramic stack 6, right end cap 7, and sealing ring 8 all located within the tool holder housing. When the tool cuts metal, the tool holder vibrates radially (up and down) under the cutting force. The vibration energy is transmitted from the left end cap 1, right end cap 7, and center rod 4 through the left rubber ring 2 and right rubber ring 5 to the counterweight 3, which reciprocates radially. When the counterweight 3 vibrates and rubs against the damping fluid, the vibration energy is consumed. When the excitation frequency is not within the vibration absorption frequency range, the tool holder vibration intensifies. The controller receives the vibration signal output by the acceleration sensor 9 and obtains the tool holder vibration frequency through data processing. The driving voltage of the piezoelectric ceramic stack 6 is adjusted according to the vibration frequency to change its output displacement, thereby changing the preload of the rubber ring, and further changing the stiffness of the rubber ring and the natural frequency of the vibration absorber. This causes the anti-resonance point of the tool holder amplitude-frequency response curve to shift, thus achieving good vibration absorption under different processing environments (different excitation frequencies). The vibration absorption capacity and vibration absorption working range can also be adjusted by changing the number of piezoelectric ceramic stacks (6), the mass of counterweight (3), and the pre-tightening of the left rubber ring (2) and right rubber ring (5).

[0035] Finally, it should be noted that the above examples are merely specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of this invention should be considered within the scope of protection of this invention.

Claims

1. A piezoceramic based semi-active damped vibration reducing tool holder comprising a central rod (4), characterized in that: The knife bar further comprises a left end cover (1) and a right end cover (7) positioned at both ends of the center rod, a counterweight (3) coaxially sleeved on the center rod and positioned between the left end cover (1) and the right end cover (7), an acceleration sensor (9) mounted on the left end cover, a piezoelectric ceramic stack (6) mounted in the right end cover (7), and a controller electrically connecting the acceleration sensor (9) and the piezoelectric ceramic stack (6).

2. Piezoceramic based semi-active damped vibration reducing tool holder according to claim 1, characterized in that Rubber rings (2) are mounted between the counterweight (3) and the left end cover (1) and between the counterweight (3) and the right end cover (7), and the center rod (4) penetrates the counterweight (3) and keeps a radial gap with the hole wall of the counterweight (3).

3. Piezoceramic based semi-active damped vibration reducing tool holder according to claim 2, characterized in that The space between the left end cover (1), the left rubber ring (2), the counterweight (3), the right rubber ring (5), the right end cover (7) and the center rod (4) is used for adding damping liquid.

4. Piezoceramic based semi-active damped vibration reducing tool holder according to claim 3, characterized in that An annular mounting groove is formed on the end surface of the right end cover (7) facing the counterweight (3), and the piezoelectric ceramic stack (6) is fixed in the mounting groove.

5. Piezoceramic based semi-active damped tool holder according to claim 4, characterized in that The left end cover (1) and the right end cover (7) are positioned at both ends of the center rod (4) through a threaded structure, and the left rubber ring (2), the right rubber ring (5) and the counterweight (3) are pressed tightly by the left end cover (1) and the piezoelectric ceramic stack (6) mounted in the right end cover (7), so that the left rubber ring (2) and the right rubber ring (5) are axially fixed on the center rod (4).

6. Piezoceramic based semi-active damped vibration reducing tool holder according to claim 5, characterized in that The left rubber ring (2) and the right rubber ring (5) are axially pressed and radially expanded, and seal the damping liquid.

7. Piezoceramic based semi-active damped vibration reducing tool holder according to claim 6, characterized in that The acceleration sensor (9) is arranged on the outer end surface of the left end cover (1).

8. Piezoceramic based semi-active damped vibration reducing tool holder according to claim 7, characterized in that Sealing rings (8) are mounted on the outer circumferential surfaces of the left end cover and the right end cover for sealing, so as to prevent cutting fluid from entering the internal absorber.

9. Piezoceramic based semi-active damped vibration reducing tool holder according to claim 8, characterized in that The center rod (4) is a tubular structure, and the inside is filled with cooling liquid.

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