Method for straightening camshaft through shot peening impact

Abstract

The invention relates to a method for straightening a cam shaft through shot peening impact, in particular to a method capable of straightening the cam shaft made of steel with poor toughness. The camshaft is straightened by measuring the runout value of the camshaft, determining the straightened point of the camshaft, determining the direction of the shot blasting head, adjusting parameters of the shot blasting machine, straightening the straightened point and repeatedly straightening all the straightening points, the runout value of the camshaft is reduced, and the runout value of the main shaft position of the camshaft reaches the qualified range. By means of the straightening method, the cam shafts which are poor in toughness and prone to being broken by pressing can be straightened, the precision and the product quality of the straightened cam shafts can be improved, the production cost is reduced, and the production time is shortened.

Description

Technical Field

[0001] The invention relates to a method for straightening a camshaft by shot peening, and belongs to the technical field of straightening mechanical parts. Background Art

[0002] In the production process of camshafts, heat treatment is a key step to improve the hardness and wear resistance of materials. However, the heat treatment process often causes changes in the internal stress of the material, which causes slight changes in the shape and size of the camshaft, resulting in excessive runout values ​​of the main shaft position, which will directly affect the performance and reliability of the engine. Therefore, for camshafts with excessive runout values ​​after heat treatment, straightening treatment must be carried out.

[0003] At present, the traditional camshaft straightening method mainly uses external pressure, which directly applies downward pressure to the high point of the workpiece to reduce the runout value. This method can effectively reduce the runout value of the camshaft to a certain extent, but it has obvious limitations. First, for steels with poor toughness and easy to break, the traditional method cannot be implemented, because excessive pressure may cause the steel to break, resulting in an increase in the scrap rate. Secondly, even for steels with good toughness, it is difficult for traditional methods to accurately control the size and point of action of the pressure, which can easily lead to over-correction or under-correction, affecting the straightening effect. In addition, traditional methods usually require multiple repetitive operations to achieve the desired effect, which increases production costs and time. Summary of the invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for straightening a camshaft by shot peening. The present invention can straighten camshafts with poor toughness and easily broken, and the present invention can improve the accuracy and product quality of straightening the camshaft and reduce production costs and time.

[0005] To achieve the above object, the technical solution provided by the present invention is a method for straightening a camshaft by shot peening, comprising the following steps:

[0006] (1) Measure the spindle position runout value of the camshaft to be straightened, and hang the measured camshaft vertically on the hanger of the shot peening machine;

[0007] (2) according to the spindle position runout value of the camshaft in step (1), determining the camshaft straightening points 1, 2, 3, ..., n, n ≥ 2;

[0008] (3) determining the direction of the lowest point of the runout value of the camshaft being aligned at point 1 in step (2), and aligning the shot peening head of the shot peening machine with the direction of the lowest point of the runout value of the camshaft being aligned at point 1;

[0009] (4) Start the shot peening machine and adjust the shot peening speed and flow rate according to the runout value of the straightened point;

[0010] (5) Determine the shot peening time of the shot peening machine according to the runout value of the straightened point. When the shot peening time reaches the determined time, stop the shot peening machine, take out the camshaft and measure the runout value of the straightened point of the camshaft. If the runout value of the straightened point of the camshaft reaches the qualified range, proceed to step (6); otherwise, repeat steps (3), (4) and (5);

[0011] (6) According to the positions of the camshaft straightening points 2, 3, ..., n, n ≥ 2, repeat steps (3), (4) and (5) until the runout value of the camshaft straightening point n reaches the qualified range, n ≥ 2, and the camshaft straightening is completed.

[0012] Further improvements to the above technical solution are:

[0013] In step (4), the injection speed of the steel shot is fixed at 80 m / s; assuming the runout value of the straightened point is x mm, when 0.60<x<1.0, the injection flow rate of the steel shot is 160 kg / min; when 1.0 mm≤x<1.5, the injection flow rate of the steel shot is 180 kg / min; when x≥1.5, the injection flow rate of the steel shot is 200 kg / min.

[0014] The method for determining the spraying time of the shot peening machine in step (5) is as follows:

[0015] Assume that the runout value of the straightened point is x mm, when 0.60<x<1.0, the shot peening machine spraying time is (6+10(x-0.6))min; when 1.0≤x<1.2, the shot peening machine spraying time is (8+10(x-0.6))min; when x≥1.2, the shot peening machine spraying time is (10+10(x-0.6))min;

[0016] The qualified range of the camshaft straightening point runout value in step (5) is no more than 0.60 mm.

[0017] According to the above technical solution, the camshaft shot peening impact straightening method provided by the present invention straightens the camshaft by measuring the camshaft runout value, determining the camshaft straightening point, determining the direction of the shot peening head, adjusting the parameters of the shot peening machine, straightening the straightened point and repeating the straightening of all the straightening points, thereby reducing the camshaft runout value and making the camshaft main shaft position runout value reach the qualified range. Compared with the prior art, the present invention has the following advantages:

[0018] (1) Since the technical solution adopted by the present invention straightens the camshaft by a shot peening machine, the present invention can straighten camshafts with poor toughness and easily broken, and is applicable to more types of materials and a wider range of workpieces.

[0019] (2) Because the technical solution adopted by the present invention accurately calculates the injection speed, flow rate and time of the shot peening machine, the present invention can complete the straightening process more quickly, improve production efficiency and reduce production costs.

[0020] (3) Because the technical solution adopted by the present invention can accurately control the position and force of the straightening by measuring the spindle position runout value and determining the specific straightening point, and at the same time, by calculating the appropriate shot peening parameters of the shot peening machine, the problem of over-correction or under-correction is avoided, thereby ensuring the accuracy of the straightening. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A flow chart of a method for straightening a camshaft by shot peening;

[0022] Figure 2 Schematic diagram of shot peening to straighten a camshaft. DETAILED DESCRIPTION

[0023] The present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited to the following embodiments.

[0024] The present invention provides a method for shot peening and straightening a camshaft, the flow chart of which is as follows: Figure 1 As shown, taking the 7E9980 alloy cast iron camshaft model as an example, the schematic diagram of shot peening and straightening the camshaft is as follows Figure 2 As shown, follow the steps below to align:

[0025] (1) Use a yaw meter to measure the spindle position runout value of the camshaft that needs to be straightened, and hang the measured camshaft vertically on the hanger of the shot peening machine;

[0026] (2) According to the spindle position runout value of the camshaft in step (1), the camshaft alignment point is determined. In this embodiment, the camshaft has a total of 10 alignment points.

[0027] (3) determining the direction of the lowest point of the runout value of the camshaft being aligned at point 1 in step (2), and aligning the shot peening head of the shot peening machine with the direction of the lowest point of the runout value of the camshaft being aligned at point 1;

[0028] (4) Start the shot peening machine and adjust the shot peening speed and flow rate according to the runout value of the straightened point;

[0029] (5) Determine the shot peening time of the shot peening machine according to the runout value of the straightened point. When the shot peening time reaches the determined time, stop the shot peening machine, take out the camshaft and measure the runout value of the straightened point of the camshaft. If the runout value of the straightened point of the camshaft is not greater than 0.60 mm, proceed to step (6); otherwise, repeat steps (3), (4) and (5);

[0030] The corresponding relationship between the runout value of the straightened point and the shot peening machine's shot velocity, flow rate and duration is shown in Table 1;

[0031] Table 1 Correspondence between the runout value of the straightened point and the shot peening machine steel shot jet speed, flow rate and duration

[0032]

[0033] (6) According to the positions of the camshaft straightening points 2, 3, ..., 10, n ≥ 2, repeat steps (3), (4) and (5) until the runout value of the camshaft straightening point 10 is no more than 0.60 mm and the camshaft straightening is completed.

[0034] The data of the alloy cast iron camshaft before and after straightening in this embodiment are shown in Table 2.

[0035] Table 2 Alignment record of alloy cast iron camshaft

[0036]

[0037]

Claims

1. A method for straightening a camshaft by shot peening, characterized in that: The following steps are involved: (1) Measure the spindle position runout value of the camshaft to be straightened, and hang the measured camshaft vertically on the hanger of the shot peening machine; (2) according to the spindle position runout value of the camshaft in step (1), determine the camshaft straightening points 1, 2, 3, ..., n, n ≥ 2; (3) determining the direction of the lowest point of the runout value of the camshaft being aligned at point 1 in step (2), and aligning the shot peening head of the shot peening machine with the direction of the lowest point of the runout value of the camshaft being aligned at point 1; (4) Start the shot peening machine and adjust the shot peening speed and flow rate according to the runout value of the straightened point; (5) Determine the shot peening time of the shot peening machine according to the runout value of the straightened point. When the shot peening time reaches the determined time, stop the shot peening machine, take out the camshaft and measure the runout value of the straightened point of the camshaft. If the runout value of the straightened point of the camshaft reaches the qualified range, proceed to step (6); otherwise, repeat steps (3), (4) and (5); (6) According to the positions of the camshaft straightening points 2, 3, ..., n, n ≥ 2, repeat steps (3), (4) and (5) until the runout value of the camshaft straightening point n reaches the qualified range, n ≥ 2, and the camshaft straightening is completed.

2. The method for straightening a camshaft by shot peening according to claim 1, characterized in that: In step (4), the injection speed of the steel shot is fixed at 80 m / s; assuming the runout value of the straightened point is x mm, when 0.60<x<1.0, the injection flow rate of the steel shot is 160 kg / min; when 1.0 mm≤x<1.5, the injection flow rate of the steel shot is 180 kg / min; when x≥1.5, the injection flow rate of the steel shot is 200 kg / min.

3. The method for straightening a camshaft by shot peening according to claim 1, characterized in that The method for determining the spraying time of the shot peening machine in step (5) is as follows: Assume that the runout value of the straightened point is x mm. When 0.60<x<1.0, the shot peening machine spraying time is (6+10(x-0.6))min; when 1.0≤x<1.2, the shot peening machine spraying time is (8+10(x-0.6))min; when x≥1.2, the shot peening machine spraying time is (10+10(x-0.6))min.

4. The method for straightening a camshaft by shot peening according to claim 1, characterized in that: The qualified range of the camshaft straightening point runout value in step (5) is no more than 0.60 mm.

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