A connecting rod body and connecting rod bushing fit detection method

Abstract

The present application relates to a kind of connecting rod body and connecting rod bushing fitting degree detection method, first in the inner hole surface of connecting rod body processing helical groove;Connecting rod body is placed in oven box and kept warm;Real machine connecting rod bushing is placed in liquid nitrogen, until liquid nitrogen stops boiling, take out connecting rod bushing and install in connecting rod body, do not allow to knock or press-in by press;Connecting rod body with connecting rod bushing is installed at room temperature and stationary;Using the method that does not damage connecting rod bushing, cut open connecting rod body, take out connecting rod bushing;Examine the spiral trace line of connecting rod bushing outer circle, if spiral trace line extends along one end of connecting rod bushing to the other end, and clear, continuous, it indicates that the fitting degree of connecting rod bushing and connecting rod body is 100%;If connecting rod bushing outer circle spiral line structure is discontinuous, it indicates that connecting rod bushing and connecting rod body are not completely fitted, i.e. fitting degree is less than 100%.The present application can directly and accurately obtain the fitting degree value of connecting rod bushing and connecting rod body, and can also be extended to other interference assemblies, and has popularization significance.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of engines, and particularly relates to a connecting rod body and a connecting rod bushing fitting degree detection method. BACKGROUND

[0002] The connecting rod body and the connecting rod bushing are connected in interference, and engineering personnel hope that the outer surface of the connecting rod bushing and the inner hole surface of the connecting rod body are uniformly and continuously fitted. The fitting degree of the connecting rod bushing and the connecting rod body is an important index for guaranteeing the connection strength, and the fitting degree index directly affects the reliability of the connecting rod. If the connecting rod body and the connecting rod bushing are connected loosely, the bearing pair works invalidly, which can cause the piston pin to run unsmoothly, the piston pin hole to be abnormally worn, the piston to be pulled, and the like, and can cause the engine to be scrapped. At present, the fitting degree of the connecting rod bushing and the connecting rod body is checked by using an eddy current method, but the method has not been applied in actual operation due to poor precision. SUMMARY

[0003] The application provides a connecting rod body and a connecting rod bushing fitting degree detection method, and solves the defects of the prior art.

[0004] In order to solve the above technical problems, the application provides a connecting rod body and a connecting rod bushing fitting degree detection method, which is characterized by comprising the following steps.

[0005] S1, a spiral groove is processed on the inner hole surface of the connecting rod body;

[0006] S2, the connecting rod body is placed in an oven for heat preservation; the actual machine connecting rod bushing is placed in liquid nitrogen until the liquid nitrogen stops boiling, the connecting rod bushing is taken out and is installed in the connecting rod body, and knocking or pressure machine pressing is not allowed; the connecting rod body with the installed connecting rod bushing is placed at room temperature;

[0007] S3, the connecting rod body is cut open by a method without damaging the connecting rod bushing, and the connecting rod bushing is taken out;

[0008] S4, the spiral trace line of the outer circle of the connecting rod bushing is checked, if the spiral trace line spirally extends from one end of the connecting rod bushing to the other end and is clear and continuous, it is indicated that the fitting degree of the connecting rod bushing and the connecting rod body is 100%; if the spiral line structure of the outer circle of the connecting rod bushing is discontinuous, it is indicated that the connecting rod bushing and the connecting rod body are not completely fitted, that is, the fitting degree is less than 100%.

[0009] Beneficial effects: the application has the advantages of intuitive and convenient detection; the fitting degree value of the connecting rod bushing and the connecting rod body can be directly and accurately obtained, and the application can be popularized to other interference assemblies and has popularization significance. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 Structure diagram of a spiral groove in a connecting rod inner hole

[0011] Figure 2Helical mark line of outer circle of connecting rod bushing

[0012] Figure 3 Helical mark line discontinuity of connecting rod bushing

[0013] Figure 4 Rectangular diagram. DETAILED DESCRIPTION

[0014] In order to make the purpose, content and advantages of the present application more clear, the specific embodiments of the present application are described in further detail below.

[0015] The present application provides a connecting rod body and a connecting rod bushing fitting degree detection method, comprising the following steps:

[0016] S1, determine the connecting rod body: the connecting rod body can be a real machine connecting rod body or a non-standard part with the same technical state as the real machine connecting rod body, and the technical state includes material, performance, processing method, tool, roughness, etc.

[0017] S2, process a helical groove on the inner hole surface of the real machine connecting rod body or the non-standard connecting rod body with the same technical state as the real machine connecting rod body, and the depth of the helical groove is 0.5mm, the width is 0.2mm, and the pitch is 3mm; the connecting rod body helical groove structure diagram is shown in Figure 1 .

[0018] S3, place the real machine connecting rod body or the non-standard connecting rod body with the same technical state as the real machine connecting rod body in a 70℃ oven for 2 hours; place the real machine connecting rod bushing in liquid nitrogen until the liquid nitrogen stops boiling, and then take out the connecting rod bushing and easily put it into the connecting rod body, without knocking or pressing into the connecting rod body with a press. The connecting rod body or the non-standard connecting rod body with the same technical state as the real machine connecting rod body is placed at room temperature for 24 hours after the connecting rod bushing is installed.

[0019] S4, use wire cutting or other methods that do not damage the connecting rod bushing to cut open the connecting rod body and take out the connecting rod bushing.

[0020] Because the connecting rod bushing is interference fitted into the helical groove in the connecting rod body, a corresponding helical mark line will be generated. Use a 6x magnifying lens to check the helical mark line of the outer circle of the connecting rod bushing. If the helical mark line extends along one end of the connecting rod bushing to the other end, and is clear and continuous, as shown in Figure 2 , it indicates that the fitting degree of the connecting rod bushing and the connecting rod body is 100%.

[0021] S5, if the helical line structure of the outer circle of the connecting rod bushing is discontinuous, it indicates that the connecting rod bushing and the connecting rod body are not completely fitted, i.e. the fitting degree is less than 100%, and the value of the fitting degree can be accurately determined according to the following method.

[0022] a) Calculate the outer circle surface area S of the connecting rod bushing according to the engineering drawing or numerical model of the connecting rod bushing;

[0023] b) find the area (one or more) where the helix of the connecting rod bushing is discontinuous, as shown in Figure 3 ;

[0024] c) along the connecting rod bushing outer circle helix at the start and end of the discontinuity, draw two perpendicular lines, forming a rectangle with the adjacent helix, as shown in Figure 4 ;

[0025] d) using a measuring tool of a certain accuracy, determine the length a and width b of the rectangle, and calculate the area S1 = a x b;

[0026] e) the fit A = S1 ÷ S.

[0027] The above only describes the preferred embodiments of the present application, and it should be noted that for those skilled in the art, without departing from the technical principles of the present application, a number of improvements and modifications can be made, and these improvements and modifications should also be considered as the protection scope of the present application.

Claims

1. A method for detecting the fit between a connecting rod body and a connecting rod bushing, characterized in that: The following steps are involved: S1. Process a spiral groove on the inner surface of the connecting rod body. The spiral groove has a depth of 0.5 mm, a width of 0.2 mm, and a pitch of 3 mm. S2. Place the connecting rod body in an oven to keep it warm; place the actual connecting rod bushing in liquid nitrogen until the liquid nitrogen stops boiling, remove the connecting rod bushing and install it into the connecting rod body. Do not knock or press it in with a press; let the connecting rod body with the connecting rod bushing stand at room temperature; S3. Cut open the connecting rod body and remove the connecting rod bushing by a method that does not damage the connecting rod bushing. S4. Check the spiral traces on the outer circle of the connecting rod bushing. If the spiral traces extend from one end of the connecting rod bushing to the other end and are clear and continuous, the connecting rod bushing and the connecting rod body are 100% fit. If the spiral traces on the outer circle of the connecting rod bushing are discontinuous, it indicates that the connecting rod bushing and the connecting rod body are not completely fit, that is, the fit is less than 100%; The following method is used to accurately determine the value of the fit: a) Calculate the outer surface area S of the connecting rod bushing according to the connecting rod bushing engineering drawing or digital model; b) Find the area where the connecting rod bushing helix is ​​discontinuous; c) Draw two perpendicular lines along the discontinuous starting and ending positions of the outer spiral line of the connecting rod bushing to form a rectangle with the adjacent spiral lines; d) Determine the length a and width b of the rectangle and find the area of ​​the rectangle S1 = a × b; e) Degree of fit: A = S1 ÷ S.

2. A method for detecting the fit between a connecting rod body and a connecting rod bushing according to claim 1, characterized in that: In S1, the connecting rod body is replaced by an actual connecting rod body or a non-standard part with the same technical status as the actual connecting rod body.

3. A method for detecting the fit between a connecting rod body and a connecting rod bushing according to claim 2, characterized in that: The technical status includes material, performance, processing method and tool, and roughness.

4. The method for detecting the fit between a connecting rod body and a connecting rod bushing according to claim 1, wherein: In S2, the connecting rod body is placed in an oven at 70°C for 2 hours.

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