Device and method for detecting fitting degree of connecting rod bushing by ultrasonic wave

1 . A device for detecting a fitting degree of a connecting rod bushing by an ultrasonic wave, a connecting rod being placed on the device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave when in use, wherein the device comprises a mobile platform, a rack, a fixture assembly and a detection assembly;

the rack comprises a top portion, a bottom portion and a side wall;

and the side wall is provided with an opening on an opposite side, and the top portion and the bottom portion are opposite, and are both perpendicular to the side wall;

the mobile platform is mounted on the top portion of the rack;

the fixture assembly comprises a big head hole fixture, a connecting rod body fixture and a fixture base;

the detection assembly comprises an ultrasonic flaw detection card, an ultrasonic probe and a computer;

the big head hole fixture comprises a plurality of positioning blocks, the positioning blocks in a transverse section have a common point, and the common point is located in a center of circle of the big head hole when the connecting rod is placed on the device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave;

the fixture base is arranged on an upper surface of the bottom portion of the rack, the ultrasonic probe is arranged at a lower end of the mobile platform, and the ultrasonic probe is capable of moving up-down and left-right, and is capable of rotating;

the big head hole fixture and the connecting rod body fixture are arranged on an upper surface of the fixture base;

the ultrasonic probe is connected with the ultrasonic flaw detection card, the ultrasonic flaw detection card is connected with the computer, the ultrasonic flaw detection card is capable of stimulating the ultrasonic probe to emit the ultrasonic wave, and the ultrasonic flaw detection card collects echo data and sends the echo data back to the computer for analysis; and

the plurality of positioning blocks are capable of moving and contacting with an inner wall of the big end hole, and stop moving after contacting with the inner wall of the big end hole, the connecting rod body fixture is capable of moving and clamping the connecting rod, and the ultrasonic probe is capable of moving to attach to the connecting rod bushing.

2 . The device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 1 , wherein each positioning block is provided with a positioning block sliding rail, and the positioning block is capable of moving along the corresponding sliding rail.

3 . The device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 2 , wherein when the device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave works, the plurality of positioning blocks move at a constant speed from the common point to a direction far away from the common point.

4 . The device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 1 , wherein an included angle between two adjacent positioning blocks in the transverse section is less than or equal to 120 degrees.

5 . The device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 4 , wherein three positioning blocks are provided, and an included angle between adjacent positioning blocks in the transverse section is 120 degrees.

6 . The device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 1 , wherein the connecting rod body fixture comprises two clamping blocks arranged oppositely.

7 . The device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 6 , wherein a longitudinal section of the clamping block is arc-shaped.

8 . The device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 7 , wherein the clamping block is an elastomer or an elastomer is arranged on an arc-shaped inner wall of the clamping block.

9 . A method for detecting a fitting degree of a connecting rod bushing by an ultrasonic wave, using the device for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 1 , and comprising the following steps of:

manufacturing a standard sample and measuring a standard ultrasonic echo signal of fitting of the connecting rod bushing in the standard sample;

making the plurality of positioning blocks move towards the inner wall of the big head hole at the constant speed, and making the plurality of positioning blocks stop moving after contacting with an interior of the big head hole;

making the connecting rod body fixture move and clamp a connecting rod to be detected;

making the ultrasonic probe move to contact with the bushing;

stimulating the ultrasonic probe to emit the ultrasonic wave by the ultrasonic flaw detection card, and acquiring an ultrasonic echo signal of a certain detection point of the connecting rod to be detected by the ultrasonic flaw detection card;

comparing the acquired ultrasonic echo signal of the certain detection point of the connecting rod to be detected with the standard ultrasonic echo signal, and if a difference between the two signals exceeds a preset threshold, judging that the detection point is not fitted, otherwise, the detection point is fitted;

detecting a plurality of detection points one by one and judging whether the detection points are fitted; and

calculating a ratio of a total number of the fitted detection points to a total number of all detection points to obtain the fitting degree of the connecting rod bushing.

10 . The method for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 9 , wherein the standard sample is a cuboid in a preset length-width range and a preset thickness range which is manufactured with a material of the connecting rod and a material of the bushing respectively.

11 . The method for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 10 , wherein a matching state of the bushing in a small head hole of the connecting rod is simulated by applying a pressure to one side of the material of the bushing in the standard sample.

12 . The method for detecting the fitting degree of the connecting rod bushing by the ultrasonic wave according to claim 11 , wherein the pressure is calculated by the following formula:

P

=

Δ

d

×

1

(

d

2

+

d

1

2

d

2

-

d

1

2

-

μ

1

)

E

1

+

(

d

2

2

+

d

2

d

2

2

-

d

2

-

μ

2

)

E

2

wherein:

Δ is a magnitude of interference, which is specifically a difference between an outer diameter of the bushing and an inner diameter of the small head hole of the connecting rod;

E 1 and E 2 are elastic moduli of the material of the bushing and the material of the connecting rod respectively;

μ 1 and μ 2 are Poisson's ratios of the material of the bushing and the material of the connecting rod respectively;

d 1 and d 2 are an inner diameter of the bushing and an outer diameter of the small head hole respectively;

d is a nominal size of the outer diameter of the bushing or the inner diameter of the small head hole of the connecting rod; and

P is a surface pressure of the bushing in the standard sample.