A method of cold forming a tooth profile with double-point positioning

Abstract

This invention discloses a method and apparatus for cold forming gear teeth with double-center positioning, comprising the following steps: 1) machining two center holes at both ends of a cold forging; 2) fixing the cold forging with the two center holes as positioning references, and forming a gear tooth shape on the cold forging. The double-center positioning method of this invention first pre-machines center holes into the cold forging, and then forms the gear tooth shape based on the double center holes as positioning references. This method effectively avoids the difficulty of centering the gear after cold precision forging, and the processed product only needs to be directly aligned with the double center holes for subsequent processing, greatly improving production efficiency and stability, and reducing manufacturing costs.

Description

Technical Field

[0001] This invention belongs to the field of machining technology, and in particular relates to a method for cold forming of tooth profiles with double-center positioning. Background Technology

[0002] The traditional method for machining cold-forged gear teeth involves first cold-forging the gear shape, then using machining to find the pitch circle datum and machining a shaft or hole as the datum for the gear shape. This datum is then used to machine other shapes. The biggest problem with this method is the need for datum conversion, which places very high demands on the pitch circle fixture and machining equipment. Therefore, the traditional manufacturing method suffers from high precision and high cost in finding the datum for cold-forged gear teeth.

[0003] Therefore, a cold forming method for tooth profiles with dual-center positioning is needed to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to overcome the problems existing in the prior art and provide a tooth profile cold forming method with double-center positioning.

[0005] The tooth profile cold forming method with double-center positioning of the present invention includes the following steps:

[0006] 1) Two center holes are machined at both ends of the cold forging;

[0007] 2) Fix the cold forging with the two center holes as positioning references, and form a tooth shape on the cold forging.

[0008] Preferably, in step 2), when forming the tooth shape on the cold forging, shapes other than the tooth shape do not participate in the forming process. The double-center forming tooth shape process falls into the category of micro-deformation, so the forming force of the tooth shape is small. The small forming force results in small elastic deformation of the mold, and the manufactured product has higher tooth shape precision.

[0009] Preferably, in step 2), when fixing the cold forging with the two center holes as positioning references, only the first and second centers are used to fix the cold forging through the two center holes.

[0010] Preferably, in step 2), a double-center mold is used to fix the cold forging. The double-center mold includes a first center, which includes a first center shaft and a first center sleeve. The first center sleeve has a first inner hole in the middle, which is connected to the first center shaft. The outer side of the first center sleeve has a toothed forming structure.

[0011] Preferably, the double-center mold further includes a second center, which includes a second center shaft and a second center sleeve. The second center sleeve has a second inner hole in the middle, and the second inner hole is connected to the second center shaft.

[0012] Preferably, in step 2), a double-center forging device is used to fix the cold forging and form a toothed shape on the cold forging. The double-center forging device includes an upper pressure ring, a punch, a punch pad, a center support block, a lower rectangular spring, an upper rectangular spring, an upper spring positioning pad, an upper pad, a first center, an upper template, an upper ring, a lower pad, a second center, a lower die, a lower template, a lower ring, and a lower pressure ring.

[0013] The lower template and the upper template are fixedly connected by a mold frame, and the upper template is set on the lower template;

[0014] A lower pad is provided below the lower template. The lower mold and the lower ring are provided on the lower template. The lower ring is provided on the outside of the lower mold. The lower pressure ring is provided on the lower ring and fixes the lower mold.

[0015] The lower template is provided with a first positioning hole, and the top support block and the lower rectangular spring are both provided in the first positioning hole. One end of the lower rectangular spring is connected to the top support block, and the other end of the lower rectangular spring is connected to the second top.

[0016] The upper spring positioning pad and the upper ring are both located below the upper template, and the upper ring is located on the outside of the upper spring positioning pad.

[0017] A punch pad is provided below the upper spring positioning pad, and the punch is mounted on the punch pad; the upper pressure ring is located below the upper ring and fixes the punch.

[0018] The upper spring positioning pad is provided with a second positioning hole, the upper rectangular spring and the first tip are disposed in the second positioning hole, and the upper rectangular spring is connected to the first tip.

[0019] Preferably, the assembly also includes a cylinder, a cylinder support plate, and a material blocking block. The cylinder support plate is mounted on the lower die plate, and the material blocking block is positioned above the lower pressure ring. The cover plate secures the material blocking block, and the cylinder is mounted on the outer side of the material blocking block. The cylinder is fixed by the cylinder support plate. This part of the structure is a mechanism to assist in the demolding of cold forgings. During the forming of the cold forging, the cylinder pushes the material blocking block in. When the cold forging is completed and the punch is pulled back, the forging will adhere tightly to the punch, and the material blocking plate mounted on the cylinder can firmly fix the forging onto the die under the action of the cover plate. After the punch is completely detached from the forging, the cylinder pulls out, pulling the material blocking plate away from the flange diameter of the forging. At this time, the forging can be removed from the die.

[0020] Beneficial effects: The double-center positioning tooth cold forming method of the present invention first pre-machines center holes into the cold forging part, and then forms the tooth shape based on the double center holes as positioning references. This method can effectively avoid the difficulty of finding the center of the gear after cold precision forging. The processed product only needs to be directly aligned with the double center holes for subsequent processing, which greatly improves production efficiency and stability, and reduces manufacturing costs. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a double-center forging device;

[0022] Figure 2 This is a cross-sectional view of the double-center forging device along the AA direction;

[0023] Figure 3 This is a schematic diagram of the first top-level structure;

[0024] Figure 4 It is the first apex AA-direction cross-section diagram;

[0025] Figure 5 This is a schematic diagram of the second apex structure;

[0026] Figure 6 This is the second-highest BB-direction cross-section. Implementation

[0027] The invention will now be described in further detail with reference to the accompanying drawings. Example

[0028] Please see Figure 3 As shown, the tooth profile cold forming method with double-center positioning of the present invention includes the following steps:

[0029] 1) Machin two center holes at both ends of the cold forging;

[0030] 2) Fix the cold forging 5 using the two center holes as positioning references, and form a tooth shape on the cold forging 5.

[0031] Preferably, in step 2, when forming the tooth shape on the cold forging, shapes other than the tooth shape do not participate in the forming process. The double-center tooth forming process falls under the category of small deformation, so the forming force of the tooth is small. The small forming force results in small elastic deformation of the mold, leading to higher tooth precision in the manufactured product. Specifically, in step 2, when fixing the cold forging 5 using the two center holes as positioning references, only the first center 14 and the second center 18 are used to fix the cold forging 5 through the two center holes. To meet the self-centering requirement of the double centers, the die and product only undergo coarse positioning with a large clearance fit. Before the mold's double centers are fully engaged, no mold restricts the product's degree of freedom. Under the action of the spring, the centers always protrude from the tooth forming area, ensuring that the double centers preferentially contact the workpiece, making it more reliable.

[0032] Please participate Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown, preferably, in step 2, a double-center mold is used to fix the cold forging. The double-center mold includes a first center 14, which includes a first center shaft 141 and a first center sleeve 142. The first center sleeve 142 has a first inner hole in its center, which is connected to the first center shaft 141. The outer side of the first center sleeve 142 has a toothed forming structure. The double-center mold also includes a second center 18, which includes a second center shaft 181 and a second center sleeve 182. The second center sleeve 182 has a second inner hole in its center, which is connected to the second center shaft 182. The split-type center structure fully considers the rationality of manufacturing, manufacturing the center and the outer sleeve separately. The outer sleeve can be machined with high-precision manufacturing methods to produce the tooth shape and its corresponding inner diameter, and then matched with the center. Such a center not only has high positioning accuracy but also more reliable manufacturing.

[0033] Please see Figure 1 and Figure 2As shown, a double-center forging device is used to fix and process the cold forging part 5, forming a toothed shape on the cold forging part 5. The double-center forging device includes an upper pressure ring 1, a punch 2, a punch pad 3, a center support block 4, a lower rectangular spring 7, an upper rectangular spring 8, an upper spring positioning pad 12, an upper pad plate 13, a first center 14, an upper template 15, an upper ring 16, a lower pad plate 17, a second center 18, a lower die 19, a lower template 20, a lower ring 21, and a lower pressure ring. The lower template 20 and the upper template 15 are fixedly connected by a die frame, with the upper template 15 set on the lower template 20. A lower pad plate 17 is set below the lower template 20. The lower die 19 and the lower ring 21 are set on the lower template 20, with the lower ring 21 located on the outside of the lower die 19. The lower pressure ring is set on the lower ring 21 and fixes the lower die 19. The lower template 20 is provided with a first positioning hole. The top support block 4 and the lower rectangular spring 7 are both set in the first positioning hole. One end of the lower rectangular spring 7 is connected to the top support block 4, and the other end of the lower rectangular spring 7 is connected to the second top 18.

[0034] Both the upper spring positioning pad 12 and the upper ring 16 are located below the upper template 15, with the upper ring 16 positioned outside the upper spring positioning pad 12. A punch pad 3 is located below the upper spring positioning pad 12, and a punch 2 is mounted on the punch pad 3. An upper pressure ring 1 is located below the upper ring 16 and secures the punch 2. The upper spring positioning pad 12 has a second positioning hole, within which the upper rectangular spring 8 and the first tip 14 are positioned, with the upper rectangular spring 8 connected to the first tip 14.

[0035] Preferably, it also includes a cover plate 6, a cylinder 10, a cylinder support plate 11, and a material blocking block 22. The cylinder support plate 11 is disposed on the lower template 20, and the material blocking block 22 is disposed above the lower pressure ring. The cover plate 6 fixes the material blocking block 22, and the cylinder 10 is disposed on the outside of the material blocking block 22. The cylinder 10 is fixed by the cylinder support plate 11.

[0036] As soon as the mold contacts the workpiece, the double centers act on the workpiece, holding it firmly. The toothed die corrects its position under the action of the upper center, preparing for the tooth forming process. The tooth is formed, and the upper center gradually retracts; when it reaches the lower limit, the tooth forming ends, and the mold is lifted for demolding.

[0037] Invention Principle: The double-center positioning forging tooth profile cold extrusion method of this invention avoids the problem of centering in transmission forged gears, making it simpler and cheaper to center the forged gear. Furthermore, the double-center forming process falls within the category of micro-deformation, resulting in low forming force. Low forming force leads to low elastic deformation of the die, resulting in higher precision tooth profiles in the manufactured product. The length of the formed tooth profile can be very long, and compared to traditional cold extrusion processes, there is no bending or taper of the tooth profile.

[0038] The tooth profile cold forming method with double-center positioning of the present invention first pre-machines center holes into the cold forging part, and then forms the tooth profile based on the double-center holes as positioning references. This method can effectively avoid the difficulty of finding the center of the gear after cold precision forging. The processed product only needs to be directly aligned with the double-center holes for subsequent processing, which greatly improves production efficiency and stability, and reduces manufacturing costs.

Claims

1. A method of cold forming a tooth profile with double-point positioning, characterized in that, It comprises the following steps: 1) two top hole are processed in both ends of cold forging piece; 2) two top hole is used as positioning reference to fix cold forging piece (5), and the shape of tooth profile is formed on the cold forging piece (5); In step 2), the double top die device is used to fix the cold forging piece (5), and the shape of tooth profile is formed on the cold forging piece (5), the double top die device comprises upper pressing ring (1), punch (2), punch pad (3), top support block (4), lower rectangular spring (7), upper rectangular spring (8), upper spring positioning pad (12), upper pad plate (13), first top (14), upper die plate (15), upper ring (16), lower pad plate (17), second top (18), lower die (19), lower die plate (20), lower ring (21) and lower pressing ring; The lower die plate (20) and the upper die plate (15) are fixedly connected through the die frame, and the upper die plate (15) is arranged above the lower die plate (20); The lower side of the lower die plate (20) is provided with a lower pad plate (17), the lower die (19) and the lower ring (21) are arranged on the lower die plate (20), the lower ring (21) is arranged on the outer side of the lower die (19), and the lower pressing ring is arranged on the lower ring (21) and fixes the lower die (19); The lower die plate (20) is provided with a first positioning hole, the top support block (4) and the lower rectangular spring (7) are arranged in the first positioning hole, one end of the lower rectangular spring (7) is connected with the top support block (4), and the other end of the lower rectangular spring (7) is connected with the second top (18); The upper spring positioning pad (12) and the upper ring (16) are arranged below the upper die plate (15), and the upper ring (16) is arranged on the outer side of the upper spring positioning pad (12); The lower side of the upper spring positioning pad (12) is provided with a punch pad (3), and the punch (2) is arranged on the punch pad (3); the upper pressing ring (1) is arranged below the upper ring (16) and fixes the punch (2); The upper spring positioning pad (12) is provided with a second positioning hole, the upper rectangular spring (8) and the first top (14) are arranged in the second positioning hole, and the upper rectangular spring (8) is connected with the first top (14).

2. The dual-anvil positioned cold shaping method of claim 1, wherein, In step 2), when the shape of tooth profile is formed on the cold forging piece, the shapes other than the tooth profile do not participate in the forming process.

3. The dual-anvil positioned cold shaping method of claim 1, wherein, In step 2), when the cold forging piece (5) is fixed by taking two top holes as positioning reference, only the first top (14) and the second top (18) are used to fix the cold forging piece (5) through two top holes.

4. The dual-anvil positioned cold shaping method of claim 1, wherein, In step 2), the double top die is used to fix the cold forging piece, and the double top die comprises a first top (14), the first top (14) comprises a first top shaft (141) and a first top sleeve (142), a first inner hole is arranged in the middle of the first top sleeve (142), the first inner hole is connected with the first top shaft (141), and a tooth forming structure is arranged on the outer side of the first top sleeve (142).

5. The dual-anvil positioned cold shaping method of claim 1, wherein, The double top die further comprises a second top pin (18), the second top pin (18) comprises a second top pin shaft (181) and a second top pin sleeve (182), a second inner hole is arranged in the middle of the second top pin sleeve (182), and the second inner hole is connected with the second top pin shaft (182) in a matched mode.

6. The dual-anvil positioned cold shaping method of claim 1, wherein, Further comprising a cover plate (6), a cylinder (10), a cylinder support plate (11) and a material blocking block (22), the cylinder support plate (11) is arranged on the lower die plate (20), the upper side of the lower pressing ring is provided with the material blocking block (22), the cover plate (6) fixes the material blocking block (22), and the outer side of the material blocking block (22) is provided with the cylinder (10), and the cylinder (10) is fixed through the cylinder support plate (11).

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