Transmission auxiliary box welding shaft structure based on electron beam welding and machining method

Abstract

The transmission auxiliary box welding shaft structure based on electron beam welding comprises an intermediate shaft and an intermediate shaft transmission gear arranged on the intermediate shaft in an interference sleeving mode, a positioning shaft shoulder is arranged at the rear end of the connecting position of the intermediate shaft and the intermediate shaft transmission gear, and a positioning concave spigot matched with the positioning shaft shoulder in structure is formed in the rear end of the intermediate shaft transmission gear. A gap is reserved between the outer circumference of the positioning shaft shoulder and the inner circumference of the positioning concave spigot; a first exhaust ring groove is formed in the non-end part of the inner circumference of the intermediate shaft transmission gear; a second exhaust ring groove is formed in the contact position of the middle shaft and the first exhaust ring groove, a first exhaust groove communicated with the second exhaust ring groove is formed between the second exhaust ring groove and the positioning shaft shoulder, and a second exhaust groove communicating the first exhaust groove with the periphery of the positioning shaft shoulder is formed in the positioning shaft shoulder. The bottleneck that the welding seam strength of the auxiliary box welding shaft is insufficient in development of a large-torque transmission is broken, the market problem that the welding seam is opened / broken due to an argon arc welding-based auxiliary box welding shaft structure is solved, and the reliability of the transmission and the qualification rate of the welding shaft are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of transmissions, and in particular relates to a transmission auxiliary box welding shaft structure and a processing method based on electron beam welding. Background Art

[0002] As high-horsepower engine technology matures, major OEMs demand high-torque transmissions to match them. The application of high-torque transmissions makes the load-bearing capacity of the entire vehicle stronger. However, one of the main problems faced in developing high-torque transmissions is the fatigue strength of the auxiliary box welded shaft.

[0003] Currently, the auxiliary transmission shaft is welded using a mixture of CO2 and argon shielded gas welding. The welded structure utilizes a front-end circumferential fillet weld followed by a rear-end circumferential semi-U-shaped weld. Tests have confirmed that this welding method and structure no longer meet the special operating requirements of high-torque transmissions. The primary failures are the opening / fracture of the rear-end circumferential semi-U-shaped weld seam and gear tooth breakage due to excessive weld shaft position tolerance. Furthermore, due to cost factors and the limitations of the transmission's overall structure, increasing the fatigue strength of the auxiliary transmission shaft by either lengthening the weld shaft or increasing the center distance is undesirable. This makes the fatigue strength of the auxiliary transmission shaft a bottleneck restricting the development of high-torque transmissions.

[0004] At the same time, existing transmissions can experience weld seam cracking or breakage on the auxiliary shaft during use under certain road conditions and complex environments, impacting the reliability and service life of the transmission assembly. Therefore, there is an urgent need to significantly increase the fatigue life of the auxiliary shaft, both for the development of high-torque transmissions and for addressing after-sales issues with existing welded shafts. Summary of the Invention

[0005] In view of the above problems, the purpose of the present invention is to provide a transmission auxiliary box welded shaft structure and processing method based on electron beam welding to solve the problem of low fatigue life of the transmission auxiliary box welded shaft.

[0006] To achieve the above-mentioned purpose, the technical solutions adopted by the present invention include:

[0007] A transmission auxiliary box welding shaft structure based on electron beam welding includes an intermediate shaft and an intermediate shaft transmission gear with an interference sleeve arranged on the intermediate shaft, a positioning shoulder is provided at the rear end of the connection between the intermediate shaft and the intermediate shaft transmission gear, a positioning recessed stop matching the positioning shoulder structure is provided in the rear end of the intermediate shaft transmission gear, and a gap is left between the outer periphery of the positioning shoulder and the inner periphery of the positioning recessed stop; a first exhaust ring groove is provided at the non-end portion of the inner periphery of the intermediate shaft transmission gear; a second exhaust ring groove is provided at the contact point between the intermediate shaft and the first exhaust ring groove, a first exhaust groove connected to the second exhaust ring groove is provided between the second exhaust ring groove and the positioning shoulder, and a second exhaust groove connecting the first exhaust groove with the outer periphery of the positioning shoulder is provided on the positioning shoulder.

[0008] Preferably, the first exhaust ring groove and the second exhaust ring groove are both perfect circles.

[0009] Preferably, the axis of the first exhaust groove is a straight line, and the axis of the first exhaust groove is parallel to the axis of the intermediate shaft transmission gear.

[0010] Preferably, the axis of the second exhaust groove is a straight line, and the axis of the second exhaust groove is perpendicular to the axis of the intermediate shaft transmission gear.

[0011] Preferably, the annular exhaust groove formed by the first exhaust ring groove and the second exhaust ring groove has a width K1=2.8 mm, a depth h1=1.6 mm, a depth h2=0.5 mm, and a depth h3=0.5 mm.

[0012] Preferably, the interference between the intermediate shaft transmission gear and the intermediate shaft is 0.055-0.095 mm.

[0013] Preferably, the diameter of the shaft hole between the intermediate shaft transmission gear and the intermediate shaft is d1 = 112 mm, the diameter of the rear end of the intermediate shaft is d2 = 80 mm, the diameter of the positioning shoulder is d3 = 122 mm, the thickness of the positioning shoulder is H1 = 7 mm, the weld depth from the first exhaust ring groove to the front end of the intermediate shaft transmission gear is H2 = 17 mm, the weld excess height is h0 = 0 ~ 1 mm, and the length of the first exhaust groove is L = 19.1 mm.

[0014] Preferably, the parameters of electron beam welding are as follows: preheating the entire structure to 150±5° C. before welding, welding speed of 10±2.5 mm / s, electron gun high voltage of 70±5 kV, and welding beam current of 45 mA to 65 mA.

[0015] A method for processing a transmission auxiliary box welded shaft based on electron beam welding is based on the transmission auxiliary box welded shaft structure based on electron beam welding disclosed in this application, and the specific steps are as follows:

[0016] The first step is to complete the processing of the intermediate shaft transmission gear and the intermediate shaft to obtain the intermediate shaft transmission gear semi-finished product and the intermediate shaft semi-finished product;

[0017] Step 2: Clean and heat the intermediate shaft transmission gear semi-finished product and the intermediate shaft semi-finished product, and then press-fit the intermediate shaft transmission gear onto the intermediate shaft to obtain the welded shaft semi-finished product;

[0018] The third step is to perform end face circumferential electron beam welding on the semi-finished welded shaft to obtain the welded shaft;

[0019] Step 4: Grind the intermediate shaft transmission gear on the welded shaft to obtain the welded shaft after gear grinding;

[0020] Step 5: Shot peening the welded shaft after gear grinding to obtain the transmission auxiliary box welded shaft.

[0021] Compared with the prior art, the advantages of the present invention are:

[0022] (1) The transmission auxiliary box welded shaft structure and processing method based on electron beam welding of the present invention have completely broken the bottleneck of insufficient weld strength of the auxiliary box welded shaft faced by the development of high-torque transmissions, laying the foundation for the development of high-torque transmissions; it has solved the market problem of weld opening / fracture caused by the auxiliary box welded shaft structure based on argon arc welding, which can reduce the market failure rate, reduce after-sales maintenance costs, and greatly improve the reliability of the transmission; in response to the problem of thermal deformation of the tooth profile and tooth direction of the intermediate shaft transmission gear during electron beam welding, the innovative post-weld grinding process has solved its thermal deformation problem and greatly improved the qualified rate of the welded shaft.

[0023] (2) The present invention provides a transmission auxiliary box welding shaft structure and processing method based on electron beam welding. While the overall appearance and dimensions of the existing auxiliary box welding shaft remain unchanged and the existing gear tooling remains unchanged, the front end circumferential corner weld + rear end circumferential semi-U-shaped weld of the original structure is eliminated. The existing advanced electron beam welding technology is adopted, and the direction of the electron beam weld is arranged along the axial direction, that is, end face circumferential electron beam welding. From the perspective of force, the rear end circumferential semi-U-shaped weld of the original structure is subjected to bending moment, torque and axial force, while the electron beam weld is only subjected to torque and axial force.

[0024] (3) The transmission auxiliary box welding shaft structure based on electron beam welding of the present invention realizes the exhaust of gas through the cooperation of the first exhaust ring groove, the second exhaust ring groove, the first exhaust groove and the second exhaust groove, which well ensures the welding quality of the electron beam welded shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the following detailed description, they are used to explain the present invention but do not constitute a limitation of the present invention. In the accompanying drawings:

[0026] Figure 1 The figure is a schematic diagram of the existing auxiliary box welding shaft structure based on argon arc welding;

[0027] Figure 2 Schematic diagram of the transmission auxiliary box welding shaft structure based on electron beam welding in Example 1;

[0028] Figure 3 for Figure 2 A partial enlarged view of detail C;

[0029] Figure 4 for Figure 2 A three-dimensional view of the intermediate shaft transmission gear;

[0030] Figure 5 for Figure 2 A perspective view of the intermediate shaft;

[0031] Figure 6 Schematic diagram of the processing method of Example 2.

[0032] The symbols in the figure represent:

[0033] 1 intermediate shaft transmission gear, 1-1 first exhaust ring groove, 1-2 positioning concave stop;

[0034] 2 intermediate shaft, 2-1 positioning shaft shoulder, 2-2 second exhaust ring groove, 2-3 first exhaust groove, 2-4 second exhaust groove. DETAILED DESCRIPTION

[0035] The invention is not limited to the following specific embodiments, and all equivalent modifications made on the basis of the technical solution of this application fall within the protection scope of the present invention.

[0036] It should be noted that the directional terms mentioned in this article, such as "inner cavity", "inner periphery", "inner wall" and "outside", are consistent with the specific directions on the paper in the drawings of the specification or the corresponding directions of the space shown in the drawings; all components and equipment in the present invention, unless otherwise specified, are all components and equipment known in the prior art.

[0037] Example 1

[0038] The present embodiment discloses a transmission auxiliary box welded shaft structure based on electron beam welding, comprising an intermediate shaft 2 and an intermediate shaft transmission gear 1 with an interference sleeve mounted on the intermediate shaft 2. A positioning shoulder 2-1 is provided at the rear end of the connection between the intermediate shaft 2 and the intermediate shaft transmission gear 1. A positioning recessed stop 1-2 matching the structure of the positioning shoulder 2-1 is provided in the rear end of the intermediate shaft transmission gear 1, with a gap being left between the outer periphery of the positioning shoulder 2-1 and the inner periphery of the positioning recessed stop 1-2. A first exhaust ring groove 1-1 is provided on the inner periphery of the intermediate shaft transmission gear 1 at a non-end portion. A second exhaust ring groove 2-2 is provided at the contact portion between the intermediate shaft 2 and the first exhaust ring groove 1-1. A first exhaust groove 2-3 communicating with the second exhaust ring groove 2-2 is provided between the second exhaust ring groove 2-2 and the positioning shoulder 2-1. A second exhaust groove 2-4 communicating with the first exhaust groove 2-3 and the outer periphery of the positioning shoulder 2-1 is provided on the positioning shoulder 2-1.

[0039] While maintaining the overall dimensions of the existing auxiliary gearbox welded shaft and the existing gear alignment tooling, the original structure's front-end circumferential fillet weld and rear-end circumferential semi-U-shaped weld were eliminated. Advanced electron beam welding technology was adopted, with the electron beam welds arranged axially, i.e., end-face circumferential electron beam welding. Analysis of the forces involved revealed that the rear-end circumferential semi-U-shaped weld in the original structure was subject to bending moment, torque, and axial force, while the electron beam weld was only subject to torque and axial force.

[0040] It has overall broken the bottleneck of insufficient weld strength of the auxiliary box welded shaft faced by the development of high-torque transmissions, laying the foundation for the development of high-torque transmissions; it has solved the market problem of weld opening / fracture caused by the auxiliary box welded shaft structure based on argon arc welding, which can reduce the market failure rate, reduce after-sales maintenance costs, and greatly improve the reliability of the transmission; in response to the problem of thermal deformation of the tooth profile and tooth direction of the intermediate shaft transmission gear during electron beam welding, the innovative post-weld grinding process has solved its thermal deformation problem and greatly improved the qualified rate of the welded shaft.

[0041] In this embodiment, since the welding depth H2 is 17 mm, which is relatively deep, and considering that the internal gas cannot be discharged during the electron beam welding process, resulting in the formation of porosity defects inside the weld, the gas is discharged through the cooperation of the first exhaust ring groove 1-1, the second exhaust ring groove 2-2, the first exhaust groove 2-3 and the second exhaust groove 2-4, thereby ensuring the welding quality of the electron beam welded shaft. The gas exhaust path is as follows: Figure 3 As shown by the red arrow in .

[0042] In this embodiment, the parameters of electron beam welding between the intermediate shaft transmission gear 1 and the intermediate shaft 2 are as follows: preheating the entire assembly to 150±5°C before welding, welding speed 10±2.5 mm / s, electron gun high voltage 70±5 kV, welding beam current 45 mA to 65 mA.

[0043] In this embodiment, the first exhaust ring groove 1-1 and the second exhaust ring groove 2-2 are both perfect circles; the axis of the first exhaust groove 2-3 is a straight line, and the axis of the first exhaust groove 2-3 is parallel to the axis of the intermediate shaft transmission gear 1; the axis of the second exhaust groove 2-4 is a straight line, and the axis of the second exhaust groove 2-4 is perpendicular to the axis of the intermediate shaft transmission gear 1.

[0044] In this embodiment, the annular exhaust groove formed by the first exhaust ring groove 1-1 and the second exhaust ring groove 2-2 has a width K1 of 2.8 mm and a depth h1 of 1.6 mm. The first exhaust groove 2-3 has a depth h2 of 0.5 mm, and the second exhaust groove 2-4 has a depth h3 of 0.5 mm. The interference fit between the intermediate shaft transmission gear 1 and the intermediate shaft 2 is 0.055 to 0.095 mm. The matching diameter of the shaft hole between the intermediate shaft transmission gear 1 and the intermediate shaft 2 is d1 of 112 mm, the rear end diameter of the intermediate shaft 2 is d2 of 80 mm, the diameter of the locating shoulder 2-1 is d3 of 122 mm, and the thickness of the locating shoulder 2-1 is H1 of 7 mm. The weld depth H2 from the first exhaust ring groove 1-1 to the front end of the intermediate shaft transmission gear 1 is 17 mm, the weld reinforcement h0 is 0 to 1 mm, and the length L of the first exhaust groove 2-3 is 19.1 mm.

[0045] The weld depth H2 of this embodiment can reach 17 mm, which greatly improves the strength of the connection between the intermediate shaft transmission gear 1 and the intermediate shaft 2 .

[0046] The weld reinforcement h0 of this embodiment is 0~1mm. The analysis results of CAE software show that this is beneficial to reducing the stress value of the weld toe and can effectively improve the weld quality. There are two main measures to control the weld reinforcement. First, the welding parameters are controlled during the welding process to directly control the weld reinforcement. Second, the weld reinforcement is indirectly controlled by grinding after welding. After experimental verification, the weld reinforcement of the auxiliary box welding shaft based on electron beam welding in this patent can be directly controlled by welding process parameters, which greatly improves production efficiency.

[0047] The shaft hole fitting diameter d1 of this embodiment is 112 mm, and the interference is 0.055 to 0.095 mm. Compared with the argon arc welding auxiliary box welding shaft, the shaft hole fitting diameter is increased by 2 times. After theoretical calculation, the interference torque transmission energy of the auxiliary box welding shaft structure based on electron beam welding can be increased by 2.8 times, which greatly alleviates the bearing pressure of the electron beam weld.

[0048] The rear end diameter d2 of the intermediate shaft in this embodiment is 80 mm. Since the front end circular corner weld + rear end circular semi-U-shaped weld of the original structure are cancelled and the weld excess height problem is not considered, the rear end diameter of the intermediate shaft is increased to 80 mm. Compared with the argon arc welding auxiliary box welded shaft, the diameter at the rear end weld is increased by 1.1 times. The increase in the diameter of the intermediate shaft at this position significantly improves the torsional and bending resistance of the intermediate shaft.

[0049] The locating shoulder 2-1 of this embodiment has a single-side height of (d3-d1) / 2 = 5 mm and a thickness of H1 = 7 mm. This locating shoulder has two main functions: first, it press-fits the intermediate shaft transmission gear 1 onto the intermediate shaft 2 for axial positioning; second, during actual operation, the locating shoulder 2-1 of the auxiliary gearbox welded shaft withstands the backward axial force.

[0050] In this embodiment, the front end surface of the interference fit section of the intermediate shaft 2 is forged into an annular groove structure in consideration of material cost, thereby achieving the dual purposes of reducing cost and weight.

[0051] Example 2

[0052] This embodiment discloses a method for processing a transmission auxiliary box welding shaft based on electron beam welding. Based on the transmission auxiliary box welding shaft structure of Example 1, the specific steps are as follows:

[0053] The first step is to complete the processing of intermediate shaft transmission gear 1, that is, only complete all pre-heating processes (differential gear grinding process and shot peening process); and complete the processing of intermediate shaft 2, that is, only complete all pre-shot peening processes (differential shot peening process), to obtain the semi-finished intermediate shaft transmission gear 1 and the semi-finished intermediate shaft 2;

[0054] Step 2: Clean and heat the intermediate shaft transmission gear 1 and intermediate shaft 2 semi-finished products, then press fit the intermediate shaft transmission gear 1 onto the intermediate shaft 2 by interference fit to obtain the welded shaft semi-finished product;

[0055] Step 3: After the semi-finished welded shaft is cooled, the end face circumferential electron beam welding operation is performed to obtain the welded shaft;

[0056] Step 4: Grind the intermediate shaft transmission gear 1 on the welded shaft to obtain a welded shaft after gear grinding;

[0057] Step 5: Shot peening the welded shaft after gear grinding to obtain the transmission auxiliary box welded shaft.

[0058] There are two differences in the assembly process compared to the original structure. First, due to the increase in the interference fit, the preheating temperature of the intermediate shaft transmission gear 1 is appropriately increased before press-fitting. Second, since the welding method is replaced by electron beam welding instead of the original argon arc welding, the welding equipment and welding tooling have changed. At the same time, in order to achieve the required welding depth, the welding process parameters need to be completely adjusted and optimized. The process parameters involved in the entire process are not described in detail here.

[0059] Compared with the original grinding-then-welding process, this patented post-weld gear grinding process solves the problem of severe thermal deformation and warping of the intermediate shaft transmission gear 1. The total tooth profile deviation Fα of the intermediate shaft transmission gear 1 is increased from 21.6 to 6.7, an increase of 68%; the tooth profile shape deviation ffα is increased from 7.3 to 4.5, an increase of 38%; the total tooth direction deviation Fβ is increased from 61.1 to 4.7, an increase of 92%; the tooth direction shape deviation ffβ is increased from 3.4 to 1.5, an increase of 56%, significantly improving the product qualification rate.

[0060] Under identical test conditions and parameters, when equipped with a high-torque, heavy-duty mechanical transmission, the patented electron-beam-welded transmission auxiliary shaft structure, compared to the existing argon-arc-welded transmission auxiliary shaft structure, showed a 2-3x improvement in fatigue life and a 1.4x increase in cost. Therefore, the patented electron-beam-welded transmission auxiliary shaft structure can significantly improve transmission reliability in high-torque transmissions.

[0061] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings. However, the present disclosure is not limited to the specific details of the above embodiments. Within the technical concept of the present disclosure, various simple modifications can be made to the technical solutions of the present disclosure, and these simple modifications all fall within the scope of protection of the present disclosure.

[0062] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0063] In addition, the various different implementation methods disclosed in this solution can also be arbitrarily combined, as long as they do not violate the ideas of this disclosure, they should also be regarded as the content invented by this disclosure.

Claims

1. A transmission auxiliary box welding shaft structure based on electron beam welding, characterized in that: The invention comprises an intermediate shaft (2) and an intermediate shaft transmission gear (1) which is interference-fitted on the intermediate shaft (2); a positioning shoulder (2-1) is provided at the rear end of the connection between the intermediate shaft (2) and the intermediate shaft transmission gear (1); a positioning concave stop (1-2) which matches the structure of the positioning shoulder (2-1) is provided inside the rear end of the intermediate shaft transmission gear (1); a gap is left between the outer periphery of the positioning shoulder (2-1) and the inner periphery of the positioning concave stop (1-2); The intermediate shaft transmission gear (1) is provided with a first exhaust ring groove (1-1) at a non-end portion of the inner circumference; A second exhaust ring groove (2-2) is provided at the contact point between the intermediate shaft (2) and the first exhaust ring groove (1-1); a first exhaust groove (2-3) communicating with the second exhaust ring groove (2-2) is provided between the second exhaust ring groove (2-2) and the positioning shoulder (2-1); and a second exhaust groove (2-4) communicating the first exhaust groove (2-3) with the outer periphery of the positioning shoulder (2-1) is provided on the positioning shoulder (2-1).

2. The transmission auxiliary box welding shaft structure based on electron beam welding according to claim 1 is characterized in that: The first exhaust ring groove (1-1) and the second exhaust ring groove (2-2) are both perfect circles.

3. The transmission auxiliary box welding shaft structure based on electron beam welding according to claim 1 is characterized in that: The axis of the first exhaust groove (2-3) is a straight line, and the axis of the first exhaust groove (2-3) is parallel to the axis of the intermediate shaft transmission gear (1).

4. The transmission auxiliary box welding shaft structure based on electron beam welding according to claim 1, characterized in that: The axis of the second exhaust groove (2-4) is a straight line, and the axis of the second exhaust groove (2-4) is perpendicular to the axis of the intermediate shaft transmission gear (1).

5. The transmission auxiliary box welded shaft structure based on electron beam welding according to any one of claims 1 to 4, characterized in that: The annular exhaust groove formed by the first exhaust ring groove (1-1) and the second exhaust ring groove (2-2) has a width K1=2.8mm and a depth h1=1.6mm. The first exhaust groove (2-3) has a depth h2=0.5mm, and the second exhaust groove (2-4) has a depth h3=0.5mm.

6. The transmission auxiliary box welding shaft structure based on electron beam welding according to claim 5, characterized in that: The interference between the intermediate shaft transmission gear (1) and the intermediate shaft (2) is 0.055-0.095 mm.

7. The transmission auxiliary box welding shaft structure based on electron beam welding according to claim 6, characterized in that: The shaft hole matching diameter d1 between the intermediate shaft transmission gear (1) and the intermediate shaft (2) is 112 mm, the diameter d2 of the rear end of the intermediate shaft (2) is 80 mm, the diameter d3 of the positioning shoulder (2-1) is 122 mm, the thickness H1 of the positioning shoulder (2-1) is 7 mm, the weld depth H2 from the first exhaust ring groove (1-1) to the front end of the intermediate shaft transmission gear (1) is 17 mm, the weld height h0 is 0 to 1 mm, and the length L of the first exhaust groove (2-3) is 19.1 mm.

8. The transmission auxiliary box welding shaft structure based on electron beam welding according to claim 7 is characterized in that: The specific parameters of electron beam welding are: overall preheating to 150±5℃ before welding, welding speed 10±2.5mm / S, electron gun high voltage 70±5kv, welding beam current 45mA~65mA.

9. A method for processing a transmission auxiliary box welding shaft based on electron beam welding, characterized in that: The transmission auxiliary box welding shaft structure based on electron beam welding according to any one of claims 1 to 8 comprises the following specific steps: The first step is to complete the processing of the intermediate shaft transmission gear (1) and the intermediate shaft (2) to obtain the intermediate shaft transmission gear (1) semi-finished product and the intermediate shaft (2) semi-finished product; The second step is to clean and heat the intermediate shaft transmission gear (1) semi-finished product and the intermediate shaft (2) semi-finished product, and then press-fit the intermediate shaft transmission gear (1) onto the intermediate shaft (2) to obtain a welded shaft semi-finished product; The third step is to perform end face circumferential electron beam welding on the semi-finished welded shaft to obtain the welded shaft; Step 4: Grind the intermediate shaft transmission gear (1) on the welded shaft to obtain a welded shaft after gear grinding; Step 5: Shot peening the welded shaft after gear grinding to obtain the transmission auxiliary box welded shaft.

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