Manufacturing Method of a Flexoelectric Coil Periodic Spring Structure Sensor for Monitoring Vibration of Complex Paths

Abstract

The present invention belongs to the field of piezoelectric measurement devices, and particularly relates to a flexoelectric coil periodic spring structure sensor for monitoring vibrations in complex paths, comprising a PVDF thin film coil and a force-bearing base. The PVDF thin film coil is in a spiral spring structure and is embedded in the force-bearing base. In the present invention, the PVDF thin film is wound into a spiral spring structure and embedded in the force-bearing base, that is, a three-dimensional structure in space is formed by the PVDF thin film coil in the force-bearing base. When the force-bearing base is subjected to complex forces such as tension, compression, and shear, deformations can be generated on the PVDF thin film coil, and corresponding electrical signals are generated through these deformations, providing hardware conditions for actual measurement of complex forces.

Description

Technical Field

[0001] The present invention belongs to the field of piezoelectric measurement devices, and particularly relates to a flexoelectric coil periodic spring structure sensor for monitoring vibrations of complex paths and a manufacturing method thereof. Background Art

[0002] PVDF film, namely polyvinylidene fluoride piezoelectric film, is an energy exchange material and can be used for manufacturing sensor components such as pressure sensors.

[0003] Currently, piezoelectric ceramic sensors are mainly used as measurement modules in engineering monitoring. Since piezoelectric ceramics can only respond to the force applied in their normal direction, the data obtained by piezoelectric ceramic sensors is incomplete. For example, in tunnel engineering, it is necessary to monitor the rupture and damage states of surrounding rocks and concrete linings. The rock burst of surrounding rocks exhibits a stress state of complex paths including pressure, tension, shear force, etc. However, the currently mainstream piezoelectric ceramic sensors cannot synchronously monitor the vibration characteristics of the stress states of these complex paths. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a flexoelectric coil periodic spring structure sensor for monitoring vibrations of complex paths, which can synchronously monitor the vibration characteristics of complex stress states such as pressure, tension, and shear force, and meet the requirements of tunnel safety monitoring.

[0005] The specific technical solution adopted by the present invention is as follows:

[0006] A flexoelectric coil periodic spring structure sensor for monitoring vibrations of complex paths includes a PVDF film coil and a force-bearing base. The PVDF film coil is embedded in the force-bearing base in a helical spring structure.

[0007] The force-bearing base has a rectangular block structure, and multiple PVDF film coils are arranged at intervals in the middle of the force-bearing base in an array.

[0008] The axis of the PVDF film coil is parallel to the force-bearing direction of the force-bearing base.

[0009] The PVDF film used is a silver-plated film, with a width of 1.5 mm - 3 mm, a thickness of 12 microns, and the length of the PVDF film coil is 10 mm.

[0010] It also includes a manufacturing method of this spring structure.

[0011] Step 1, manufacture a mold box for casting the force-bearing base;

[0012] Step 2, pull auxiliary lines in the cavity of the mold box;

[0013] Step 3: Wind the PVDF thin film wire into a PVDF thin film coil with a helical spring-like structure by means of the temporary support of the auxiliary wire;

[0014] Step 4: Inject glue into the mold box to embed the PVDF thin film coil to form a force-bearing base;

[0015] Step 5: After waiting for the glue to initially solidify, draw out the auxiliary wire, and after the glue solidifies, remove the mold box to obtain the finished product.

[0016] The auxiliary wire is arranged in multiple layers from bottom to top, and the vertical distance between the auxiliary wires is equal to the pitch of the PVDF thin film coil.

[0017] The auxiliary wire is coated with glue, and the PVDF thin film wire is temporarily bonded in Step 3 by means of the viscosity of the glue.

[0018] The mold box includes a box cover, and a plurality of glue injection ports are arranged on the box cover. The glue injection ports are located at the gaps between the PVDF thin film coils, and the glue injection operation in Step 4 is completed by injecting glue through the plurality of glue injection ports simultaneously.

[0019] A metal hoop is additionally arranged around the outer circumference of the force-bearing base in a surrounding manner.

[0020] The beneficial effects of the present invention are as follows:

[0021] The present invention adopts the method of winding the PVDF thin film into a helical spring structure and embedding it in the force-bearing base, that is, a three-dimensional structure in space is formed by the PVDF thin film coil in the force-bearing base. When the force-bearing base is subjected to complex path forces such as tension, compression, and shear, deformation can be generated on the PVDF thin film coil, and corresponding electrical signals are generated through this deformation, providing hardware conditions for actual measurement of complex forces. Description of the Drawings

[0022] Figure 1 It is a schematic structural diagram of the present invention;

[0023] Figure 2 It is a schematic structural diagram of the mold box;

[0024] In the drawings, 1, PVDF thin film coil; 2, force-bearing base; 3, mold box; 4, glue injection port; 5, auxiliary wire. Detailed Embodiments

[0025] The present invention will be further described below in conjunction with the drawings and specific embodiments:

[0026] Specific embodiments are as Figure 1 shown. The present invention is a flexoelectric coil periodic spring structure sensor for monitoring complex path vibrations, including a PVDF thin film coil 1 and a force-bearing base 2. The PVDF thin film coil 1 is embedded in the force-bearing base 2 in a helical spring structure.

[0027] When in use, both ends of the PVDF thin film coil 1 are respectively connected to wires to collect the change in the electrical signal generated by its deformation. Since the PVDF thin film coil 1 is wound into a spatial helical spring structure, when the force-bearing base 2 is subjected to forces such as tensile force, compressive force, and shear force, it can undergo different degrees of deformation, thereby generating different electrical signals. Thus, the current force-bearing situation can be known by detecting the change in the electrical signal.

[0028] Furthermore, the force-bearing base 2 has a rectangular block structure, and multiple PVDF thin film coils 1 are arranged at intervals in the middle of the force-bearing base 2 in an array.

[0029] As Figure 1 shown, by increasing the number of PVDF thin film coils 1 in the force-bearing base 2 and increasing the measurement sites, it helps to increase the detection accuracy.

[0030] Furthermore, the axis of the PVDF thin film coil 1 is parallel to the force-bearing direction of the force-bearing base 2. When the force-bearing base 2 is subjected to compressive force, the PVDF thin film coil 1 is compressed. When subjected to tensile force, the PVDF thin film coil 1 is stretched. When subjected to shear force, the PVDF thin film coil 1 is stretched and the axis is offset, thereby generating different electrical signals for measurement and analysis.

[0031] Furthermore, the PVDF thin film is a silver-plated thin film, with a width of 1.5 mm - 3 mm, a thickness of 12 microns, and the length of the PVDF thin film coil 1 is 10 mm.

[0032] Due to the gradient effect of the compression displacement of the cylindrical spring, in order to avoid waste of resources caused by too large a length of the spring under the action of a small vibration load, the length of the PVDF thin film coil 1 is set to 10 mm, and this length is the axial length after the PVDF thin film coil 1 is formed.

[0033] The width of the PVDF thin film is set to 1.5 mm - 3 mm, preferably 2 mm, which is convenient for the PVDF thin film coil 1 to sense elastic deformation and improve the monitoring sensitivity.

[0034] Furthermore, as Figure 2 shown, it also includes the manufacturing method of this spring structure,

[0035] Step 1, manufacture the mold box 3 for casting the force-bearing base 2;

[0036] Step 2, pull the auxiliary wire 5 in the cavity of the mold box 3;

[0037] Step 3, wind the PVDF thin film wire into a helical spring-shaped PVDF thin film coil 1 with the temporary support of the auxiliary wire 5;

[0038] Step 4: Inject glue into the mold box 3 to embed the PVDF thin film coil 1 to form the stress-bearing base 2;

[0039] Step 5: After waiting for the glue to initially solidify, extract the auxiliary wire 5. After the glue solidifies, remove the mold box 3 to obtain the finished product.

[0040] Furthermore, multiple layers of the auxiliary wire 5 are arranged from bottom to top, and the vertical distance between the auxiliary wires 5 is equal to the pitch of the PVDF thin film coil 1.

[0041] When winding the PVDF thin film coil 1, through the arrangement of multiple auxiliary wires 5 from high to low, each spiral of the PVDF thin film is supported and positioned by means of the auxiliary wire 5 to ensure that the pitch of each spiral is equal.

[0042] The auxiliary wire 5 is coated with glue, and the glue is used to temporarily bond the PVDF thin film wire in Step 3. The auxiliary wire 5 is bonded to the side of the PVDF thin film wire, thus avoiding affecting the spiral shape of the coil.

[0043] After the thin film is wound into the PVDF thin film coil 1, the thin film is in a vertical state; whether the thin film is placed horizontally or vertically has little impact on the monitoring results. However, due to the positioning method using the auxiliary wire 5, the thin film is in a vertical state for convenient bonding, which can improve the preparation efficiency.

[0044] Furthermore, as Figure 2 shown, the mold box 3 includes a box cover, and a plurality of glue injection ports 4 are provided on the box cover. The glue injection ports 4 are located at the gaps between the PVDF thin film coils 1, and the glue injection operation in Step 4 is completed by injecting glue through the plurality of glue injection ports 4 simultaneously.

[0045] Polydimethylsiloxane is used to be simultaneously poured through the plurality of glue injection ports 4, so that the glue liquid plane in the box rises relatively evenly everywhere, avoiding the glue liquid from deflecting the PVDF thin film wire and ensuring the good forming of the PVDF thin film coil 1.

[0046] Furthermore, a metal hoop is additionally provided around the outer circumference of the stress-bearing base 2 in a surrounding manner. This enables the device to increase the structural stability when in a high-stress state.

Claims

1. Method for manufacturing a flexoelectric coil periodic spring structure sensor for monitoring vibration of complex paths, Characterized in that: The sensor includes a PVDF thin film coil (1) and a force-bearing base (2), and the PVDF thin film coil (1) is embedded in the force-bearing base (2) in a spiral spring structure; The method for manufacturing the spring structure sensor includes the following steps, Step 1, manufacture a mold box (3) for casting the force-bearing base (2); Step 2, pull a support wire (5) in the cavity of the mold box (3); Step 3, wind the PVDF thin film wire into a PVDF thin film coil (1) with a spiral spring-like structure by means of the temporary support of the support wire (5); Step 4, inject glue into the mold box (3) to embed the PVDF thin film coil (1) to form the force-bearing base (2); Step 5, wait for the glue to initially solidify and then draw out the support wire, and remove the mold box (3) after the glue solidifies to obtain the finished product.

2. The method for manufacturing a flexoelectric coil periodic spring structure sensor for monitoring vibration of complex paths according to claim 1, Characterized in that: The force-bearing base (2) has a rectangular block structure, and a plurality of PVDF thin film coils (1) are arranged at intervals in the middle of the force-bearing base (2) in an array.

3. The method for manufacturing a flexoelectric coil periodic spring structure sensor for monitoring vibration of complex paths according to claim 1, Characterized in that: The axis of the PVDF thin film coil (1) is parallel to the force-bearing direction of the force-bearing base (2).

4. The method for manufacturing a flexoelectric coil periodic spring structure sensor for monitoring vibration of complex paths according to claim 1, Characterized in that: The PVDF thin film is a silver-plated thin film, with a width of 1.5 mm - 3 mm, a thickness of 12 microns, and the length of the PVDF thin film coil (1) is 10 mm.

5. The method for manufacturing a flexoelectric coil periodic spring structure sensor for monitoring vibration of complex paths according to claim 1, Characterized in that: The support wire (5) is arranged in multiple layers from bottom to top, and the vertical distance between the support wires (5) is equal to the pitch of the PVDF thin film coil (1).

6. The method for manufacturing a flexoelectric coil periodic spring structure sensor for monitoring vibration of complex paths according to claim 1, Characterized in that: The support wire (5) is coated with glue, and the PVDF thin film wire is temporarily bonded in step 3 by means of the viscosity of the glue.

7. The method for manufacturing a flexoelectric coil periodic spring structure sensor for monitoring vibration of complex paths according to claim 1, Characterized in that: The mold box (3) includes a box cover, and a plurality of glue injection ports (4) are arranged on the box cover. The glue injection ports (4) are located at the gaps between the PVDF thin film coils (1), and the glue injection operation in step 4 is completed by injecting glue simultaneously through the plurality of glue injection ports (4).

8. The method for manufacturing a flexoelectric coil periodic spring structure sensor for monitoring vibration of complex paths according to claim 1, Characterized in that: A metal hoop is additionally provided around the outer circumference of the force-bearing base (2).

Images