CN115266905B - Crack detection method and equipment for recycling and remanufacturing engine crankshaft of heavy-duty commercial vehicle - Google Patents
Crack detection method and equipment for recycling and remanufacturing engine crankshaft of heavy-duty commercial vehicle Download PDFInfo
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Abstract
The invention belongs to the technical field of recycling and remanufacturing of key parts of an engine, and particularly relates to a crack flaw detection method and equipment for recycling and remanufacturing an engine crankshaft of a heavy-duty commercial vehicle; the short-time high-current power is conducted on the lubricating oil duct between the crankshaft main journal and the connecting rod shaft diameter through the short-time current device, so that the remanence phenomenon is generated at the position of the crankshaft core near the lubricating oil duct between the crankshaft main journal and the connecting rod shaft diameter, the remanence measuring device is used for measuring the remanence of the crankshaft core near the lubricating oil duct, and the crankshaft with cracks or cracks is screened out through a comparison method, so that the crankshaft quality detection efficiency in the recovery and remanufacturing process of the crankshaft of the scrapped automobile engine is greatly improved, and the method has a wide market prospect.
Description
Technical Field
The invention belongs to the technical field of recycling and remanufacturing of key parts of an engine, and particularly relates to a crack flaw detection method and equipment for recycling and remanufacturing an engine crankshaft of a heavy-duty commercial vehicle.
Background
With the continuous development of remanufacturing industry, how to ensure the quality of remanufactured parts has become one of the important concerns in the industry; analysis is carried out on the recovery and remanufacturing process of the engine crankshaft, and the remanufacturing process of the crankshaft is divided into three conditions: the first is that after the crankshaft is recovered, the crankshaft is directly used after detection and confirmation, and the crankshaft does not need to be repaired, and only surface treatments such as clarity, sand blasting and the like are adopted, so that the remanufacturing requirement can be met; the second is that the crankshaft is checked and confirmed to be worn or cracked, but the crankshaft meets the relevant conditions, the remanufacturing can be carried out, and the third is that the crankshaft does not meet the relevant conditions, and the crankshaft is directly abandoned.
In the second case, in the detection and confirmation process, the abrasion or crack of the crankshaft is considered as a main quality problem when the crankshaft of the engine is recovered, the surfaces of the main journal and the connecting rod are abraded, and the detection means aiming at the surface abrasion mainly comprises a manual detection or automatic size detection device, and processes such as grinding, coating repair and the like are carried out after detection; under the action of long-term alternating load, the crankshaft needs related special detection equipment when cracks or split holes are generated; one of the positions of cracks or split holes is that stress concentration is easy to generate at the journal fillet, so that fatigue cracks are initiated to cause fatigue failure of the crankshaft, and the positions comprise a main journal fillet and a connecting rod journal fillet; the other position is near the inside of the main journal-connecting rod shaft diameter lubricating oil hole, and the load born by the section of the nearby material is larger than that of other parts due to the occurrence of the lubricating oil hole, so that fatigue cracks are easy to occur after long-term use; in order to ensure the remanufacturing safety of the crankshaft, if the size of cracks or split holes on the surface of the crankshaft exceeds the requirement, the crankshaft needs to be abandoned, for example, if the cracks or split holes appear in the crankshaft, the crankshaft needs to be abandoned for safety;
for surface cracks at the fillet, common methods comprise nondestructive detection means such as magnetic powder inspection and magnetic memory detection, wherein the magnetic memory detection method has higher detection precision, higher automation degree and wider application range;
For example, in the prior art, the invention patent with the patent number 201410292551.X discloses a crankshaft automatic eddy current and magnetic memory composite nondestructive testing device, the device uses an industrial robot to clamp a testing sensor through a testing sensor clamp assembly and test a crankshaft, an eddy current magnetic memory testing instrument collects and stores signals of the testing sensor into testing data, then the testing data are transmitted to an upper computer for processing, and an eddy current and magnetic memory composite testing method is adopted to comprehensively test external cracks and internal cracks of the crankshaft;
However, the part mainly detected by the method is a surface crack at a fillet or an internal crack near the surface, the structure of the crankshaft is complex, multiple detection at multiple angles is often needed for improving the judging accuracy, then the surface crack at the fillet or the internal crack near the surface can be better judged through complex data fitting, and the crack detection on the core part of the crankshaft journal is often low in accuracy; the reason for the lower accuracy is that the structure of the crankshaft is complex, the position and the size of the crack are difficult to accurately judge, and on the other hand, the measuring position of the existing magnetic memory detection device is that a probe is placed on the surface of a main journal or the surface of a connecting rod shaft diameter, as shown in fig. 1, the method has certain accuracy on the surface contact area of the main journal or the connecting rod shaft diameter near the probe, but for the crankshaft of a heavy-duty commercial vehicle engine, the diameter of the main journal or the connecting rod shaft diameter is much larger than that of a common engine crankshaft, so that the crack of the main journal core of the large-size crankshaft, especially the crack of the core near the lubricating oil hole is more difficult to detect due to the shielding of the pore structure of the lubricating oil hole. In order to detect the cracks or the split holes of the core, in the prior art, a CT scanning method can be used for better detection, but equipment is very expensive, the method is not suitable for detection in the remanufacturing process of the crankshaft, other detection methods, such as a flaw detection method, a vibration test method and the like, need multiple methods for comprehensive test and judgment, and the accuracy of single use is low.
Therefore, no existing method or equipment can accurately detect core cracks near the main journal of the crankshaft and the connecting rod journal lubricating oil holes under the condition of lower cost at present; therefore, the team cooperates with related enterprises to develop a corresponding method and equipment capable of solving the problems, and the special flaw detection equipment is specially applied for patent application in order to ensure the use and popularization of the special flaw detection equipment.
Disclosure of Invention
The invention aims to provide a crack detection method and equipment for recycling and remanufacturing a crankshaft of a heavy-duty commercial vehicle engine.
In order to achieve the aim of the invention, the invention adopts the following technical scheme: the crack detection method for the recovery and remanufacturing of the engine crankshaft of the heavy-duty commercial vehicle comprises the following steps in sequence:
a. Selecting a brand new crankshaft which is consistent with the model specification of the engine crankshaft to be scrapped, wherein the crankshaft is called a standard crankshaft;
b. The standard crankshaft is horizontally arranged on the bracket assembly, so that the oil hole of the lubricating oil duct at the main journal is not blocked, and the oil hole of the lubricating oil duct at the shaft diameter of the connecting rod is not blocked;
c, penetrating the end of the positive electrode lead of the short-time current device into a certain depth H 1 from the lubricating oil hole at the main journal, penetrating the negative electrode lead of the short-time current device into the same lubricating oil hole from the shaft diameter of the connecting rod into a certain depth H 2, wherein the clearance value between the positive electrode lead and the end of the negative electrode lead is delta;
d. the short-time current device is electrified for a certain time T by a certain current I, and then the short-time current device is taken out; step e is entered;
e. The probe of the residual magnetism measuring device is penetrated from the lubricating oil hole at the main journal, the residual magnetism of the change is continuously recorded to form a residual magnetism map, and the residual magnetism map is recorded as a standard map B (L);
f. Disassembling a crankshaft of the engine to be scrapped, wherein the crankshaft is called a crankshaft to be detected;
g. C, replacing the standard crankshaft on the bracket with a crankshaft to be detected, repeating the steps b to e to obtain a residual magnetic quantity spectrum corresponding to the engine crankshaft to be scrapped, and recording the residual magnetic quantity spectrum as a spectrum D (L) to be detected;
h. Comparing the standard spectrum with the to-be-detected spectrum, judging whether the core near the lubricating oil hole at the corresponding position of the scrapped engine crankshaft has cracks or split holes according to the comparison result, if no cracks or split holes exist, marking the crankshaft as a remanufacturable part, entering a step i, otherwise marking the crankshaft as a abandoned part, and carrying out abandon treatment;
i. And (5) putting the scrapped engine crankshaft into demagnetizing equipment for demagnetizing again.
Preferably, in the step a, the surface of the standard crankshaft is cleaned, and a lubrication oil duct connecting the main journal of the standard crankshaft and the shaft diameter of the connecting rod is cleaned, so that the lubrication oil duct is smooth and free of lubricating oil and impurities; drying the standard crankshaft after cleaning; demagnetizing the standard crankshaft by using demagnetizing equipment;
in the step f, the surface of the crankshaft to be detected is cleaned, and the lubricating oil channels at the main journal and the shaft diameter of the connecting rod of the crankshaft to be detected are cleaned, so that the lubricating oil channels are free of lubricating oil and impurities; drying the crankshaft to be detected after cleaning; then demagnetizing the crankshaft to be detected by using demagnetizing equipment;
In the step e, the abscissa in the standard map B (L) is the distance L of the probe of the residual magnetism measuring device penetrating into the lubricating oil hole, and the ordinate is the residual magnetism corresponding to the change of L, and the standard map B (L) further comprises an H 1 value, an H 2 value, a delta value, a current I value and an energizing time T value.
Preferably, in the step h, the method for comparing the standard spectrum with the spectrum to be detected comprises the following steps:
S1, in the step a, N brand new crankshafts with the same specification are selected, and the steps a-e are repeated respectively, wherein N is more than or equal to 4; n standard patterns B (L 1)、B(L2)……B(LN) are obtained, and each standard pattern B (LN) is subjected to empirical mode decomposition (EMD adaptive decomposition) by the following decomposition method:
N in the above formula is the number of IMF components decomposed by an empirical mode decomposition method; c j represents the j-th IMF component, j=1, 2,3 …, n; r n is the residual component;
S2, respectively calculating kurtosis values of each C j (j=1, 2,3.. The number n) in a standard map B (L 1), selecting two maximum and second maximum C j values in a plurality of C j, and linearly superposing the two C j values to obtain a kurtosis characteristic type residual magnetic signal;
The kurtosis characteristic residual magnetic signals are averagely divided into m sections according to the length of the probe penetrating distance L, and signals corresponding to different length sections are marked as F 1-Fm;
S3, estimating Alpha stable distribution parameters of the F 1-Fm sections and calculating probability density functions of the F 1-Fm sections, extracting feature indexes Alpha (0 < Alpha is less than or equal to 2), symmetrical parameters beta (-1 is less than or equal to beta is less than or equal to 1), dispersion coefficients gamma (gamma is more than 0), position parameters delta (delta-infinity is less than or equal to infinity) and extremum values h (h is more than 0) of the probability density functions, and forming m Alpha stable distribution features, wherein each Alpha stable distribution feature has 5 feature parameters;
S4, replacing B (L 1) in the step S2 with B (L 2)……B(LN), and repeating the steps S2-S3 to obtain Alpha stable distribution characteristics contained in F 1……Fm sections corresponding to the B (L 1)……B(LN) respectively;
S5, repeating the steps S1-S3 on the map D (L) to be detected to obtain respective Alpha stable distribution characteristics in each segment of F 1-Fm corresponding to the map D (L) to be detected, wherein 5 characteristic parameters included in the Alpha stable distribution characteristics of the F m segment are Alpha d-m、βd-m、γd-m、δd-m、hd-m;
And comparing the Alpha stable distribution characteristics contained in the F 1……Fm sections corresponding to the B (L 1)……B(LN) with the Alpha stable distribution characteristics in the F 1-Fm sections corresponding to the to-be-detected map D (L).
Preferably, in the step S5, the method for comparing the Alpha stable distribution characteristics contained in the F 1……Fm segment corresponding to each B (L 1)……B(LN) with the Alpha stable distribution characteristics in the F 1-Fm segments corresponding to the spectrum D (L) to be detected includes:
s5-1, respectively comparing 5 parameters in Alpha stable distribution characteristics contained in F 1 section corresponding to B (L 1)……B(LN), removing the maximum value and minimum value of each of the 5 parameters, extracting the maximum value and minimum value of each residual value of the 5 parameters, and forming the standard range of each of the 5 parameters corresponding to the standard map F 1 section ：[α1-min,α1-max]、[β1-min,β1-max]、[γ1-min,γ1-max]、[δ1-min,δ1-max]、[h1-min,h1-max];
S5-2, repeating the step S5 for each F 2……Fm segment corresponding to each B (L 1)……B(LN) to obtain each standard range corresponding to each segment of the standard map F 2……Fm, wherein the standard range corresponding to each segment of the standard map F m is [αm-min,αm-max]、[βm-min,βm-max]、[γm-min,γm-max]、[δm-min,δm-max]、[hm-min,hm-max];
S5-3, comparing 5 parameters alpha d-1、βd-1、γd-1、δd-1、hd-1 corresponding to the section 1 of the to-be-detected map F with respective standard ranges [α1-min,α1-max]、[β1-min,β1-max]、[γ1-min,γ1-max]、[δ1-min,δ1-max]、[h1-min,h1-max] of 5 parameters corresponding to the section 1 of the standard map F, and if at least 2 parameters in the 5 characteristic parameters exceed the compared standard ranges, judging the comparison result as unqualified;
S5-4, replacing the section F 1 corresponding to the to-be-detected spectrum D (L) in the step S5-3 with the section F 2……Fm respectively, and comparing the sections with the standard ranges of the 5 parameters corresponding to the section F 2……Fm of the standard spectrum respectively.
Preferably, in the step S5-4, m comparison results are obtained in total; if two continuous comparison results are unqualified or at least 3 comparison results are unqualified in the m comparison results, judging that a crack or a crack hole exists at the core position of the crankshaft near the lubrication oil duct at the corresponding position of the crankshaft to be detected, which corresponds to the map D (L) to be detected, and discarding the crankshaft to be detected; otherwise, enter step i.
Preferably, in the step a, a used crankshaft with the same specification as the model of the engine crankshaft to be scrapped is selected, the accumulated driving mileage of the crankshaft does not exceed the rated driving mileage, and after the vibration detection method, the flaw detection method or the CT scanning method is adopted to detect, the core part has no crack or split hole, and the crankshaft is called a standard crankshaft.
Preferably, in the step S1, N crankshafts with the same specification are selected, and the steps a to e are repeated respectively; the range of the accumulated driving mileage of the used crankshafts with the same specification is between 10 and 20 kilometers; the difference between the accumulated driving mileage of N used crankshafts with the same specification is not more than 1 ten thousand kilometers.
The flaw detection equipment based on the heavy-duty commercial vehicle engine crankshaft recovery remanufacturing flaw detection method comprises a bracket component, a short-time current device, a remanence measuring device, a data recording device and a demagnetizing device; the bracket assembly comprises a fixed bracket, wherein a plurality of main journal brackets with adjustable height are arranged on the fixed bracket at intervals along the longitudinal direction of the fixed bracket, the number of the main journal brackets is consistent with that of main journals for disassembling a crankshaft of an engine to be scrapped, and the upper end of the main journal bracket is provided with a circular arc main journal bracket; a plurality of connecting rod shaft diameter brackets with adjustable height are respectively arranged on the left side and the right side of the main journal bracket along the transverse direction of the fixed bracket, the number of the connecting rod shaft diameter brackets is consistent with that of the connecting rod shaft diameter of the engine crankshaft to be scrapped in disassembly, and arc-shaped connecting rod shaft diameter brackets are arranged at the upper ends of the connecting rod shaft diameter brackets.
Preferably, the length of the main journal bracket is set as follows: when the engine crankshaft to be scrapped is disassembled and placed horizontally, the oil hole of the lubricating oil duct at the main journal is not blocked by the main journal bracket; the length of the connecting rod shaft diameter bracket is set as follows: when the engine crankshaft to be scrapped is disassembled and horizontally placed, the oil hole of the lubricating oil duct at the shaft diameter of the connecting rod is not blocked by the bracket of the shaft diameter of the connecting rod; the main journal bracket and the connecting rod shaft diameter bracket are made of insulating materials.
Preferably, the short-time current device comprises a direct-current stabilized power supply UPS, wherein the positive output end and the negative output end of the direct-current stabilized power supply UPS are respectively connected with a positive electrode wire and a negative electrode wire, the end head of the positive electrode wire is connected with a positive electrode probe, and the outer side of the rear end of the positive electrode probe is sleeved with an arc-shaped insulating cover, so that after the positive electrode probe is inserted into a lubricating oil duct at a main journal, the insulating cover is tightly attached to the surface of the main journal of a crankshaft of an engine to be scrapped; the end of the negative electrode lead is connected with a negative electrode probe, and an arc-shaped insulating cover is sleeved outside the rear end of the negative electrode probe, so that the insulating cover is tightly attached to the surface of the shaft diameter of the connecting rod for disassembling the engine crankshaft to be scrapped after the negative electrode probe is inserted into the lubricating oil duct at the shaft diameter of the connecting rod; the short-time current device also comprises a grounding protection wire, wherein the grounding protection wire is respectively overlapped with the copper clamp sleeved on the outer side of the front end and the outer side of the rear end of the crankshaft.
The invention has the advantages that: carrying out short-time high-current electrifying on a lubricating oil duct between a crankshaft main journal and a connecting rod shaft diameter through a short-time current device to enable a residual magnetism phenomenon to occur at a crankshaft core position near the lubricating oil duct between the crankshaft main journal and the connecting rod shaft diameter, measuring residual magnetism of the crankshaft core position near the lubricating oil duct by using a residual magnetism measuring device, and enabling the residual magnetism of the crack or the residual magnetism near the crack to be inconsistent with the residual magnetism of the crankshaft core position under normal conditions when the crack or the crack exists at the crankshaft core position; the crankshaft with cracks or cracks is screened out by a comparison method, so that the crankshaft quality detection efficiency in the recovery and remanufacturing process of the crankshaft of the scraped car engine is greatly improved;
the short-time current device, the residual magnetism measuring device, the bracket component and other components used by the application have simple structure, low cost and simple use method, are very suitable for the recovery field of scraped cars, and have wide market prospect; in addition, an empirical mode decomposition (EMD self-adaptive decomposition) and a subsequent special comparison method are adopted in the comparison process, so that the accuracy of the detection result is further improved.
Drawings
FIG. 1 is a top view of a crankshaft of a 4-cylinder engine;
FIG. 2 is a schematic illustration of the crankshaft being placed horizontally on a bracket assembly;
FIG. 3 is a schematic view of a negative electrode probe, wherein the current from the positive electrode probe is conducted to the shaft diameter of the connecting rod through the core part of the main journal of the crankshaft after the short-time current device is electrified;
FIG. 4 is a flow chart of steps a to i in claim 1;
FIG. 5 is a flow chart of steps S1-S11 in claim 2;
Fig. 6 is a graph B (L) of residual magnetism after detection of a lubrication oil passage at a connecting rod shaft diameter corresponding to a second cylinder piston of a brand new crankshaft for a certain heavy commercial vehicle.
Detailed Description
The present invention will be described in further detail with reference to preferred examples of the present invention, but the embodiments of the present invention are not limited thereto.
Thus, the following detailed description of the embodiments of the invention, as presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures.
In the description of the present invention, it should be noted that the terms "first," "second," "third," and the like are used merely to distinguish between descriptions and are not to be construed as indicating or implying relative importance.
The terms "upper," "lower," "left," "right," "inner," "outer," and the like refer to an orientation or positional relationship based on that shown in the drawings, or that is conventionally put in place when the inventive product is used, merely to facilitate description of the invention and simplify description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore should not be construed as limiting the invention.
Furthermore, the terms "vertical" and the like do not denote absolute perpendicularity between the required components, but may be slightly inclined. As "vertical" simply means that its direction is relatively more vertical, and does not mean that the structure must be perfectly vertical, but may be slightly tilted.
In the description of the present invention, it should also be noted that the terms "disposed," "mounted," "connected," and the like are to be construed broadly, unless otherwise specifically defined and limited. For example, the connection can be fixed connection, detachable connection or integrated connection; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communication between two elements. The specific meaning of the above terms in the present invention will be understood in specific cases by those of ordinary skill in the art.
The crack detection equipment comprises a bracket component, a short-time current device, a remanence measuring device, a data recording device and a demagnetizing device; the bracket assembly comprises a fixed bracket 1, wherein a plurality of main journal brackets 2 with adjustable height are arranged on the fixed bracket 1 at intervals along the longitudinal direction of the fixed bracket, the number of the main journal brackets 2 is consistent with that of main journals for disassembling a crankshaft of an engine to be scrapped, and a circular arc-shaped main journal bracket 3 is arranged at the upper end of the main journal bracket 2; a plurality of connecting rod shaft diameter brackets 4 with adjustable height are respectively arranged along the transverse direction of the fixed bracket 1 and the left side and the right side of the main journal bracket 2, the number of the connecting rod shaft diameter brackets 4 is consistent with that of the connecting rod shaft diameters of the engine crankshafts to be scrapped after disassembly, and arc-shaped connecting rod shaft diameter brackets 5 are arranged at the upper ends of the connecting rod shaft diameter brackets 4.
As shown in fig. 2, the length of the main journal bracket 3 is set as follows: when the engine crankshaft to be scrapped is disassembled and placed horizontally, the oil hole of the lubricating oil duct at the main journal is not blocked by the main journal bracket 3; the length of the connecting rod shaft diameter bracket 5 is set as follows: when the engine crankshaft to be scrapped is disassembled and horizontally placed, the oil hole of the lubricating oil duct at the shaft diameter of the connecting rod is not blocked by the bracket 5 of the shaft diameter of the connecting rod; the main journal bracket 3 and the connecting rod shaft diameter bracket 5 are made of insulating materials.
The short-time current device comprises a direct-current stabilized power supply UPS, wherein the positive output end and the negative output end of the direct-current stabilized power supply UPS are respectively connected with a positive electrode lead and a negative electrode lead, the end head of the positive electrode lead is connected with a positive electrode probe, the outer side of the rear end of the positive electrode probe is sleeved with an arc-shaped insulating cover, and after the positive electrode probe is inserted into a lubricating oil duct at a main journal, the insulating cover is tightly attached to the surface of the main journal of a crankshaft of an engine to be scrapped; the end of the negative electrode lead is connected with a negative electrode probe, and an arc-shaped insulating cover is sleeved outside the rear end of the negative electrode probe, so that the insulating cover is tightly attached to the surface of the shaft diameter of the connecting rod for disassembling the engine crankshaft to be scrapped after the negative electrode probe is inserted into the lubricating oil duct at the shaft diameter of the connecting rod; after the positive electrode probe is inserted into the lubricating oil duct at the main journal, the arc-shaped insulating cover at the outer side of the positive electrode probe is tightly attached to the surface of the main journal, so that the depth of the positive electrode probe penetrating into the lubricating oil duct is kept to be H 1, and similarly, the depth of the negative electrode probe penetrating into the lubricating oil duct is kept to be H 1, and the distance between the positive electrode probe and the negative electrode probe is delta;
As shown by the broken line with an arrow in FIG. 3, when a short-time heavy current is introduced into the positive electrode probe, the current is transmitted to the negative electrode probe at the shaft diameter of the connecting rod through the core part of the main journal of the crankshaft, in the process, after the heavy current passes through the metal conductor of the core part of the crankshaft, the metal conductor of the core part of the crankshaft is magnetized, after the power is cut off, part of the magnetic induction intensity of the metal conductor of the core part still remains, the method for measuring the magnetic field intensity is called a remanence test method, and the method is also used in the fields of fire disaster identification of electrical equipment, and in the fire disaster field identification, the remanence on the metal conductor is read through a Tesla meter, so that the short circuit position of the electrical equipment is judged; in the technical scheme, when the crank shaft core around the lubricating oil duct has defects such as cracks or split holes, the reserved magnetic induction intensity value is inconsistent with the reserved magnetic induction intensity value when the crank shaft core is normal, and whether the crank shaft core around the lubricating oil duct has the defects can be judged by measuring the magnetic induction intensity value.
In order to ensure safety and accurate test results in the test process, the main journal bracket 3 and the connecting rod journal bracket 5 are made of insulating materials, and meanwhile, the test process is required to be forbidden to approach the crankshaft; the better protection method is that the short-time current device also comprises a grounding protection wire which is respectively overlapped with copper hoops sleeved on the outer sides of the front end and the rear end of the crankshaft; safety is provided by means of ground protection of the crankshaft.
The residual magnetism measuring device is a tesla meter or a gauss meter, and the signal input end of the data recording device is respectively in communication connection with the signal output ends of the short-time current device and the residual magnetism measuring device; the data recording device is a Mitsubishi plc industrial personal computer, or an AT89C52 singlechip with a storage function, or an STM32 singlechip module; the demagnetizing device is a TCK-12 demagnetizer or a frame demagnetizer of Su magnetic mechanical company.
Example 1
As shown in fig. 4, the crack detection method for recycling and remanufacturing the engine crankshaft of the heavy-duty commercial vehicle comprises the following steps in sequence:
a. Selecting a brand new crankshaft which is consistent with the model specification of the engine crankshaft to be scrapped, wherein the crankshaft is called a standard crankshaft;
b. The standard crankshaft is horizontally arranged on the bracket assembly, so that the oil hole of the lubricating oil duct at the main journal is not blocked, and the oil hole of the lubricating oil duct at the shaft diameter of the connecting rod is not blocked;
c, penetrating the end of the positive electrode lead of the short-time current device into a certain depth H 1 from the lubricating oil hole at the main journal, penetrating the negative electrode lead of the short-time current device into the same lubricating oil hole from the shaft diameter of the connecting rod into a certain depth H 2, wherein the clearance value between the positive electrode lead and the end of the negative electrode lead is delta;
d. the short-time current device is electrified for a certain time T by a certain current I, and then the short-time current device is taken out; step e is entered;
e. The probe of the residual magnetism measuring device is penetrated from the lubricating oil hole at the main journal, the residual magnetism of the change is continuously recorded to form a residual magnetism map, and the residual magnetism map is recorded as a standard map B (L);
f. Disassembling a crankshaft of the engine to be scrapped, wherein the crankshaft is called a crankshaft to be detected;
g. C, replacing the standard crankshaft on the bracket with a crankshaft to be detected, repeating the steps b to e to obtain a residual magnetic quantity spectrum corresponding to the engine crankshaft to be scrapped, and recording the residual magnetic quantity spectrum as a spectrum D (L) to be detected;
h. Comparing the standard spectrum with the to-be-detected spectrum, judging whether the core near the lubricating oil hole at the corresponding position of the scrapped engine crankshaft has cracks or split holes according to the comparison result, if no cracks or split holes exist, marking the crankshaft as a remanufacturable part, entering a step i, otherwise marking the crankshaft as a abandoned part, and carrying out abandon treatment;
i. And (5) putting the scrapped engine crankshaft into demagnetizing equipment for demagnetizing again.
In the step a, cleaning the surface of a standard crankshaft, and cleaning a lubricating oil duct connecting the main journal of the standard crankshaft and the shaft diameter of a connecting rod, so that lubricating oil and impurities are free from the lubricating oil duct; drying the standard crankshaft after cleaning; demagnetizing the standard crankshaft by using demagnetizing equipment;
in the step f, the surface of the crankshaft to be detected is cleaned, and the lubricating oil channels at the main journal and the shaft diameter of the connecting rod of the crankshaft to be detected are cleaned, so that the lubricating oil channels are free of lubricating oil and impurities; drying the crankshaft to be detected after cleaning; then demagnetizing the crankshaft to be detected by using demagnetizing equipment;
In the step e, the abscissa in the standard map B (L) is the distance L of the probe of the residual magnetism measuring device penetrating into the lubricating oil hole, and the ordinate is the residual magnetism corresponding to the change of L, and the standard map B (L) further comprises an H 1 value, an H 2 value, a delta value, a current I value and an energizing time T value.
Example two
In the step h, as shown in fig. 5, the method for comparing the standard spectrum with the spectrum to be detected comprises the following steps: in the step h, the method for comparing the standard spectrum with the spectrum to be detected comprises the following steps:
S1, in the step a, N brand new crankshafts with the same specification are selected, and the steps a-e are repeated respectively, wherein N is more than or equal to 4; n standard patterns B (L 1)、B(L2)……B(LN) are obtained, and each standard pattern B (LN) is subjected to empirical mode decomposition (EMD adaptive decomposition) by the following decomposition method:
N in the above formula is the number of IMF components decomposed by an empirical mode decomposition method; c j represents the j-th IMF component, j=1, 2,3 …, n; r n is the residual component;
s2, respectively calculating kurtosis values of each C j (j=1, 2,3 …, n) in a standard map B (L 1), selecting two maximum and second maximum C j values in a plurality of C j, and linearly superposing the two C j values to obtain a kurtosis characteristic type residual magnetic signal;
The kurtosis characteristic residual magnetic signals are averagely divided into m sections according to the length of the probe penetrating distance L, and signals corresponding to different length sections are marked as F 1-Fm;
S3, estimating Alpha stable distribution parameters of the F 1-Fm sections and calculating probability density functions of the F 1-Fm sections, extracting feature indexes Alpha (0 < Alpha is less than or equal to 2), symmetrical parameters beta (-1 is less than or equal to beta is less than or equal to 1), dispersion coefficients gamma (gamma is more than 0), position parameters delta (delta-infinity is less than or equal to infinity) and extremum values h (h is more than 0) of the probability density functions, and forming m Alpha stable distribution features, wherein each Alpha stable distribution feature has 5 feature parameters;
S4, replacing B (L 1) in the step S2 with B (L 2)……B(LN), and repeating the steps S2-S3 to obtain Alpha stable distribution characteristics contained in F 1……Fm sections corresponding to the B (L 1)……B(LN) respectively;
S5, repeating the steps S1-S3 on the map D (L) to be detected to obtain respective Alpha stable distribution characteristics in each segment of F 1-Fm corresponding to the map D (L) to be detected, wherein 5 characteristic parameters included in the Alpha stable distribution characteristics of the F m segment are Alpha d-m、βd-m、γd-m、δd-m、hd-m;
And comparing the Alpha stable distribution characteristics contained in the F 1……Fm sections corresponding to the B (L 1)……B(LN) with the Alpha stable distribution characteristics in the F 1-Fm sections corresponding to the to-be-detected map D (L).
Example IV
In the step S5, the method for comparing the Alpha stable distribution characteristics contained in the F 1……Fm segment corresponding to each B (L 1)……B(LN) with the Alpha stable distribution characteristics in the F 1-Fm segments corresponding to the spectrum D (L) to be detected includes:
s5-1, respectively comparing 5 parameters in Alpha stable distribution characteristics contained in F 1 section corresponding to B (L 1)……B(LN), removing the maximum value and minimum value of each of the 5 parameters, extracting the maximum value and minimum value of each residual value of the 5 parameters, and forming the standard range of each of the 5 parameters corresponding to the standard map F 1 section ：[α1-min,α1-max]、[β1-min,β1-max]、[γ1-min,γ1-max]、[δ1-min,δ1-max]、[h1-min,h1-max];
S5-2, repeating the step S5 for each F 2……Fm segment corresponding to each B (L 1)……B(LN) to obtain each standard range corresponding to each segment of the standard map F 2……Fm, wherein the standard range corresponding to each segment of the standard map F m is [αm-min,αm-max]、[βm-min,βm-max]、[γm-min,γm-max]、[δm-min,δm-max]、[hm-min,hm-max];
S5-3, comparing 5 parameters alpha d-1、βd-1、γd-1、δd-1、hd-1 corresponding to the section 1 of the to-be-detected map F with respective standard ranges [α1-min,α1-max]、[β1-min,β1-max]、[γ1-min,γ1-max]、[δ1-min,δ1-max]、[h1-min,h1-max] of 5 parameters corresponding to the section 1 of the standard map F, and if at least 2 parameters in the 5 characteristic parameters exceed the compared standard ranges, judging the comparison result as unqualified;
S5-4, replacing the section F 1 corresponding to the to-be-detected spectrum D (L) in the step S5-3 with the section F 2……Fm respectively, and comparing the sections with the standard ranges of the 5 parameters corresponding to the section F 2……Fm of the standard spectrum respectively.
The better real-time mode is: in the step S5-4, m comparison results are obtained in total; if two continuous comparison results are unqualified or at least 3 comparison results are unqualified in the m comparison results, judging that a crack or a crack hole exists at the core position of the crankshaft near the lubrication oil duct at the corresponding position of the crankshaft to be detected, which corresponds to the map D (L) to be detected, and discarding the crankshaft to be detected; otherwise, enter step i.
Example five
In the step a, a used crankshaft with the same model and specification as the crankshaft of the engine to be scrapped is selected, the accumulated driving mileage of the crankshaft is not more than the rated driving mileage, and after the vibration detection method, the flaw detection method or the CT scanning method is adopted to detect, the core part has no crack or split hole, and the crankshaft is called a standard crankshaft. In the step S1, N used crankshafts with the same specification are selected, and the steps a-e are repeated respectively; the range of the accumulated driving mileage of the used crankshafts with the same specification is between 10 and 20 kilometers; the difference between the accumulated driving mileage of N used crankshafts with the same specification is not more than 1 ten thousand kilometers.
Example six
A diesel engine for a certain heavy commercial vehicle is selected, and the engine is a 6-cylinder in-line engine with the maximum output power of 404kW, the rated rotation speed of 1800rpm, the maximum horsepower of 550 horsepower and the maximum torque of 2600 N.m, wherein the total length of a crankshaft is 1108mm, the diameter phi of a main journal is 100mm, and the diameter phi of a connecting rod shaft is 75mm;
Randomly selecting 1 brand new crankshaft of the same specification of the engine, wherein the crankshaft is marked as Q1, selecting a lubrication oil passage at the shaft diameter of a connecting rod corresponding to a second cylinder piston of the crankshaft as the lubrication oil passage to be tested, and repeating the steps a-h, wherein a standard map B (L) obtained in the step e is shown in figure 6; m=5 in the step S2, obtaining a total of 5 groups of Alpha stable distribution characteristics of F 1-F5, wherein 5 parameter values of the Alpha stable distribution characteristics of the F 3 segment are shown in table 1;
and randomly selecting 9 brand-new crankshafts of the same specification of the engine, marking as Q2-Q9, selecting lubricating oil ducts at the same positions for detection, and repeating the steps a-h to obtain F 1-F5 sections of corresponding Alpha stable distribution characteristics corresponding to the Q2-Q9, wherein 5 parameter values of the F 3 sections of Alpha stable distribution characteristics corresponding to the Q2-Q9 are shown in a table 1.
TABLE 1 Q1-Q5F 3 section Alpha stability distribution characteristic parameters
According to the table 1, removing the maximum value and the minimum value in each parameter, and selecting each parameter range as shown in table 2;
TABLE 2 Standard Spectrum F 3 section Alpha stability distribution characteristics ranges of parameters
| α | β | γ | δ | h | |
| Upper limit value | 0.7565 | 0.0424 | 0.0624 | -0.0488 | 0.8245 |
| Lower limit value | 0.7414 | 0.0387 | 0.0591 | -0.0512 | 0.7996 |
Selecting a scrapped engine crankshaft, wherein cracks exist near a lubricating oil duct at the same position of the crankshaft, and the cracks start to appear from the surface of the shaft diameter of the connecting rod and are expanded to the core part near the lubricating oil duct; the crankshaft is recorded as Q00, the steps a-h are repeated to obtain F 1-F5 sections of corresponding Alpha stable distribution characteristics corresponding to the Q00, wherein 5 parameter values of the F 3 sections of Alpha stable distribution characteristics are shown in Table 3
TABLE 3 values of parameters of Alpha stability distribution characteristics at section F 3 of Q00
| αd-3 | βd-3 | γd-3 | δd-3 | hd-3 |
| 0.7625 | 0.0455 | 0.0656 | -0.0492 | 0.8325 |
Table 3 shows that each parameter of the F3 section corresponding to Q00 exceeds each parameter range of the Alpha stable distribution characteristic of the F3 section of the standard map, the comparison result of the F3 section corresponding to Q00 is unqualified, and the comparison results of the other sections of Q00 are shown in Table 4; and judging the crankshaft as a waste part according to the judgment standard, and conforming to the actual result.
Table 4 Q00 results of each segment comparison
| F1 | F2 | F3 | F4 | F5 |
| Qualified product | Qualified product | Failure to pass | Failure to pass | Failure to pass |
As can be seen from the above examples, the present application conducts short-time high-current energization to the lubrication oil passage between the crank main journal and the connecting rod shaft diameter by a short-time current device, so that the remanence phenomenon is generated at the crank core position near the lubrication oil passage between the crank main journal and the connecting rod shaft diameter, and then the remanence measuring device is used to measure the remanence of the crank core position near the lubrication oil passage, when the crank core position has a crack or a crack hole, the remanence of the crack hole or the crack vicinity is inconsistent with the remanence of the crank core position under normal conditions; and the crankshaft with cracks or cracks is screened out by a comparison method, so that the crankshaft quality detection efficiency in the recovery and remanufacturing process of the crankshaft of the scraped car engine is greatly improved, and the used short-time current device, the remanence measuring device, the bracket component and other components are simple in structure and low in cost, so that the method is very suitable for the recovery field of the scraped car and has a wide market prospect.
Example seven
When the driving mileage of the heavy commercial vehicle is far beyond the specified driving mileage, the abrasion loss of the crankshaft is larger than that of the general case, and the driving mileage of the engine far beyond the specified driving mileage can reach 50-60 ten thousand kilometers. Therefore, the standard spectrum B (L) measured by using the brand new crankshaft is greatly different from the to-be-detected spectrum D (L) of the engine crankshaft to be scrapped, and in order to judge the quality of the crankshaft core in the same way for the special case, a better implementation mode is as follows:
In the step a, a used crankshaft with the same model and specification as the crankshaft of the engine to be scrapped is selected, the accumulated driving mileage of the crankshaft is not more than the rated driving mileage (generally 20 ten thousand kilometers), and after the accumulated driving mileage is detected by a vibration detection method, a flaw detection method or a CT scanning method, the core part is free from cracks or cracks, and the crankshaft is called a standard crankshaft; the standard crankshaft is compared with a scrapped engine crankshaft under the condition of far exceeding the specified driving mileage.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, but various modifications and variations can be made to the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (4)
1. The crack detection method for the recovery and remanufacturing of the engine crankshaft of the heavy-duty commercial vehicle is characterized by comprising the following steps of:
The method comprises the following steps in sequence:
a. Selecting a brand new crankshaft which is consistent with the model specification of the engine crankshaft to be scrapped, wherein the crankshaft is called a standard crankshaft;
b. The standard crankshaft is horizontally arranged on the bracket assembly, so that the oil hole of the lubricating oil duct at the main journal is not blocked, and the oil hole of the lubricating oil duct at the shaft diameter of the connecting rod is not blocked;
c, penetrating the end of the positive electrode lead of the short-time current device into a certain depth H 1 from the lubricating oil hole at the main journal, penetrating the negative electrode lead of the short-time current device into the same lubricating oil hole from the shaft diameter of the connecting rod into a certain depth H 2, wherein the clearance value between the positive electrode lead and the end of the negative electrode lead is delta;
d. the short-time current device is electrified for a certain time T by a certain current I, and then the short-time current device is taken out; step e is entered;
e. The probe of the residual magnetism measuring device is penetrated from the lubricating oil hole at the main journal, the residual magnetism of the change is continuously recorded to form a residual magnetism map, and the residual magnetism map is recorded as a standard map B (L);
f. Disassembling a crankshaft of the engine to be scrapped, wherein the crankshaft is called a crankshaft to be detected;
g. C, replacing the standard crankshaft on the bracket with a crankshaft to be detected, repeating the steps b to e to obtain a residual magnetic quantity spectrum corresponding to the engine crankshaft to be scrapped, and recording the residual magnetic quantity spectrum as a spectrum D (L) to be detected;
h. Comparing the standard spectrum with the to-be-detected spectrum, judging whether a crack or a split hole exists in a core part near the lubrication oil hole at the corresponding position of the to-be-detected crankshaft according to a comparison result, if the crack or the split hole does not exist, marking the crankshaft as a remanufacturable part, entering a step i, otherwise marking the crankshaft as a abandoned part, and carrying out abandon treatment;
i. putting the scrapped engine crankshaft into demagnetizing equipment for demagnetizing again;
in the step h, the method for comparing the standard spectrum with the spectrum to be detected comprises the following steps:
S1, in the step a, N brand new crankshafts with the same specification are selected, and the steps a-e are repeated respectively, wherein N is more than or equal to 4; n standard patterns B (L 1)、B(L2)……B(LN) are obtained, and each standard pattern B (L N) is subjected to empirical mode decomposition by the following decomposition method:
N in the above formula is the number of IMF components decomposed by an empirical mode decomposition method; c j represents the j-th IMF component, j=1, 2,3 …, n; r n is the residual component;
s2, respectively calculating kurtosis values of each C j (j=1, 2,3 …, n) in a standard map B (L 1), selecting two maximum and second maximum C j values in a plurality of C j, and linearly superposing the two C j values to obtain a kurtosis characteristic type residual magnetic signal;
The kurtosis characteristic residual magnetic signals are averagely divided into m sections according to the length of the probe penetrating distance L, and signals corresponding to different length sections are marked as F 1-Fm;
S3, estimating Alpha stable distribution parameters of the F 1-Fm sections and calculating probability density functions of the F 1-Fm sections, extracting feature indexes Alpha (0 < Alpha is less than or equal to 2), symmetrical parameters beta (-1 is less than or equal to beta is less than or equal to 1), dispersion coefficients gamma (gamma is more than 0), position parameters delta (delta-infinity is less than or equal to infinity) and extremum values h (h is more than 0) of the probability density functions, and forming m Alpha stable distribution features, wherein each Alpha stable distribution feature has 5 feature parameters;
S4, replacing B (L 1) in the step S2 with B (L 2)……B(LN), and repeating the steps S2-S3 to obtain Alpha stable distribution characteristics contained in F 1……Fm sections corresponding to the B (L 1)……B(LN) respectively;
S5, repeating the steps S1-S3 on the map D (L) to be detected to obtain respective Alpha stable distribution characteristics in each segment F 1-Fm corresponding to the map D (L) to be detected, wherein 5 characteristic parameters included in the Alpha stable distribution characteristics of the Fm segment are Alpha d-m、βd-m、γd-m、δd-m、hd-m;
Comparing Alpha stable distribution characteristics contained in F 1……Fm sections corresponding to B (L 1)……B(LN) with Alpha stable distribution characteristics in F 1-Fm sections corresponding to the to-be-detected map D (L);
In the step S5, the method for comparing the Alpha stable distribution characteristics contained in the F 1……Fm segment corresponding to each B (L 1)……B(LN) with the Alpha stable distribution characteristics in the F 1-Fm segments corresponding to the spectrum D (L) to be detected includes:
s5-1, respectively comparing 5 parameters in Alpha stable distribution characteristics contained in the F 1 section corresponding to each B (L 1)……B(LN), removing the maximum value and the minimum value of each of the 5 parameters, extracting the maximum value and the minimum value of each residual value of the 5 parameters, and forming the standard range of each of the 5 parameters corresponding to the standard map F1 section ：[α1-min,α1-max]、[β1-min,β1-max]、[γ1-min,γ1-max]、[δ1-min,1-max]、[h1-min,h1-max];
S5-2, repeating the step S5 for each F 2……Fm segment corresponding to each B (L 1)……B(LN) to obtain each standard range corresponding to each segment of the standard map F 2……Fm, wherein the standard range corresponding to each segment of the standard map F m is [αm-min,αm-max]、[βm-min,βm-max]、[γm-min,γm-max]、[δm-min,δm-max]、[hm-min,hm-max];
S5-3, comparing 5 parameters alpha d-1、βd-1、γd-1、δd-1、hd-1 corresponding to the section 1 of the to-be-detected map F with respective standard ranges [α1-min,α1-max]、[β1-min,β1-max]、[γ1-min,γ1-max]、[δ1-min,δ1-max]、[h1-min,h1-max] of 5 parameters corresponding to the section 1 of the standard map F, and if at least 2 parameters in the 5 characteristic parameters exceed the compared standard ranges, judging the comparison result as unqualified;
S5-4, replacing the section F 1 corresponding to the to-be-detected spectrum D (L) in the step S5-3 with the section F 2……Fm respectively, and comparing the sections with the standard ranges of the 5 parameters corresponding to the section F 2……Fm of the standard spectrum respectively;
In the step S5-4, m comparison results are obtained in total; if two continuous comparison results are unqualified or at least 3 comparison results are unqualified in the m comparison results, judging that a crack or a crack hole exists at the core position of the crankshaft near the lubrication oil duct at the corresponding position of the crankshaft to be detected, which corresponds to the map D (L) to be detected, and discarding the crankshaft to be detected; otherwise, enter step i.
2. The method for crack detection in heavy duty commercial vehicle engine crankshaft recycling remanufacturing according to claim 1, wherein: in the step a, cleaning the surface of a standard crankshaft, and cleaning a lubricating oil duct connecting the main journal of the standard crankshaft and the shaft diameter of a connecting rod, so that lubricating oil and impurities are free from the lubricating oil duct; drying the standard crankshaft after cleaning; demagnetizing the standard crankshaft by using demagnetizing equipment;
in the step f, the surface of the crankshaft to be detected is cleaned, and the lubricating oil channels at the main journal and the shaft diameter of the connecting rod of the crankshaft to be detected are cleaned, so that the lubricating oil channels are free of lubricating oil and impurities; drying the crankshaft to be detected after cleaning; then demagnetizing the crankshaft to be detected by using demagnetizing equipment;
In the step e, the abscissa in the standard map B (L) is the distance L of the probe of the residual magnetism measuring device penetrating into the lubricating oil hole, and the ordinate is the residual magnetism corresponding to the change of L, and the standard map B (L) further comprises an H 1 value, an H 2 value, a delta value, a current I value and an energizing time T value.
3. The method for crack detection in heavy duty commercial vehicle engine crankshaft recycling remanufacturing according to claim 2, wherein: in the step a, a used crankshaft with the same model and specification as the crankshaft of the engine to be scrapped is selected, the accumulated driving mileage of the crankshaft is not more than the rated driving mileage, and after the vibration detection method, the flaw detection method or the CT scanning method is adopted to detect, the core part has no crack or split hole, and the crankshaft is called a standard crankshaft.
4. The method for crack detection in heavy duty commercial vehicle engine crankshaft recycling remanufacturing according to claim 1, wherein: in the step S1, N used crankshafts with the same specification are selected, and the steps a-e are repeated respectively; the range of the accumulated driving mileage of the used crankshafts with the same specification is between 10 and 20 kilometers; the difference between the accumulated driving mileage of N used crankshafts with the same specification is not more than 1 ten thousand kilometers.
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