One-piece double gear cold extrusion molding die and cold extrusion molding method

Abstract

The present application relates to a mold and a cold extrusion molding method for an integrated double gear. The mold includes a lower template, a lower die seat, a limiting plate, a lower die, an upper die, a punch and an upper template. The lower die seat is arranged on the lower template; a lower die for forming small teeth and an upper die for forming large teeth are arranged on the inner side of the lower die seat. A gap for injecting lubricating oil is formed between the outer wall of the lower die and the inner wall of the lower die seat, and between the outer wall of the upper die and the inner wall of the lower die seat. The lower die is arranged on the lower template, and the upper die is arranged on the lower die; the limiting plate is annular and arranged on the top of the lower die seat; the punch is located above the lower template, and the upper template is connected to the top of the punch. The existing scheme adopts a cutting process, which requires processing two large and small teeth separately, which is time-consuming. The present application adopts a mold cold extrusion to form once, so the processing cycle is short and the efficiency is high. In the molding process, almost no excess material waste will be caused, so it has the advantages of high material utilization and low cost.

Description

Technical Field

[0001] The present application relates to the technical field of automobile gear processing, and in particular to a mold and a cold extrusion molding method for cold extrusion molding of an integrated double gear. Background Art

[0002] At present, the domestic double gear structure includes integral type and assembled type. The large and small gears of the assembled type are processed separately and then assembled. There are two ways to process the two gears. One is to cut them separately from round billets, and the other is to combine forging and cutting. The main assembly methods are electron beam welding, interference fit, etc. Its manufacturing method is inefficient, with low material utilization, long production cycle and high cost. The integral double gear uses forging billets to be rough-turned and fine-turned into gear billets. The large gear is processed by hobbing and the small gear is processed by gear shaping. It also has the disadvantages of low material utilization, long processing cycle and high cost. Summary of the invention

[0003] The embodiments of the present application provide a mold and a cold extrusion method for cold extrusion molding of an integrated double gear to solve the shortcomings of low material utilization, long processing cycle and high cost in the related art.

[0004] In a first aspect, a mold for cold extrusion molding of an integrated double gear is provided, comprising:

[0005] Next template;

[0006] A lower die base, the lower die base is arranged on the lower die plate; a lower die for forming small teeth and an upper die for forming large teeth are arranged on the inner side of the lower die base, a gap for pouring lubricating oil is formed between the outer wall of the lower die and the inner wall of the lower die base, and between the outer wall of the upper die and the inner wall of the lower die base, the lower die is arranged on the lower die plate, and the upper die is arranged on the lower die;

[0007] A limiting plate, which is annular and disposed on the top of the lower die base;

[0008] A male die, which is located above the lower die plate;

[0009] The upper mold plate is connected to the top of the punch.

[0010] In some embodiments, the large teeth are straight teeth, and the small teeth are straight teeth;

[0011] Or, the large teeth are helical and the small teeth are oblique;

[0012] Alternatively, the large teeth are straight and the small teeth are helical;

[0013] Alternatively, the large teeth are helical and the small teeth are straight.

[0014] In some embodiments, the helix angle of the helical teeth is less than or equal to 20°.

[0015] In some embodiments, the inner wall of the upper die is composed of a guide flow limiting area and a large tooth forming area from top to bottom;

[0016] And / or, a self-lubricating DLC ​​coating is deposited on the surfaces of the lower mold plate, the lower mold base, the limiting plate, the lower concave mold, the upper concave mold and the punch.

[0017] In some embodiments, the entry angle β of the upper die is 30° to 50°, and / or the working band length L1 of the upper die is 3 to 5 mm.

[0018] In some embodiments, the entry angle γ of the lower die is 40° to 50°, and / or the working band length L2 of the lower die is 3 to 5 mm.

[0019] In a second aspect, a cold extrusion forming method of an integrated double gear is provided, comprising:

[0020] Under protective atmosphere, the blank is annealed to reduce the hardness of the blank to below 130HB;

[0021] Shot peening is performed on the annealed blank;

[0022] The shot-peened blank is placed in the mold for cold extrusion of the one-piece double gear as described above, and cold extruded once to obtain a blank;

[0023] The blank is tempered and adjusted to a preset hardness to obtain an integrated duplex gear.

[0024] In some embodiments, the annealing process comprises the following steps:

[0025] The blank is heated to a first temperature and kept warm for a first time, wherein the first temperature is 760° C. to 800° C. and the first time is 23 h to 25 h;

[0026] Cooling the blank to a second temperature and keeping it at a second temperature for a second time, wherein the second temperature is 660° C. to 700° C. and the second time is 17 h to 19 h;

[0027] Finally, the furnace is stopped and cooled to the third temperature, and then air-cooled. The third temperature is 390°C to 410°C.

[0028] In some embodiments, the first temperature is 780° C., and the first time is 24 h;

[0029] The second temperature is 680°C and the second time is 18h;

[0030] The third temperature is 400°C.

[0031] In some embodiments, after the shot peening is completed and before the shot peened blank is placed into the mold, the following steps are further included:

[0032] The blank is immersed in a polymer lubricant and air-dried after being treated for a period of time.

[0033] The beneficial effects of the technical solution provided by this application include:

[0034] The existing solutions all have cutting processes. Compared with the existing solutions, the present application adopts a mold cold extrusion to form in one time. During the forming process, almost no excess material waste will be caused. Therefore, it has the advantages of high material utilization and low cost.

[0035] The existing solution uses cutting technology, which requires processing two large and small teeth separately, which is time-consuming. The present application uses a mold cold extrusion to form in one step, and the process only takes tens of seconds, so the processing cycle is short and the efficiency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0037] Figure 1 A schematic diagram of a mold closed according to an embodiment of the present application;

[0038] Figure 2 A schematic diagram of a mold opened according to an embodiment of the present application;

[0039] Figure 3 A schematic diagram of the die entry angle and working zone provided in the embodiment of the present application;

[0040] Figure 4 A flow chart of the cold extrusion molding method of an integrated double gear provided in an embodiment of the present application;

[0041] Figure 5 A schematic diagram of a bar material sawn to a specified size provided in an embodiment of the present application;

[0042] Figure 6 A schematic diagram of a blank having an inner hole punched into a specified shape provided in an embodiment of the present application;

[0043] Figure 7 A schematic diagram of a blank provided in an embodiment of the present application;

[0044] Figure 8 Schematic diagram of an integrated double gear provided in an embodiment of the present application.

[0045] In the figure: 1, lower template; 2, lower die base; 3, limiting plate; 4, lower die; 5, upper die; 50, guide flow limiting area; 51, large tooth forming area; 6, punch; 7, upper template. DETAILED DESCRIPTION

[0046] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0047] See also Figure 1 , Figure 2 and Figure 3 As shown, an embodiment of the present application provides a mold for cold extrusion molding of an integrated double gear, which includes a lower mold plate 1, a lower mold base 2, a limiting plate 3, a lower die 4, an upper die 5, a punch 6 and an upper mold plate 7.

[0048] Among them, the lower die base 2 is annular, and its internal area is the lower die cavity, and the lower die base 2 is arranged on the lower template 1; the lower die 4 and the upper die 5 are arranged on the inner side of the lower die base 2, and the lower die 4 and the upper die 5 are located in the above-mentioned lower die cavity, the lower die 4 is used to form small teeth, and the upper die 5 is used to form large teeth. A gap filled with lubricating oil is formed between the outer wall of the lower die 4 and the inner wall of the lower die base 2, and between the outer wall of the upper die 5 and the inner wall of the lower die base 2. Under the action of the gap and the lubricating oil, the lower die 4 and the upper die 5 can rotate in the lower die base 2, and move along the axial direction of the lower die base 2 to achieve demolding. The lower die 4 is arranged on the lower template 1, and the upper die 5 is arranged on the lower die 4.

[0049] The limit plate 3 is annular and is arranged on the top of the lower die base 2. The inner diameter of the limit plate 3 is smaller than the inner diameter of the lower die base 2. The punch 6 is located above the lower die plate 1, and the upper die plate 7 is connected to the top of the punch 6.

[0050] The mold for cold extrusion molding of the integrated double gear of the present application comprises a lower die 4 and an upper die 5, wherein the lower die 4 is used to form small teeth, and the upper die 5 is used to form large teeth. The molding of large and small teeth can be achieved at one time through cold extrusion, and because a gap filled with lubricating oil is formed between the outer wall of the lower die 4 and the inner wall of the lower die base 2, and between the outer wall of the upper die 5 and the inner wall of the lower die base 2, under the action of the gap and the lubricating oil, the lower die 4 and the upper die 5 can rotate in the lower die base 2, and move along the axial direction of the lower die base 2, thereby achieving smooth demolding of the double gear.

[0051] The existing solutions all have cutting processes. Compared with the existing solutions, the present application adopts a mold cold extrusion to form in one time. During the forming process, almost no excess material waste will be caused. Therefore, it has the advantages of high material utilization and low cost.

[0052] The existing solution uses cutting technology, which requires processing two large and small teeth separately, which is time-consuming. The present application uses a mold cold extrusion to form in one step, and the process only takes tens of seconds, so the processing cycle is short and the efficiency is high.

[0053] For duplex gears, the large teeth can be straight teeth or helical teeth, and the small teeth can also be straight teeth or helical teeth.

[0054] That is to say, there are four types of double gears, namely: A. The big teeth are straight teeth and the small teeth are straight teeth; B. The big teeth are helical teeth and the small teeth are helical teeth; C. The big teeth are straight teeth and the small teeth are helical teeth; D. The big teeth are helical teeth and the small teeth are straight teeth.

[0055] Based on this, the mold for cold extrusion molding of an integrated double gear provided in the present application has a gap filled with lubricating oil formed between the outer wall of the lower die 4 and the inner wall of the lower die base 2, and between the outer wall of the upper die 5 and the inner wall of the lower die base 2. Under the action of the gap and the lubricating oil, the lower die 4 and the upper die 5 can rotate in the lower die base 2 and move axially along the lower die base 2. Therefore, the above four gears can be smoothly cold extruded and demolded.

[0056] Among them, the helix angle of the helical teeth is less than or equal to 20°.

[0057] The rotation of the mold used for cold extrusion of one-piece double gears during the cold extrusion process and demoulding process is determined by the shape of the large and small gears of the double gears. The details are as follows:

[0058] A. Both the large and small teeth are straight teeth, and the parts can be demoulded directly after being ejected.

[0059] B. Both the large and small teeth are helical teeth. When the part is ejected, the upper die 5 and the lower die 4 rotate to demould the part.

[0060] C. The small tooth part is helical, the large tooth part is straight, the lower die 4 rotates, the upper die 5 does not rotate, and the parts are demoulded.

[0061] D. The small tooth part is straight teeth, the large tooth part is helical teeth, the upper die 5 rotates, the lower die 4 does not rotate, and the parts are demoulded.

[0062] See also Figure 2 As shown, in some preferred embodiments, the inner wall of the upper die 5 is composed of a guide flow limiting area 50 and a large tooth forming area 51 from top to bottom.

[0063] The upper half of the upper die 5 has no teeth, forming a guide flow limiting area 50. The purpose of the flow limiting area is to limit the flow direction of the metal during the cold extrusion process, so that the metal does not flow upward, causing the part to be drum-shaped during the extrusion process, resulting in the inability to successfully complete the cold extrusion process. The lower half is a large tooth forming area 51, see Figure 3 As shown, the die angle β of the upper die 5 is 30° to 50°. If the die angle β is less than 30°, the forming force is too large, which is not conducive to cold extrusion forming; if the die angle β is greater than 50°, the burr at the rear end of the large tooth of the part is large, and the front end collapse angle becomes smaller, and the front end of the tooth shape is not full. The working band length L1 is 3 to 5mm. If the working band length L1 is less than 3mm, the tooth shape deviation is large and the part precision is low. If the working band length L1 is greater than 5mm, it will cause metal sticking to the die.

[0064] See also Figure 3 As shown, the lower die 4 is not provided with a guide area. In order to prevent the blank from forming a drum shape during the cold extrusion process, the diameter of the small tooth part of the cold extruded blank is set to be smaller than the final outer diameter (the value of the smaller diameter depends on the specific part and the volume distribution, ensuring that the excess metal flows to the top of the tooth and preventing too much metal from flowing upward to form a drum shape). The entry angle γ of the lower die 4 is 40° to 50°. If the entry angle γ is too small, the forming force is large and it is easy to form a drum shape. If the entry angle γ is too large, the burr at the rear end of the small tooth of the part is long, the part to be processed becomes longer, and the front end collapse angle becomes smaller, and the front end of the tooth shape is not full. The working band length L2 of the lower die 4 is 3 to 5 mm. If the working band length L2 is less than 3 mm, the tooth shape deviation is large and the part precision is low. If the working band length L2 is greater than 5 mm, it will cause metal to stick to the die.

[0065] The lower die plate 1, the lower die seat 2, the limit plate 3, the lower die 4, the upper die 5 and the punch 6 are coated with self-lubricating DLC ​​(DIAMOND-LIKE CARBON) coating. This ensures that the die can rotate autonomously during the cold extrusion process, the helical teeth forming and demolding process, and the cold extrusion process and demolding process are carried out smoothly. At the same time, it increases the wear resistance and life of the working part of the mold. The parts of the mold that need to rotate are all provided with circulating lubricating oil to ensure that the upper and lower dies can rotate.

[0066] See also Figure 4 As shown, the embodiment of the present application provides an integrated double gear cold extrusion forming method, which includes the following steps:

[0067] 101: As Figure 5 As shown, a high-speed band saw is used to cut the bar material to the specified size, and warm forging is performed on the forging equipment to forge and punch the inner hole of the bar material to the specified shape of the blank, such as Figure 6 As shown. Under protective atmosphere, the blank is annealed to reduce the hardness of the blank to below 130HB.

[0068] Among them, warm forging is warm forging punching, the purpose of which is to forge the blanked bar into the shape required by the cold extruded billet, and the temperature is generally below the recrystallization temperature, such as 700±50°C. Compared with hot forging, the warm forging process adopted in this application has the advantages of low billet energy consumption and less oxidation and decarburization layer.

[0069] In the present application, the blank may be made of materials commonly used for duplex gears, such as 20CrMnTi, and the protective atmosphere may be argon or the like.

[0070] The purpose of annealing is to reduce the hardness of cold extrusion blanks, reduce the force of cold extrusion molding, and facilitate molding. The hardness is reduced to below 130HB. The cold extrusion gear has high precision and can reach level 8.5. Among them, the annealing process can be carried out in the following steps:

[0071] 201: placing the blank into a furnace, heating the blank to a first temperature, and keeping the temperature for a first time, wherein the first temperature is 760° C. to 800° C., and the first time is 23 h to 25 h; preferably, the first temperature is 780° C., and the first time is 24 h.

[0072] 202: Cooling the furnace to cool the blank to a second temperature and keeping it at the second temperature for a second time, wherein the second temperature is 660° C. to 700° C. and the second time is 17 h to 19 h; preferably, the second temperature is 680° C. and the second time is 18 h.

[0073] 203: Finally, the furnace is stopped and cooled to a third temperature, followed by air cooling. The third temperature is 390° C. to 410° C., and preferably, the third temperature is 400° C.

[0074] 102: Shot peening is performed on the annealed blank to remove the oxide scale, the blank is preheated to 80℃±2℃, and then immersed in a 40℃±2℃ polymer lubricant in a dry state. The blank basket is lifted up and down during immersion to ensure uniform immersion of the blank. After keeping it for 20s to 30s, it is lifted up and air-dried for extrusion. The polymer lubricant can be a commonly used water-based polymer lubricant.

[0075] 103: Put the shot peened blank into the above mold and cold extrude it once to obtain a blank. Figure 7 shown.

[0076] 104: The blank is tempered and adjusted to a preset hardness, and the excess part and other necessary parts are processed to obtain an integrated double gear, such as Figure 8 The purpose of tempering is to remove stress. The tempering temperature is 580℃, and the furnace is cooled after keeping it for 2 hours.

[0077] In the above step 101, the hardness of the blank is reduced to 130HB through annealing treatment. If the hardness of the blank is greater than 130HB, when the large and small teeth have helical teeth that need to be formed, the extrusion force is too large, resulting in low precision of the cold extruded sample, and even the tooth shape cannot be smoothly extruded in one cold extrusion forming.

[0078] In the above step 201, if the first temperature is less than 760°C, or the first time is less than 23h, the pearlite is not fully austenitized, and the structure is austenite + ferrite + pearlite. The final content of lamellar pearlite is high, so that the hardness cannot drop below 130HB. If the first temperature is greater than 800°C, or the first time is greater than 25h, the temperature is too high, resulting in excessively large grains, poor plastic forming properties of the parts, and poor cold extrusion properties of the billet.

[0079] In the above step 202, if the second temperature is less than 660°C, or the second time is less than 17h, the temperature is too low, the internal stress is too large, and bainite will appear when the temperature is lower than 550°C, so that the hardness cannot be reduced to below 130HB. If the second temperature is greater than 700°C, or the second time is greater than 19h, the temperature difference is too small, the transformation power is insufficient, the austenite cannot be completely transformed, the structure is uneven, and the final hardness cannot be reduced to below 130HB, which is not conducive to cold extrusion and subsequent processing.

[0080] Hereinafter, the present application will be described in detail through some embodiments and comparative examples.

[0081] Example 1

[0082] A cold extrusion molding method for an integrated double gear includes the following steps:

[0083] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0084] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0085] (2) Shot peening the annealed blank;

[0086] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0087] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0088] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0089] Example 2

[0090] A cold extrusion molding method for an integrated double gear includes the following steps:

[0091] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0092] The annealing furnace is heated to 790°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0093] (2) Shot peening the annealed blank;

[0094] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0095] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0096] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0097] Example 3

[0098] A cold extrusion molding method for an integrated double gear includes the following steps:

[0099] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0100] The annealing furnace is heated to 800°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0101] (2) Shot peening the annealed blank;

[0102] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0103] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0104] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0105] Example 4

[0106] A cold extrusion molding method for an integrated double gear includes the following steps:

[0107] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0108] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 23 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0109] (2) Shot peening the annealed blank;

[0110] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0111] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0112] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0113] Example 5

[0114] A cold extrusion molding method for an integrated double gear includes the following steps:

[0115] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0116] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 25 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0117] (2) Shot peening the annealed blank;

[0118] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0119] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0120] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0121] Example 6

[0122] A cold extrusion molding method for an integrated double gear includes the following steps:

[0123] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0124] The annealing furnace is heated to 800°C, the blank is placed in and kept warm for 23 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0125] (2) Shot peening the annealed blank;

[0126] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0127] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0128] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0129] Example 7

[0130] A cold extrusion molding method for an integrated double gear includes the following steps:

[0131] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0132] The annealing furnace is heated to 760°C, the blank is placed in and kept warm for 25 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0133] (2) Shot peening the annealed blank;

[0134] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0135] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0136] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0137] Example 8

[0138] A cold extrusion molding method for an integrated double gear includes the following steps:

[0139] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0140] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 700°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0141] (2) Shot peening the annealed blank;

[0142] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0143] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0144] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0145] Example 9

[0146] A cold extrusion molding method for an integrated double gear includes the following steps:

[0147] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0148] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 17 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0149] (2) Shot peening the annealed blank;

[0150] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0151] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0152] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0153] Example 10

[0154] A cold extrusion molding method for an integrated double gear includes the following steps:

[0155] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0156] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 19 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0157] (2) Shot peening the annealed blank;

[0158] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0159] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0160] The final cold extruded sample structure is granularly distributed pearlite + ferrite, the grain size grade is 8, and the gear accuracy is 8.5.

[0161] Comparative Example 1

[0162] A cold extrusion molding method for an integrated double gear includes the following steps:

[0163] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0164] The annealing furnace is heated to 720°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0165] (2) Shot peening the annealed blank;

[0166] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0167] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0168] The final cold extruded sample structure is granular pearlite + lamellar pearlite + ferrite, the grain size grade is 7.5, and the gear accuracy is 10.

[0169] Comparative Example 2

[0170] A cold extrusion molding method for an integrated double gear includes the following steps:

[0171] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0172] The annealing furnace is heated to 880°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0173] (2) Shot peening the annealed blank;

[0174] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0175] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0176] The final cold extruded sample has a granular distribution of pearlite + ferrite, a grain size grade of 7, and a gear accuracy of 10.

[0177] Comparative Example 3

[0178] A cold extrusion molding method for an integrated double gear includes the following steps:

[0179] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0180] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 18 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0181] (2) Shot peening the annealed blank;

[0182] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0183] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0184] The final cold extruded sample structure is granular pearlite + lamellar pearlite + ferrite, the grain size grade is 7, and the gear accuracy is 11.

[0185] Comparative Example 4

[0186] A cold extrusion molding method for an integrated double gear includes the following steps:

[0187] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0188] The annealing furnace is heated to 800°C, the blank is placed in and kept warm for 36 hours; the furnace temperature is then lowered to 680°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0189] (2) Shot peening the annealed blank;

[0190] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0191] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0192] The final cold extruded sample has a granular distribution of pearlite + ferrite. The long holding time leads to grain growth. The grain size level is 7 and the gear accuracy is 10.

[0193] Comparative Example 5

[0194] A cold extrusion molding method for an integrated double gear includes the following steps:

[0195] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0196] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 600°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0197] (2) Shot peening the annealed blank;

[0198] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0199] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0200] The final cold extrusion sample structure is granular pearlite + ferrite, the grain size level is 8, the second temperature is low, the internal stress is too large, resulting in high annealing hardness. The gear accuracy is 10.

[0201] Comparative Example 6

[0202] A cold extrusion molding method for an integrated double gear includes the following steps:

[0203] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0204] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 720°C and kept warm for 18 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0205] (2) Shot peening the annealed blank;

[0206] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0207] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0208] The final cold extruded sample structure is granularly distributed pearlite + ferrite + lamellar pearlite, the grain size grade is 7, and the gear accuracy is 11.

[0209] Comparative Example 7

[0210] A cold extrusion molding method for an integrated double gear includes the following steps:

[0211] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0212] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 8 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0213] (2) Shot peening the annealed blank;

[0214] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0215] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0216] The final cold extruded sample structure is granularly distributed pearlite + ferrite + lamellar pearlite, the grain size grade is 7, and the gear accuracy is 11.

[0217] Comparative Example 8

[0218] A cold extrusion molding method for an integrated double gear includes the following steps:

[0219] (1) Under a protective atmosphere, the blank is annealed. The annealing steps are as follows:

[0220] The annealing furnace is heated to 780°C, the blank is placed in and kept warm for 24 hours; the furnace temperature is then lowered to 680°C and kept warm for 24 hours; finally, the furnace is stopped and cooled to 400°C, followed by air cooling.

[0221] (2) Shot peening the annealed blank;

[0222] (3) placing the shot peened blank into a mold and cold extruding it once to obtain a blank;

[0223] (4) The blank is tempered and adjusted to 170-180HB for subsequent processing to obtain an integrated duplex gear.

[0224] The final cold extruded sample has a granular distribution of pearlite + ferrite, a long heat preservation time, poor economic efficiency, a grain size level of 7, and a gear accuracy of 10.

[0225] Table 1: Annealing conditions and duplex gear performance of various embodiments and comparative examples

[0226]

[0227]

[0228] Note: S stands for “Example”, such as S1 is Example 1; D stands for “Comparative Example”, such as D1 is Comparative Example 1.

[0229] In the description of the present application, it should be noted that the terms "upper", "lower", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" 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 a direct connection, or it can be an indirect connection through an intermediate medium, or it can be a connection between the two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to the specific circumstances.

[0230] It should be noted that, in this application, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0231] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A cold extrusion molding method for an integrated double gear, characterized in that: The mold for cold extrusion of one-piece duplex gears includes: Lower template (1); A lower die base (2), the lower die base (2) being arranged on the lower die plate (1); a lower die (4) for forming small teeth and an upper die (5) for forming large teeth are arranged on the inner side of the lower die base (2); a gap for injecting lubricating oil is formed between the outer wall of the lower die (4) and the inner wall of the lower die base (2), and between the outer wall of the upper die (5) and the inner wall of the lower die base (2); the lower die (4) is arranged on the lower die plate (1), and the upper die (5) is arranged on the lower die (4); A limiting plate (3) which is annular and is arranged on the top of the lower die base (2); A male mold (6) located above the lower mold plate (1); An upper mold plate (7) connected to the top of the male mold (6); The inner wall of the upper concave die (5) comprises, from top to bottom, a guide flow limiting area (50) and a large tooth forming area (51); The die entry angle β of the upper die (5) is 30° to 50°, and / or the working band length L1 of the upper die (5) is 3 to 5 mm; The entry angle γ of the lower concave die (4) is 40° to 50°, and / or the working band length L2 of the lower concave die (4) is 3 to 5 mm; The one-piece duplex gear cold extrusion forming method comprises: Under protective atmosphere, the blank is annealed to reduce the hardness of the blank to below 130HB; Shot peening is performed on the annealed blank; The shot-peened blank is placed in a mold for cold extrusion of the one-piece double gear, and cold extruded once to obtain a blank; The annealing process comprises the following steps: The blank is heated to a first temperature and kept warm for a first time, wherein the first temperature is 760°C to 800°C and the first time is 23h to 25h; Cooling the blank to a second temperature and keeping it at a second temperature for a second time, wherein the second temperature is 660° C. to 700° C. and the second time is 17 h to 19 h; Finally, the furnace is stopped and cooled to the third temperature, and then air-cooled. The third temperature is 390°C~410°C.

2. The cold extrusion forming method of an integrated double gear according to claim 1, characterized in that: The large teeth are straight teeth, and the small teeth are straight teeth; Or, the large teeth are helical and the small teeth are oblique; Alternatively, the large teeth are straight and the small teeth are helical; Alternatively, the large teeth are helical and the small teeth are straight.

3. The cold extrusion forming method of an integrated double gear according to claim 2, characterized in that: The helix angle of the helical teeth is less than or equal to 20°.

4. The cold extrusion forming method of an integrated double gear according to claim 1, characterized in that: A self-lubricating DLC ​​coating is deposited on the surfaces of the lower mold plate (1), the lower mold base (2), the limiting plate (3), the lower concave mold (4), the upper concave mold (5) and the punch (6).

5. The cold extrusion molding method of an integrated double gear according to claim 1, characterized in that: The first temperature is 780°C, and the first time is 24h; The second temperature is 680°C and the second time is 18h; The third temperature is 400°C.

6. The cold extrusion forming method of an integrated double gear according to claim 1, characterized in that: After the shot peening is completed, before the shot peened blank is placed in the mold, the following steps are also included: The blank is immersed in a polymer lubricant and air-dried after being treated for a period of time.

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