A tooling and method for manufacturing driven bevel gear assemblies using bar stock with a large aspect ratio.

Abstract

This invention relates to a tooling and method for fabricating driven bevel gear assemblies using high aspect ratio bar stock. This method involves separately forming the driven bevel gear and its shaft, then welding them together to achieve integrated forming and welding. This results in the overall forming of the driven bevel gear assembly, avoiding welding deformation issues caused by the structural features of the assembly, improving the assembly's yield rate, and providing a solution for assembly structural design. This method can utilize smaller diameter raw material bars to fabricate driven bevel gear assemblies, not only achieving overall forming of the driven bevel gear assembly but also improving material utilization, increasing efficiency, and reducing costs.

Description

Technical Field

[0001] This invention relates to a tooling and method for preparing driven bevel gear assemblies using bar stock with a large aspect ratio, belonging to the field of driven bevel gear assembly processing and manufacturing technology. Background Technology

[0002] Driven bevel gear assemblies are critical components in the mechanical transmission systems of aero-engines, helicopters, and other weapon systems. Operating under conditions of high speed, heavy load, complex stress, and drastic changes, they directly impact the performance and operational safety of these systems; failure can lead to catastrophic accidents. Domestically produced driven bevel gear assemblies typically consist of a driven bevel gear and a driven bevel gear shaft. Due to the relatively small diameter of the raw material bars used in high-performance driven bevel gear assemblies, the current manufacturing process involves separately forming the driven bevel gear and shaft before welding. This, coupled with pre-welding preparation, undoubtedly increases the number of steps, reduces efficiency, and, because of the thin walls of the driven bevel gear and shaft, easily causes stress concentration during welding, leading to deformation and ultimately component failure, thus increasing operating costs. Summary of the Invention

[0003] This invention addresses the aforementioned state of the prior art by providing a tooling and method for fabricating driven bevel gear assemblies using bar stock with a large aspect ratio. The purpose is to fabricate driven bevel gear assemblies using raw material bars with a smaller diameter, which not only enables the overall forming of the driven bevel gear assembly but also improves material utilization, increases efficiency, and reduces costs.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] This invention provides a tooling solution for manufacturing driven bevel gear assemblies using bar stock with a large aspect ratio. The tooling includes a limiting cylinder 3, the lower end of which is placed at the bottom of a basin-shaped bottom mold base 6. The central axes of the limiting cylinder 3 and the mold base 6 coincide. A through hole is machined at the center of the bottom of the mold base 6, within the inner diameter range of the limiting cylinder 3. A flow-guiding cylindrical plug 7 is installed inside the through hole. An annular pressing ring 2 is inserted into the upper part of the limiting cylinder 3. A cylindrical pressing head 1 is installed inside the pressing ring 2. The central axes of the pressing head 1 and the pressing ring 2 coincide with the central axis of the mold base 6. The pressing head 1, the pressing ring 2, the limiting cylinder 3, and the flow-guiding plug 7 can all move axially up and down. The diameter of the pressing head 1 is the same as the diameter of the through hole at the bottom of the mold base 6.

[0006] During implementation, the pressure head 1 and pressure ring 2, the pressure ring 2 and limit cylinder 3, and the shape control mold base 6 and guide plug 7 in this tooling are all transition fits.

[0007] During implementation, the pressure head 1, pressure ring 2, limiting cylinder 3, shape control mold base 6, and flow guide plug 7 in this tooling are all made of high-temperature alloy mold material.

[0008] The present invention also provides a method for preparing a driven bevel gear assembly using a bar stock with a large aspect ratio and the above-mentioned tooling, characterized in that the method comprises the following steps:

[0009] Step 1: Preparation of bar stock

[0010] Two steel bars of the same diameter are cut. One steel bar has a height-to-diameter ratio of 4 to 5 and is used as the driven bevel gear bar 5. The other steel bar has a height-to-diameter ratio of 1 to 2 and is used as the driven bevel gear shaft bar 4. The driven bevel gear bar 5 and the driven bevel gear shaft bar 4 together constitute the bar material for preparing the driven bevel gear assembly.

[0011] The driven bevel gear bar 5 and the driven bevel gear shaft bar 4 are machined on a lathe and their surfaces are cleaned with acetone and alcohol.

[0012] Step 2: Preparation before molding

[0013] After assembling the tooling, including the lower pressure head 1, lower pressure ring 2, limiting cylinder 3, shape control mold base 6, and guide plug 7, place them together in a heating furnace for heating at 400℃~600℃ for 2h~4h. After heating, clean the driven bevel gear shaft bar 4 and driven bevel gear bar 5 again with a 5% hydrochloric acid alcohol solution. Apply an antioxidant lubricant to the circumferential surface of the driven bevel gear shaft bar 4 and driven bevel gear bar 5, and place them into the assembled mold in sequence. The driven bevel gear bar 5 is located at the lower part of the limiting cylinder 3, and the driven bevel gear shaft bar 4 is located at the upper part of the limiting cylinder 3. Place the assembled mold and bar together in the heating furnace for reheating at 900℃~1070℃ for 1h~3h.

[0014] Step 3: Forming the driven bevel gear shaft

[0015] Keeping the limiting cylinder 3, the shaping mold base 6, and the guide plug 7 stationary, the lower pressure head 1 moves downward to form a reverse extrusion action on the driven bevel gear shaft bar 4. The pressure applied by the lower pressure ring 2 is 50MPa to 100MPa, and the movement speed of the lower pressure ring 2 is 0.5mm / s to 1mm / s. At the same time, the lower pressure ring 2 moves upward under its own weight and with the overflow of the reverse extrusion action of the driven bevel gear shaft bar 4. When the lower surface of the lower pressure head 1 contacts the upper surface of the driven bevel gear bar 5, the forming of the driven bevel gear shaft is completed.

[0016] Step 4: Forming the mating surface of the driven bevel gear assembly

[0017] After the driven bevel gear shaft is formed, the pressing head 1 maintains the downward pressure and movement speed in step three, but forces the pressing ring 2 to stop moving upward, so that the pressure of the pressing head 1 forming the reverse extrusion effect on the pressing ring 2 increases to 200MPa~300MPa, and is maintained at this pressure for 10s~30s, so that the mating surface of the driven bevel gear assembly is formed.

[0018] Step 5: Forming the driven bevel gear assembly

[0019] After completing the holding time in step four, keep the shape control mold base 6 and the guide plug 7 stationary, and move the lower pressure head 1 and the lower pressure ring 2 downwards simultaneously, while the limiting cylinder 3 moves upwards. The two movements are at the same speed, both 0.5mm / s to 1mm / s, so that the driven bevel gear bar 5 flows out from the gap between the lower end of the limiting cylinder 3 and the shape control mold base 6. After the inner cavity of the shape control mold base 6 is completely filled with the flowing driven bevel gear bar 5, the lower pressure ring 2 stops moving downwards, and the guide plug 7 is removed downwards, so that the lower pressure head 1 continues to move downwards at a speed of 0.5mm / s to 1mm / s, so that the lower pressure head 1 moves downwards through the through hole.

[0020] Step Six: Post-processing

[0021] Remove the pressure ring 2 and the limiting cylinder 3, take out the driven bevel gear assembly, and after cooling to room temperature, perform sandblasting.

[0022] In implementation, in step one, the height-to-diameter ratio of the driven bevel gear bar 5 is 4.5, and the height-to-diameter ratio of the driven bevel gear shaft bar 4 is 2.

[0023] In implementation, in step three, the pressure applied by the pressure ring 2 is 100 MPa, and the movement speed of the pressure ring 2 is 1 mm / s.

[0024] During implementation, in step four, the pressure on the pressure ring 2 caused by the reverse squeezing effect of the downward pressure head 1 should reach 300 MPa, and the pressure should be maintained for 20 seconds.

[0025] In practice, in step five, the downward movement of the pressing head 1 and the pressing ring 2 and the upward movement of the limiting cylinder 3 are at a speed of 1 mm / s.

[0026] The features and beneficial effects of the technical solution of this invention are as follows:

[0027] 1. The driven bevel gear and the driven bevel gear shaft are formed separately and then welded together, which improves the process to form a single welded assembly. This achieves the overall forming of the driven bevel gear assembly, avoids welding deformation problems caused by the structural features of the assembly, improves the qualification rate of the assembly, and provides a solution for the structural design of the assembly.

[0028] 2. The use of smaller diameter raw material bars to achieve integral forming of driven bevel gear components has promoted the advancement of manufacturing technology and avoided a series of related problems caused by slow material research and development and substandard quality, such as difficulty in controlling the microstructure of forgings and large machining volume.

[0029] 3. In the technical solution of the present invention, the driven bevel gear shaft is formed by reverse extrusion, the outer shape of the driven bevel gear is formed by reverse extrusion, and the internal through hole is formed by forward extrusion. By utilizing the tooling design and its reasonable mutual cooperation, forward extrusion and reverse extrusion are effectively combined, realizing the one-time integral forming of the driven bevel gear assembly with thin walls and complex structure, improving work efficiency and reducing work costs. Attached Figure Description

[0030] Figure 1 This is a diagram of the driven bevel gear assembly before it is formed.

[0031] Figure 2 Diagram showing the forming state of the driven bevel gear shaft;

[0032] Figure 3 This is a diagram showing the forming state of the driven bevel gear;

[0033] Figure 4 This is a diagram showing the state of the driven bevel gear assembly after forming.

[0034] Figure 5 This is a schematic diagram of the driven bevel gear assembly. Detailed Implementation

[0035] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0036] See appendix Figure 1 As shown, the tooling for preparing the driven bevel gear assembly using a high aspect ratio bar stock in the technical solution of this invention includes a limiting cylinder 3. The lower end of the limiting cylinder 3 is placed at the bottom of a basin-shaped bottom control mold base 6. The central axes of the limiting cylinder 3 and the control mold base 6 coincide. A through hole is machined at the center of the bottom of the control mold base 6. The through hole is located within the inner diameter range of the limiting cylinder 3. A flow-guiding cylindrical plug 7 is installed in the through hole. An annular pressing ring 2 is inserted into the upper part of the limiting cylinder 3. A cylindrical pressing head 1 is installed in the pressing ring 2. The central axes of the pressing head 1 and the pressing ring 2 coincide with the central axis of the control mold base 6. The pressing head 1, the pressing ring 2, the limiting cylinder 3, and the flow-guiding plug 7 can all move up and down along the axial direction. The diameter of the pressing head 1 is the same as the diameter of the through hole at the bottom of the control mold base 6.

[0037] In this fixture, the lower pressure head 1 and the lower pressure ring 2, the lower pressure ring 2 and the limiting cylinder 3, and the shape control mold base 6 and the flow guide plug 7 are all transition fits. In this fixture, the lower pressure head 1, the lower pressure ring 2, the limiting cylinder 3, the shape control mold base 6, and the flow guide plug 7 are all made of high-temperature alloy mold material.

[0038] The steps for preparing the driven bevel gear assembly using a bar stock with a large aspect ratio and the aforementioned tooling are as follows:

[0039] Step 1: Preparation of bar stock

[0040] Two steel bars of the same diameter are cut. One steel bar has a height-to-diameter ratio of 4.5 and is used as the driven bevel gear bar 5. The other steel bar has a height-to-diameter ratio of 2 and is used as the driven bevel gear shaft bar 4. The driven bevel gear bar 5 and the driven bevel gear shaft bar 4 together constitute the bar material for preparing the driven bevel gear assembly.

[0041] The driven bevel gear bar 5 and the driven bevel gear shaft bar 4 are machined on a lathe and their surfaces are cleaned with acetone and alcohol.

[0042] Step 2: Preparation before molding

[0043] After assembling the tooling, including the lower pressure head 1, lower pressure ring 2, limiting cylinder 3, shape control mold base 6, and guide plug 7, they are placed together in a heating furnace for heating at 500℃ for 4 hours. After heating, the driven bevel gear shaft bar 4 and driven bevel gear bar 5 are cleaned again with a 5% hydrochloric acid alcohol solution. Antioxidant lubricant is applied to the circumferential surface of the driven bevel gear shaft bar 4 and driven bevel gear bar 5, and they are placed into the assembled mold in sequence. The driven bevel gear bar 5 is located at the lower part of the limiting cylinder 3, and the driven bevel gear shaft bar 4 is located at the upper part of the limiting cylinder 3. The assembled mold and bar are then placed together in the heating furnace for reheating at 1000℃ for 2 hours.

[0044] Step 3: Forming the driven bevel gear shaft

[0045] Keeping the limiting cylinder 3, the shaping mold base 6, and the guide plug 7 stationary, the lower pressure head 1 moves downward to form a reverse extrusion action on the driven bevel gear shaft bar 4. The pressure applied by the lower pressure ring 2 is 100MPa, and the movement speed of the lower pressure ring 2 is 1mm / s. At the same time, the lower pressure ring 2 moves upward under its own weight and with the overflow of the reverse extrusion action of the driven bevel gear shaft bar 4. When the lower surface of the lower pressure head 1 contacts the upper surface of the driven bevel gear bar 5, the forming of the driven bevel gear shaft is completed.

[0046] Step 4: Forming the mating surface of the driven bevel gear assembly

[0047] After the driven bevel gear shaft is formed, the pressing head 1 maintains the downward pressure and movement speed in step three, but forces the pressing ring 2 to stop moving upward, so that the pressure of the pressing head 1 forming the reverse extrusion effect on the pressing ring 2 increases to 300MPa, and is maintained at this pressure for 20s, so that the mating surface of the driven bevel gear assembly is formed.

[0048] Step 5: Forming the driven bevel gear assembly

[0049] After the holding time in step four is completed, keep the control mold base 6 and the guide plug 7 stationary, and move the lower pressure head 1 and the lower pressure ring 2 downwards simultaneously, while the limiting cylinder 3 moves upwards. The two movements are at the same speed, both 0.5mm / s to 1mm / s, so that the driven bevel gear bar 5 flows out from the gap between the lower end of the limiting cylinder 3 and the control mold base 6. After the inner cavity of the control mold base 6 is completely filled with the flowing driven bevel gear bar 5, the lower pressure ring 2 stops moving downwards, and the guide plug 7 is removed downwards, so that the lower pressure head 1 continues to move downwards at a speed of 1mm / s, so that the lower pressure head 1 moves downwards through the through hole.

[0050] Step Six: Post-processing

[0051] Remove the pressure ring 2 and the limiting cylinder 3, take out the driven bevel gear assembly, and after cooling to room temperature, perform sandblasting.

Claims

1. A tooling for fabricating driven bevel gear assemblies using bar stock with a large aspect ratio, characterized in that: The tooling includes a limiting cylinder (3), the lower end of which is placed at the bottom of a basin-shaped bottom control mold base (6). The central axes of the limiting cylinder (3) and the control mold base (6) coincide. A through hole is machined at the center of the bottom of the control mold base (6). The through hole is located within the inner diameter range of the limiting cylinder (3). A flow guide cylindrical plug (7) is installed in the through hole. An annular pressing ring (2) is inserted into the upper part of the limiting cylinder (3). A cylindrical pressing head (1) is installed in the pressing ring (2). The central axes of the pressing head (1) and the pressing ring (2) coincide with the central axis of the control mold base (6). The pressing head (1), the pressing ring (2), the limiting cylinder (3), and the flow guide plug (7) can all move up and down along the axial direction. The diameter of the pressing head (1) is the same as the diameter of the through hole at the bottom of the control mold base (6).

2. The tooling for fabricating driven bevel gear assemblies using bar stock with a large aspect ratio as described in claim 1, characterized in that: In this tooling, the lower pressure head (1) and the lower pressure ring (2), the lower pressure ring (2) and the limiting cylinder (3), and the shape control mold base (6) and the guide plug (7) are all transition fits.

3. The tooling for fabricating driven bevel gear assemblies using bar stock with a large aspect ratio as described in claim 1, characterized in that: In this tooling, the lower pressure head (1), lower pressure ring (2), limiting cylinder (3), shape control mold base (6) and flow guide plug (7) are all made of high temperature alloy mold material.

4. A method for preparing a driven bevel gear assembly using a bar stock with a large aspect ratio and the above-mentioned tooling, characterized in that: The steps of this method are as follows: Step 1: Preparation of bar stock Two steel bars of the same diameter are cut. One steel bar has a height-to-diameter ratio of 4 to 5 and is used as the driven bevel gear bar (5). The other steel bar has a height-to-diameter ratio of 1 to 2 and is used as the driven bevel gear shaft bar (4). The driven bevel gear bar (5) and the driven bevel gear shaft bar (4) together constitute the bar material for preparing the driven bevel gear assembly. The driven bevel gear bar stock (5) and the driven bevel gear shaft bar stock (4) are machined on a lathe and the surfaces are cleaned with acetone and alcohol. Step 2: Preparation before molding After assembling the tooling, the pressure head (1), pressure ring (2), limiting cylinder (3), control mold base (6) and guide plug (7), put them together in the heating furnace for heating at a temperature of 400℃~600℃ and a holding time of 2h~4h. After heating, the driven bevel gear shaft bar (4) and driven bevel gear bar (5) are cleaned again with a 5% hydrochloric acid alcohol solution. Antioxidant lubricant is applied to the circumferential surface of the driven bevel gear shaft bar (4) and driven bevel gear bar (5), and they are placed into the assembled mold in sequence. The driven bevel gear bar (5) is located at the lower part of the limiting cylinder (3), and the driven bevel gear shaft bar (4) is located at the upper part of the limiting cylinder (3). The assembled mold and bar are put into the heating furnace for heating again at a temperature of 900℃~1070℃ and a holding time of 1h~3h. Step 3: Forming the driven bevel gear shaft Keeping the limiting cylinder (3), the shaping mold base (6) and the guide plug (7) stationary, the lower pressure head (1) moves downward to form a reverse extrusion action on the driven bevel gear shaft bar (4). The pressure applied by the lower pressure ring (2) is 50MPa to 100MPa, and the movement speed of the lower pressure ring (2) is 0.5mm / s to 1mm / s. At the same time, the lower pressure ring (2) moves upward under its own weight and with the overflow of the reverse extrusion action of the driven bevel gear shaft bar (4). When the lower surface of the lower pressure head (1) contacts the upper surface of the driven bevel gear bar (5), the forming of the driven bevel gear shaft is completed. Step 4: Forming the mating surface of the driven bevel gear assembly After the driven bevel gear shaft is formed, the pressing head (1) maintains the pressing force and speed in step three, but forces the pressing ring (2) to stop moving upward, so that the pressure of the pressing head (1) on the pressing ring (2) increases to 200MPa~300MPa and is maintained at this pressure for 10s~30s, so that the mating surface of the driven bevel gear assembly is formed. Step 5: Forming the driven bevel gear assembly After completing the holding time in step four, keep the shape control mold base (6) and the flow guide plug (7) still, and make the lower pressure head (1) and the lower pressure ring (2) move downward at the same time, while the limiting cylinder (3) moves upward. The two movements are at the same speed, both 0.5mm / s to 1mm / s, so that the driven bevel gear bar material (5) flows out from the gap between the lower end of the limiting cylinder (3) and the shape control mold base (6). After the inner cavity of the shape control mold base (6) is completely filled by the flowing driven bevel gear bar material (5), the lower pressure ring (2) stops moving downward, and the flow guide plug (7) is removed downward, so that the lower pressure head (1) continues to move downward at a speed of 0.5mm / s to 1mm / s, so that the lower pressure head (1) moves downward through the through hole. Step Six: Post-processing Remove the pressure ring (2) and the limiting cylinder (3), take out the driven bevel gear assembly, and after cooling to room temperature, perform sandblasting.

5. The method for preparing a driven bevel gear assembly using a bar stock with a large aspect ratio and the above-described tooling according to claim 4, characterized in that: In step one, the height-to-diameter ratio of the driven bevel gear bar stock (5) is 4.5, and the height-to-diameter ratio of the driven bevel gear shaft stock (4) is 2.

6. The method for preparing a driven bevel gear assembly using a bar stock with a large aspect ratio and the above-described tooling according to claim 4, characterized in that: In step three, the pressure applied by the pressure ring (2) is 100 MPa, and the movement speed of the pressure ring (2) is 1 mm / s.

7. The method for preparing a driven bevel gear assembly using a bar stock with a large aspect ratio and the above-described tooling according to claim 4, characterized in that: In step four, the pressure on the pressure ring (2) formed by the downward pressing head (1) should reach 300 MPa, and the pressure should be maintained for 20 seconds.

8. The method for preparing a driven bevel gear assembly using a bar stock with a large aspect ratio and the above-described tooling according to claim 4, characterized in that: In step five, the downward movement of the pressing head (1) and the pressing ring (2) and the upward movement of the limiting cylinder (3) are at a speed of 1 mm / s.

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