A method for reworking, repairing and remanufacturing of an engine connecting rod

Abstract

The invention relates to a rework, repair and remanufacturing method for an engine connecting rod, the method comprising the steps of cleaning the connecting rod once; removing the bushing of the small end of the connecting rod; cleaning the connecting rod twice; assembling the bushing of the small end of the connecting rod; and secondary processing of the bushing of the small end of the connecting rod. The assembled connecting rod is clamped and fixed, a machining center respectively measures and calculates the center position of the connecting rod big head hole and the center position of the small head bushing hole, calculates the machining position of the machining center according to the center position of the connecting rod big head hole and the center position of the small head bushing hole, and cuts the connecting rod big head hole and the small head bushing hole. The method can realize the removal of the bushing, machining of a new small head bushing and machining of the big head hole, and the first manufacturing of the connecting rod during the rework, repair and remanufacturing of the connecting rod with the same fixture, shortens the cycle of the rework, repair and manufacturing of the connecting rod and reduces the cost investment, and at the same time realizes the damage-free removal of the connecting rod bushing, ensures the surface quality and shape and position tolerance of the small head hole of the connecting rod and the fit between the new small head bushing and the connecting rod.

Description

Technical Field

[0001] The invention belongs to the technical field of engine remanufacturing, and relates to a method for reworking, repairing and remanufacturing an engine connecting rod. Background Art

[0002] The engine connecting rod is one of the important parts of the engine and one of the key parts that is easy to damage. The scrap volume and demand in the market are far greater than that of the engine. However, the precision requirements of the engine connecting rod are high. The connecting rods replaced from the engine generally have the phenomenon of large head hole, small head hole, center distance and parallelism and other important dimensional parameters exceeding the tolerance. At the same time, there are also bending and twisting deformation of the rod body, and the process benchmark is damaged, which is difficult to repair. The remanufacturing of the engine connecting rod has become a technical problem that needs to be overcome to achieve engine remanufacturing.

[0003] As one of the important components of the engine connecting rod, the connecting rod bushing is mainly used to reduce vibration, isolate noise, reduce fatigue, and increase service life, which plays a vital role in the operational stability of the vehicle. However, the connecting rod bushing is also the component that is most easily worn and has the lowest service life in the connecting rod. Once the bushing is damaged, the entire connecting rod is damaged and cannot work normally. However, in fact, except for the connecting rod bushing, the other parts of the connecting rod are still intact. If the connecting rod is scrapped as a whole, the cost loss will be large. However, through the rework and repair or remanufacturing technology of the connecting rod, the shape and precision of the connecting rod can be restored, so that the quality of the remanufactured product reaches or exceeds that of a new product, greatly reducing material waste and reducing costs.

[0004] However, in the prior art, the bushing of the small end of the connecting rod is mostly taken out by using a bushing press or other pressure equipment to press out the bushing. In this state, the temperature of the bushing and the small end hole of the connecting rod are the same, and the bushing and the small end hole of the connecting rod are interference fit. There are sharp edges on the end face profile of the bushing of the small end of the connecting rod and the oil hole profile, which can easily cause scratches on the small end hole of the connecting rod. As a result, after the new bushing of the small end of the connecting rod is pressed into the small end hole of the connecting rod, the fitting degree of the bushing of the small end of the connecting rod cannot meet the requirement of more than 85%, resulting in the risk of scrapping the connecting rod; and in the process of pressing out, the small end hole of the connecting rod is deformed and the surface texture is squeezed smooth due to uneven interference force. After the new bushing of the small end of the connecting rod is pressed, there is a risk of rotation of the bushing of the small end of the connecting rod and the small end hole of the connecting rod when the connecting rod is in working state;

[0005] In addition, the connecting rod needs to be processed again after the small-end bushing is installed. By cutting the small-end bushing and the big-end hole of the connecting rod, the distance accuracy of the connecting rod big-end hole and the center of the connecting rod bushing hole is ensured to be ±0.02. However, since the big-end hole of the connecting rod will also cause wear during the use of the connecting rod, for the connecting rod produced by rework or remanufacturing technology, the cutting allowance of the big-end hole is insufficient and the big-end hole cannot be cut. In addition, the distance between the big-end hole diameter and the wall thickness of the connecting rod threaded hole is generally required to be greater than 0.8mm. If the big-end hole of the connecting rod is cut too much, the strength and stiffness of the wall of the big-end hole will be reduced. On the contrary, after the connecting rod is assembled to the engine, the cylindricality will be out of tolerance due to the influence of the above-mentioned wall thickness, and the above-mentioned wall thickness will vibrate slightly during the high-speed operation of the engine, causing engine failure. Therefore, the connecting rod with severe wear of the big-end hole cannot be reworked or remanufactured in real time. Summary of the invention

[0006] In response to the problems existing in the above-mentioned prior art, the present invention discloses a method for reworking, repairing and remanufacturing of an engine connecting rod, which can achieve damage-free removal of the connecting rod bushing during the rework, repair and remanufacturing process of the connecting rod, ensure that the inner wall of the connecting rod small head hole is not damaged, and thus ensure the surface quality and shape and position tolerance of the connecting rod small head hole and the fit between the new small head bushing and the connecting rod.

[0007] The present invention specifically discloses a method for reworking, repairing and remanufacturing an engine connecting rod, which comprises the following steps:

[0008] S1. Cleaning the connecting rod once: remove the connecting rod bolts, separate the connecting rod cap from the connecting rod body, and use ultrasonic cleaning equipment to clean each part of the connecting rod. After cleaning, assemble them together;

[0009] S2. Removing the bushing of the small end of the connecting rod: After the connecting rod is clamped and fixed, the machining center measures and calculates the coordinates of the center hole of the bushing of the small end of the connecting rod, and then the machining spindle of the machining center is moved to the top of the center hole of the bushing of the small end of the connecting rod, and the bushing of the small end of the connecting rod is cut to remove the bushing of the small end of the connecting rod;

[0010] S3. Secondary cleaning of connecting rod: Clean the connecting rod again after removing the small head bushing;

[0011] S4. Assembly of connecting rod bushing: After heating the connecting rod bushing hole to a certain temperature, press the new bushing into the connecting rod bushing hole;

[0012] S5. Secondary processing of the small end bushing of the connecting rod: Clamp and fix the assembled connecting rod, and the machining center measures and calculates the center position of the large end hole of the connecting rod and the center position of the small end bushing hole respectively. The machining position of the machining center is calculated according to the center position of the large end hole of the connecting rod and the center position of the small end bushing hole, and the large end hole of the connecting rod and the small end bushing hole are cut.

[0013] Furthermore, the specific method for measuring and calculating the hole center coordinates of the connecting rod small end bushing in step S2 is:

[0014] Use a tool measuring instrument or a low-pressure micrometer to adjust the radial runout of the measuring bead at the end of the measuring needle to less than 0.001mm;

[0015] Use the sensor to evenly select at least 4 point coordinates along the inner surface of the bushing hole of the small end of the connecting rod, and the coordinate value accuracy is less than 0.0001mm;

[0016] The center coordinates of the connecting rod bushing hole are calculated by the CNC system of the machining center using variable calculation method.

[0017] Furthermore, in step S2, the specific steps of the machining center cutting and removing the connecting rod bushing are as follows:

[0018] Adjust the machining spindle of the single-spindle machining center to the position above the center coordinate of the bushing hole at the small end of the connecting rod;

[0019] Install the tool to the tool fixture of the single-spindle machining center, and use the tool setting instrument to adjust the tool to a position 0.2 to 0.3 mm away from the inner diameter of the small head hole of the connecting rod;

[0020] The machining center is started, and the tool rotates to cut the inner wall of the connecting rod bushing hole until the connecting rod bushing is axially penetrated;

[0021] Through tool cutting, the wall thickness of the connecting rod small end bushing remains 0.10 to 0.15 mm, and the connecting rod bushing is removed using auxiliary tools.

[0022] Furthermore, in step S2, the cutting methods adopted by the machining center when cutting the connecting rod small end bushing include boring, reaming, boring and reaming combined processing, wire cutting, and laser cutting.

[0023] Furthermore, the specific method for measuring and calculating the center coordinates of the connecting rod big end hole and the small end bushing hole in step S5 is:

[0024] Use a tool measuring instrument or a low-pressure micrometer to adjust the radial runout of the measuring bead at the end of the measuring needle to less than 0.001mm;

[0025] Use the sensor to evenly select at least 4 point coordinates along the inner surface of the bushing hole of the small end of the connecting rod, and the coordinate value accuracy is less than 0.0001mm; Use the sensor to evenly select at least 4 point coordinates along the inner surface of the big end hole of the connecting rod, and the coordinate value accuracy is less than 0.0001mm;

[0026] The CNC system of the single-spindle machining center uses variable calculation methods to calculate the center point coordinates of the small end bushing hole of the connecting rod according to the coordinates of points selected from the inner surface of the small end bushing hole of the connecting rod; and calculates the center point coordinates of the big end bushing hole of the connecting rod according to the coordinates of points selected from the inner surface of the big end hole of the connecting rod.

[0027] Furthermore, the specific process of measuring and calculating the center of the connecting rod bushing hole at the small end in step S2 is as follows:

[0028] First, select four point coordinates on the inner surface of the connecting rod bushing hole. The four point coordinates are P 11 (X 11 ,Y 11 ), P 12 (X 12 ,Y 12 ), P 13 (X 13 ,Y 13 ), P 14 (X 14 ,Y 14 ), the coordinates of the four points are evenly distributed along the circumference of the small head bushing hole, among which P 11 With P 12 About Small Head Hole Center O 10 The center is symmetric, and P 11 With P 12 About the center of the small hole of the connecting rod 10 The Y-axis is symmetrical, and the symmetry is less than 5mm; 13 With P 14 About Small Head Hole Center O 10 The center is symmetric, and P 13 With P 14 About the center of the small head hole O 10 The symmetry axis of the X-axis is axially symmetrical, and the degree of symmetry is less than 5mm;

[0029] The center coordinates of the bushing hole at the small end of the connecting rod are calculated based on the coordinates of the four points of the bushing hole at the small end of the connecting rod. 10 (X 10 ,Y 10 ):

[0030] X 10 =(X 11 +X 12 ) / 2,Y 10 =(Y 13 +Y 14 ) / 2.

[0031] Furthermore, the specific process of measuring and calculating the center of the small end bushing hole and the large end hole of the connecting rod by the machining center in step S5 is as follows:

[0032] First, select four points on the inner surface of the bushing hole of the connecting rod small end. The coordinates of the four points are P 21 (X 21 ,Y 21 ), P 22 (X 22 ,Y 22 ), P 23 (X 23 ,Y 23 ), P 24 (X 24 ,Y 24 ); the coordinates of the four points are evenly distributed along the bushing hole of the connecting rod small end, P 21 With P 22 About O 20 The center is symmetrical and the axis of symmetry about the Y axis passing through the center of the small head bushing hole is symmetrical, and the symmetry is less than 5mm; P 23 With P 24 About O 20 The center is symmetrical and the axis of symmetry about the X axis passing through the center of the small head bushing hole is symmetrical, and the degree of symmetry is less than 5mm;

[0033] The inner surface of the connecting rod big end hole is selected with 4 point coordinates, the 4 point coordinates are P 31 (X 31 ,Y 31 ), P 32 (X 32 ,Y 32 ), P 33 (X 33 ,Y 33 ), P 34 (X 34 ,Y 34 ), the coordinates of the four points are evenly distributed along the big end hole of the connecting rod, P 31 With P 32 About O 30 The center is symmetrical and the axis of symmetry about the Y axis passing through the center of the large head hole is symmetrical, and the symmetry is less than 5mm; P 33 With P 34 About O 30 The center is symmetrical and the axis is symmetrical about the X axis passing through the center of the large head hole, and the degree of symmetry is less than 5mm;

[0034] The center coordinates of the bushing hole at the small end of the connecting rod are calculated based on the coordinates of the four points of the bushing hole at the small end of the connecting rod. 20 (X 20 ,Y 20 ):

[0035] X 20 =(X 21 +X 22 ) / 2,Y 20 =(Y23 +Y 24 ) / 2;

[0036] The center coordinates of the connecting rod big end hole are calculated based on the coordinates of the four points of the connecting rod big end hole. 30 (X 30 ,Y 30 ):

[0037] X 30 =(X 31 +X 32 ) / 2,Y 30 =(Y 33 +Y 34 ) / 2.

[0038] Furthermore, in step S5, the specific method for calculating the machining position of the machining center according to the center position of the connecting rod big end hole and the center position of the small end bushing hole is:

[0039] First, the center O of the bushing hole at the small end of the connecting rod is obtained according to the measurement and calculation. 20 Center of connecting rod big end hole O 30 Distance L1:

[0040] L1=SQRT(ABS((X 30 -X 20 ) 2 +(Y 30 -Y 20 ) 2 )),

[0041] Where ABS is the absolute value function, SQRT is the positive square root function;

[0042] Then, according to the principle of triangle similarity or trigonometric function, the machining position coordinates O0 (X0, Y0) of the machining center can be obtained:

[0043] X0=X 30 +a*L0;Y0=Y 30 +b*L0;

[0044] in

[0045] 1) In the engine connecting rod rework, repair and remanufacturing method of the present invention, when removing the old small-end bushing, the small-end bushing is cut to a thin-walled structure to reduce the stiffness and strength of the connecting rod, and the bushing can be smoothly removed by gently pushing it, thereby avoiding the existing technology of pressing out the bushing with high pressure equipment, which causes damage to the inner wall of the small-end hole of the connecting rod, thereby ensuring the surface quality and shape and position tolerances of the small-end hole of the connecting rod, and ensuring the fit between the new small-end bushing and the connecting rod. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1Schematic diagram of the process of reworking, repairing and remanufacturing method of engine connecting rod in Embodiment 2;

[0047] Figure 2 This is a schematic diagram of the structure of the engine connecting rod rework, repair and remanufacturing device in this embodiment 1;

[0048] Figure 3 Schematic diagram of the top view of the connecting rod in the embodiment 1;

[0049] Figure 4 is a schematic diagram of a side cross-sectional structure of a connecting rod in this embodiment 1;

[0050] Figure 5 This is a measurement schematic diagram of the online measurement system during the stage of removing the connecting rod small end bushing in Example 2;

[0051] Figure 6 This is a measurement schematic diagram of the online measurement system during the assembly phase of the connecting rod small end bushing in Example 2;

[0052] Figure 7 This is a schematic diagram of the position of the machining center during the secondary machining stage of the connecting rod small end bushing in Example 2. DETAILED DESCRIPTION

[0053] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0054] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0055] Embodiment 1:

[0056] Combination Figure 2-4As shown, this embodiment 1 specifically discloses an engine connecting rod rework, repair and remanufacturing device, which includes a single-spindle machining center 1, an online measurement system 2, a connecting rod 3 and a connecting rod clamp assembly 4, wherein the online measurement system 2 is used to measure the connecting rod small end bushing and large end hole for coordinate measurement, and at the same time feed back the measurement signal to the single-spindle machining center 1; the single-spindle machining center 1 is used as the main processing equipment for cutting the connecting rod 3; the single-spindle machining center 1 includes a machining spindle 101 for connecting a tool, a CNC center 102 and a workbench 103, the CNC center 102 receives the test signal of the online measurement system 2 and outputs the control signal of the machining spindle 101, the connecting rod clamp assembly 4 is arranged on the workbench 103, and the connecting rod clamp assembly 4 fixes the connecting rod 3. The connecting rod 3 consists of three parts: a big head end, a small head end and a connecting rod body, wherein the small head end is provided with a small head hole 301, in which a connecting rod small head bushing is installed, and the big head end is provided with a big head hole 302. The big head end of the connecting rod mostly adopts a split structure, and the big head end of the connecting rod is composed of two semicircular components, which are spliced ​​and fixed by connecting bolts 304.

[0057] The online measurement system 2 includes a wireless sensor 201, a signal receiver 202 and a signal line 203. The signal receiver 202 is electrically connected to the CNC center 102 via the signal line 203 with a shielding function. The wireless sensor 201 is installed on the machining spindle 101. The wireless sensor 201 measures the coordinate data of the connecting rod 3 and wirelessly transmits the coordinate data of the connecting rod 3 to the signal receiver 202. The signal receiver 202 transmits the received coordinate data of the connecting rod 3 to the CNC center 102 via the signal line 203.

[0058] The connecting rod clamp assembly 4 specifically includes three parts: a clamp body 403, a small head positioning clamp assembly and a large head positioning clamp assembly. The clamp body 403 is provided with a small head pin hole and a large head pin hole, the small head positioning clamp assembly is installed in the small head pin hole, and the large head positioning clamp assembly is installed in the large head pin hole, and the connecting rod 3 is clamped and fixed by the small head positioning clamp assembly and the large head positioning clamp assembly.

[0059] The small head fixture assembly includes a small head bushing hole positioning pin shaft 401, a small head bushing pin extraction cylinder 404 and a small head end face pressure arm 405, wherein the small head pin hole is provided with a small head guide shaft sleeve 402, the small head bushing hole positioning pin shaft 401 is connected to the small head pin hole through the small head guide shaft sleeve 402, the bottom of the small head bushing hole positioning pin shaft 401 is connected to the small head bushing pin extraction cylinder 404, and the small head bushing pin extraction cylinder 404 is arranged inside the fixture body 403, The small head bushing hole positioning pin 401 is driven to move axially by the small head bushing pin extraction cylinder 404; the small head end face pressing arm 405 is installed on the upper surface of the fixture body 403, and the small head end face pressing arm 405 is close to the side of the small head end face of the connecting rod 3, and the small head end face pressing arm 405 is pressed down to press the small head end face of the connecting rod 3, wherein the small head end face pressing arm 405 is connected to the first hydraulic cylinder 406, and the small head end face pressing arm 405 is driven to move vertically by the first hydraulic cylinder 406. In this embodiment, the connecting rod small head bushing hole positioning pin 401 is 0.4-0.6mm smaller than the connecting rod small head bushing hole diameter.

[0060] Similarly, the big head clamp assembly includes a big head hole positioning pin shaft 409, a big head hole pin extraction cylinder 412 and a big head end face pressure arm 408, wherein the big head pin hole is provided with a big head guide shaft sleeve 411, the big head hole positioning pin shaft 409 is connected to the big head pin hole through the big head guide shaft sleeve 411, the bottom of the big head hole positioning pin shaft 409 is connected to the big head hole pin extraction cylinder 412, and the big head hole pin extraction cylinder 412 is arranged inside the clamp body 403, The big head hole pin extraction cylinder 412 drives the big head hole positioning pin 409 to move axially; the big head end face pressing arm 408 is installed on the upper surface of the fixture body 403, and the big head end face pressing arm 408 is close to the big head end face of the connecting rod 3. The big head end face pressing arm 408 is pressed down to press the big head end face of the connecting rod 3. The big head end face pressing arm 408 is connected to the second hydraulic cylinder 410, and the big head end face pressing arm 408 is driven to move vertically by the second hydraulic cylinder 410. In this embodiment, the big head hole positioning pin 409 of the connecting rod 3 is 0.4-0.6mm smaller than the diameter of the big head hole of the connecting rod 3.

[0061] The small end bushing hole 301 and the large end hole 303 of the connecting rod 3 cooperate with the small end bushing hole positioning pin 401 and the large end hole positioning pin 409 respectively to position the connecting rod 3. At the same time, a connecting rod body supporting oil cylinder 407 is provided below the connecting rod body 302 at the middle position of the connecting rod 3, which is biased towards the small end bushing hole. The connecting rod body supporting oil cylinder 407 extends to lift the connecting rod 3, and the connecting rod 3 is clamped by the small end face pressure arm 405 and the large end face pressure arm 408. After the connecting rod 3 is clamped, the small end bushing hole positioning pin 401 and the large end hole positioning pin 409 are pulled out, and the two ends of the connecting rod 3 are cut by the single spindle machining center 1 respectively.

[0062] Embodiment 2:

[0063] Combination Figure 1 As shown, this embodiment 2 specifically discloses a method for reworking, repairing and remanufacturing an engine connecting rod, which includes the following steps:

[0064] S1. Cleaning the connecting rod once: remove the connecting rod bolts, separate the connecting rod cap from the connecting rod body, and use ultrasonic cleaning equipment to clean each part of the connecting rod. After cleaning, assemble them together;

[0065] The S1 process specifically includes:

[0066] (1) Disassembling the connecting rod bolts: First, disassemble the connecting rod bolts and separate the connecting rod into two parts: the connecting rod cap and the connecting rod body. Meanwhile, the connecting rod bolts that have been used twice or more are replaced with new ones, or with connecting rod bolts that have been used once. This step can maximize the reuse of the connecting rod bolts while ensuring that the quality of the repaired connecting rod is not reduced.

[0067] (2) Cleaning the connecting rod surface: Use ultrasonic cleaning equipment to clean the connecting rod cover, connecting rod body and connecting rod bolts respectively, and remove foreign matter such as rust, oil spots, and sticky particles on the surface of the above parts;

[0068] (3) Assembling the connecting rod bolts: After the connecting rod is cleaned, use the connecting rod assembly equipment to reassemble the connecting rod cover, connecting rod body and connecting rod bolts to form a complete connecting rod.

[0069] S2. Removing the bushing at the small end of the connecting rod: The connecting rod is clamped and fixed, and the machining center measures and calculates the center coordinates of the hole of the bushing at the small end of the connecting rod, and then the bushing at the small end of the connecting rod is cut to remove the bushing at the small end of the connecting rod;

[0070] Among them, in the stage of clamping the connecting rod, it is first necessary to use high-pressure air to clean the tools and fixtures used in processing the big head hole and the small head bushing hole. In this embodiment, the connecting rod is positioned using the small head bushing hole locating pin and the big head hole locating pin. The small head bushing hole locating pin and the big head hole locating pin are extended respectively, and the small head bushing hole and the big head hole of the connecting rod are respectively matched with the small head bushing hole locating pin and the big head hole locating pin to achieve preliminary positioning. Then, the two ends of the connecting rod are clamped by the cylinder and the end face pressure arm, and the connecting rod body is supported by the hydraulic cylinder to achieve connecting rod clamping. Then, the big head hole locating pin and the small head bushing hole locating pin are lowered to leave space for the tool's cutting processing.

[0071] After the connecting rod is fixed, first use a tool measuring instrument or a low-pressure micrometer to adjust the radial runout of the probe end of the wireless sensor to less than 0.001.

[0072] In this embodiment, a wireless sensor is set above the connecting rod bushing hole at a position approximately half the height of the connecting rod thickness to measure the coordinates of at least three points on the inner surface of the connecting rod bushing hole, wherein the accuracy of the coordinate values ​​is not less than 0.0001 mm.

[0073] In this embodiment, the number of point coordinates is preferably 4, specifically, Figure 5 As shown, the coordinates of the four points are P 11 (X 11 ,Y 11 ), P 12 (X 12 ,Y 12 ), P 13 (X 13 ,Y 13 ), P 14 (X 14 ,Y 14 ), during the measurement process, the coordinates of the four points are evenly distributed along the circumference of the small head bushing hole, among which the coordinate of the center point of the small head bushing hole is O 10 (X 10 ,Y 10 ), where P 11 With P 12 About O 10 The center is symmetrical and close to the axis of symmetry about the Y axis passing through the center of the small head hole, and the symmetry is less than 5mm; P 13 With P 14 About O 10 The center is symmetrical and close to the axis of symmetry about the X axis passing through the center of the small head hole. The symmetry is less than 5mm. The CNC system of the single-spindle machining center uses the variable calculation method to calculate the center point coordinate O of the bushing hole of the small head of the connecting rod. 10 (X 10 ,Y 10 ).

[0074] Then, an indexable boring insert made of carbide, cubic boron nitride or metal ceramic is installed in the tool fixture of the single-spindle machining center. In this embodiment, the main rake angle of the tool is 90°. The purpose is to reduce the radial force of the boring process, so as to reduce the premature falling off of the bushing caused by the radial force during the machining process. The boring tool diameter of the single-spindle machining center is adjusted to a position 0.2 to 0.3 mm smaller than the inner diameter of the small head hole of the connecting rod with the help of a tool setting instrument, and the tool is installed on the machining spindle of the single-spindle machining center, and the connecting rod small head bushing is bored until the connecting rod small head bushing is axially penetrated. In this embodiment, the linear speed of the boring process is controlled at 200-350 m / min, and the feed rate is 0.1 to 0.25 mm / r.

[0075] Through tool boring processing, the wall thickness of the connecting rod small end bushing is only 0.10-0.15mm, presenting a thin-walled structure. In this state, the rigidity and elasticity of the connecting rod small end bushing disappear, and the fitting pressure between the connecting rod small end hole and the connecting rod small end bushing is reduced or even disappears. The connecting rod bushing can be smoothly removed by gently pushing with soft material auxiliary tools such as nylon rods. After the connecting rod bushing is removed, the original surface quality and form and position tolerances of the connecting rod small end hole are kept intact. The purpose of the above-mentioned cutting processing is to ensure that the scratches and surface texture on the inner wall of the connecting rod small end hole are not damaged, so as to provide guarantee for the subsequent re-pressing of the new connecting rod bushing and improve the fit.

[0076] Before pressing and installing a new connecting rod bushing, first use a deburring scraper to remove the sharp edges and burrs on the upper and lower end surfaces of the connecting rod small head hole to prevent scratches on the connecting rod small head hole and the back of the connecting rod small head bushing when pressing and installing the new connecting rod bushing later.

[0077] S3. Secondary cleaning of connecting rod: Clean the connecting rod again after removing the small head bushing;

[0078] Before pressing the new connecting rod bushing, the small head hole of the connecting rod needs to be cleaned twice. In this embodiment, the connecting rod is placed horizontally in the connecting rod cleaning equipment to ensure that the end faces of the large and small head holes of the connecting rod are placed horizontally. Then, an environmentally friendly water cleaning agent is mixed with filtered soft water in a certain volume ratio to form an environmentally friendly water cleaning liquid. The environmentally friendly water cleaning liquid is heated to about 50°C, and the cleaning equipment is started. The cleaning basket and the high-pressure spray nozzle perform a swirling and reciprocating compound motion together to spray and clean the small head bushing hole of the connecting rod, so that the small head bushing hole of the connecting rod and other parts of the connecting rod are thoroughly cleaned, and the cleaning quality reaches an impurity weight of 3mg / piece, and the maximum metal particle length is 0.6mm, ensuring that there is no obvious oil stain on the surface of the workpiece. Furthermore, the cleaning equipment is equipped with an oil-water separator, a magnetic separator, a centrifugal particle separator, a filter element and a filter bag filter and a sedimentation box, etc., which can ensure the purity of the environmentally friendly water cleaning liquid. After the connecting rod is cleaned, the connecting rod is dried by hot air and the residual heat after cleaning. The anti-rust components of the environmentally friendly water-based cleaning machine will form a protective film on the surface of the connecting rod to isolate the air, effectively preventing the connecting rod from rusting.

[0079] S4. Assembly of connecting rod bushing: After heating the connecting rod bushing hole to a certain temperature, press the new bushing into the connecting rod bushing hole;

[0080] The specific operation is: first use a dust-free cloth to wipe the small end hole of the connecting rod, place the small end hole of the connecting rod on the electromagnetic heating equipment, start the electromagnetic heating to heat the small end hole of the connecting rod to 130℃±10℃, so that the small end hole of the connecting rod will expand due to the heat until the diameter increases.

[0081] After heating is completed, the connecting rod is immediately transferred to the installation station of the connecting rod bushing hydraulic or servo pressing equipment, the connecting rod small end bushing is placed at the predetermined position, and the connecting rod bushing pressing equipment is started to press the connecting rod small end bushing into the connecting rod small end hole. During the pressing process, the temperature of the connecting rod small end hole position and the bushing pressure are monitored in real time.

[0082] When the press-fitting is completed, place the pressed connecting rod in a clean connecting rod turnover box and cool it naturally to room temperature. Then use a feeler gauge to check the gap between the connecting rod small end hole and the back of the connecting rod small end bushing. In order to reduce the workload, the fit of the connecting rod bushing can be checked at a certain frequency. The fit inspection method includes but is not limited to ultrasonic inspection and table coloring area method inspection.

[0083] S5. Secondary processing of the small end bushing of the connecting rod: Clamp and fix the assembled connecting rod, and the machining center measures and calculates the center position of the large end hole of the connecting rod and the center position of the small end bushing hole respectively. The machining position of the machining center is calculated according to the center position of the large end hole of the connecting rod and the center position of the small end bushing hole, and the large end hole and the small end bushing hole of the connecting rod are cut. The purpose of this step is to ensure that the center distance between the small end bushing hole of the connecting rod and the center of the large end hole meets the requirement of L0±0.02, where L0 is to ensure smooth operation of the connecting rod during use.

[0084] Specifically, the operation method of this step is:

[0085] First, clamp it in a single-spindle machining center and use high-pressure air to clean the connecting rod fixture assembly that will process the connecting rod big end hole and the small end bushing hole. The fixture has a connecting rod big end hole locating pin and a connecting rod small end hole locating pin. The big end hole locating pin is 0.4 to 0.6 mm smaller than the diameter of the connecting rod big end hole, and the connecting rod small end hole locating pin is 0.05 to 0.15 mm smaller than the diameter of the connecting rod small end bushing hole. Then raise the big head hole locating pin and the small head bushing hole locating pin to the upper limit position, position the connecting rod on the fixture through the big head hole locating pin and the small head bushing hole locating pin, respectively match the small head bushing hole locating pin and the big head hole locating pin for preliminary positioning, then use the cylinder and the end face pressure arm to tighten the two ends of the connecting rod, and support the connecting rod body through the hydraulic cylinder to clamp the connecting rod, then lower the big head hole locating pin and the small head bushing hole locating pin to leave space for the tool to cut.

[0086] After the connecting rod is fixed, first use a tool measuring instrument or a low-pressure micrometer to adjust the radial runout of the probe end of the wireless sensor to less than 0.001.

[0087] In the present embodiment, a wireless sensor is arranged at a position above the connecting rod small end bushing hole at a height of approximately half the connecting rod thickness to measure the coordinates of multiple points on the inner surface of the connecting rod small end bushing hole, wherein the coordinate value accuracy is not less than 0.0001mm, and the number of point coordinates of the connecting rod small end bushing hole is 4 in the embodiment; and 4 point coordinates are taken on the inner surface of the connecting rod big end hole, and the point coordinate value accuracy of the connecting rod big end hole is not less than 0.0001mm.

[0088] like Figure 6 As shown in the figure, the coordinates of the four measuring points of the bushing hole of the connecting rod small end are P 21 (X 21 ,Y 21 ), P 22 (X 22 ,Y 22 ), P 23 (X 23 ,Y 23 ), P 24 (X 24 ,Y 24 ) and are evenly distributed in the bushing hole of the connecting rod small end, and the center point of the small end hole is O 20 (X 20 ,Y 20 ). More specifically, P 21 With P 22 About O 20 The center is symmetrical and the axis of symmetry about the Y axis passing through the center of the small head hole is symmetrical, and the symmetry is less than 5mm; P 23 With P 24 About O 20 The center is symmetrical and the axis is symmetrical about the X axis passing through the center of the small head hole, and the degree of symmetry is less than 5mm. Then the CNC system of the single spindle machining center uses variable calculation to calculate the center O of the small head bushing hole of the connecting rod. 20 Coordinate (X 20 ,Y 20 ), using the following formula X 20 =(X 21 +X 22 ) / 2,Y 20 =(Y 23 +Y 24 ) / 2 to calculate the center of the connecting rod bushing hole O 20 coordinate.

[0089] The coordinates of the four measuring points of the connecting rod big end hole are P 31 (X 31 ,Y 31 ), P 32 (X 32 ,Y 32 ), P 33 (X 33 ,Y33 ), P 34 (X 34 ,Y 34 ) and are evenly distributed in the bushing hole of the small end of the connecting rod, and the center point of the large end hole is O 30 (X 30 ,Y 30 ). 31 With P 32 About O 30 The center is symmetrical and the axis of symmetry about the Y axis passing through the center of the small head hole is symmetrical, and the symmetry is less than 5mm; P 33 With P 34 About O 30 The center is symmetrical and the axis is symmetrical about the X axis passing through the center of the small head hole, and the degree of symmetry is less than 5mm. The center of the connecting rod big head hole O is calculated by the single-axis machining center CNC system using variable calculation 30 Coordinate (X 30 ,Y 30 ), using the following formula X 30 =(X 31 +X 32 ) / 2,Y 30 =(Y 33 +Y 34 ) / 2 to calculate the center of the connecting rod big end hole O 30 .

[0090] After calculating the center coordinates of the connecting rod's big head hole and the small head bushing hole, the distance tolerance between the center of the small head bushing hole and the big head hole of the connecting rod is generally ±0.05mm, while the distance tolerance set in actual use is generally ±0.02mm. After the small head bushing of the connecting rod is pressed, the small head bushing of the connecting rod has a certain unevenness due to the interference force on the back of the small head bushing and the circumferential thickness of the small head bushing of the connecting rod. 20 Center of connecting rod big end hole O 30 The distance L1 generally does not meet the requirement that the distance between the center of the connecting rod small end bushing hole and the center of the connecting rod large end hole is L0±0.02. Figure 7 As shown, the two hole walls of the connecting rod need to be cut twice, and then the machining position coordinates O0 (X0, Y0) of the machining center need to be calculated.

[0091] The calculation formula can be carried out according to the following formula:

[0092] First, the center O of the bushing hole at the small end of the connecting rod is obtained according to the measurement and calculation. 20 Center of connecting rod big end hole O 30 Distance L1:

[0093] L1=SQRT(ABS((X 30 -X 20) 2 +(Y 30 -Y 20 ) 2 )),

[0094] Where ABS is the absolute value function, SQRT is the positive square root function;

[0095] Then, according to the principle of triangle similarity or trigonometric function, the machining position coordinates O0 (X0, Y0) of the machining center can be obtained:

[0096] X0=X 30 +a*L0;Y0=Y 30 +b*L0;

[0097] in

[0098] Next, a machining center is used for cutting. In this embodiment, the indexable diamond blade is first installed on the tool fixture. A large radius finishing blade is used at the transition between the main cutting edge and the secondary cutting edge of the blade. The first rake angle is designed with a positive rake angle to reduce the cutting force, and the second rake angle is designed with a negative rake angle to prevent the continuous chips from scratching the processed surface during the cutting process. After the tool diameter is adjusted to the processing size using a tool setting instrument, the tool is installed on the machining spindle of the machining center, and the machining center processing program is started to process the connecting rod small end bushing with O0 as the center. When the processing is completed, the machining center automatically changes the tool, and uses an aluminum-based granular nylon brush to brush off the sharp edges and burrs generated by the cutting of the connecting rod small end bushing hole.

[0099] When the connecting rod big end hole needs to be processed, the machining center automatically changes the tool after the connecting rod small end bushing is processed. The tool with the indexable insert of carbide, cubic boron nitride or metal ceramic material adjusted to the size of the connecting rod big end hole is used to cut the connecting rod big end center O 30 Coordinate cutting of the connecting rod big head hole. When the cutting is completed, the machining center automatically changes the tool and uses an aluminum-based particle nylon brush to brush away the sharp edges and burrs produced by the cutting of the connecting rod big head hole.

[0100] S6 Finally, the processed connecting rod can be subjected to subsequent post-processing steps such as cleaning, marking, testing, and packaging. Specifically, in this embodiment, the operations are as follows:

[0101] First, the surface of the processed connecting rod is cleaned using a cleaning device, such as a crawler-type cleaning machine;

[0102] Then, the connecting rod comprehensive inspection, weighing and marking composite equipment is used to comprehensively check the key and important dimensions of the connecting rod, weigh the connecting rod, and engrave identifiers such as QR codes and connecting rod weight grouping codes on the connecting rod;

[0103] Next, visual inspection equipment is used to inspect the appearance and surface quality of the connecting rod big end, connecting rod small end, connecting rod blank surface, connecting rod logo, QR code and other parts;

[0104] For the connecting rod products that have passed the inspection, they will be disassembled again into the connecting rod body, connecting rod cover, and connecting rod bolts, and placed in the connecting rod assembly cleaning basket respectively. Ultrasonic composite cleaning equipment will be used to clean the connecting rod cover, connecting rod body and connecting rod bolts respectively, and foreign matter such as rust, oil spots, and sticky particles on the surface of the above parts will be removed. After cleaning, they will be reassembled and the connecting rod bolts will be pre-tightened to 10N.m~15N.m; finally, packaging equipment / manual packaging will be used.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for reworking, repairing and remanufacturing an engine connecting rod, characterized in that: The steps include: S1. Cleaning the connecting rod once: remove the connecting rod bolts, separate the connecting rod cap from the connecting rod body, and use ultrasonic cleaning equipment to clean each part of the connecting rod. After cleaning, assemble them together; S2. Removing the bushing at the small end of the connecting rod: The connecting rod is clamped and fixed, and after the machining center measures and calculates the coordinates of the center of the hole of the bushing at the small end of the connecting rod, the machining spindle of the machining center is moved to the top of the center of the hole of the bushing at the small end of the connecting rod, and the bushing at the small end of the connecting rod is cut to remove the bushing at the small end of the connecting rod; S3. Secondary cleaning of connecting rod: Clean the connecting rod again after removing the small head bushing; S4. Assembly of connecting rod bushing: After heating the connecting rod bushing hole to a certain temperature, press the new bushing into the connecting rod bushing hole; S5. Secondary processing of the small end bushing of the connecting rod: The assembled connecting rod is clamped and fixed, and the machining center measures and calculates the center position of the large end hole of the connecting rod and the center position of the small end bushing hole respectively. The machining position of the machining center is calculated according to the center position of the large end hole of the connecting rod and the center position of the small end bushing hole, and the large end hole of the connecting rod and the small end bushing hole are cut; The specific steps of the machining center in step S2 for cutting and removing the connecting rod bushing are as follows: Adjust the machining spindle of the single-spindle machining center to the position above the center coordinate of the bushing hole at the small end of the connecting rod; Install the tool to the tool fixture of the single-spindle machining center, and use the tool setting instrument to adjust the tool to a position 0.2 to 0.3 mm away from the inner diameter of the small head hole of the connecting rod; The machining center is started, and the tool rotates to cut the inner wall of the connecting rod bushing hole until the connecting rod bushing is axially penetrated; Through tool cutting, the wall thickness of the connecting rod small end bushing remains 0.10 to 0.15 mm, and the connecting rod bushing is removed using auxiliary tools.

2. The engine connecting rod rework, repair and remanufacturing method according to claim 1, characterized in that: The specific method for measuring and calculating the hole center coordinates of the connecting rod bushing in step S2 is: Use a tool measuring instrument or a low-pressure micrometer to adjust the radial runout of the measuring bead at the end of the measuring needle to less than 0.001mm; Use the sensor to evenly select at least 4 point coordinates along the inner surface of the bushing hole of the small end of the connecting rod, and the coordinate value accuracy is less than 0.0001mm; The center coordinates of the connecting rod bushing hole are calculated by the CNC system of the machining center using variable calculation method.

3. The engine connecting rod rework, repair and remanufacturing method according to claim 1 is characterized by: In the step S2, the cutting methods adopted by the machining center when cutting the connecting rod small end bushing include boring, reaming, boring and reaming combined processing, wire cutting, and laser cutting.

4. The engine connecting rod rework, repair and remanufacturing method according to claim 1, characterized in that: The specific method for measuring and calculating the center coordinates of the connecting rod big end hole and the small end bushing hole in step S5 is: Use a tool measuring instrument or a low-pressure micrometer to adjust the radial runout of the measuring bead at the end of the measuring needle to less than 0.001mm; Use the sensor to evenly select at least 4 point coordinates along the inner surface of the bushing hole of the small end of the connecting rod, and the coordinate value accuracy is less than 0.0001mm; Use the sensor to evenly select at least 4 point coordinates along the inner surface of the big end hole of the connecting rod, and the coordinate value accuracy is less than 0.0001mm; The CNC system of the single-spindle machining center uses variable calculation methods to calculate the center point coordinates of the small end bushing hole of the connecting rod according to the coordinates of points selected from the inner surface of the small end bushing hole of the connecting rod; and calculates the center point coordinates of the big end bushing hole of the connecting rod according to the coordinates of points selected from the inner surface of the big end hole of the connecting rod.

5. The engine connecting rod rework, repair and remanufacturing method according to claim 2, characterized in that: The specific process of measuring and calculating the center of the connecting rod bushing hole at the small end in step S2 is as follows: First, select four points on the inner surface of the bushing hole of the connecting rod small end. The coordinates of the four points are P 11 (X 11 ,Y 11 ), P 12 (X 12 ,Y 12 ), P 13 (X 13 ,Y 13 ), P 14 (X 14 ,Y 14 ), the coordinates of the four points are evenly distributed along the circumference of the small head bushing hole, among which P 11 With P 12 About Small Head Hole Center O 10 The center is symmetric, and P 11 With P 12 About the center of the connecting rod small head hole O 10 The Y-axis is symmetrical, and the degree of symmetry is less than 5 mm; P 13 With P 14 About Small Head Hole Center O 10 The center is symmetric, and P 13 With P 14 About the center of the small head hole O 10 The symmetry axis of the X-axis is axially symmetrical, and the degree of symmetry is less than 5mm; The center coordinates of the bushing hole at the small end of the connecting rod are calculated based on the coordinates of the four points of the bushing hole at the small end of the connecting rod. 10 (X 10 ,Y 10 ): X 10 =(X 11 +X 12 ) / 2,Y10=(Y 13 +Y 14 ) / 2。 6. The engine connecting rod rework, repair and remanufacturing method according to claim 4, characterized in that: The specific process of measuring and calculating the center of the small end bushing hole and the large end hole of the connecting rod by the machining center in step S5 is as follows: First, select four points on the inner surface of the bushing hole of the connecting rod small end. The coordinates of the four points are P 21 (X 21 ,Y 21 ), P 22 (X 22 ,Y 22 ), P 23 (X 23 ,Y 23 ), P 24 (X 24 ,Y 24 ); the coordinates of the four points are evenly distributed along the bushing hole of the connecting rod small end, P 21 With P 22 About O 20 The center is symmetrical and the axis of symmetry about the Y axis passing through the center of the small head bushing hole is symmetrical, and the symmetry is less than 5mm; P 23 With P 24 About O 20 The center is symmetrical and the axis of symmetry is symmetrical about the X axis passing through the center of the small head bushing hole, and the degree of symmetry is less than 5mm; The inner surface of the connecting rod big end hole is selected with 4 point coordinates, the 4 point coordinates are P 31 (X 31 ,Y 31 ), P 32 (X 32 ,Y 32 ), P 33 (X 33 ,Y 33 ), P 34 (X 34 ,Y 34 ), the coordinates of the four points are evenly distributed along the big end hole of the connecting rod, P 31 With P 32 About O 30 The center is symmetrical and the axis of symmetry about the Y axis passing through the center of the large head hole is symmetrical, and the symmetry is less than 5mm; P 33 With P 34 About O 30 The center is symmetrical and the axis of symmetry about the X axis passing through the center of the large head hole is symmetrical, and the degree of symmetry is less than 5mm; The center coordinates of the bushing hole at the small end of the connecting rod are calculated based on the coordinates of the four points of the bushing hole at the small end of the connecting rod. 20 (X 20 ,Y 20 ): X 20 (X) 21 +X 22 ) / 2,And 20 (And 23 +Y 24 ) / 2; The center coordinates of the connecting rod big end hole are calculated based on the coordinates of the four points of the connecting rod big end hole. 30 (X 30 ,Y 30 ): X 30 (X) 31 +X 32 ) / 2,And 30 (And 33 +Y 34 ) / 2。 7. The engine connecting rod rework, repair and remanufacturing method according to claim 6, characterized in that: The specific method for calculating the machining position of the machining center according to the center position of the connecting rod big end hole and the center position of the small end bushing hole in step S5 is: First, the center O of the bushing hole at the small end of the connecting rod is obtained according to the measurement and calculation. 20 Center of connecting rod big end hole O 30 Distance L1: L1=SQRT(ABS((X 30 -X 20 ) 2 +(And 30 -AND 20 ) 2 )), Where ABS is the absolute value function, SQRT is the positive square root function; Then, according to the principle of triangle similarity or trigonometric function, the machining position coordinates O0 (X0, Y0) of the machining center can be obtained: X0=X 30 +a*L0;Y0=Y 30 +b*L0; in

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