Method for designing, processing and verifying a precise cylinder hole of an aluminum cylinder block

Abstract

The application belongs to the technical field of aluminum cylinder block manufacturing, and discloses a design, machining and verification method of a fine round cylinder hole of an aluminum cylinder block, which comprises the following steps: S1, cylinder block structure design; S2, setting aluminum cylinder block and cylinder liner casting temperature, and casting the aluminum cylinder block; S3, fine round machining of the cast aluminum cylinder block through machining equipment; and S4, assembling deformation inspection and cylinder block thermal state inspection of the machined aluminum cylinder block; and the method solves the problem of large deformation of the cylinder hole in the aluminum cylinder block during work.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of aluminum cylinder block manufacturing, in particular to a design, processing and verification method of a precision round cylinder hole of an aluminum cylinder block. BACKGROUND

[0002] At present, the existing passenger car engine cylinder block has generally adopted die-cast aluminum cylinder block. Compared with cast iron cylinder block, the aluminum material has small density and good thermal conductivity, so that good light weight and heat dissipation effects can be obtained, and rapid warm-up can be more easily realized. However, the matching of the die-cast aluminum cylinder block with the aluminum piston is not good, and generally cast iron cylinder liners need to be inserted at the inner wall of the cylinder barrel or inner hole spraying needs to be performed. Meanwhile, the aluminum piston has high expansion coefficient, low elastic modulus and slightly lower material performance than cast iron, and the problem of large cylinder hole deformation is often caused. The friction coefficient between the aluminum piston and the die-cast aluminum cylinder block is high, the wear resistance is poor, and the cylinder hole deformation is often caused, which leads to the gap between the piston in contact with the cylinder hole and the inner wall of the cylinder hole. This results in large piston gas leakage, which easily causes early combustion, knocking and emission exceeding the standard; causes early cylinder hole wear, and in severe cases, causes cylinder pulling and piston ring jamming; causes engine oil burning and blue smoke from the exhaust pipe; increases friction work, and reduces the performance indicators of the whole machine, increases oil consumption and other problems.

[0003] In order to control the cylinder hole deformation and make the cylinder hole close to the precision round state, that is, the pure round state, during work, manufacturers often control the deformation through finite element calculation during structure design. However, the engine still has the above quality problems caused by cylinder hole deformation during work. This is mainly because the real cylinder block needs to withstand high temperature and high burst pressure for a long time in the working state, and needs to face various different working conditions. The finite element calculation can only simulate the cylinder hole deformation under a single working condition in the steady state, and the finite element calculation result cannot adapt to the working condition with high complexity. Meanwhile, the casting and machining of the aluminum cylinder block also have great influence on the cylinder hole deformation, which cannot be simulated by the finite element calculation. Therefore, the cylinder hole deformation often exceeds the standard during actual work. SUMMARY

[0004] The present application aims to provide a design, processing and verification method of a precision round cylinder hole of an aluminum cylinder block, and solve the problem of large cylinder hole deformation of the aluminum cylinder block during work.

[0005] To achieve this purpose, the following technical solutions are adopted in the present application: the present application provides a design, processing and verification method of a precision round cylinder hole of an aluminum cylinder block, which comprises the following steps:

[0006] S1, cylinder block structure design;

[0007] S2, setting the cylinder liner casting temperature of the aluminum cylinder block, and casting the aluminum cylinder block;

[0008] S3, the aluminum cylinder body after casting is processed by machining equipment;

[0009] S4, the aluminum cylinder body after processing is assembled and deformed, and the cylinder body is tested in hot state.

[0010] As preferred, the S1 comprises the following steps:

[0011] S11, the bolt hole is arranged in the same circle, the bolt hole boss radius is greater than or equal to n times the bolt diameter, the screwing depth of the bolt is greater than or equal to n times the bolt diameter (n≥1), the bolt counterbore depth is calculated according to the axial force by finite element calculation, and the cylinder head is calculated according to the finite element calculation result;

[0012] S12, the wall thickness of the cylinder body at the center axis position is A, the wall thickness of the cylinder body at the adjacent position is B, A>B, B has a lower limit value, and the cylinder hole has the fine round condition when B is higher than the lower limit value, and the wall thickness of the two sides of the edge cylinder front and rear end is greater than the thickness of B;

[0013] S13, the outer surface of the cylinder sleeve needs to be sprayed with aluminum or burr structure, the cylinder sleeve has a basic wall thickness, and the numerical value of the cylinder sleeve is not less than the basic wall thickness, and the top of the cylinder sleeve is locally thickened by about 1 / 4 area.

[0014] As preferred, the following steps are set after step S12:

[0015] S121, the boss force transmission rib equivalent diameter is greater than or equal to n times the bolt diameter.

[0016] As preferred, the following steps are included in the S2:

[0017] S21, the cylinder sleeve is heated first during casting, and heated to a temperature at which cast iron and aluminum can be attached, while the casting position degree is controlled to make the stiffness around the cylinder body uniform, and the material performance of the cylinder body area is the same as that of the main bearing seat.

[0018] As preferred, the following steps are set after S21:

[0019] S22, after casting is completed, the cylinder body is quenched by air or polymer, and at this time the temperature value of the cylinder body needs to be greater than the reference value, and needs to be heat treated to meet the fine round processing condition.

[0020] As preferred, the following steps are included in the S3:

[0021] S31, process cylinder cover processing is adopted, the equivalent finite element processing data of the real cylinder cover assembly is used, and the cylinder gasket of the formal product is used during processing;

[0022] S32, the machining equipment is divided into three parts of rough boring, semi-fine boring and fine boring, and the allowance of fine boring processing is less than the first allowance;

[0023] S33, honing the cylinder bore, the total machining allowance of honing is less than the second allowance, the semi-fine honing is less than the third allowance, and the machining allowance of fine honing is less than the fourth allowance.

[0024] As preferred, the S4 specifically comprises the following steps:

[0025] S41, after assembling the cylinder head, cylinder gasket and cylinder head bolt in the cold state, measuring the deformation of the cylinder bore, and evaluating the deformation result, if it meets the standard, the hot state test of the cylinder body can be carried out;

[0026] S42, the cylinder body is sent to a heating furnace for heating, heated to a target temperature, and kept at the target temperature, then taken out of the heating furnace for natural cooling, and the deformation degree of the cylinder bore is measured at room temperature, if it meets the standard, it proves that the cylinder body is qualified.

[0027] As preferred, in step S41, the Fourier transform is performed on the cylinder bore deformation amount to obtain five groups of values from the second order to the sixth order, and the standard values from the second order to the sixth order are compared, if the values exceed the standard, it is unqualified, if it meets the standard, step S42 is carried out.

[0028] As preferred, after step S42, the cylinder body is taken out and naturally cooled, and the Fourier transform is performed on the cylinder bore deformation amount to obtain five groups of values from the second order to the sixth order, and the standard values from the second order to the sixth order are compared, if the values are within the standard, the cylinder body design is qualified, if the values exceed the standard or are close to the standard, the cylinder body design is unqualified.

[0029] Beneficial effects: through the four steps in the aluminum cylinder body fine round cylinder bore design, machining and verification method, after the cylinder body is designed, the cylinder body is cast according to the standard, then the cylinder body is machined according to the standard through machining, each step increases the design accuracy of the fine round, after the machining is completed, before other parts are installed in the cylinder body, the cold state (room temperature) assembly deformation test and the hot state test are directly carried out on the cylinder body, the size of the post-deformation amount of the cold deformation and the thermal deformation of the cylinder body fine round is evaluated, the machining accuracy and production efficiency of the aluminum cylinder body fine round are improved, the anti-deformation ability of the aluminum cylinder body is stronger when it works normally, the problems such as early grinding, knocking, burning oil of the engine are reduced, and the performance of the engine is improved. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 is the front view of the cylinder bore of the application;

[0031] Figure 2 is the cross-sectional view of the cylinder bore of the application.

[0032] In the figure: 1-cylinder bore; 2-bolt hole; 3-bolt hole boss radius; 4-bolt counterbore depth; 5-wall thickness at the position of the cylinder body center axis; 6-wall thickness at the adjacent position of the cylinder body. Detailed Implementation

[0033] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, the accompanying drawings show only the parts relevant to the present invention, and not all of the structures.

[0034] In the description of this invention, unless otherwise explicitly specified and limited, the terms "connected," "linked," and "fixed" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0035] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0036] In the description of this embodiment, the terms "upper," "lower," "right," etc., refer to the orientation or positional relationship shown in the accompanying drawings. They are used only for ease of description and simplification of operation, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the present invention. In addition, the terms "first" and "second" are used only for distinction in description and have no special meaning.

[0037] In the current process of machining aluminum cylinder blocks, inspection is required after the cylinder block parts are assembled. If problems are found during inspection, the parts need to be disassembled and reassembled, which reduces work efficiency. Under the current technology, the cylinder bores machined in the cylinder body cannot always maintain a perfectly round state before and after the working state, which will lead to gaps between the piston rings and the cylinder bores.

[0038] To solve the above problems, such as Figures 1-2 As shown, this invention provides a method for designing, machining, and verifying precision round cylinder bores in aluminum cylinder blocks, comprising the following steps:

[0039] S1, cylinder block structure design;

[0040] S2, set the cylinder liner casting temperature of the aluminum cylinder block, and cast the aluminum cylinder block;

[0041] S3, the cast aluminum cylinder block is precision-rounded using machining equipment;

[0042] S4. Perform assembly deformation inspection and hot state inspection on the aluminum cylinder block after processing.

[0043] This invention, through the above four steps, achieves a reduction in the deformation of the aluminum cylinder block during operation. The deformation is more than twice that of commonly used cylinder blocks on the market, meeting the latest China VI B emission requirements and enabling the engine to achieve better performance and reliability. Simultaneously, the reduced deformation of the cylinder bore within the aluminum cylinder block lowers cylinder bore friction work, improving overall engine performance and economy, reducing piston leakage to well below national standard limits, improving emissions, reducing knocking, reducing wear on piston rings, pistons, and cylinder bores, enhancing overall engine reliability and durability, and reducing oil consumption to within 50% of national standard limits, extending the first maintenance mileage, and saving at least 50% of cylinder block development time and significant development costs.

[0044] Step S1 includes the following steps:

[0045] S11, such as Figure 1 As shown, the bolt holes are arranged in the same circle, the radius of the bolt hole boss is ≥ n times the bolt diameter, the bolt engagement depth is ≥ n times the bolt diameter (n≥1), the bolt countersunk hole depth is calculated by finite element method based on the axial force, and the condition of the cylinder top plate can also be calculated by finite element method; S11 enables the cylinder design to meet the prerequisite of perfect roundness.

[0046] S12, the wall thickness at the central axis of the cylinder is A, and the wall thickness at the adjacent position of the cylinder is B. A>B, A>B, B has a lower limit value, and the cylinder bore has the condition of being perfectly round only when it is higher than this lower limit value.

[0047] There are multiple sets of cylinder bores on the cylinder body. The cylinder bores at the edge are called side cylinders, and the cylinder bores in the middle are called middle cylinders. Since the bolts next to the side cylinder bores are subjected to almost twice the force of the cylinder bores in the middle cylinders, the wall thickness of the cylinder bores at the front and rear ends of the side cylinders at the two edges of the cylinder body is greater than the B value of the middle cylinder bores. This makes the wall thickness of the side cylinder bores thicker, reduces the deformation of the cylinder body, and improves the roundness of the cylinder bores.

[0048] S13, the outer surface of the cylinder liner needs to be sprayed with aluminum or a burr structure, the cylinder liner has a basic wall thickness, the value of the cylinder liner is not less than the basic wall thickness, and the top of the cylinder liner can be partially thickened by about 1 / 4. Due to the working of the aluminum cylinder, the position with the highest explosion pressure is about 1 / 4 of the top of the cylinder liner, so thickening is performed here to reduce the deformation of the cylinder hole.

[0049] In addition, when selecting the bolts on the cylinder head, bolts that meet the minimum bolt axial force required for cylinder gasket sealing need to be used, and the equivalent diameter of the transmission rib under the boss also needs to be greater than an integer multiple of the diameter of the bolt. After calculation, if the minimum axial force cannot meet the sealing requirements, the parameters of the bolt need to be changed and adjusted in time to make the cylinder body meet the prerequisite condition of precision roundness.

[0050] By step S1, the deformation of the aluminum cylinder in the engine can be reduced when designing the aluminum cylinder, the deformation of the cylinder hole is reduced, and the strength of the cylinder is higher when working. In addition, the bolt counterbore depth can be determined according to the axial force condition, the size data of the cylinder head, and the calculation results of the finite element. After the results are obtained by finite element calculation, five groups of data from the second order to the sixth order are obtained. According to the above data and the previous qualified standard, if it is out of range, the bolt counterbore depth needs to be redesigned according to the axial force condition, the cylinder head, and other numerical values. If it is within the calibrated range, the next step can be performed.

[0051] Step S2 includes the following steps:

[0052] S21, the cylinder liner is heated first during casting, and is heated to a temperature at which the cast iron cylinder liner and the aluminum cylinder body can be attached. The temperature should not be too high, so that the final precision roundness effect is better. According to the different casting processes, the error is controlled within 10℃, which can increase the attachment degree of the cylinder liner and the cylinder body, and make the structural strength of the cylinder body higher. At the same time, the casting position degree is controlled, the stiffness around the cylinder body is made uniform, and the precision roundness effect is better. The temperature and duration of the heating of the cylinder liner can be flexibly adjusted according to the detection results of the thermal state during the later part verification.

[0053] If the cylinder body is cast by low-pressure casting, gravity casting, etc., a quenching step is needed. Air quenching or polymer quenching is used to reduce the stress of the cylinder body and make the deformation of the cylinder hole smaller, close to the precision roundness effect. At the time of quenching, the temperature value of the cylinder body needs to be greater than the reference value, which is measured by experiment. Greater than the reference value can make the precision roundness effect better, and long-term heat preservation is needed to meet the precision roundness processing effect.

[0054] The material performance of the cylinder body area should be basically the same as that of the main bearing seat, and the casting defects should be strictly controlled, so that the qualified rate of the deformation of the final cylinder body is higher.

[0055] S3 includes the following steps:

[0056] S31, using a process cylinder head to process, the finite element processing data of the process cylinder head equivalent to the real cylinder head assembly, and using the cylinder gasket of the formal product during processing.

[0057] In this way, the real cylinder head can be equivalent, and the process cylinder head can be processed more conveniently without comparing and processing the real cylinder head. The design of the process cylinder head is prior art, which is not described here.

[0058] S32, the machining is divided into rough boring, semi-fine boring and fine boring by machining equipment, and the residual amount during fine boring processing is less than the first residual amount.

[0059] S33, honing the cylinder hole, the total machining residual amount of honing is less than the second residual amount, the semi-fine honing is less than the third residual amount, and the machining residual amount of fine honing is less than the fourth residual amount.

[0060] The first residual amount, the second residual amount, the third residual amount and the fourth residual amount are repeatedly measured by experiments. Only when the machining residual amount of fine boring, honing and fine honing meets the requirements, the fine round effect of the cylinder body can be better.

[0061] The machining residual amount of fine boring should be as small as possible, and the total machining residual amount of honing should be controlled within a reasonable range, so that the deformation amount of the final cylinder hole can meet the requirements in both cold state and hot state.

[0062] S4 specifically includes the following steps:

[0063] S41, after assembling the cylinder head, the cylinder gasket and the cylinder head bolt of the cylinder body in the cold state (normal temperature), measuring the cylinder hole deformation, evaluating the deformation result, performing Fourier transform on the deformation amount of the cylinder hole to obtain five groups of values from the second order to the sixth order, comparing the standard values from the second order to the sixth order, if the values exceed the standard, it is unqualified, if it meets the standard, proceed to step S42.

[0064] S42, the cylinder body is sent to a heating furnace for heating to a target temperature, and long-time heat preservation is performed at the target temperature to simulate the measurement of the fine round effect of the cylinder body in the full cycle life state, the cylinder body is taken out and naturally cooled, and Fourier transform is performed on the deformation amount of the cylinder hole to obtain five groups of values from the second order to the sixth order, and the standard values from the second order to the sixth order are compared. If the values are within the standard, the cylinder body design is qualified, if the values exceed the standard or are close to the standard, the cylinder body design is unqualified.

[0065] The standard values from the second order to the sixth order in steps S41 and S42 are measured by experiments. Only when the values are close to the above standard values, the cylinder body is determined to be qualified, and the cylinder hole is in the fine round state in both cold state and working state and after cooling.

[0066] Through mathematical measurement relation, the deformation of the cylinder hole is divided into 2 orders to 6 orders, only the cylinder which meets the deformation can be adopted, and the other unqualified cylinder is scrapped, and the deformation is detected through the cold state and hot state experiment of the cylinder after the machining is completed, so that the deformation of the cylinder hole is more than 2 times smaller than the common cylinder on the market.

[0067] Obviously, the above embodiments of the present application are only examples for clearly illustrating the present application, and are not intended to limit the embodiments of the present application. For those skilled in the art, various obvious changes, re-adjustments and substitutions can be made without departing from the protection scope of the present application. Here, all the embodiments need not and cannot be exhausted. Any modification, equivalent substitution and improvement within the spirit and principle of the present application shall be included in the protection scope of the claims of the present application.

Claims

1. A method for designing, machining, and verifying precision round cylinder bores in an aluminum cylinder block, characterized in that, Includes the following steps: S1, cylinder block structure design; S2, set the cylinder liner casting temperature of the aluminum cylinder block, and cast the aluminum cylinder block; S3, the cast aluminum cylinder block is precision-rounded using machining equipment; S4, Perform assembly deformation inspection and cylinder hot state inspection on the aluminum cylinder block after processing; S1 includes the following steps: S11, bolt holes are arranged in the same circle, the radius of the bolt hole boss is ≥ n times the bolt diameter, the bolt engagement depth is ≥ n times the bolt diameter (n≥1), the bolt countersunk hole depth is calculated by finite element method based on the axial force, and the cylinder top plate is calculated based on the finite element calculation results; S12, the wall thickness at the central axis of the cylinder is A, the wall thickness at the adjacent position of the cylinder is B, A>B, B has a lower limit value, the cylinder bore can meet the condition of being perfectly round only after B is higher than the lower limit value, the wall thickness at the front and rear ends of the side cylinders on both sides of the cylinder is greater than the thickness of B. S13, the outer surface of the cylinder liner must be aluminum sprayed or have a burr structure. The cylinder liner has a basic wall thickness, and the value of the cylinder liner is not less than the basic wall thickness. At the same time, the top 1 / 4 area of ​​the cylinder liner is locally thickened. S3 includes the following steps: S31 uses process cylinder head machining, and the process cylinder head is equivalent to the finite element machining data of the real cylinder head assembly. The cylinder head gasket of the formal product is used during machining. S32 is processed in three parts by machining equipment: rough boring, semi-finish boring and finish boring. The allowance during finish boring should be smaller than the first allowance. S33, honing the cylinder bore. The machining allowance for the overall honing should be less than the second allowance, the semi-finish honing allowance should be less than the third allowance, and the finishing honing allowance should be less than the fourth allowance.

2. The method for designing, machining, and verifying the precision round cylinder bore of an aluminum cylinder block according to claim 1, characterized in that, After step S12, follow these steps: S121, the equivalent diameter of the boss force transmission rib is ≥ n times the bolt diameter.

3. The method for designing, machining, and verifying the precision round cylinder bore of an aluminum cylinder block according to claim 1, characterized in that, S2 includes the following steps: S21, during casting, the cylinder liner is heated first, and heated to a temperature at which the cast iron and aluminum can fit together. At the same time, its casting position is controlled to make the rigidity around the cylinder body uniform, and the material properties of the cylinder body area are the same as those of the main bearing seat.

4. The method for designing, machining, and verifying the precision round cylinder bore of an aluminum cylinder block according to claim 3, characterized in that, The following steps are provided after S21: S22. After casting, the cylinder block should be air-quenched or polymer-quenched. At this time, the temperature value of the cylinder block should be greater than the reference value, and heat preservation is required to achieve the conditions for precision rounding.

5. The method for designing, machining, and verifying the precision round cylinder bore of an aluminum cylinder block according to claim 1, characterized in that, S4 specifically includes the following steps: S41. After assembling the cylinder head, cylinder gasket, and cylinder head bolts in a cold state, measure the cylinder bore deformation and evaluate the deformation results. If the results meet the standards, a hot test of the cylinder block can be carried out. S42, the cylinder block is sent into the heating furnace for heating to the target temperature and held at the target temperature. After that, it is taken out of the heating furnace and allowed to cool naturally. The degree of cylinder bore deformation is measured at room temperature. If it meets the standard, it proves that the cylinder block has passed the test.

6. The method for designing, machining, and verifying the precision round cylinder bore of an aluminum cylinder block according to claim 5, characterized in that, In step S41, the cylinder bore deformation is subjected to Fourier transform to obtain five sets of values ​​from the 2nd to the 6th order. These values ​​are then compared with the standard values ​​from the 2nd to the 6th order. If the values ​​exceed the standard, the cylinder bore deformation is considered unqualified. If the values ​​meet the standard, the process proceeds to step S42.

7. The method for designing, machining, and verifying the precision round cylinder bore of an aluminum cylinder block according to claim 5, characterized in that, After step S42, the cylinder block is removed and allowed to cool naturally. The cylinder bore deformation is subjected to Fourier transform to obtain five sets of values ​​from the second to the sixth order. These values ​​are compared with the standard values ​​from the second to the sixth order. If the values ​​are within the standard range, the cylinder block design is qualified. If the values ​​exceed or are close to the standard values, the cylinder block design is unqualified.

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