Curved longitudinal vibration type underwater acoustic transmitting transducer based on 3D printing technology and preparation method

Abstract

The invention relates to the technical field of underwater acoustic transmitting transducers, and particularly discloses a curved longitudinal vibration type underwater acoustic transmitting transducer based on a 3D printing technology and a preparation method thereof, the curved longitudinal vibration type underwater acoustic transmitting transducer comprises a metal shell, a plurality of groups of rigid foam plastic, a plurality of groups of piezoelectric ceramic wafer piles, a plurality of prestressed bolts, a metal mass block and a transmitting end with a cavity, each group of piezoelectric ceramic wafer stack is composed of forward polarization piezoelectric ceramics and negative polarization piezoelectric ceramics, the polarization directions of the forward polarization piezoelectric ceramics and the negative polarization piezoelectric ceramics are opposite, and brass gaskets are arranged in the middle and on the two sides of each group of piezoelectric ceramic wafer stack respectively and used for leading out electrodes; according to the underwater acoustic transmitting transducer, the transmitting end is manufactured through the 3D printing technology, the integrality is high, the influence of secondary assembly on work of the underwater acoustic transmitting transducer is reduced, and good work stability of the underwater acoustic transmitting transducer can be guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of underwater acoustic emission transducers, and in particular to a curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology and a preparation method thereof. Background Art

[0002] Sonar systems use acoustic signals to detect and locate underwater targets, identify their features, and transmit information. The transmitting transducer, a core component of a sonar system, primarily consists of a mechanical vibration system and an electromagnetic energy storage element. When the electromagnetic energy storage element receives an alternating electrical signal, it induces periodic variations in the electric or magnetic field. This electromagnetic effect converts electrical energy into mechanical vibration energy through the inverse piezoelectric effect of piezoelectric materials or the magnetostrictive effect of ferromagnetic materials. The alternating stresses induce forced vibrations in the driver unit, which in turn stimulate the surrounding water to radiate acoustic waves, ultimately achieving efficient conversion of electrical energy into acoustic energy. The performance of the underwater acoustic transducer determines the performance of the entire sonar system. Existing underwater acoustic transducers require secondary assembly at the transmitting end, which is cumbersome and complex. Furthermore, the transmitting voltage response of existing underwater acoustic transducers is relatively low during use. To address this issue, a curved longitudinal vibration underwater acoustic transmitting transducer based on 3D printing technology and a method for its fabrication are provided. Summary of the Invention

[0003] The purpose of the present invention is to address the defects of the prior art and provide a curved longitudinal vibration underwater acoustic emission transducer and a preparation method based on 3D printing technology to solve the problems raised by the above background technology.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical solutions: a curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology and a preparation method thereof, comprising a metal shell, a rigid foam plastic, a piezoelectric ceramic chip stack, a prestressed bolt, a metal mass block and a transmitting end with a cavity, wherein the piezoelectric ceramic chip stack is provided with several groups, each group of piezoelectric ceramic chip stacks is composed of positively polarized piezoelectric ceramics and negatively polarized piezoelectric ceramics, the polarization directions of the positively polarized piezoelectric ceramics and the negatively polarized piezoelectric ceramics are opposite, and each group of piezoelectric ceramic crystal stacks is respectively provided with A brass gasket is used to lead out the electrode; several metal mass blocks are provided and are sandwiched between two groups of piezoelectric ceramic chip stacks. The prestressed bolt passes through the metal mass block and the piezoelectric ceramic chip stack through an elastic washer and is connected to the transmitting end with a cavity. The prestressed bolt applies a certain prestress to the piezoelectric ceramic chip stack to increase the impedance of the piezoelectric vibrator, thereby improving the transmit power that can be tolerated. The piezoelectric ceramic chip stack, the metal mass block and the transmitting end with a cavity are all wrapped by hard foam plastic, and the hard foam plastic is encapsulated by a metal shell.

[0005] As a preferred technical solution of the present invention, the metal shell is made of aluminum and is used for electromagnetic shielding of the device.

[0006] As a preferred technical solution of the present invention, the positively polarized piezoelectric ceramics and the negatively polarized piezoelectric ceramics are both made of PZT-4 piezoelectric ceramic material and are 3D printed into thin annular piezoelectric ceramic wafers.

[0007] As a preferred technical solution of the present invention, the metal mass block is made of steel, and its main function is to achieve the effect of counterweight. The size of the mass block also affects the stable working effect of the transmitting transducer.

[0008] As a preferred technical solution of the present invention, the transmitting end with a cavity is made of aluminum material and is integrally formed by 3D printing. It has a curved shape and is used to convert the vibration of the piezoelectric ceramic chip stack into sound waves and emit them.

[0009] As a preferred technical solution of the present invention, the transmitting end with the cavity is sealed with the external interface through a polyurethane layer, and the polyurethane layer is connected to the metal shell to increase the contact area with the metal shell, thereby achieving a better sealing effect.

[0010] A method for preparing the curved longitudinal vibration underwater acoustic emission transducer as described above comprises the following specific steps:

[0011] Step 1: Prepare a cavity-bearing emitter: Clean the 3D printed substrate, preheat it, and then use selective laser melting (SLM) technology to melt and deposit aluminum alloy powder layer by layer through a 3D printing process to form a curved emitter with a cavity. The cavity structure is integrally formed with the emitter.

[0012] Step 2: Prepare a piezoelectric ceramic wafer stack: Use a dedicated piezoelectric ceramic 3D printing device to print piezoelectric ceramic wafers piece by piece using lead zirconate titanate (PZT) powder as the raw material. The wafers are in the shape of a ring. The printed piezoelectric ceramic wafers are stacked in a positive and negative form, and brass gaskets are placed in the middle and on both sides of the crystal stack to form electrode leads. The piezoelectric ceramic wafers are polarized, so that adjacent piezoelectric ceramic wafers are polarized in opposite directions.

[0013] Step 3: Prepare a metal mass block: The metal mass block is processed and prepared by a CNC lathe. The material is steel. The metal mass block is annular in shape. The thickness of the rear mass block is greater than that of the front and middle mass blocks.

[0014] Step 4: Prestressed assembly: Use prestressed bolts to penetrate all metal mass blocks and the central through-hole of the piezoelectric ceramic wafer stack; the ends of the bolts are threadedly connected to the transmitting end, applying axial prestress and locking the elastic washers;

[0015] Step 5: Encapsulation: Immerse the structure except the transmitting end in liquid rigid foam plastic, solidify it to form a uniform wrapping layer; cover it with a metal shell and seal it;

[0016] Step 6, interface sealing: connecting and sealing the polyurethane layer with the metal shell, ensuring the contact area of the polyurethane layer with the metal shell and the water tightness of the connection;

[0017] Step 7, post-processing: impedance matching debugging and water tightness testing, calibration of the emission response characteristics in the frequency band of 0-60 kHz.

[0018] Compared with the prior art, the beneficial effects of the present application are:

[0019] 1. The curved longitudinal vibration type underwater acoustic emission transducer of the present application uses 3D printing technology to manufacture the emission end, has strong integrity, reduces the influence of secondary assembly on the operation of the underwater acoustic emission transducer, and can ensure good working stability of the underwater acoustic emission transducer.

[0020] 2. The curved longitudinal vibration type underwater acoustic emission transducer of the present application adopts a sandwich type stacking of piezoelectric ceramic wafers, and separates them by mass blocks, forming multiple excitations, which can effectively improve the emission voltage response of the underwater acoustic emission transducer. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a structural schematic diagram of the curved longitudinal vibration type underwater acoustic emission transducer of the present application.

[0022] In the figure: 1. Metal shell; 2. Hard foam plastic; 3. Pre-stressed bolt; 4. Metal mass block; 5. Brass gasket; 6. Positive polarization piezoelectric ceramic; 7. Negative polarization piezoelectric ceramic; 8. Emission end with cavity; 9. Polyurethane layer. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings, so that the advantages and features of the present application can be more easily understood by those skilled in the art, and the protection scope of the present application can be more clearly and explicitly defined.

[0024] Embodiment: Please refer to Figure 1The present invention provides a technical solution: a curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology and a preparation method thereof, comprising a metal shell 1, a hard foam plastic 2, a piezoelectric ceramic chip stack, a prestressed bolt 3, a metal mass block 4 and a transmitting end 8 with a cavity, wherein the piezoelectric ceramic chip stack is provided with several groups, each group of piezoelectric ceramic chip stacks is composed of positively polarized piezoelectric ceramics 6 and negatively polarized piezoelectric ceramics 7, the polarization directions of the positively polarized piezoelectric ceramics 6 and the negatively polarized piezoelectric ceramics 7 are opposite, and each group of piezoelectric ceramic crystal stacks is provided with yellow in the middle and on both sides respectively. The copper gasket 5 is used to lead out the electrode; several metal mass blocks 4 are provided and are sandwiched between two groups of piezoelectric ceramic chip stacks. The prestressed bolt 3 passes through the metal mass block 4 and the piezoelectric ceramic chip stack through an elastic washer and is connected to the transmitting end 8 with a cavity. The prestressed bolt 3 applies a certain prestress to the piezoelectric ceramic chip stack to increase the impedance of the piezoelectric vibrator, thereby increasing the transmit power that can be tolerated. The piezoelectric ceramic chip stack, the metal mass block 4 and the transmitting end 8 with a cavity are all wrapped by a hard foam plastic 2, and the hard foam plastic 2 is encapsulated by a metal shell 1.

[0025] The metal shell 1 is made of aluminum and is used for electromagnetic shielding of the device.

[0026] The positively polarized piezoelectric ceramic 6 and the negatively polarized piezoelectric ceramic 7 are both made of PZT-4 piezoelectric ceramic material and are 3D printed into thin annular piezoelectric ceramic wafers.

[0027] The metal mass block 4 is made of steel, and its main function is to achieve the effect of counterweight. The size of the mass block also affects the stable working effect of the transmitting transducer.

[0028] The transmitting end 8 with the cavity is made of aluminum material and is integrally formed through 3D printing. It has a curved shape and is used to convert the vibration of the piezoelectric ceramic chip stack into sound waves and emit them.

[0029] The emission end 8 with the cavity is sealed with the external interface through the polyurethane layer 9. The polyurethane layer 9 is connected to the metal shell 1 to increase the contact area with the metal shell 1, thereby achieving a better sealing effect.

[0030] A method for preparing a curved longitudinal vibration underwater acoustic emission transducer, the specific steps are as follows:

[0031] Step 1: Prepare a cavity-bearing emitter 8: Clean the 3D printed substrate, preheat the substrate, and use selective laser melting (SLM) technology to melt and deposit aluminum alloy powder layer by layer through a 3D printing process to form a curved emitter with a cavity. The cavity structure is integrally formed with the emitter.

[0032] Step 2, preparation of piezoelectric ceramic wafer stack: using a 3D printing equipment dedicated to piezoelectric ceramics, piezoelectric ceramic sheets are printed one by one with lead zirconate titanate (PZT) powder as raw material, and the wafer is in the form of a circular ring; the printed piezoelectric ceramic sheets are stacked in the form of one positive and one negative, and brass gaskets are placed in the middle and on both sides of the wafer stack to form electrode leads; the piezoelectric ceramic sheets are polarized, and the polarization directions of adjacent piezoelectric ceramic sheets are opposite;

[0033] Step 3, preparation of metal mass block 4: the metal mass block 4 is prepared by numerical control lathe, and the material is steel; the metal mass block 4 is in the form of a circular ring as a whole, and the thickness of the rear mass block is greater than that of the front and middle mass blocks;

[0034] Step 4, pre-stress assembly: a pre-stress bolt 3 penetrates through the central through hole of all metal mass blocks 4 and piezoelectric ceramic wafer stack; the end of the bolt is threadedly connected with the transmitting end, axial pre-stress is applied and the elastic washer is locked;

[0035] Step 5, encapsulation process: immerse the structure except the transmitting end in liquid rigid foam plastic, and solidify to form a uniform wrapping layer; cover with a metal shell and seal;

[0036] Step 6, interface sealing: connect and seal the polyurethane layer 9 with the metal shell 1, ensure the contact area of the polyurethane layer 9 with the metal shell 1 and ensure the water tightness of the connection;

[0037] Step 7, post-processing: impedance matching debugging and water tightness test are carried out, and the transmitting response characteristics are calibrated in the frequency band of 0-60 kHz.

[0038] Working principle: the curved longitudinal vibration type underwater acoustic transmitting transducer and preparation method based on 3D printing technology, the transmitting end 8 with a cavity is printed by 3D printing technology, then the negative polarization piezoelectric ceramic 7 is printed, the brass gasket 5 is placed on the surface of the negative polarization piezoelectric ceramic 7, then the positive polarization piezoelectric ceramic 6 is printed, then the metal mass block 4 is placed on the surface of the positive polarization piezoelectric ceramic 6, and a plurality of piezoelectric ceramic wafer stacks composed of positive polarization piezoelectric ceramic 6 and negative polarization piezoelectric ceramic 7 are printed in this way, then the pre-stress bolt 3 penetrates through the metal mass block 4 and the middle part of the piezoelectric ceramic wafer stack and is threadedly connected with the transmitting end 8 with a cavity, the pre-stress bolt 3 applies a certain pre-stress to the piezoelectric ceramic wafer stack to increase the impedance of the piezoelectric vibrator, thereby increasing the transmitting power that can be withstood, then the rigid foam plastic 2 is wrapped on the whole, and then the metal shell 1 is used for packaging.

[0039] The piezoelectric ceramic chip stack is mechanically connected in series to the prestressed bolt 3, and is connected in parallel in the circuit to form a piezoelectric vibrator. The adjacent ceramic chips in each group of piezoelectric ceramic chip stacks have opposite polarities. When an alternating voltage is applied to the vibrator, the vibrator will generate axial vibration, thereby causing the transmitting end 8 with a cavity to radiate sound waves outward. The transducer of the present invention has a large transmitting voltage response and also has a large and stable working bandwidth.

[0040] The above embodiments merely illustrate the implementation methods of the present invention. Although the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the scope of the present invention, and these modifications and improvements fall within the scope of protection of the present invention.

Claims

1. A curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology, comprising a metal shell (1), a rigid foam plastic (2), a piezoelectric ceramic wafer stack, a prestressed bolt (3), a metal mass block (4), and an emission end (8) with a cavity, characterized in that: The piezoelectric ceramic chip stacks are provided with several groups, each group of piezoelectric ceramic chip stacks is composed of positively polarized piezoelectric ceramics (6) and negatively polarized piezoelectric ceramics (7), the polarization directions of the positively polarized piezoelectric ceramics (6) and the negatively polarized piezoelectric ceramics (7) are opposite, and brass gaskets (5) are respectively provided in the middle and on both sides of each group of piezoelectric ceramic crystal stacks for lead-out electrodes; the metal mass blocks (4) are provided with several groups and are sandwiched between the two groups of piezoelectric ceramic chip stacks, the prestressed bolts (3) pass through the metal mass blocks (4) and the piezoelectric ceramic chip stacks through elastic washers and are connected to the emitting end (8) with a cavity, the piezoelectric ceramic chip stacks, the metal mass blocks (4) and the emitting end (8) with a cavity are all wrapped by hard foam plastic (2), and the hard foam plastic (2) is encapsulated by a metal shell (1).

2. The curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology according to claim 1, characterized in that: The metal shell (1) is made of aluminum and is used for electromagnetic shielding of the device.

3. The curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology according to claim 1, characterized in that: The positively polarized piezoelectric ceramic (6) and the negatively polarized piezoelectric ceramic (7) are both made of PZT-4 type piezoelectric ceramic material and are 3D printed into thin annular piezoelectric ceramic wafers.

4. The curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology according to claim 1, characterized in that: The metal mass block (4) is made of steel.

5. The curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology according to claim 1, characterized in that: The transmitting end (8) with a cavity is made of aluminum material and is integrally formed by 3D printing. It has a curved shape and is used to convert the vibration of the piezoelectric ceramic chip stack into sound waves and transmit them.

6. The curved longitudinal vibration underwater acoustic emission transducer based on 3D printing technology according to claim 1, characterized in that: The emission end (8) with the cavity is sealed with an external interface via a polyurethane layer (9), and the polyurethane layer (9) is connected to the metal shell (1) to increase the contact area with the metal shell (1).

7. A method for preparing a curved longitudinal vibration underwater acoustic emission transducer according to any one of claims 1 to 6, characterized in that: The specific steps are as follows: Step 1, preparing a transmitter with a cavity (8): cleaning a 3D printing substrate, preheating the substrate, using selective laser melting (SLM) technology, using aluminum alloy powder as raw material, and melting and stacking it layer by layer through a 3D printing process to form a curved transmitter with a cavity, and the cavity structure is integrally formed with the transmitter; Step 2: Prepare a piezoelectric ceramic wafer stack: Use a dedicated piezoelectric ceramic 3D printing device to print piezoelectric ceramic wafers piece by piece using lead zirconate titanate (PZT) powder as the raw material. The wafers are in the shape of a ring. The printed piezoelectric ceramic wafers are stacked in a positive and negative form, and brass gaskets are placed in the middle and on both sides of the crystal stack to form electrode leads. The piezoelectric ceramic wafers are polarized, so that adjacent piezoelectric ceramic wafers are polarized in opposite directions. Step 3, preparing a metal mass block (4): The metal mass block (4) is processed and prepared by a CNC lathe, and the material is steel; the metal mass block (4) is in a circular ring shape as a whole, and the thickness of the rear mass block is greater than the thickness of the front and middle mass blocks; Step 4, prestressed assembly: use prestressed bolts (3) to penetrate all metal mass blocks (4) and the central through hole of the piezoelectric ceramic wafer stack; the end of the bolt is threadedly connected to the transmitting end, axial prestress is applied and the elastic washer is locked; Step 5: Encapsulation: Immerse the structure except the transmitting end in liquid rigid foam plastic, solidify it to form a uniform wrapping layer; cover it with a metal shell and seal it; Step 6, interface sealing: connect and seal the polyurethane layer (9) and the metal shell (1), ensure the contact area between the polyurethane layer (9) and the metal shell (1) and ensure the watertightness of the connection; Step 7, post-processing: perform impedance matching debugging and water tightness test, and calibrate the transmission response characteristics within the 0-60kHz frequency band.

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