A resistance welding process and structure for a gear shaft hub assembly

Abstract

The present invention relates to a resistance welding process and structure for a gear shaft hub assembly, comprising the following steps: S1: Prepare the gear and the shaft hub; S2: Load the gear and the shaft hub in sequence; S3: Perform welding. The resistance welding machine is started, and the upper electrode descends to press the shaft hub. After the shaft hub is pressed, the lower surface of the shaft hub contacts the annular boss, and a fusion zone is formed between the lower surface of the shaft hub and the upper surface boss of the gear. After the pressure reaches the set value, the welding machine discharges electricity and the fusion zone generates heat, and the metal in the fusion zone liquefies. After the liquefied metal in the fusion zone solidifies, a fusion core is formed to connect the gear and the shaft hub together, and the excess metal enters the storage groove; S4: Take the workpiece. When the resistance welding machine discharges electricity, a large current passes through the fusion zone, and the metal in the fusion zone liquefies. After the fusion zone cools down, the gear and the shaft hub are welded together. This welding process has the characteristics of small heat-affected area and short welding time, etc. The workpiece has little deformation during welding, and at the same time, the production efficiency is independent of the diameter of the welded part, and the welding time is greatly shortened.

Description

Technical Field

[0001] The present invention relates to the field of resistance welding, and particularly relates to a resistance welding process and structure for a gear shaft hub assembly. Background Art

[0002] The current welding process for the gear and shaft hub of a gearbox is electron beam welding or laser welding. The process characteristics will cause the workpiece to deform due to overheating, and it is difficult to ensure the tolerances and dimensions such as coaxiality and runout after welding the gear and shaft hub. Moreover, this process requires the welding head to surround the outer side of the gear for one week, and the welding time is relatively long. The larger the gear, the longer the required welding time. Under the same production efficiency, the equipment investment is greater.

[0003] In the prior art, for example, Chinese Patent Application Publication No. CN113714642A discloses a gear welding method and a welded gear assembly. It uses a laser to perform formal welding on the upper end of the main interface. The pre-welding speed is within the first speed range, and a relatively deep weld seam will not be formed. Moreover, it provides an overall preheating effect to reduce the cooling stress of the part during formal welding, which can make the surfaces where the engaging teeth are connected to the gear have good bearing capacity and are not easily deformed after long-term use. However, the defect is that it still cannot ensure coaxiality and achieve short-time welding. Summary of the Invention

[0004] Aiming at the above-mentioned defects in the prior art, the technical problem to be solved by the present invention is how to ensure fast welding speed and small deformation of the gear shaft hub. The specific technical solutions are as follows:

[0005] A resistance welding process for a gear shaft hub assembly includes the following steps:

[0006] S1: Prepare a gear and a shaft hub. Both the gear and the shaft hub are made of conductive materials. The upper surface of the gear is pre-formed with annularly arranged bosses and surplus grooves;

[0007] S2: Load the gear and the shaft hub in sequence, use a positioning tooling to position and fix the gear and the shaft hub coaxially, electrically connect the gear to the lower electrode, and align the position of the upper electrode with the shaft hub;

[0008] S3: Perform welding. The resistance welding machine is started, the upper electrode descends to press the shaft hub. After the shaft hub is pressed, the lower surface of the shaft hub contacts the annular boss, and a fusion zone is formed between the lower surface of the shaft hub and the upper surface boss of the gear. After the pressure reaches the set value, the welding machine discharges electricity and the fusion zone generates heat. The metal in the fusion zone liquefies. After the liquefied metal in the fusion zone solidifies, a fusion core is formed to connect the gear and the shaft hub together, and the excess metal enters the surplus groove;

[0009] S4: Take the workpiece. The upper electrode returns to its original position, and the welded gear and shaft hub combined component is taken out.

[0010] As a preferred embodiment of the present invention, the boss is a continuous annular shape or an annular shape separated into several segments, and there are two circles of surplus grooves located on the inner and outer sides of the annular boss respectively.

[0011] As a preferred embodiment of the present invention, the cross-sectional shape of the boss is arc-shaped or triangular.

[0012] As a preferred embodiment of the present invention, a lower boss is provided at the bottom of the shaft hub, the bottom surface of the lower boss is the lower surface, and the upper electrode descends to press on the lower boss.

[0013] As a preferred embodiment of the present invention, the pressure set value is ≥12T, the average welding current is ≥35KA, and the peak current is ≥500KA.

[0014] As a preferred embodiment of the present invention, the positioning tooling includes an insert support member, a clamping transition member, a shaft hub positioning member, a movable insert, a lifting drive unit and a lifting drive shaft. The clamping transition member is movably sleeved inside the insert support member. A clamping transition conical surface is provided on the outer peripheral side of the upper part of the clamping transition member. The shaft hub positioning member is movably sleeved inside the clamping transition member. The shaft hub positioning member is of a hollow structure. A shaft hub conical surface is provided on the outer peripheral side of the upper part of the shaft hub positioning member. The shaft hub positioning member is provided with a plurality of shaft hub positioning empty grooves arranged circumferentially around the axis of the shaft hub positioning member. The lower shaft of the shaft hub is inserted into the center of the shaft hub positioning member. The movable insert is movably installed above the insert support member. The lifting drive unit drives the lifting drive shaft to move up and down. The upper end of the lifting drive shaft is connected to the shaft hub positioning member. When the shaft hub positioning member moves downwards, it contracts and clamps the lower shaft of the shaft hub. At the same time, the clamping transition member drives the movable insert to move outwards, and the movable insert abuts against the inner side of the gear.

[0015] As a preferred embodiment of the present invention, the insert support member, the clamping transition member and the shaft hub positioning member are coaxially arranged. There are a plurality of movable inserts and they are arranged circumferentially around the central axis of the clamping transition member, and adjacent movable inserts are separated from each other.

[0016] As a preferred embodiment of the present invention, each movable insert is provided with a kidney-shaped groove. A screw passes through the kidney-shaped groove and is screwed to the insert support member. A spring is installed in the kidney-shaped groove. One end of the spring abuts against the inner wall of the kidney-shaped groove and the other end abuts against the screw.

[0017] A structure made by a resistance welding process of the above-mentioned gear shaft hub assembly, including a gear and a shaft hub, and the bottom surface of the shaft hub and the upper surface of the gear are bonded and fixed together by liquefied metal.

[0018] Beneficial effects: The welding area includes a boss and the surface contacting it. Since the lower surface of the shaft hub first contacts the annular boss after the shaft hub is pressed, when the resistance welding machine discharges, a large current passes through the welding area, and the metal in the welding area liquefies. After the welding area cools, the gear and the shaft hub are welded together. This welding process has the characteristics of a small heat-affected area and a short welding time. The workpiece has little deformation during welding, and at the same time, the production efficiency is independent of the diameter of the welded part, and the welding time is greatly shortened. In addition, due to the existence of the surplus groove, affected by the pressing force of the upper electrode, the excess liquefied metal can be squeezed into the surplus groove, and there will be no excess liquefied metal and gaps between the lower surface of the shaft hub and the boss on the upper surface of the gear. Brief Description of the Drawings

[0019] Figure 1 is the overall flow chart of the present invention;

[0020] Figure 2 is the schematic diagram of the cooperation between the shaft hub and the gear of the present invention;

[0021] Figure 3 is the structural cross-sectional view of the present invention;

[0022] Figure 4 is the three-dimensional view of the first embodiment of the annular boss of the present invention;

[0023] Figure 5 is the three-dimensional view of the second embodiment of the annular boss of the present invention;

[0024] Figure 6 is the three-dimensional view of the shaft hub of the present invention;

[0025] Figure 7 is the three-dimensional view of the positioning tooling of the present invention;

[0026] Figure 8 is the exploded view of the positioning tooling of the present invention;

[0027] Figure 9 is the top view of the positioning tooling of the present invention;

[0028] Figure 10 is the structural schematic diagram of the shaft hub and the gear before welding of the present invention;

[0029] Figure 11 is the structural schematic diagram of the shaft hub and the gear after welding of the present invention;

[0030] Figure 12 is the metallographic diagram of the welding fusion zone of the present invention. Detailed Embodiments

[0031] The following further describes the detailed embodiments of the present invention in conjunction with the drawings:

[0032] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the indicated position or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0033] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] As Figures 1 to 3 shown, a resistance welding process for a gear shaft hub assembly includes the following steps:

[0035] S1: Prepare the gear 1 and the shaft hub 2. Both the gear 1 and the shaft hub 2 are made of conductive materials to facilitate subsequent electrode power-on. The gear 1 is hollow and has a plurality of teeth on its outer peripheral side. A ring-shaped boss 11 and a surplus groove 12 are pre-formed on the upper surface of the gear 1 in a ring arrangement.

[0036] S2: Load the gear 1 and the shaft hub 2 in sequence. Place the gear 1 and the shaft hub 2 on the workbench of the resistance welding machine, and use the positioning tooling 3 to position and fix the gear 1 and the shaft hub 2 coaxially. Electrically connect the gear 1 to the lower electrode 4. Specifically, place the gear 1 directly on the lower electrode 4 and make it contact, and align the position of the upper electrode 5 with the shaft hub.

[0037] S3: Perform welding. Start the resistance welding machine. The upper electrode 5 descends to press the shaft hub 2. After the shaft hub 2 is pressed, the welding lower surface of the shaft hub 2 contacts the ring-shaped boss 11, and a fusion zone is formed between the lower surface of the shaft hub 2 and the upper surface boss of the gear 1. After the pressure reaches the set value, the welding machine discharges and the fusion zone heats up. The metal in the fusion zone liquefies to fix the gear 1 and the shaft hub 2 together as one body, and the excess metal enters the surplus groove 12.

[0038] S4: Take the workpiece. The upper electrode 5 resets, and take out the combined component of the gear 1 and the shaft hub 2 after welding.

[0039] As Figure 4 shown, Embodiment 1 of the ring-shaped boss: The ring-shaped boss 11 is a continuous ring. As Figure 5As shown in the figure, Embodiment 2 of the annular boss: The annular boss 11 is an annular shape separated into several segments. There are two circles of surplus grooves 12 located on the inner and outer sides of the annular boss 11 respectively, and the molten excess liquefied metal will flow into the surplus grooves 12. In addition, the cross-sectional shape of the annular boss 11 is arc-shaped or triangular.

[0040] As Figure 6 shown in the figure, a lower boss 21 is provided at the bottom of the shaft hub 2. The bottom surface of the lower boss 21 is the lower surface. The upper electrode 5 descends to press on the lower boss 21, and a lower shaft 22 is provided below the center of the shaft hub 2. The pressure setting value when the upper electrode 5 descends to press on the lower boss 21 is ≥12T. When the pressure is qualified, the capacitor discharges and is transmitted to the two workpieces through the electrodes. The electrode welding current is the welding average current ≥35KA, and the peak current ≥500KA. The welding area melts instantaneously, and the intermediate charging time of the capacitor does not exceed three seconds, enabling rapid welding.

[0041] As Figure 3 、 7 、As shown in Figure 8, the positioning tooling 3 includes an insert support 31, a clamping transition member 32, a shaft hub positioning member 33, a movable insert 34, a lifting drive unit 35, and a lifting drive shaft 36. The insert support 31 is installed in a fixed sleeve 37, and the fixed sleeve 37 is installed below a fixed plate 38. The clamping transition member 32 is movably sleeved inside the insert support 31. A clamping transition conical surface 32a is provided on the outer peripheral side of the upper part of the clamping transition member 32. The shaft hub positioning member 33 is movably sleeved inside the clamping transition member 32a. The shaft hub positioning member 33 is a hollow structure. A shaft hub conical surface 33a is provided on the outer peripheral side of the upper part of the shaft hub positioning member 33. The shaft hub positioning member 33 is provided with a plurality of shaft hub positioning slots 33b arranged circumferentially around the axis of the shaft hub positioning member. The lower shaft 22 of the shaft hub 2 is inserted into the center of the shaft hub positioning member 33. The movable insert 34 is movably installed above the insert support 31. The lifting drive unit 35 is preferably a cylinder for driving the lifting drive shaft 36 to move up and down.

[0042] As Figure 3 shown in the figure, the lifting drive shaft 36 is provided with a large outer diameter section 361, a medium outer diameter section 362, and a small outer diameter section 363 from bottom to top. The diameter of the large outer diameter section 361 is greater than the diameter of the medium outer diameter section 362, and the diameter of the medium outer diameter section 362 is greater than the diameter of the small outer diameter section 363. The upper end of the small outer diameter section 363 is threadedly connected to the shaft hub positioning member 33. The large outer diameter section 361 passes through the insert support 31, and the upper step surface of the large outer diameter section 361 will abut against the bottom of the clamping transition member 32. The medium outer diameter section 362 passes through the clamping transition member 32. The small outer diameter section 363 is threadedly connected to the shaft hub positioning member 33. The insert support 31, the clamping transition member 32, and the shaft hub positioning member 33 are coaxially arranged. There are multiple movable inserts 34 arranged circumferentially around the central axis of the clamping transition member 32, and adjacent movable inserts 34 are separated from each other.

[0043] When the lifting drive shaft 36 moves upward, it drives the hub shaft positioning member 33 and the clamping transition member 32 to move upward. At this time, the hub shaft positioning member 33 and the movable block 34 are in a loose state. When the lifting drive shaft 36 is pulled downward, it drives the hub shaft positioning member 33 to move downward under the downward pulling force. When it moves downward a certain distance, the outer conical surface of the hub shaft positioning member 33 contacts the inner conical surface of the clamping transition member 32, and the contacting conical surface drives the clamping transition member 32 to also move downward. When the clamping transition member 32 moves downward a certain distance, the outer conical surface of the clamping transition member 32 contacts the outer conical surface of the movable block 34 that is partially around the circumference. The clamping transition conical surface 32a drives the movable block 34 to expand outward until it supports the inner hole of the gear 1. At the same time, the outer conical surface of the hub shaft positioning member 33 is deformed inward by the reaction force to initially clamp the lower shaft of the shaft hub, making the gear and the shaft hub initially coaxial and achieving the positioning of two coaxial centers. Moreover, when the upper electrode presses on the shaft hub, the lower end surface of the lower shaft 22 of the shaft hub will exert a downward pressure on the hub shaft positioning member 33, making the clamping force of the hub shaft positioning member 33 on the lower shaft 22 of the shaft hub and the outward tension of the movable block 34 on the inner hole of the gear 1 greater, and the positions of the gear 1 and the shaft hub 2 more accurate.

[0044] As Figure 9 shown, the movable block 34 is provided with a waist-shaped groove 341. The screw 38 passes through the waist-shaped groove 341 and is screwed to the block support member 31. A spring 39 is installed in the waist-shaped groove 341. One end of the spring 39 abuts against the inner wall of the waist-shaped groove 341 and the other end abuts against the screw 38. When the clamping transition member 32 is in the upper position, the spring 39 drives the movable block 34 to contract to facilitate the insertion of the gear. When the clamping transition member 32 is in the lower position, the movable block 34 expands outward to facilitate supporting the gear.

[0045] As Figures 10 to 12 shown, a structure made by the resistance welding process of the above-mentioned gear shaft hub assembly includes a gear 1 and a shaft hub 2. The bottom surface of the shaft hub 1 and the annular boss on the upper surface of the gear are fixed together by melting and bonding. It can be seen from the metallographic diagram that the fusion zone is good, and the shapes of the two sides of the edge of the welding zone are not very different, and the welding effect is good.

[0046] In summary, the advantages of the resistance welding process and structure of a gear shaft hub assembly of the present invention are as follows:

[0047] ⑴ The design of the welding area is reasonable. The annular boss reduces the contact area, resulting in a large resistance. Under the condition of being subjected to a large pressure, a high current is applied, causing the annular boss to quickly heat up and melt. Then the upper and lower welding surfaces contact and are welded together. It has the characteristics of a small heat-affected area and a short welding time. The existence of the surplus groove ensures that there is no gap between the lower welding surface of the shaft hub and the upper welding surface of the gear due to excessive molten slurry, further enhancing the welding strength;

[0048] ⑵ Through the positioning function of the positioning tooling, the gear and the shaft hub are positioned and fixed coaxially. The deformation of the workpiece during welding is small. At the same time, the production efficiency is independent of the diameter of the welded part, and the welding time is greatly shortened.

[0049] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific implementation of the present invention is only limited to these descriptions. For those of ordinary skill in the technical field to which the present invention pertains, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, and all should be regarded as belonging to the protection scope of the present invention.

Claims

1. A resistance welding process for a gear hub assembly, characterized in that: The following steps are involved: S1: Prepare the gear and the hub. The gear and the hub are both made of conductive materials. The upper surface of the gear is pre-formed with an annular boss and a storage groove; S2: Install the gear and the hub in sequence, use a positioning tool to position and fix the gear and the hub coaxially, electrically connect the gear to the lower electrode, and align the upper electrode with the hub; S3: Welding is carried out. The resistance welding machine is started, and the upper electrode descends to press the hub. After the hub is pressed, the lower surface of the hub contacts the annular boss, and a fusion zone is formed between the lower surface of the hub and the upper surface boss of the gear. When the pressure reaches the set value, the welder discharges and heats the fusion zone, and the metal in the fusion zone liquefies. After the liquefied metal in the fusion zone solidifies, a molten core is formed to connect the gear and the hub together, and the excess metal enters the storage tank; S4: Take the material, reset the upper electrode, and take out the gear and hub assembly components after welding. The positioning tooling includes an insert support, a clamping transition piece, a hub positioning piece, a movable insert, a lifting drive unit and a lifting drive shaft, the insert support has a movably mounted clamping transition piece inside, the upper outer peripheral side of the clamping transition piece is provided with a clamping transition conical surface, the clamping transition piece has a movably mounted hub positioning piece inside, the hub positioning piece is a hollow structure, the upper outer peripheral side of the hub positioning piece is provided with a hub conical surface, the hub positioning piece is provided with a plurality of hub positioning slots arranged around the circumference of the hub positioning piece axis, the lower shaft of the hub is inserted into the center of the hub positioning piece, the movable insert is movably installed above the insert support, the lifting drive unit drives the lifting drive shaft to move up and down, the upper end of the lifting drive shaft is connected to the hub positioning piece, and the lower shaft of the clamping hub is contracted when the hub positioning piece moves downward, and at the same time, the clamping transition piece drives the movable insert to move outward and the movable insert presses against the inner side of the gear.

2. The resistance welding process for a gear shaft hub assembly according to claim 1, characterized in that: The boss is in the form of a continuous ring or a ring divided into several sections, and the residual groove has two circles respectively located on the inner and outer sides of the annular boss.

3. The resistance welding process for a gear shaft hub assembly according to claim 1 or 2, characterized in that: The cross-section of the boss is arc-shaped or triangular.

4. The resistance welding process for a gear shaft hub assembly according to claim 1, characterized in that: A lower boss is provided at the bottom of the hub, the bottom surface of the lower boss is the lower surface, and the upper electrode presses down on the lower boss.

5. The resistance welding process for a gear shaft hub assembly according to claim 1, characterized in that: Pressure setting value ≥12T, average welding current ≥35KA, peak current ≥500KA.

6. The resistance welding process for a gear shaft hub assembly according to claim 1, characterized in that: The insert support, the clamping transition piece and the shaft hub positioning piece are coaxially arranged. There are multiple movable inserts which are arranged circumferentially around the central axis of the clamping transition piece, and adjacent movable inserts are separated.

7. The resistance welding process for a gear shaft hub assembly according to claim 1, characterized in that: Each movable insert is provided with a waist-shaped groove. The screw passes through the waist-shaped groove and is screwed to the insert support. A spring is installed in the waist-shaped groove. One end of the spring presses against the inner wall of the waist-shaped groove and the other end presses against the screw.

8. A structure manufactured by the resistance welding process of the gear hub assembly according to any one of claims 1 to 7, characterized in that: The utility model comprises a gear and a shaft hub, wherein the bottom surface of the shaft hub and the upper surface of the gear are bonded and fixed together by liquefied metal.

Images