Control method for achieving high cylinder bore position precision of v12 engine cylinder block

Abstract

A control method for achieving high cylinder bore position precision of a V12 engine cylinder block. A non-uniform scaling design is used, the scaling of a cylinder block is no longer a mean value x, and is divided into a scaling in the X direction of cylinder bore arrangement, a scaling in the Y and Z directions, and a scaling of the inner wall of a region around a cylinder liner along the axis direction of the cylinder liner, with the proportional relationship being: x, x(1+a), and 0. Also disclosed is a V12 engine cylinder block, which is manufactured by means of the control method for achieving high cylinder bore position precision of a V12 engine cylinder block. The control of the solidification contraction of aluminum alloys on the position precision of cylinder bores in the cylinder block is implemented by means of the non-uniform scaling design, the effect of core assembly errors on the position precision of the cylinder block is reduced by means of the design of a core assembly mode, and the position precision of cylinder bores is further improved by means of the control of the precision of sand cores and the design of the anti-deformation allowance of sand cores.

Description

High-precision cylinder hole position degree control method for V12 engine cylinder block TECHNICAL FIELD

[0001] The application belongs to the technical field of engine cylinder blocks, and relates to a high-precision cylinder hole position degree control method for a V12 engine cylinder block. BACKGROUND

[0002] The position degree of the cylinder hole of a V12 aluminum alloy engine cylinder block is relatively high, and the diameter affects the use performance of the product.

[0003] If the cylinder hole position degree (i.e., the position precision of the cylinder hole) is too low, it will have many influences on the performance of the cylinder block:

[0004] ① It will reduce the uniformity of the wall thickness of the processed cylinder liner, thereby causing the durability of the cylinder block to decrease and the cracking tendency to increase during long-time high-load work; ② It will increase the sealing performance of the water jacket through hole between the cylinder holes; therefore, the cylinder hole position degree often needs to be controlled within the range of ±0.5 mm, and some products even require to be controlled within the range of ±0.35 mm. For a straight four-cylinder cylinder block, the cylinder hole position degree is only affected by the dimensional error in the x and y directions, while for a V-type cylinder block, the cylinder hole position degree is affected by the dimensional error in the x, y and z directions. The control difficulty is increased. Compared with V6 and V8 cylinder blocks, the V12 cylinder block has more cylinder holes, and the distance between the distal end cylinder holes is larger, so the control difficulty of the cylinder hole position degree is further increased.

[0005] Patent document CN109899172A discloses a V-type 12-cylinder cylinder block, which comprises a V-type top portion, a V-type top portion comprising a plurality of cylinders arranged in two rows left and right, the cylinders being provided with cylinder liners, wherein the included angle of the two rows of cylinders is 90°; two bottom portions, each of which is provided with a plurality of U-shaped reinforcing ribs; and a plurality of V-shaped reinforcing plates, each of which is arranged between two adjacent cylinders, the V-shaped reinforcing plate extending along the width direction of the V-type 12-cylinder cylinder block to the inner wall of the V-type 12-cylinder cylinder block, and the height of the V-shaped reinforcing plate reaching the middle position of the cylinder liner; wherein two crankcase ventilation channels are formed in the V-shaped reinforcing plate, the two crankcase ventilation channels being symmetrically arranged, the two crankcase ventilation channels being through in the front and back directions of the crankshaft, the two crankcase ventilation channels being connected to each other, and each of the two crankcase ventilation channels being connected to the crankcase of each cylinder; and an oil-gas separation structure cover plate is arranged above the end of one of the two crankcase ventilation channels. The above patent document only relates to the structure design of the cylinder block and does not relate to a high-precision cylinder hole position degree control scheme.

[0006] Patent document CN103121082A discloses a V8 type cylinder block casting pouring method, which is poured by using a core assembly, and comprises the following technical measures: 1) setting a casting pouring position; 2) setting a pouring system; 3) assembling the core assembly; and 4) pouring operation. Compared with the prior art, the core assembly structure is relatively simple, the finished product rate is high, and the production cost is low. The above patent document is not related to the aluminum alloy cylinder block, and does not involve the control of the aluminum alloy casting scale and the cylinder hole position.

[0007] Patent document CN103121083A discloses a V type cylinder block casting core separation process. The V type cylinder block casting core separation process adopts an overall surrounding type core separation, and comprises the following specific steps: first, the cylinder top direction of the V type cylinder block is downward, the machine foot direction is upward, the sand core bottom surface and the sand core outer side are designed; then, the entire sand core is separated into a front end insert core and a rear end insert core and a plurality of main body sand cores between the front end insert core and the rear end insert core through a core separation line from the front end of the V type cylinder block to the rear end; finally, a common tappet chamber sand core is separately designed on each main body sand core. The overall surrounding type core separation is adopted, and the sand core positioning measures are supplemented, so that the number of sand cores is reduced, the mold manufacturing process is simplified, the outer shape structure is simplified, the sand core is conveniently lowered and positioned, the positioning accuracy is high, the sand core strength is ensured, the deformation amount in the flowing and pouring process is avoided, the production efficiency is improved, and the production cost is saved. The above patent document is different from the analysis scheme of the present application, and does not design a non-uniform scale and a cylinder hole position measure. SUMMARY

[0008] The technical problem to be solved by the present application is to overcome the above-mentioned problems existing in the prior art, and to provide a V12 engine cylinder block high-precision cylinder hole position control method.

[0009] It should be noted that, in this text, relational terms such as first and second are used merely to distinguish one entity or action from another, and do not necessarily require or imply that there is any such actual relationship or order between these entities or actions. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the process, method, article or equipment including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or equipment.

[0010] To solve the above technical problems, the present application is realized by using the following technical scheme:

[0011] A V12 engine cylinder block high-precision cylinder hole position control method, characterized in that it comprises:

[0012] Non-uniform shrinkage design is adopted: based on the 8‰~10‰ shrinkage used in automotive castings, an additional shrinkage coefficient 'a' is added to the shrinkage in the cylinder bore arrangement direction; the shrinkage of the casting near the cylinder liner is limited by the cylinder liner and no macroscopic shrinkage occurs, and the shrinkage of the inner wall of the cylinder block attached to the cylinder liner is 0; the shrinkage of the cylinder block is no longer the average value x, but is divided into the shrinkage in the cylinder bore arrangement X direction, the shrinkage in the Y and Z directions, and the shrinkage of the inner wall of the area around the cylinder liner along the cylinder liner axis, and the ratio of the three is: x, x(1+a), 0.

[0013] Furthermore, a = 0.8‰ ~ 1.2‰

[0014] A method for high-precision cylinder bore position control of V12 engine cylinder block also includes an integrated tube core design: the sand core for fixing the cylinder liner and the sand core that forms a riser above the top surface of the casting are made into an integrated tube core.

[0015] Furthermore, reinforcing ribs are added inside the riser cavity on the riser forming side of the integrated tube core to increase the rigidity of the integrated tube core and reduce the deformation of the integrated tube core under the action of the gravity of the sand core and attached cylinder liner and the pressure of the aluminum alloy liquid during the casting filling and solidification process.

[0016] Furthermore, the tube position is increased with anti-deformation amount, and the six cylinder holes of the integrated tube core on the left and right sides are offset sequentially towards the central axis of the cylinder body. The offset amounts of the six cylinder holes are: 0, b, 2b, 2b, b, 0.

[0017] Furthermore, b = 0.05~0.2.

[0018] A method for high-precision cylinder bore position control of V12 engine cylinder block also includes precision control of integrated tube core: the error |ΔL| between the actual measured average distance L' of the distance between the two tube axes at the farthest end of the integrated tube core in each batch and the theoretical design value L0 is controlled to be ≤0.3mm. If |ΔL|>0.3mm, the deviation of the cylinder distance is offset by adding anti-deformation amount to the sand core.

[0019] A method for high-precision cylinder bore position control of a V12 engine cylinder block also includes a core assembly design: first, the cylinder liner is fixed to each tube of the integrated tube core using a cylinder liner assembly fixture; then, the integrated tube core is assembled into a sandbag; the bottom of the integrated tube core is fixed to the crankcase core via the core heads of the six tubes below; the crankcase core adopts a split design, meaning each tube corresponds to an independent crankcase core, avoiding the error between the core heads of each crankcase core from affecting the tube core and thus impacting the cylinder bore accuracy; the top of the integrated tube core is fixed to the front and rear cores via the core heads on both sides, and then pressed tightly by the upper large cover core.

[0020] Furthermore, the core gap is 0.1~0.3mm.

[0021] A V12 engine block is manufactured using the high-precision cylinder bore position control method described above.

[0022] Compared with the prior art, the beneficial effects of the present invention are:

[0023] This invention controls and achieves the accuracy requirements of cylinder bore position in aluminum alloy cylinder blocks by using a non-uniform scaling design for castings; reduces the influence of small core errors on cylinder block position by designing the core assembly method; and further improves cylinder bore position accuracy by controlling sand core accuracy and designing sand core anti-deformation amount. Attached Figure Description

[0024] The invention will now be further described with reference to the accompanying drawings:

[0025] Figure 1 is a schematic diagram of the various scaling directions involved in the V12 cylinder block;

[0026] In Figure 1:

[0027] 1. V12 cylinder block;

[0028] 2. Cylinder bore;

[0029] 3. X direction (cylinder bore arrangement direction);

[0030] 4. Y direction;

[0031] 5. Z direction;

[0032] 6. Cylinder bore axis direction;

[0033] Figure 2 is a schematic diagram of the assembly of the cylinder liner and the integrated tube core;

[0034] In Figure 2:

[0035] 1. Integrated tube core;

[0036] 2. Tube forming section;

[0037] 3. Riser forming section;

[0038] 4. Cylinder liner;

[0039] 5. Spacing between the axes of the two furthest tubes;

[0040] Figure 3 is a schematic diagram of the integrated tube core assembly;

[0041] In Figure 3:

[0042] 1. Integrated tube core;

[0043] 2. Crankcase core;

[0044] 3. Crankcase core head;

[0045] 4. Front-end chip;

[0046] 5. Back-end chip;

[0047] 6. Integrated tube core with core ends at both ends;

[0048] Figure 4 is a flowchart of the high-precision cylinder bore position control method for V12 engine block according to the present invention. Detailed Implementation

[0049] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be described in more detail below with reference to the accompanying drawings.

[0050] In the accompanying drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are some, but not all, of the embodiments of the present invention.

[0051] The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0052] In the description of this invention, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, 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 limiting the scope of protection of this invention.

[0053] The present invention will now be described in detail with reference to the accompanying drawings:

[0054] The casting process of V-type cylinder blocks can be simply divided into several parts: core making, core assembly, pouring, and solidification. These process steps all affect the position of the cylinder bores in the V12 cylinder block.

[0055] This invention is for the core assembly process of V12 cylinder blocks with embedded cylinder liners. During the process design stage, special designs are made for the key links of the above-mentioned processes to ensure the position accuracy of the cylinder bores in the cylinder block.

[0056] As shown in Figure 4, specific technical solutions are proposed according to the order of consideration in process design, including non-uniform scaling design, integrated tube core design, core assembly method design, tube position anti-deformation design, and sand core precision control.

[0057] Non-uniform scaling:

[0058] As shown in Figures 1 and 4, this invention provides a high-precision cylinder bore position control method for V12 engine cylinder blocks. Instead of using conventional uniform shrinkage, this invention addresses the uneven shrinkage characteristic of V12 cylinder blocks with embedded cylinder liners by employing a unique uniform shrinkage method. Based on the 8‰~10‰ shrinkage used in automotive castings, an additional shrinkage coefficient 'a' is added to the shrinkage in the cylinder bore arrangement direction (a = 0.8‰~1.2‰; for example, using a 10‰ shrinkage, the shrinkage in the cylinder bore arrangement direction is 10.8‰~11.2‰). Since the shrinkage of the casting near the cylinder liner is limited by the cylinder liner and does not result in macroscopic shrinkage, the shrinkage of the inner wall of the cylinder block attached to the cylinder liner is 0. Therefore, the cylinder block shrinkage is no longer a mean value x, but is divided into the shrinkage in the cylinder bore arrangement direction (X direction), the shrinkage in the other two directions (Y and Z directions), and the shrinkage of the inner wall of the area surrounding the cylinder liner along the cylinder liner axis. The proportional relationship between these three is: x, x(1+a), 0.

[0059] Integrated tube core design:

[0060] As shown in Figure 2, the sand core for fixing the cylinder liner and the sand core forming the riser on the top surface of the casting are made into an integrated tube core, eliminating the assembly error caused by separate tube cores. Reinforcing ribs are added inside the riser cavity on the riser forming side of the integrated tube core to increase its rigidity and reduce deformation caused by the weight of the sand core and attached cylinder liner, as well as the pressure of the aluminum alloy liquid, during the casting filling and solidification process. Furthermore, to address any remaining deformation of the integrated tube core, a counter-deformation amount is added to the tube position. The six cylinder holes on the left and right sides of the integrated tube core are sequentially offset towards the central axis of the cylinder body. The offset amounts of the six cylinder holes are: 0, b, 2b, 2b, b, 0, where b = (0.05~0.2).

[0061] Integrated tube core precision control:

[0062] The error |ΔL| between the actual measured average distance L' of the distance between the two tube axes at the farthest end of the integrated tube core and the theoretical design value L0 for each batch should be controlled within ≤0.3mm. If |ΔL|>0.3mm, an anti-deformation amount should be added to the sand core to compensate for the deviation in the cylinder distance.

[0063] Core assembly design:

[0064] As shown in Figure 3, the cylinder liner is first fixed to each tube of the integrated tube core using a cylinder liner assembly fixture. Then, the integrated tube core is assembled into the sandbag. The bottom of the integrated tube core is fixed to the crankcase core via the core heads of the six tubes below. The crankcase core adopts a split design, meaning each tube corresponds to an independent crankcase core, to avoid the error between the core heads of each crankcase core affecting the tube core and thus impacting the cylinder bore accuracy. The top of the integrated tube core is fixed to the front and rear cores via the core heads on both sides, and then pressed tightly by the top large cap core. To ensure the core assembly accuracy of the sand core, the core assembly gap (usually 0.1~0.3mm) is controlled as close to the lower limit as possible according to production conditions.

[0065] The sand core forming each tube and the sand core forming the riser are designed as an integrated structure. When assembling the core, the cylinder liner is first assembled onto the tube of the integrated tube core and fixed by interference fit.

[0066] This invention provides a V12 engine block manufactured using the aforementioned high-precision cylinder bore position control method.

[0067] The cylinder bore position accuracy is controlled by the solidification shrinkage of aluminum alloy through non-uniform scaling design. The influence of small core error on cylinder bore position accuracy is reduced by the core assembly method design. The position accuracy of cylinder bore is further improved by controlling the sand core precision and designing the sand core anti-deformation amount.

[0068] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in the present invention, and within the spirit and principles of the present invention, should be included within the scope of protection of the present invention. Furthermore, all content not described in detail in this specification is prior art known to those skilled in the art.

Claims

1. A method for high-precision cylinder bore position control of a V12 engine block, characterized in that, include: Non-uniform shrinkage design is adopted: based on the 8‰~10‰ shrinkage used in automotive castings, an additional shrinkage coefficient 'a' is added to the shrinkage in the cylinder bore arrangement direction; the shrinkage of the casting near the cylinder liner is limited by the cylinder liner and no macroscopic shrinkage occurs, and the shrinkage of the inner wall of the cylinder block attached to the cylinder liner is 0; the shrinkage of the cylinder block is no longer the average value x, but is divided into the shrinkage in the cylinder bore arrangement X direction, the shrinkage in the Y and Z directions, and the shrinkage of the inner wall of the area around the cylinder liner along the cylinder liner axis, and the ratio of the three is: x, x(1+a), 0.

2. The method for high-precision cylinder bore position control of a V12 engine block according to claim 1, characterized in that: a=0.8‰~1.2‰。 3. The method for high-precision cylinder bore position control of a V12 engine block according to claim 1, characterized in that: It also includes an integrated tube core design: the sand core for fixing the cylinder liner and the sand core that forms the riser on the top surface of the casting are made into an integrated tube core.

4. The method for high-precision cylinder bore position control of a V12 engine block according to claim 3, characterized in that: Reinforcing ribs are added inside the riser cavity on the riser forming side of the integrated tube core to increase the rigidity of the integrated tube core and reduce the deformation of the integrated tube core under the action of the gravity of the sand core and attached cylinder liner and the pressure of the aluminum alloy liquid during the casting filling and solidification process.

5. The method for high-precision cylinder bore position control of a V12 engine block according to claim 3, characterized in that: To increase the amount of reverse deformation at the position of the tube, the six cylinder holes of the integrated tube core on the left and right sides are offset sequentially towards the central axis of the cylinder body. The offset amounts of the six cylinder holes are: 0, b, 2b, 2b, b, 0.

6. The method for high-precision cylinder bore position control of a V12 engine block according to claim 5, characterized in that: b=0.05~0.2。 7. The method for high-precision cylinder bore position control of a V12 engine block according to claim 1, characterized in that: It also includes precision control of the integrated tube core: the error |ΔL| between the actual measured average distance L' of the distance between the two tube axes at the farthest end of the integrated tube core in each batch and the theoretical design value L0 is controlled to be ≤0.3mm. If |ΔL|>0.3mm, the deviation of the cylinder distance is offset by adding anti-deformation amount to the sand core.

8. A method for high-precision cylinder bore position control of a V12 engine block according to claim 1, characterized in that: It also includes the core assembly method design: first, the cylinder liner is fixed to each tube of the integrated tube core using the cylinder liner assembly tooling, and then the integrated tube core is assembled into the sandbag. The bottom of the integrated tube core is fixed to the crankcase core through the core heads under the six tubes. The crankcase core adopts a split design, that is, each tube corresponds to an independent crankcase core, to avoid the error between the core heads of each crankcase core from acting on the tube core and affecting the cylinder bore accuracy. The top of the integrated tube core is fixed to the front core and rear core through the core heads on both sides, and then pressed by the top large cover core.

9. The method for high-precision cylinder bore position control of a V12 engine block according to claim 8, characterized in that: The core gap is 0.1~0.3mm.

10. A V12 engine block, characterized in that, It is manufactured using the high-precision cylinder bore position control method described in any one of claims 1 to 9.

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