Numerical control machining method for crankshaft main journal based on follow-up grinder

Abstract

The application discloses a numerical control machining method for crankshaft main journal based on a follow-up grinding machine, which comprises the following steps: 1) supporting the second, fourth, sixth and eighth grades of the main journal on a center frame; 2) rough grinding the crankshaft main journal; 3) rough grinding the first, third, fifth, seventh and ninth grades of the main journal; 4) detecting the run-out of the first, third, fifth, seventh and ninth grades of the main journal; 5) correcting the run-out of the main journal; 6) moving the center frame to the first, third, fifth, seventh and ninth grades of the main journal; 7) rough grinding the second, fourth, sixth and eighth grades of the main journal; 8) fine grinding the first, third, fifth, seventh and ninth grades of the main journal; and 9) fine grinding the second, fourth, sixth and eighth grades of the main journal. The application can solve the problem of the run-out of the crankshaft main journal machined by the follow-up grinding machine and improve the machining quality of the crankshaft main journal.

Description

Technical Field

[0001] This invention relates to a CNC machining method for a marine diesel engine crankshaft, and more particularly to a CNC machining method for the main journal of a marine diesel engine crankshaft on a follower grinder, belonging to the field of CNC machining technology. Background Technology

[0002] The crankshaft is one of the key components of a marine diesel engine, characterized by its complex structure, poor rigidity, and high technical requirements. Its quality directly affects the overall quality of the diesel engine. Previously, multi-cylinder crankshaft grinding was performed on an external cylindrical grinding machine, simulating the actual motion of the crankshaft using floating grinding. However, external cylindrical grinding machines have low processing efficiency, and the machining accuracy often cannot be guaranteed. Follower grinding machines offer high processing efficiency and good machining quality. When machining the main journals of multi-cylinder crankshafts using follower grinding machines, double-center clamping is generally used. Due to the long length of the multi-cylinder crankshaft and the pressure on both ends, the crankshaft deflection increases, causing the runout of the main journals during machining to often exceed tolerances and be difficult to control, significantly affecting the machining quality of the main journals of the multi-cylinder crankshaft. Summary of the Invention

[0003] The purpose of this invention is to provide a CNC machining method for crankshaft main journals based on a follower grinder, which can effectively solve the problem of runout exceeding tolerance when machining crankshaft main journals using a follower grinder.

[0004] This invention is achieved through the following technical solution:

[0005] A CNC machining method for crankshaft main journals based on a follower grinding machine includes the following steps:

[0006] 1) Hoist the crankshaft onto the follower grinding machine, and support the second, fourth, sixth and eighth gears of the crankshaft main journal on the center support respectively. At the same time, clamp the crankshaft and establish a coordinate system.

[0007] 2) Rough grinding to ensure all crankshaft main journals are of uniform size and smooth.

[0008] 3) Rough grind the crankshaft main journals in gears I, III, V, VII, and IX to the machining allowance b;

[0009] 4) Hoist the crankshaft to the inspection platform and test the runout of the crankshaft main journal in gears I, III, V, VII and IX respectively, and record the magnitude and direction of the runout in each gear;

[0010] 5) The crankshaft is repositioned to the follower grinding machine. Based on the detection data from step 4), the crankshaft journals with excessive runout are deflected, and the first, third, fifth, seventh, and ninth grades of the crankshaft journals are machined to the machining allowance c.

[0011] 6) Move the center support so that the first, third, fifth, seventh, and ninth gears of the crankshaft main journal are respectively supported on the center support;

[0012] 7) Rough grind the crankshaft main journals in the second, fourth, sixth, and eighth gears to the machining allowance d;

[0013] 8) Grind the crankshaft main journals in gears I, III, V, VII and IX to the required dimensions, and monitor the shift table data in real time during the machining of each gear;

[0014] 9) Grind the crankshaft journals of gears II, IV, VI and VIII to the required dimensions.

[0015] The objectives of this invention can also be further achieved through the following technical measures.

[0016] The aforementioned CNC machining method for crankshaft main journals based on a follower grinding machine, wherein the offset method in step 5) is as follows: if the runout of the crankshaft main journal with excessive runout is 'a' and the runout angle is 'α', then it is necessary to compensate 'a / 2' in the 'α' direction. Compensation is performed when machining to a 0.8mm allowance in each gear. The program is run to offset the center of the crankshaft main journal with excessive runout by 'a / 2' in the 'α' direction, thereby eliminating the runout.

[0017] The aforementioned CNC machining method for crankshaft main journals based on a follower grinding machine, wherein the machining sequence in step 8) is as follows: first, the main journal in the middle of the crankshaft is machined, and then the main journals at both ends of the crankshaft are machined. That is, the machining sequence in step 8) is V, III, VII, IX and I.

[0018] In the aforementioned CNC machining method for crankshaft main journal based on a follower grinding machine, in step 8), when monitoring the data of the shift gauge in real time, the height of the center rest is adjusted in a timely manner according to the data of the shift gauge to ensure that the error of the shift gauge is within 0.01 during the machining process.

[0019] In the aforementioned CNC machining method for crankshaft main journal based on a follower grinding machine, the machining allowance b in step 3) is 2mm, the machining allowance c in step 5) is 0.8mm, and the machining allowance d in step 7) is 0.8mm.

[0020] This invention effectively solves the problem of excessive runout in crankshaft main journals during machining by detecting the magnitude and direction of runout and eliminating it using process compensation methods. Furthermore, in the subsequent fine grinding stage, the invention employs a machining measure of first machining the main journals with large deflection in the middle of the crankshaft and then machining the main journals with small deflection at both ends of the crankshaft. This not only greatly improves the machining quality of the crankshaft main journals and ensures their machining accuracy, but also results in high machining efficiency and a stable and reliable machining process.

[0021] The advantages and features of the present invention will be illustrated and explained by the following non-limiting description of preferred embodiments, which are given by way of example only with reference to the accompanying drawings. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure in step 1) of the present invention where the crankshaft is supported on the central frame;

[0023] Figure 2 This is a schematic diagram of the structure in step 6) of the present invention, in which the crankshaft is supported on the central frame. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0025] This invention is illustrated using a 9L32 type nine-cylinder crankshaft as an example.

[0026] A CNC machining method for crankshaft main journals based on a follower grinding machine includes the following steps:

[0027] 1) such as Figure 1 As shown, crankshaft 1 is hoisted onto the follower grinding machine, and the second, fourth, sixth and eighth gears of the main journal of crankshaft 1 are supported on the center frame 2 respectively. At the same time, the two ends of crankshaft 1 are clamped and a coordinate system is established. This makes it easy to ensure that the support position of the center frame 2 is consistent with the support position during the final inspection after the center frame 2 is moved during subsequent fine grinding.

[0028] 2) Rough grinding to ensure all crankshaft main journals are of uniform size and smooth.

[0029] 3) Rough grind the crankshaft main journals in the first, third, fifth, seventh, and ninth gears to the machining allowance b, where b = 2 mm;

[0030] 4) Hoist crankshaft 1 to the inspection platform and test the runout of the main journal of crankshaft 1 in gears I, III, V, VII and IX respectively, and record the magnitude and direction of the runout in each gear;

[0031] 5) Re-lift crankshaft 1 to the follower grinding machine. Based on the detection data from step 4), offset the crankshaft main journal with excessive runout. Machin the first, third, fifth, seventh, and ninth grades of the crankshaft main journal to the machining allowance c, where c = 0.8 mm. The offset method is as follows: Let the runout of the crankshaft main journal with excessive runout be a, and the runout angle be α. Then, it is necessary to compensate a / 2 in the α direction. Compensation is performed when each grade is machined to the 0.8 mm allowance. Run the program to offset the center of the crankshaft main journal with excessive runout by a / 2 in the α direction, thereby eliminating the runout.

[0032] 6) such as Figure 2As shown, the center frame 2 is moved so that the first, third, fifth, seventh and ninth gears of the crankshaft main journal are respectively supported on the center frame 2;

[0033] 7) Rough grind the crankshaft main journals in the second, fourth, sixth and eighth gears to the machining allowance d, where d = 0.8 mm;

[0034] 8) Grind the crankshaft main journals in sections I, III, V, VII, and IX to the required dimensions. During the machining of each section, monitor the shift gauge data in real time and adjust the height of the center frame 2 accordingly to ensure that the error of the shift gauge is within 0.01 during machining. The specific machining sequence is as follows: first machine the main journals with large deflection in the middle of crankshaft 1, and then machine the main journals with small deflection at both ends of crankshaft 1. That is, the machining sequence is section V, section III, section VII, section IX, and section I. This facilitates control and reduces machining errors.

[0035] 9) Grind the main journals of crankshaft 1 in gears II, IV, VI and VIII to the required dimensions.

[0036] In addition to the above embodiments, the present invention may have other implementation methods. All technical solutions formed by equivalent substitution or equivalent transformation fall within the protection scope claimed by the present invention.

Claims

1. A CNC machining method for crankshaft main journals based on a follower grinding machine, comprising the following steps: 1) Hoist the crankshaft onto the follower grinding machine, and support the second, fourth, sixth and eighth gears of the crankshaft main journal on the center support respectively. At the same time, clamp the crankshaft and establish a coordinate system. 2) Rough grinding to ensure all crankshaft main journals are of uniform size and smooth. 3) Rough grind the crankshaft main journals in gears I, III, V, VII, and IX to the machining allowance b; 4) Hoist the crankshaft to the inspection platform and test the runout of the crankshaft main journal in gears I, III, V, VII and IX respectively. Record the magnitude and direction of the runout in each gear. 5) The crankshaft is repositioned to the follower grinding machine. Based on the detection data from step 4), the crankshaft journals with excessive runout are deflected, and the first, third, fifth, seventh, and ninth grades of the crankshaft journals are machined to the machining allowance c. 6) Move the center support so that the first, third, fifth, seventh, and ninth gears of the crankshaft main journal are respectively supported on the center support; 7) Rough grind the crankshaft main journals in gears II, IV, VI and VIII to the machining allowance d; 8) Grind the crankshaft main journals at the first, third, fifth, seventh, and ninth gears to the required dimensions, and monitor the gear shift table data in real time during the machining of each gear; 9) Fine-grind the crankshaft journals of gears II, IV, VI, and VIII to the required dimensions; The feature is that the biasing method in step 5) is as follows: if the runout of the crankshaft main journal with excessive runout is a and the runout angle is α, then it is necessary to compensate a / 2 in the α direction. The compensation is performed when the machining allowance is 0.8mm in each gear. The program is run to offset the center of the crankshaft main journal with excessive runout by a / 2 in the α direction, thereby eliminating the runout.

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