Connecting rod inner hole surface strengthening method

Abstract

The invention relates to a connecting rod machining method, in particular to a connecting rod inner hole surface strengthening method which comprises the steps that a connecting rod inner hole is finely bored till the surface roughness of the connecting rod inner hole reaches a preset range; the connecting rod is fixed to a shot blasting workbench, the axis of an outlet of a shot blasting device is adjusted to be perpendicular to the surface of an inner hole of the connecting rod, and shot blasting process parameters are set for pre-shot blasting; and after pre-shot blasting is finished, measuring the surface pressure stress of the inner hole of the connecting rod, resetting the shot blasting process parameters according to the surface pressure stress of the inner hole of the connecting rod, and carrying out vertical shot blasting treatment again, so that the surface pressure stress of the inner hole of the connecting rod reaches a qualified range. The pressure stress tolerance requirement of the surface of the shot blasting inner hole of the connecting rod can be directly met, micro burrs are not generated, a finished product is obtained after shot blasting, and manual plier deburring is not needed.

Description

Technical Field

[0001] The invention relates to a connecting rod processing method, in particular to a connecting rod inner hole surface strengthening method. Background Art

[0002] With the development of the times, the domestic requirements for the service life of connecting rods are getting higher and higher. The design has narrowed the compressive stress tolerance range of the shot blasted inner hole surface of the connecting rod, and added requirements that there should be no micro burrs on the edge of the oil groove towards the inner hole and no traces of clamp repair on the shot blasted inner hole surface. This has brought great challenges to the production and manufacturing process technology, and a series of problems need to be solved: the traditional shot blasting process cannot guarantee the reduced compressive stress tolerance, manual deburring cannot 100% guarantee that the inner hole will not be damaged during clamp repair, and the detection of micro burrs is difficult. The process technology urgently needs innovation and upgrading. Summary of the invention

[0003] The purpose of the present invention is to provide a connecting rod inner hole surface strengthening method, which can directly meet the compressive stress tolerance requirements of the connecting rod inner hole surface by shot blasting, so that it does not produce microscopic burrs, and the finished product is achieved after shot blasting, and no manual pliers are required to remove burrs.

[0004] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A connecting rod inner hole surface strengthening method, comprising: Fine boring the inner hole of the connecting rod until the surface roughness of the inner hole of the connecting rod reaches the preset range; Fix the connecting rod on the shot blasting workbench, adjust the outlet axis of the shot blasting machine to be perpendicular to the inner hole surface of the connecting rod, and set the shot blasting process parameters for pre-shot blasting; After the pre-shot blasting is completed, the compressive stress on the inner hole surface of the connecting rod is measured, and the shot blasting process parameters are reset according to the compressive stress on the inner hole surface of the connecting rod, and the vertical shot blasting is performed again to make the compressive stress on the inner hole surface of the connecting rod reach the qualified range.

[0005] Furthermore, the shot blasting machine is fixed on the rotating shaft of the workbench, and the axis of the rotating shaft coincides with the axis of the inner hole of the connecting rod fixed on the workbench.

[0006] Furthermore, the shot blasting machine comprises a left half and a right half which are fixedly connected, and grooves corresponding to each other are arranged on opposite sides of the left half and the right half; The groove on the left half and the groove on the right half together form a channel for accelerated passage of shot blasting, and the channel includes an entrance section, an arc section and an exit section connected in sequence, the entrance section is straight and the entrance of the entrance section is connected to the shot blasting feeding equipment, the outlet of the exit section is arranged on the side wall of the shot blasting machine, and the axis of the exit section is perpendicular to the axis of the entrance section.

[0007] Furthermore, the process parameter settings of the pre-shot blasting include: setting the shot blasting pressure to 1~5 bar, setting the rotation speed of the shot blasting machine relative to the circumference of the inner hole of the connecting rod to 7~15 rpm, and setting the feed speed of the shot blasting machine relative to the axial direction of the inner hole of the connecting rod to 5~15 mm / min.

[0008] Furthermore, the preset range of the surface roughness of the inner hole of the connecting rod is Ra0.8~Ra1.6.

[0009] Furthermore, the acceptable range of the compressive stress on the surface of the inner hole of the connecting rod is 517~621MPa.

[0010] The present invention has the following unexpected beneficial effects: the present invention first performs pre-shot blasting by adjusting the outlet axis of the shot blaster to be perpendicular to the inner hole surface of the connecting rod, thereby reducing the energy attenuation of the shot blasting and ensuring the quality of the shot blasting. In addition, by pre-shot blasting first, resetting the shot blasting process parameters according to the compressive stress on the inner hole surface of the connecting rod after pre-shot blasting, and performing vertical shot blasting again, the compressive stress on the inner hole surface of the connecting rod reaches the qualified range, and then adaptive adjustment can be made for connecting rods of different materials, directly meeting the compressive stress tolerance requirements of the inner hole surface of the connecting rod shot blasting, so that it does not produce microscopic burrs, and the finished product is achieved after shot blasting, and no manual pliers are required to remove burrs, thereby improving the product qualification rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 A schematic flow chart of the connecting rod inner hole surface strengthening method of the present invention is shown.

[0012] Figure 2 The schematic diagram of the structure of the shot blasting machine of the present invention is shown.

[0013] Figure 3 The schematic diagram of the structure of the left half of the shot blasting machine of the present invention is shown.

[0014] In the figure, 10 is the left half, 20 is the right half, 30 is the channel, 31 is the entrance section, 32 is the arc section, 33 is the exit section, and 40 is the mounting hole. DETAILED DESCRIPTION

[0015] The following will describe the embodiments of the present invention with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention, not for limiting the scope of protection of the present invention.

[0016] In one embodiment, see Figure 1As shown, the present invention provides a connecting rod inner hole surface strengthening method, comprising: The inner hole of the connecting rod is precision bored until the surface roughness of the inner hole of the connecting rod reaches the preset range.

[0017] Fix the connecting rod on the shot blasting table, adjust the axis of the shot blasting machine outlet to be perpendicular to the inner hole surface of the connecting rod, set the shot blasting process parameters for pre-shot blasting; the arrangement of the shot blasting machine makes the shot material's projection direction mainly perpendicular to the workpiece surface or at a small angle to the vertical direction. This vertical projection method can ensure that the shot material hits the workpiece surface evenly, and compared with projections at other angles, it reduces the situation where the shot material's energy is not fully utilized after rebounding.

[0018] After the pre-shot blasting is completed, the compressive stress on the inner hole surface of the connecting rod is measured, and the shot blasting process parameters are reset according to the compressive stress on the inner hole surface of the connecting rod, and the vertical shot blasting is performed again to make the compressive stress on the inner hole surface of the connecting rod reach the qualified range.

[0019] The present invention first performs pre-shot blasting by adjusting the outlet axis of the shot blaster to be perpendicular to the inner hole surface of the connecting rod, thereby reducing the energy attenuation of the shot blasting and ensuring the quality of the shot blasting. In addition, by pre-shot blasting first, and resetting the shot blasting process parameters according to the compressive stress on the inner hole surface of the connecting rod after pre-shot blasting, and performing vertical shot blasting again, the compressive stress on the inner hole surface of the connecting rod reaches the qualified range, and then adaptive adjustment can be made for connecting rods of different materials, directly meeting the compressive stress tolerance requirements of the inner hole surface of the connecting rod shot blasting, so that it does not produce microscopic burrs, and the finished product is achieved after shot blasting, and no manual pliers are required to remove burrs, thereby improving the product qualification rate.

[0020] In a preferred embodiment, the shot blasting machine is fixed on a rotating shaft of a workbench, and the axis of the rotating shaft coincides with the axis of the inner hole of a connecting rod fixed on the workbench.

[0021] When the rotating shaft drives the shot blaster to rotate, since its axis coincides with the axis of the inner hole of the connecting rod, the shot thrown by the shot blaster can act on various parts of the inner hole surface of the connecting rod at a relatively uniform angle and distance. No matter where the shot blaster is in the rotation process, the shot will hit the inner hole surface in a relatively consistent manner, thus effectively avoiding the problem of excessive or insufficient shot blasting in some areas of the inner hole surface due to differences in projectile angles or distances, so that the entire inner hole surface can be evenly and appropriately shot blasted.

[0022] In this structure where the axes overlap, the strengthening effects such as compressive stress on the inner hole surface of the connecting rod caused by shot blasting can be more accurately controlled. Because the angle and action point of shot blasting are relatively fixed and evenly distributed on the inner hole surface, the shot blasting process parameters such as shot material speed and shot blasting time can be adjusted more accurately according to the pre-set goals, thereby ensuring that strengthening indicators such as compressive stress on the inner hole surface can accurately reach the qualified range and improve the overall performance and quality of the connecting rod.

[0023] In a preferred embodiment, see Figure 2 and Figure 3 As shown, the shot blasting machine includes a left half 10 and a right half 20 which are fixedly connected. This split design facilitates manufacturing, assembly, and possible subsequent maintenance and repair work.

[0024] The left half 10 and the right half 20 are provided with grooves corresponding to each other on the opposite sides. When the left half 10 and the right half 20 are fixedly connected, the two corresponding grooves are combined to form a channel 30 for the accelerated operation of the shot blasting.

[0025] The channel 30 includes an entrance section 31, an arc section 32 and an exit section 33 connected in sequence. The entrance section 31 is straight and the entrance of the entrance section 31 is connected to the shot blasting supply device. Such a straight line design is conducive to the smooth entry of the shot blasting from the supply device into the channel, reducing the possibility of blockage or uneven flow of the shot blasting at the entrance, and ensuring that the shot blasting can enter the subsequent acceleration operation stage with a relatively stable flow rate and initial velocity.

[0026] The arc section 32 is located after the inlet section 31, and its arc design plays an important role in changing the running direction of the shot blasting. When the shot enters the arc section 32 from the inlet section 31, due to the special shape of the arc section, the shot is subjected to the centripetal force and other forces exerted by the channel wall in the channel, thereby gradually changing the running direction, and finally preparing to be thrown out from the outlet section 33 at a suitable angle and high speed.

[0027] The outlet of the outlet section 33 is arranged on the side wall of the shot blasting machine, and the axis of the outlet section 33 is perpendicular to the axis of the inlet section 31. This vertical setting enables the shot to be thrown out at a high speed at an angle perpendicular to the inlet direction after the direction of the shot changes in the channel. This feature can be used in practical applications, such as when shot blasting a specific workpiece, the installation position and direction of the shot blasting machine can be flexibly adjusted according to the shape of the workpiece, the part to be processed, and the process requirements, so as to achieve accurate and effective shot blasting of the workpiece surface.

[0028] Furthermore, the left half 10 and the right half 20 are connected by bolts, and mounting holes for the bolts to pass through are provided at corresponding positions of the left half 10 and the right half 20 .

[0029] In a preferred embodiment, the process parameter settings of the pre-shot blasting include: setting the shot blasting pressure to 1-5 bar, setting the rotation speed of the shot blasting machine relative to the circumference of the inner hole of the connecting rod to 7-15 rpm, and setting the feed speed of the shot blasting machine relative to the axis direction of the inner hole of the connecting rod to 5-15 mm / min. These parameters cooperate and work together to achieve comprehensive, uniform and effective pre-shot blasting treatment of the inner hole surface of the connecting rod to meet the requirements of subsequent processes and product quality.

[0030] The shot blasting pressure is set to 1~5bar, which directly determines the initial velocity of the shot when it is thrown from the shot blaster. Appropriate pressure can enable the shot to obtain sufficient kinetic energy to ensure that when it hits the inner hole surface of the connecting rod, it can effectively remove surface impurities and perform surface strengthening operations. In this case, the pressure of 1~5bar can allow the shot to reach a relatively suitable speed, which can not only achieve a better treatment effect, but also avoid problems such as damage that may occur due to excessive impact on the inner hole surface caused by excessive speed.

[0031] The rotation speed of the shot blaster relative to the circumference of the inner hole of the connecting rod is set to 7~15rpm. This parameter also has an important influence on the shot blasting effect. By rotating at a speed of 7~15rpm in the circumference of the inner hole of the connecting rod, the shot blaster can cover all parts of the circumference of the inner hole of the connecting rod with the thrown shot. This can avoid the situation where some areas on the circumference of the inner hole are not shot in place while other areas are repeatedly shot blasted, ensuring the comprehensiveness and uniformity of the circumferential surface treatment of the inner hole.

[0032] The feed speed of the shot blaster relative to the axis of the inner hole of the connecting rod is set to 5~15mm / min. This feed speed ensures that the shot blaster can be gradually advanced along the axis of the inner hole of the connecting rod, so that the thrown shot can cover all parts in the axis direction of the inner hole. In this way, the axial area of ​​the inner hole is prevented from existing without being shot blasted, and the inner hole surface is fully covered in the axial direction.

[0033] In a preferred embodiment, the preset range of the surface roughness of the inner hole of the connecting rod is Ra0.8~Ra1.6. If the roughness exceeds this range, such as being too rough, it may cause uneven shot blasting effect, inconsistent energy transfer when the shot hits the surface, and affect the surface strengthening effect.

[0034] In a preferred embodiment, the qualified range of the compressive stress on the inner hole surface of the connecting rod is 517~621MPa. After the pre-shot blasting is completed, it is necessary to measure the compressive stress on the inner hole surface, and reset the shot blasting process parameters according to the measured value to perform vertical shot blasting again, the purpose of which is to make the surface compressive stress reach this qualified range. For example, if the measured compressive stress is lower than 517MPa, it means that the shot blasting does not strengthen the inner hole surface enough, and it is necessary to adjust the shot blasting parameters, such as increasing the shot blasting pressure, extending the shot blasting time, etc., to increase the surface compressive stress; on the contrary, if it is higher than 621MPa, it may mean excessive shot blasting, and it is necessary to appropriately reduce the parameters to avoid excessive strengthening of the inner hole surface and potential problems that may be caused, such as damage to the microstructure of the inner hole surface.

[0035] The appropriate surface compressive stress range is crucial to the performance of the connecting rod. In the actual application of the connecting rod, such as in the engine and other equipment, the compressive stress within this qualified range can effectively improve the fatigue strength of the connecting rod, so that it can withstand repeated forces without fatigue fracture, thereby ensuring the reliability and stability of the connecting rod during the operation of the entire equipment.

[0036] The above embodiments are only preferred embodiments for fully illustrating the present invention, and the protection scope of the present invention is not limited thereto. Any equivalent substitution or change made by a person skilled in the art based on the present invention is within the protection scope of the present invention.

Claims

1. A method for strengthening the inner hole surface of a connecting rod, characterized in that: include: Fine boring the inner hole of the connecting rod until the surface roughness of the inner hole of the connecting rod reaches the preset range; Fix the connecting rod on the shot blasting workbench, adjust the outlet axis of the shot blasting machine to be perpendicular to the inner hole surface of the connecting rod, and set the shot blasting process parameters for pre-shot blasting; After the pre-shot blasting is completed, the compressive stress on the inner hole surface of the connecting rod is measured, and the shot blasting process parameters are reset according to the compressive stress on the inner hole surface of the connecting rod, and the shot blasting treatment is performed so that the compressive stress on the inner hole surface of the connecting rod reaches the qualified range.

2. The connecting rod inner hole surface strengthening method according to claim 1, characterized in that: The shot blasting machine is fixed on the rotating shaft of the workbench, and the axis of the rotating shaft coincides with the axis of the inner hole of the connecting rod fixed on the workbench.

3. The connecting rod inner hole surface strengthening method according to claim 1, characterized in that: The shot blasting machine comprises a left half and a right half which are fixedly connected, and grooves corresponding to each other are arranged on the opposite sides of the left half and the right half; The groove on the left half and the groove on the right half together form a channel for accelerated passage of shot blasting, and the channel includes an entrance section, an arc section and an exit section connected in sequence, the entrance section is straight and the entrance of the entrance section is connected to the shot blasting feeding equipment, the outlet of the exit section is arranged on the side wall of the shot blasting machine, and the axis of the exit section is perpendicular to the axis of the entrance section.

4. The connecting rod inner hole surface strengthening method according to claim 1, characterized in that: The process parameter settings of the pre-shot blasting include: setting the shot blasting pressure to 1-5 bar, setting the rotation speed of the shot blasting machine relative to the circumference of the inner hole of the connecting rod to 7-15 rpm, and setting the feed speed of the shot blasting machine relative to the axial direction of the inner hole of the connecting rod to 5-15 mm / min.

5. The connecting rod inner hole surface strengthening method according to claim 1, characterized in that: The preset range of the surface roughness of the inner hole of the connecting rod is Ra0.8~Ra1.

6.

6. The connecting rod inner hole surface strengthening method according to claim 1, characterized in that: The acceptable range of the compressive stress on the inner hole surface of the connecting rod is 517~621MPa.

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