CN106563877B - The connection method of vibratory string in a kind of type vibration wire earth pressure gauge - Google Patents

Abstract

The invention discloses a method for connecting vibrating wires in a vibrating wire earth pressure gauge. Ultrasonic welding is used to fixedly connect the vibrating wires to a supporting base, and an ultrasonic welding device is used to apply ultrasonic vibration to the outer surface of the splint of the supporting base, thereby Weld the vibrating wires in the splint of the support seat to the splint firmly. A method for connecting vibrating wires in a vibrating wire earth pressure gauge of the present invention has the following beneficial effects: (1) the process is simple, easy to operate, and the vibrating wires do not loosen after the connection is completed, so that the tensioned vibrating wires and the splint of the support seat are permanently connected. (2) There is no need to process threaded holes on the splint of the support seat, which overcomes the problem that the vibrating wire is easy to loosen, has a long service life and good stability, and makes the measurement data of the vibrating wire earth pressure gauge accurate and consistent.

Description

A connection method of vibrating wire in vibrating wire earth pressure gauge

technical field

The invention belongs to the field of civil engineering testing instruments, relates to the field of vibrating wire earth pressure gauges, and in particular relates to an improvement of a connection method of vibrating wires in the vibrating wire earth pressure gauge.

Background technique

The vibrating wire earth pressure gauge is an effective monitoring device for measuring the compressive stress of building foundations and soils such as earth-rock dams, breakwaters, high-rise buildings, bridge piers, retaining walls, tunnels, subways, and highway structures. It can also be used to understand the measured structure The variation of earth pressure inside the object and the temperature of the buried point.

The existing vibrating wire earth pressure gauge usually consists of a back plate 1', an induction plate 2', a signal transmission cable 3', a vibrating wire 4', a support base 5' and an electromagnetic coil 6', as shown in Figure 1. Among them, the induction plate 2' is connected to the back plate 1' in a threaded manner, and a rubber gasket 7' with a diameter of 2mm is placed between the induction plate 2' and the back plate 1'. The working principle of the vibrating wire earth pressure gauge is that when the measured When the soil stress in the structure changes, the induction plate 2' will feel the change of stress synchronously, and the induction plate 2' will be deformed, and the deformation will be transferred to the vibrating wire 4' to change the stress of the vibrating wire, thereby changing the force of the vibrating wire 4'. Vibration frequency, the electromagnetic coil 6' excites the vibrating wire 4' and measures its vibration frequency, the frequency signal is transmitted to the reading device through the signal transmission cable 3', and the compressive stress value of the structure under test can be measured, and can be measured simultaneously The temperature value of the buried point. At present, vibrating wire earth pressure gauges are widely used in the measurement of physical quantities in the fields of water conservancy and hydropower, highways, railways, bridges, tunnels, mines, national defense and construction safety monitoring.

The vibrating wire of the existing vibrating wire earth pressure gauge adopts the mechanical connection method of fastening the vibrating wire with screws, and the specific connection method is as follows: firstly, a moderately sized threaded hole is processed on the splint of the support seat 5' clamping the vibrating wire 4' , and then screw the inner hexagon screw 8' into the threaded hole, and tighten the inner hexagon screw 8' to make the splint of the support seat 5' generate a clamping force to clamp the tensioned vibrating wire 4', but such a clamping method It cannot be fixed permanently.

The vibrating wire earth pressure gauge has been in a complex dynamic working environment for a long time. The current connection method of the vibrating wire of the vibrating wire earth pressure gauge will cause the following problems: (1) Due to the screw fastening method, with the prolongation of the use time And the vibration of the vibrating wire, the vibrating wire will be easy to loosen, the tension will decrease, the amplitude will decrease, etc.; (2) The loosening of the vibration will cause a large error in the data converted by the sensor, which cannot reflect the actual measured value and cannot meet the requirements of the measuring instrument. The demand for high-precision results; (3) processing threaded holes on the splint of the vibrating wire support seat will reduce its working strength.

Ultrasonic welding is a special method that uses mechanical vibration energy of ultrasonic frequency (over 16kHz) to connect the same metal or dissimilar metal. When the metal is ultrasonically welded, it neither transmits current to the workpiece nor applies a high-temperature heat source to the workpiece. Only under static pressure, the vibration energy is transformed into friction work, deformation energy and limited temperature rise between workpieces. The metallurgical bond between some metal joints is a solid state weld achieved without melting the parent metal. Therefore, ultrasonic welding not only effectively overcomes the spatter and oxidation phenomena generated during resistance welding, but also makes up for the shortcomings of arc welding that the welding heat is too high and the fuse string cannot form an effective joint.

Contents of the invention

The purpose of the present invention is to provide a method for connecting vibrating wires in a vibrating wire earth pressure gauge. The connecting method is simple in process and easy to operate. After the connection is completed, the vibrating wires will not loosen, and the permanent combination of the vibrating wires and the support seat can be realized. It overcomes the problem that the vibrating wire is easy to loosen, has a long service life and good stability, so that the measurement data of the vibrating wire earth pressure gauge is accurate.

In order to achieve the above object, the solution of the present invention is:

A method for connecting vibrating wires in a vibrating wire earth pressure gauge. The connection method is realized based on a support seat for fixing the vibrating wire. The support seat includes a left support seat and a right support seat made of aluminum, and the left support seat The upper end and the upper end of the right support seat respectively have two oppositely arranged splints, forming a gap for the vibrating wire to pass between the splints, and opening along the length direction of the left support seat in the left support seat A through hole, or a through hole is opened in the right support base along the length direction of the right support base;

The connection method includes the following steps:

(1) Pretreatment of the vibrating wire: according to the length of the left support seat and the right support seat, and the distance between the two support seats, the corresponding length of the vibrating wire located in the crack is obtained, and the corresponding length is located in the crack The vibrating wire part is sprayed with a layer of aluminum film;

(2) Fixing of the vibrating wire: After the vibrating wire passes through the through hole in the left support seat or the through hole in the right support seat, it is reversely penetrated between the cracks of the corresponding support seat, and the vibrating wire One end of the vibrating wire is clamped outside the through hole, and the other end of the vibrating wire is tensioned by the roller tensioning mechanism, and the vibrating wire is kept parallel to the horizontal plane;

(3) Determination of welding points: the welding points are located on the outer surface of the splint of the left support base and the outer surface of the splint of the right support base, and the center of the welding point on the left support base is aligned with the left support base. The distance between the left edge of the left edge is 10-15mm and the distance from the upper edge of the left support seat is 5-10mm, the distance between the center of the welding point on the right support seat and the right edge of the right support seat is 10-15mm and the distance from the upper edge of the left support seat is 10-15mm The distance between the upper edge of the right support seat is 5-10mm;

(4) Ultrasonic welding: first place the left support seat or the right support seat provided with the through hole between the two sonic poles of the ultrasonic welding device, and align each sonic pole with the corresponding support seat Welding point, apply ultrasonic vibration to the left support seat or the right support seat, and cool naturally, so that the vibrating string and the splint between the splints of the left support seat or the right support seat are welded into one, and then weld another The vibrating wires of the supporting base are finally cut off the redundant vibrating wires outside the supporting base to complete the connection between the vibrating wires and the supporting base.

The distance between the splints is 0.25mm, and the diameter of the through hole is 0.25mm.

In step (4), the welding pressure is 14-18Mpa, the welding power is 4000-4500W, the welding amplitude is 18-20μm, and the welding time is 1-1.5s.

In step (4), argon or helium is fed into the welding point while welding.

The invention relates to a method for connecting vibrating wires in a vibrating wire earth pressure gauge, which uses ultrasonic welding to fixedly connect the vibrating wires to the support base, and has the following beneficial effects:

(1) The process is simple, easy to operate, the vibrating wire does not loosen after the connection is completed, and the purpose of permanent combination of the tensioned vibrating wire and the splint of the support seat is achieved;

(2) There is no need to process threaded holes on the splint of the support seat, which overcomes the problem that the vibrating wire is easy to loosen, has a long service life and good stability, and makes the measurement data of the vibrating wire earth pressure gauge accurate.

Furthermore, the welding amplitude of the welding process is determined by the thickness and material of the weldment. As the hardness and thickness of the material increase, the selected amplitude value increases correspondingly, and the selected range is 18-20 μm; in order to prevent excessive pressure from causing excessive friction The relative movement between the weldments is weakened. The welding pressure is preferably 14Mpa. The welding time refers to the time when the ultrasonic energy is input into the weldment. There is a minimum welding time for the formation of solder joints. The welding time is not enough to destroy the oxide film on the metal surface. It cannot be welded, and the welding time for thick metal plates generally does not exceed 1.5s, so the welding time is preferably 1-1.5s.

Further, during welding, in order to prevent oxidation of the surface of the aluminum support seat due to temperature rise caused by friction, argon or helium gas can be injected for protection.

Description of drawings

Fig. 1 is the connection schematic diagram of vibrating wire in existing vibrating wire type earth pressure gauge;

Fig. 2 is a schematic diagram of the front structure of the left support seat in the present invention;

Fig. 3 is a side view structural schematic diagram of the left support seat in the present invention;

Fig. 4 is a side view structural schematic diagram of the right support seat in the present invention;

Fig. 5 is the schematic diagram of the pretreatment of vibrating wire in the present invention;

Fig. 6 is a structural schematic diagram of the connection between the support seat and the vibrating wire in the present invention;

Fig. 7 is a schematic diagram of the welding of the left support seat and the vibrating wire in the present invention;

Fig. 8 is a schematic diagram of the welding of the right support seat and the vibrating wire in the present invention;

Fig. 9 is a schematic diagram of the welding between the support seat and the vibrating wire in the present invention.

In the picture:

Backplane 1’ Sensing Board 2’

Signal Transmission Cable 3’ Vibrating Wire 4’

Stand 5’ Solenoid 6’

Rubber washer 7’ Socket head cap screw 8’

Left support seat 1 Cleat plate 11

Slit 12 Through Hole 13

Right support seat 2 splint 21

Gap 22 Vibrating wire 3

Positioning wheel 4 Roller tensioning mechanism 5

Ultrasonic welding device 6 Sonotrode 61

Sonotrode body 611 Hemispherical end face 612

Detailed ways

In order to further explain the technical solution of the present invention, the present invention will be described in detail below through specific examples.

A method for connecting a vibrating wire in a vibrating wire earth pressure gauge, the connecting method is realized based on a support seat for fixing the vibrating wire, and the connecting method includes the following steps:

(1) Processing of the splint on the support seat: as shown in Figure 2-4, the material of the support seat is LY12 aluminum alloy, the support seat includes the left support seat 1 and the right support seat 2, the upper end of the left support seat 1 and the right support The upper end of the seat 2 has two opposite splints respectively. A gap 12 for the vibrating wire to pass is formed between the splints 11 of the left support seat 1, and a gap 12 for the vibrating wire to pass is also processed between the splints 21 of the right support seat 2. The gap 22 passed through, the width b of the gap 12 and 22 is 0.25mm, the negative tolerance is -0.1mm (that is, the distance between the two splints on the same support seat is 0.25mm), and it is supported along the left side of the left support seat 1 A through hole 13 is defined in the length direction of the seat 1, and the diameter D of the through hole 13 is 0.25 mm.

(2) Pretreatment of the vibrating wire: as shown in Figure 3-Figure 5, according to the length d of the left supporting base 1 and the right supporting base 2, and the distance l between the two supporting bases, the vibrating wire 3 is located in the gap 12 and 22 Corresponding length in the inside, to be positioned at the vibrating wire part in the crack 12 and 22 spray one deck aluminum film.

(3) Fixing of the vibrating wire: as shown in Figure 3, Figure 4 and Figure 6, the first end of the vibrating wire 3 is passed through the through hole 13 from the right end of the left support base 1, and then reversed from the left support base 1 The left end of the left end penetrates in the crack 12 of the left support base 1 and the crack 22 of the right support base 2 in turn, and the second end of the vibrating string 3 is fixed outside the through hole 13 of the left support base 1 through the positioning wheel 4, and the vibrating string 3 The first end is tensioned by the roller tensioning mechanism 5, and the vibrating wire 3 is kept parallel to the horizontal plane.

(4) Determination of welding points: as shown in Figure 6, the welding points are located on the outer surfaces of the two splints 11 of the left support base 1 and the outer surfaces of the two splints 21 of the right support base 2, on the left support base 1 The distance S1 between the center of the welding point and the left edge of the left support seat 1 is 10-15mm and the distance S2 from the upper edge of the left support seat 1 is 5-10mm, and the center of the welding point on the right support seat 2 and the right support The distance S3 between the right edge of the seat 2 is 10-15 mm and the distance S4 from the upper edge of the right supporting seat is 5-10 mm.

(5) Ultrasonic welding: as shown in Fig. 3, Fig. 7-Fig. Align the welding points on the splint 11 of the left support base 1 respectively, apply ultrasonic vibration to the splint 11 of the left support base 1, the welding pressure is 14Mpa, the welding power is 4000W, the welding amplitude is 18-20μm, after welding 1-1.5s Stop the ultrasonic vibration, cool naturally, so that the vibrating string 3 between the splint 11 of the left support seat 1 and the splint 11 are welded into one, and then weld the vibrating string 3 in the right support seat 2 in the same way, and finally at a distance from the right support seat Cut off the redundant vibrating wire 3 outside the right support base 2 at 5 mm outside 2, and then complete the connection between the vibrating wire 3 and the support base.

The invention relates to a method for connecting vibrating wires in a vibrating wire earth pressure gauge, which uses ultrasonic welding to fixedly connect the vibrating wires to the support base, and has the following beneficial effects:

(1) The process is simple, easy to operate, the vibrating wire does not loosen after the connection is completed, and the purpose of permanent combination of the tensioned vibrating wire and the splint of the support seat is achieved;

(2) There is no need to process threaded holes on the splint of the support seat, which overcomes the problem that the vibrating wire is easy to loosen, has a long service life and good stability, and makes the measurement data of the vibrating wire earth pressure gauge accurate.

Further, since the vibrating string 3 is a steel wire string, and the support seat is made of aluminum alloy, a layer of aluminum film is sprayed on the vibrating string part located in the crack, the purpose is that the amplitude of the ultrasonic induction of the same metal is consistent, and after ultrasonic welding The vibrating wire located in the crack can be better welded to the splint of the support base.

Further, in step (3), the vibrating wire tension (tension degree) is adjusted through the roller tensioning mechanism 5, so that the tension degree of the vibrating wire 3 meets the requirement standard of the vibrating wire earth pressure gauge.

Furthermore, the welding amplitude of the welding process is determined by the thickness and material of the weldment. As the hardness and thickness of the material increase, the selected amplitude value increases correspondingly, and the selected range is 18-20 μm; in order to prevent excessive pressure from causing excessive friction The relative movement between the weldments is weakened. The welding pressure is preferably 14Mpa. The welding time refers to the time when the ultrasonic energy is input into the weldment. There is a minimum welding time for the formation of solder joints. The welding time is not enough to destroy the oxide film on the metal surface. It cannot be welded, and the welding time for thick metal plates generally does not exceed 1.5s, so the welding time is preferably 1-1.5s.

Further, as shown in FIG. 7 , the sonotrode 61 includes a sonotrode body 611 and a hemispherical end face 612 in contact with the welding point. The sonotrode body 611 is made of high-speed steel, and the hemispherical end face 612 is made of bearing steel GCr15. The radius of the hemispherical end face 612 is 25 mm. During welding, the center of the hemispherical end face 612 is aligned with the center of the welding point, so as to ensure the welding effect.

Furthermore, during welding, in order to prevent the surface of the aluminum support seat from being oxidized due to the temperature rise caused by friction, argon or helium can be injected into the welding point for protection.

The roller tensioning mechanism 5 and the ultrasonic welding device 6 in the present invention are all well-known equipment in the art.

The above-mentioned embodiments and drawings do not limit the form and style of the product of the present invention, and any appropriate changes or modifications made by those skilled in the art should be considered as not departing from the patent scope of the present invention.

Claims (4)

1. A connection method of vibrating wire in a vibrating wire type earth pressure gauge, the connection method is realized based on a support base for vibrating wire fixing, it is characterized in that: said support base comprises aluminum left support base and right support base, The upper end of the left support seat and the upper end of the right support seat respectively have two splints arranged oppositely, and a gap for the vibrating wire to pass is formed between the splints, and along the left A through hole is opened in the length direction of the support seat, or a through hole is opened in the right support seat along the length direction of the right support seat; The connection method includes the following steps: (1) Pretreatment of the vibrating wire: according to the length of the left support seat and the right support seat, and the distance between the two support seats, the corresponding length of the vibrating wire located in the crack is obtained, and the corresponding length is located in the crack The vibrating wire part is sprayed with a layer of aluminum film; (2) Fixing of the vibrating wire: After the vibrating wire passes through the through hole in the left support seat or the through hole in the right support seat, it is reversely penetrated between the cracks of the corresponding support seat, and the vibrating wire One end of the vibrating wire is clamped outside the through hole, and the other end of the vibrating wire is tensioned by the roller tensioning mechanism, and the vibrating wire is kept parallel to the horizontal plane; (3) Determination of welding points: the welding points are located on the outer surface of the splint of the left support base and the outer surface of the splint of the right support base, and the center of the welding point on the left support base is aligned with the left support base. The distance between the left edge of the left edge is 10-15mm and the distance from the upper edge of the left support seat is 5-10mm, the distance between the center of the welding point on the right support seat and the right edge of the right support seat is 10-15mm and the distance from the upper edge of the left support seat is 10-15mm The distance between the upper edge of the right support seat is 5-10mm; (4) Ultrasonic welding: first place the left support seat or the right support seat provided with the through hole between the two sonic poles of the ultrasonic welding device, and align each sonic pole with the corresponding support seat Welding point, apply ultrasonic vibration to the left support seat or the right support seat, and cool naturally, so that the vibrating string and the splint between the splints of the left support seat or the right support seat are welded into one, and then weld another The vibrating wires of the supporting base are finally cut off the redundant vibrating wires outside the supporting base to complete the connection between the vibrating wires and the supporting base. 2. The method for connecting vibrating wires in a vibrating wire earth pressure gauge according to claim 1, characterized in that: the distance between the splints is 0.25 mm, and the diameter of the through hole is 0.25 mm. 3. the connection method of vibrating wire in a kind of vibrating wire type earth pressure gauge according to claim 1, is characterized in that: in step (4), welding pressure is 14-18Mpa, and welding power is 4000-4500W, and welding amplitude It is 18-20μm, and the welding time is 1-1.5s. 4. The method for connecting vibrating wires in a vibrating wire earth pressure gauge according to claim 1, characterized in that: in step (4), argon or helium gas is fed into the welding point while welding.