RU2552591C1 - Manufacturing method of composite electroacoustic transducer - Google Patents

Abstract

FIELD: instrument making.

SUBSTANCE: manufacturing method of a composite electroacoustic transducer containing piezoelectric ceramic elements as active elements, which involves application onto end surfaces of piezoelectric ceramic elements of an adhesive that is hardened as a result of polymerisation, assembly of a piezoelectric unit out of them by series connection of piezoelectric ceramic elements to each other with their end surfaces. Then, electromagnetic microwave field acts on the assembled piezoelectric unit during the period of time required for hardening of the adhesive in adhesive connections. Action on the assembled piezoelectric unit by electromagnetic microwave field is performed in an intermittent mode so that there provided is total time of action corresponding to the time required for hardening of the adhesive in adhesive connections.

EFFECT: reducing an assembly period.

Description

The invention relates to the field of instrumentation, and in particular to the manufacturing technology of a composite electro-acoustic transducer containing piezoceramic active elements.

A known method of manufacturing a composite piezoelectric transducer [SU 627711], including applying an adhesive compound to the bonded surfaces of the piezoelectric elements and assembling from these elements of the piezoelectric block. The disadvantage of this method is the lack of mechanical strength of the adhesive joint.

A known method of manufacturing a composite electro-acoustic transducer containing piezoelectric elements as active elements [SU 1757131], which is selected as the closest analogue.

The method under consideration includes applying glue to the end surfaces of the piezoelectric ceramic elements, assembling a piezoblock from them by sequentially connecting the piezoceramic elements to each other by their end surfaces. Next, the piezoblock is heated until the glue cures at a temperature determined by the curing process of the glue used.

In this case, the piezoblock is simultaneously affected by a field of constant electric potential with a polarity coinciding with the polarity of the piezoelectric elements.

Exposure to this field provides an increase in the mechanical strength of the converter.

The disadvantage of this method is its duration, due to the fact that the curing of the adhesive occurs for a long time. So, in the considered method, an example of the use of DM5-65 brand epoxy adhesive is given, the curing of which is carried out at a temperature of 75-95 ° C for 24 hours.

The task of the invention is to reduce the duration of the method.

The essence of the invention lies in the fact that in the method of manufacturing a composite electro-acoustic transducer containing piezoceramic elements as active elements, including applying adhesive, cured by polymerization to the end surfaces of the piezoceramic elements, assembling the piezoblock from them by sequentially connecting the piezoceramic elements to each other with their end faces surfaces, according to the invention act on the assembled piezoblock by the microwave electromagnetic field in the period micheskoe mode with the total time of the specified exposure, corresponding to the time required for the curing of the adhesive in the adhesive joints.

It is fundamentally important in the inventive method that the curing of the adhesive in the adhesive joints is carried out under the influence of the microwave field, which, as shown by experiments, leads to a very fast (within a few minutes) curing of the adhesive. In this case, the process of exposure to the assembled piezoblock by the microwave electromagnetic field is periodically interrupted to ensure the total time of the specified exposure, corresponding to the time required for the adhesive to cure in the adhesive joints. Due to the periodic interruption of the heating process by the microwave field, a gentle mode of influence of the specified field on the material of the piezoelectric elements is ensured, in which all their electrophysical parameters are preserved.

Thus, in the inventive method, the time required for curing the adhesive in the adhesive joints is significantly reduced (at times) compared to the curing time of the adhesive according to traditional technology, including its heating at the recommended curing temperature of the adhesive used.

As shown by experimental studies, in the manufacture of the Converter according to the claimed method using widely used in the manufacture of glue based on epoxy resin, the curing process of the specified glue in the adhesive joints in the microwave field is completed in 3-10 minutes.

It should be noted that the curing time of the specified adhesive using traditional technology is about 24 hours.

The specific exposure time of the microwave electromagnetic field to the assembled piezoelectric block required to cure the adhesive used in the adhesive joints is previously determined experimentally for each specific type of adhesive.

Thus, the technical result achieved by the implementation of the proposed method is a significant reduction in the duration of the curing step of the adhesive in the adhesive joints of the piezoelectric block, which leads to a decrease in the duration of the method as a whole.

The method is implemented as follows.

The end surfaces of the piezoceramic elements are prepared for gluing by mechanical cleaning and degreasing.

Then glue is applied to the glued surfaces. It is preferable to use an adhesive that cures during the polymerization of its components, which ensures the strength of the adhesive joint, in particular epoxy adhesive.

Piezoceramic elements are assembled into a piezoblock by sequentially connecting the piezoceramic elements to each other by their end surfaces. The glued surfaces are pressed against each other with a force, the value of which depends on the type of adhesive used.

Then the piezoblock is mounted on a stand made of a material with a high dielectric loss tangent, in particular, expanded vermiculite. A piezoblock mounted on a stand is placed in a microwave oven and kept in a microwave electromagnetic field. In this case, the process of heating the piezoelectric block by the microwave field is periodically interrupted to ensure the total exposure time to the specified field, corresponding to the time required to cure the adhesive used. The indicated exposure time to the microwave field is preliminarily determined experimentally for the type of glue used.

The possibility of implementing the method shown in the examples of specific performance

Example 1

For the manufacture of an electro-acoustic transducer, piezoelectric ceramics made of TsTSSt-3 piezoceramics, which is a solid solution of lead-strontium zirconate titanate, modified with additives of zinc, bismuth, manganese, and lanthanum oxides with a perovskite structure, were used. The chemical composition of piezoceramics corresponds to the formula

Used polarized piezoceramic elements in the form of disks with a thickness of 4 mm and a diameter of 26 mm.

The end surfaces of the piezoceramic elements were prepared for gluing by mechanical cleaning and degreasing.

Then, DM5-65 brand epoxy adhesive was applied to the surfaces to be bonded.

A piezo block was assembled from piezoceramic elements.

The surfaces to be glued were pressed with the force created by the end metal plates and the load.

The assembled piezoblock was mounted on a stand made of expanded vermiculite.

Next, the piezoblock mounted on the stand was placed in a microwave oven with a power of 900 watts.

The piezoblock was kept in the microwave oven for 5 minutes, which was sufficient to cure the adhesive in the adhesive joints.

The indicated exposure time by the microwave field was previously determined experimentally for the type of glue used. To do this, put the tested glue in a microwave oven with the above power and kept it in a microwave oven until it cured.

The impact on the piezoelectric block by the microwave field was carried out in a periodic mode. At the same time, every one to two minutes, the piezoelectric block was removed from the microwave oven and cooled in air for 10-15 minutes to provide a more gentle mode of action of the microwave field on the material of the piezoceramic elements.

Example 2

For the manufacture of an electro-acoustic transducer, piezoceramic elements made of PZT-19 piezoceramics, which is a solid solution of lead zirconate titanate modified with the addition of niobium pentoxide, were used. The chemical composition of piezoceramics corresponds to the formula

Used polarized piezoelectric ceramic elements in the form of rods with a section of 20 × 15 mm and a thickness of 24 mm.

The end surfaces of the piezoceramic elements were prepared for gluing by mechanical cleaning and degreasing.

Then, DM5-65 brand epoxy adhesive was applied to the surfaces to be bonded.

A piezo block was assembled from piezoceramic elements. The surfaces to be glued were pressed with the force created by the end metal plates and the load.

The assembled piezoblock was mounted on a stand made of expanded vermiculite.

Next, the piezoblock mounted on the stand was placed in a microwave oven with a power of 900 watts.

The piezoblock was kept in the microwave oven for 7 minutes, which was sufficient to cure the adhesive in the adhesive joints.

The indicated exposure time by the microwave field was previously determined experimentally for the type of glue used. To do this, put the tested glue in a microwave oven with the above power and kept it in a microwave oven until it cured.

The impact on the piezoelectric block by the microwave field was carried out in a periodic mode. Moreover, every one to two minutes, the piezoelectric block was removed from the microwave oven and cooled in air for 5-10 minutes to provide a more gentle mode of action of the microwave field on the material of the piezoceramic elements.

Claims (1)

A method of manufacturing a composite electro-acoustic transducer containing piezoceramic elements as active elements, including applying glue to the end surfaces of the piezoceramic elements, assembling a piezo block from them by connecting the piezoceramic elements with each other by their end surfaces, characterized in that they act on the assembled piezo block with a microwave electromagnetic field in periodic mode with the total time of the specified exposure corresponding to the time required to cure the adhesive in the adhesive joints.