Rolling forming device and method for large module standard straight spur gears

Abstract

The application relates to a rolling forming device and method for a large-module standard straight-tooth cylindrical gear, which comprises an extruding device and a rolling forming device. The blank is gradually rolled in a ring rolling process, so that the blank is in local plastic deformation at any time, the forming has continuity and gradualness, the loading speed can be adjusted at any time according to the deformation condition, and the situation that the gear forming process has large load and excessively wears the die is avoided. The rolling core roller is gradually expanded in the inside, the stable contact between the die tooth shape and the blank can be effectively maintained, the tooth tip "poking" caused by the insufficient positioning accuracy in the rolling process can be effectively avoided, the forming stability is good, and the gear precision is high. The method is still applicable to the forming of a large-module gear, the situation that the size of the gear is large, the size of the forming equipment is increased by several times, the forming efficiency and stability are affected, the equipment structure is simple, and the operation is convenient; the forming process is simple, there is no flash, the metal flow line is completely preserved, the material utilization rate is high, and the formed gear has good mechanical properties.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of mechanical processing, and particularly relates to a rolling forming device and method for large-module standard straight-tooth cylindrical gears. BACKGROUND

[0002] Cylindrical gears are widely used in the industry as a basic part for transmitting power and motion. Gears with a module greater than 10 mm are generally referred to as large-module gears in industrial production. Due to their large overall size, good mechanical properties, and high reliability, large-module gears have significant advantages in terms of high load and impact resistance, and can work stably in complex and harsh environments. Therefore, they are widely used in large-scale hoisting machinery, ship transportation, geological exploration, and military equipment.

[0003] Due to the characteristics of heavy industrial equipment, large-module gears generally have higher requirements for size accuracy, surface quality, service life, and mechanical properties. The biggest feature of large-module gear forming compared to ordinary gears is the large volume and large pitch diameter of the gear, which leads to large deformation during processing. Therefore, it is easy to cause excessive forming load. At the same time, the large radial size makes it difficult to control the overall size of the forming equipment, and the forming process is difficult to control. The forming stability is difficult to guarantee, and the size accuracy is low, which need to be solved urgently. Therefore, how to reduce the forming force as much as possible while ensuring that the forming quality meets the service requirements, and how to improve the forming stability as much as possible while keeping the process controllable, have become the main problems faced by large-module gear forming.

[0004] Currently, cylindrical gears are generally produced by traditional cutting methods such as hobbing, shaving, and gear shaping. These methods have low material utilization, low production efficiency, and high processing cost. In particular, during the machining process, the metal flow lines are cut off, which reduces the mechanical properties and service life of the gear. For the closed precision forging process widely used in the machining of small-sized parts, considering the forming equipment and forming force, the large volume of large-module gears will further increase the forming force and reduce the service life of the die.

[0005] Local plastic forming process is a special continuous local metal forming process, which is mainly applied to the production of components with specific geometric shapes and mechanical properties. This process uses local loading to cause plastic deformation in a specific area, thereby forming the required shape and structure. The local plastic forming process is convenient to control the forming process and forming force, which can make up for the shortcomings of large-module gear forming. It is of great significance to promote the development of gear forming technology, and it can be divided into gear local extrusion and gear rolling process.

[0006] Gear local extrusion process is to apply pressure to the gear blank locally and form the gear through a die with a tooth shape. However, it has the defects of high forming force and flow line folding.

[0007] Chinese patent with publication number CN202010933525.6 proposes a process for forming a gear ring by a multi-directional forging hammer and a core mold extrusion, which reduces the forming force by multiple extrusions. However, due to the multiple shrinkage and expansion of the tooth sleeve, plastic deformation easily occurs, affecting the quality and the forming precision is low. Chinese patent with publication number CN1644266A proposes a gear extrusion process, which requires additional customization of corresponding tooth-shaped rollers to ensure the integrity of the gear profile for gears with a large number of teeth that cannot be evenly divided, making installation difficult and prone to flash and folding, which is not suitable for forming large-sized gears.

[0008] Gear roll forming process uses a hob or roller with a tooth shape to roll the gear blank, gradually forming the gear by multiple local pressure deformation of the metal. Currently, the roll forming process is generally suitable for the production of small and medium modulus gears and toothed parts, and is mostly hot roll forming.

[0009] Chinese patents with publication numbers CN115971382A and CN107695263A are both longitudinal roll forming processes. For large modulus gears, the above roll forming processes are highly dependent on equipment precision due to the large pitch circle diameter, which easily causes meshing deviation and affects the forming precision, making them unsuitable for large modulus gear forming.

[0010] Chinese patents with publication numbers CN205165687, CN101927309A, CN102294419A, CN107695263A, and CN104438993B all use transverse roll forming methods to achieve roll forming or improve the roll forming process with different technical means. However, positioning accuracy may be insufficient during the rolling process, leading to tooth tip "poking", poor stability, and poor high-precision processing results. Moreover, they are not suitable for hard alloy forming, the mold is easily worn, and the use cost is high. Therefore, for high-precision and high-hardness gear roll forming, similar methods are difficult to achieve the expected results.

[0011] Chinese patents with publication numbers CN106493273B, CN113210551A, and CN206046960U, and US patent with publication number US20070068211A1, all improve the stability of equipment roll forming to some extent through numerical control or mold design optimization. However, for large modulus gears, this will result in oversized forming equipment, reducing equipment stability, making installation and debugging difficult, and increasing maintenance costs, so it is also not suitable for large modulus gear forming.

[0012] The Chinese patent with the publication number CN118253676A proposes a ring forging rolling forming process, which rolls out the required structure of the inner surface of the forging by designing the core roller special-shaped structure, and the outer surface of the forging is always a cylindrical surface. However, since the forming of the external gear occurs on the outer surface of the blank, this method cannot be applied to the forming of external gear.

[0013] The Chinese patent with the publication number CN116809831A proposes a bevel gear ring rolling forming process, in which the mandrel is placed in the annular blank, the main roller rotates to drive the blank to rotate, and the mandrel moves radially to roll the blank to obtain the bevel gear product. This method uses ring rolling process to reduce the forming force. However, for large modulus gears, the blank needs to engage with the main roller multiple times, which is prone to tooth tip "poking"; and during the high temperature process, most of the blank is exposed to the air, which is prone to serious oxidation, reducing material utilization and affecting the forming quality. Therefore, for large modulus gears, if the approximate ring rolling forming is used, the process still needs to be further improved.

[0014] For the forming of large modulus standard straight tooth cylindrical gears, not only is it required to have a reasonable metal flow distribution to ensure the mechanical properties of the gear, but also to achieve a stable low load state during the forming process to reduce gear stress, mold wear and large-scale production cost; at the same time, high precision and high stability during the forming process are also pursued to meet the specific shape, strength and reliability requirements. However, none of the existing works have addressed this aspect. SUMMARY

[0015] The purpose of the present application is to avoid the shortcomings of the prior art and provide a ring rolling forming device and method for large modulus standard straight tooth cylindrical gears, which has stable process forming, complete metal flow line, high material utilization rate and high precision of gear finished products.

[0016] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows: a ring rolling forming device for large modulus standard straight tooth cylindrical gears, characterized in that it comprises an extrusion device for extruding the ring cylindrical blank and a ring rolling forming device for ring cylindrical blank rolling forming after extrusion, and the ring cylindrical blank is installed on the extrusion device through a fixed outer mold, a gear mold is arranged between the ring cylindrical blank and the fixed outer mold, and the ring cylindrical blank, the gear mold and the fixed outer mold are coaxially arranged.

[0017] The extrusion device comprises an extrusion table, an extrusion base and first and second positioning plates arranged on both sides of the extrusion base for positioning the extrusion base on the extrusion table; the surface of the extrusion base away from the extrusion table is a semicircular curved surface matched with the fixed outer mold for supporting when the ring cylindrical blank is extruded axially on both sides by the extrusion punch device.

[0018] The extrusion punch device comprises a first extrusion punch and a second extrusion punch coaxially arranged on both sides of the ring column blank, and a first punch sleeve and a second punch sleeve sleeved at the tail ends of the first extrusion punch and the second extrusion punch, the first punch sleeve and the second punch sleeve being embedded into the central hole of the ring column blank to extrude the ring column blank.

[0019] The rolling forming device comprises a rolling bottom plate, and a positioning base is arranged on the rolling bottom plate, the ring column blank, the gear mold and the fixed outer mold are coaxially arranged on the positioning base, and the rolling forming device is fixed on the ring rolling equipment through the rolling bottom plate.

[0020] Further, the rolling forming device comprises a driving wheel connected with the ring rolling equipment and a driven wheel arranged on the rolling bottom plate, the driving wheel and the driven wheel are in tangential contact with the fixed outer mold arranged on the positioning base, at least two support columns for arranging the driven wheels are uniformly arranged around the outer periphery of the fixed outer mold on the rolling bottom plate, the driven wheels are sleeved on the support columns through bearing, and the driven wheels are used to ensure stable rotation of the fixed outer mold without eccentricity when the fixed outer mold rotates with the driving wheel.

[0021] Further, the rolling forming device comprises an electromagnetic induction coil for heating the fixed outer mold and a support base, a hydraulic cylinder is arranged on the support base, a positioning pressing plate for preventing the fixed outer mold from being lifted and dislocated is fixed on the piston rod of the hydraulic cylinder, and the bottom surface of the positioning pressing plate is 2-4 mm away from the axial upper surface of the fixed outer mold; the inner curved surface of the electromagnetic induction coil has a gap with the fixed outer mold, and the electromagnetic induction coil is fixed on the support base through a connecting piece.

[0022] Further, a pair of connecting bosses are arranged on the extrusion base, and two grooves for sliding connection with the bosses are arranged on the bottom surfaces of the first positioning plate and the second positioning plate, so that the first positioning plate and the second positioning plate are clamped and positioned on the extrusion base.

[0023] Further, a semicircular groove is arranged at the center of the surface of each of the first positioning plate and the second positioning plate, so as to reserve space for rotation of the first extrusion punch and the second extrusion punch.

[0024] Further, the positioning base is a 3 / 4 cylindrical body, and a 1 / 4 notch is arranged on the side close to the driving wheel, so as to reserve space for rotation of the driving wheel.

[0025] Further, a plurality of balls are arranged on the contact surface between the positioning base and the axial bottom of the fixed outer mold, so as to reduce the friction force suffered by the fixed outer mold during rotation.

[0026] Further, the gear mold is composed of four identical gear split molds, and the four gear split molds are connected and fixed by four positioning pins arranged above and below, the outer surface of the gear mold is in angle interference fit with the inner surface of the fixed outer mold, and the fitting slope is 1°-2°.

[0027] The application further provides a large modulus standard straight-tooth cylindrical gear rolling forming method, and the specific steps are as follows.

[0028] Step one, according to the target gear, select the blank and determine the size, cut the ring column blank on the band saw bed, and heat the ring column blank to 800-1000 DEG C by using the acetylene flame to reduce the deformation resistance.

[0029] Step two, install the ring column blank in the gear mold, debug the positioning by using the positioning pin, preheat the gear mold to 300-500 DEG C, and then install the gear mold in the fixed outer mold, and the inner diameter of the fixed outer mold is tapered to match the outer diameter of the gear mold.

[0030] Step three, place the fixed outer mold axially horizontally on the extrusion base, and fix the extrusion base by using the first positioning plate and the second positioning plate, preheat the first extrusion punch and the second extrusion punch of the extrusion punch device to 300-500 DEG C by using the acetylene flame, and then drive the first extrusion punch and the second extrusion punch to axially extrude the ring column blank by two hydraulic devices at the same time, and the extrusion stroke is not more than 1 / 4 of the height of the ring column blank.

[0031] Step four, remove the first extrusion punch and the second extrusion punch together with the fixed outer mold from the extrusion device and place them in the rolling forming device, specifically, place the fixed outer mold axially vertically on the positioning base and in tangential contact with the driving wheel, adjust the positioning baffle to be pressed 2-4 mm above the axially upper surface of the fixed outer mold by the hydraulic cylinder; place the rolling core roller in the center hole of the ring column blank, connect and debug with the ring rolling equipment, and control the temperature of the electromagnetic induction coil to be 300-500 DEG C.

[0032] Step five, control the driving wheel to rotate by the ring rolling equipment, drive the fixed outer mold, the gear mold and the ring column blank to rotate synchronously, and ensure that the driven wheel rotates stably without eccentricity; the electromagnetic induction coil is kept heated; at the same time, the rolling core roller is driven to rotate around its center axis and translate towards the driving wheel by the main shaft of the ring rolling equipment, and the ring column blank is gradually rolled and formed.

[0033] Step six, remove the gear mold from the rolling forming device, remove the fixed outer mold, and separate the gear mold to obtain the standard straight-tooth cylindrical gear.

[0034] Further, in step one, the outer diameter of the ring column blank is 1-2 mm smaller than the inner diameter of the gear mold.

[0035] Further, in step three, the first extrusion punch and the second extrusion punch are composed of a cylindrical body at the tail for clamping and a conical body at the head for forming, the inclination angle of the conical body is 5-15 DEG, and the length of the cylindrical body is not more than 2 / 5 of the height of the ring column blank.

[0036] Further, in step five, the outer diameter of the rolling core roller is 0.8-0.9 times the diameter of the central hole of the ring blank; the speed of the rolling core roller translating towards the driving wheel is 0.01-0.03 times the diameter of the rolling core roller per second.

[0037] The present application has the following advantages:

[0038] 1. The present application can significantly reduce the forming load required in the forming process, gradually rolls the blank by using a similar ring rolling process, so that the blank is in local plastic deformation at all times, the forming has continuity and gradualness, and the loading speed can be adjusted at any time according to the deformation condition, avoiding the case that the gear forming process has large load and excessive damage to the mold, so it is also suitable for high hardness alloy materials, the mold damage is small, and the mold life is long.

[0039] 2. The present application has good forming stability, and the precision of the produced gear product is high. The axial compression of the blank helps positioning in the early stage of forming, and the gradual expansion of the rolling core roller inside can effectively maintain stable contact between the mold tooth shape and the blank, which can effectively avoid the "poking" of the tooth tip caused by insufficient positioning accuracy during rolling, and has good forming stability and high gear precision.

[0040] 3. The present application is still applicable to the forming of large modulus gears, and does not have the problem that the size of the gear is large, which causes the size of the forming equipment to increase several times, affecting the forming efficiency and stability. The equipment structure is simple and easy to operate; the forming process is simple, without flash, the metal flow line is complete, the material utilization rate is high, and the formed gear has good mechanical properties. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 is a schematic diagram of the extrusion device of the present application;

[0042] Figure 2 is a cross-sectional view of the extrusion device of the present application;

[0043] Figure 3 is an axonometric view of the rolling forming device of the present application;

[0044] Figure 4 is a front view of the rolling forming device of the present application;

[0045] Figure 5 is an A-A sectional view of Figure 4

[0046] Figure 6 is a right view of the rolling forming device of the present application;

[0047] ​In the figure: 1-first punch sleeve, 2-first extrusion punch, 3-second extrusion punch, 4-second punch sleeve, 5-first positioning plate, 6-extrusion base, 7-second positioning plate, 8-extrusion table, 81-boss, 9-gear mold, 10-fixed outer mold, 11-locating pin, 12-driving wheel, 13-rolling core roller, 14-locating base, 15-locating pressure plate, 16-electromagnetic induction coil, 17-driven wheel, 18-pillar, 19-support seat, 20-rolling bottom plate, 21-hydraulic cylinder, 22-ring column blank. DETAILED DESCRIPTION

[0048] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.

[0049] Example 1: Figures 1-6 As shown, a rolling forming device for a large-module standard spur gear includes an extrusion device for extruding a ring column blank 22 and a rolling forming device for rolling the ring column blank 22 in cooperation with a ring rolling device after the extrusion is completed. The ring column blank 22 is mounted on the extrusion device via a fixed outer die 10. A gear die 9 is provided between the ring column blank 22 and the fixed outer die 10. The ring column blank 22, the gear die 9, and the fixed outer die 10 are coaxially arranged.

[0050] like Figure 1 、 2 As shown, the extrusion device includes an extrusion platform 8 and an extrusion punch device. The extrusion platform 8 is provided with an extrusion base 6 and a first positioning plate 5 and a second positioning plate 7 respectively arranged on both sides of the extrusion base 6, which are used to position the extrusion base 6 on the extrusion platform 8; the surface of the extrusion base 6 facing away from the extrusion platform 8 is a semi-arc-shaped surface that matches the fixed outer die 10, which is used to support the ring column blank 22 when the extrusion punch device extrudes the ring column blank 22 on both sides in the axial direction;

[0051] The extrusion punch device includes a first extrusion punch 2 and a second extrusion punch 3 coaxially arranged on both sides of the ring column blank 22, and a first punch sleeve 1 and a second punch sleeve 4 sleeved on the tail ends of the first extrusion punch 2 and the second extrusion punch 3. The first punch sleeve 1 and the second punch sleeve 4 are embedded in the center hole of the ring column blank 22 to extrude the ring column blank 22;

[0052] like Figure 3 、 4 As shown in Figures 5 and 6, the rolling forming device includes a rolling base plate 20, on which a positioning base 14 is provided. The ring column blank 22, the gear mold 9, and the fixed outer mold 10 are coaxially mounted on the positioning base 14. The rolling forming device is fixed to the ring rolling equipment through the rolling base plate 20.

[0053] It also comprises a driving wheel 12 connected with the ring rolling equipment and a driven wheel 17 installed on the rolling base 20, both of which are tangent to the fixed outer die 10 installed on the positioning base 14, and four supporting columns 18 for installing the driven wheel 17 are evenly arranged around the outer periphery of the fixed outer die 10 on the rolling base 20, and the bottom of the driven wheel 17 is sleeved on the supporting column 18 through a bearing, so that the driven wheel 17 can ensure the stable rotation of the fixed outer die 10 without eccentricity when the fixed outer die 10 rotates with the driving wheel 12;

[0054] It also comprises an electromagnetic induction coil 16 for heating the fixed outer die 10 and a supporting seat 19, the supporting seat 19 is provided with a hydraulic cylinder 21, a positioning pressing plate 15 for preventing the upward dislocation of the fixed outer die 10 is fixedly arranged on the piston rod of the hydraulic cylinder 21, and the bottom surface of the positioning pressing plate 15 is 2-4 mm away from the axial upper surface of the fixed outer die 10; the inner curved surface of the electromagnetic induction coil 16 has a gap with the fixed outer die 10, and the electromagnetic induction coil 16 is fixed with the supporting seat 19 through a connecting piece.

[0055] The extrusion table 8 is provided with a pair of connecting bosses 81, and two recesses for sliding connection with the bosses 81 are arranged on the bottom surfaces of the first positioning plate 5 and the second positioning plate 7 respectively, so that the first positioning plate 5 and the second positioning plate 7 can be clamped and positioned on the extrusion base 6.

[0056] The surfaces of the first positioning plate 5 and the second positioning plate 7 are both provided with semicircular grooves in the centers, so as to reserve space for the rotation of the first extrusion punch 2 and the second extrusion punch 3.

[0057] The positioning base 14 is a 3 / 4 cylinder, and a 1 / 4 notch is arranged on the side close to the driving wheel 12, so as to reserve space for the rotation of the driving wheel 12.

[0058] A plurality of balls are arranged on the contact surface between the positioning base 14 and the axial bottom of the fixed outer die 10, so as to reduce the friction force suffered by the fixed outer die 10 during rotation.

[0059] The gear die 9 is composed of four identical gear split dies, and is connected and fixed by four positioning pins 11 arranged on the upper and lower surfaces, respectively. The outer surface of the gear die 9 is in angular interference fit with the inner surface of the fixed outer die 10, and the fitting slope is 1°-2°.

[0060] Embodiment 2: The application also provides a ring rolling forming method for a large modulus standard spur gear, which is taken as an example of a standard spur gear with a modulus of 22, a number of teeth of 20 and a pressure angle of 20°. The material is 17CrNiMo6, the tooth width is 420 mm, the gear pitch circle diameter is 440 mm, and the addendum circle diameter is 484 mm.

[0061] The specific steps are as follows:

[0062] Step one, according to the target gear selection blank and determine the size, in the band sawing machine blank to get the outer diameter Φ388mm, inner diameter Φ150mm, high 466mm ring column blank 22; with acetylene flame on the ring column blank 22 heated to 1000℃;

[0063] Step two, the ring column blank 22 is installed in the gear mold 9, with positioning pin 11 debugging positioning, the gear mold 9 is preheated to 300℃, then the gear mold 9 is installed in the fixed outer mold 10; fixed outer mold outer diameter Φ630mm, inner diameter Φ550~570mm taper distribution, high 546mm; gear mold outer diameter Φ550~570mm, total height 546mm; fixed outer mold 10 and gear mold 9 are connected by interference fit, positioning pin 11 diameter Φ20 mm, long 122mm; the fixed outer mold 10 is roughened on the outer surface, so that the contact friction coefficient reaches 0.5~0.6.

[0064] Step three, the fixed outer mold 10 is placed on the extrusion device, specifically the fixed outer mold 10 is placed horizontally on the extrusion base 6, and the extrusion base 6 is fixed by the first positioning plate 5 and the second positioning plate 7, the tail end of the first extrusion punch 2 is sleeved into the first punch sleeve 1, the protrusion at the front end of the first extrusion punch 2 is sleeved into the center hole at one end of the ring column blank 22, the tail end of the second extrusion punch 3 is sleeved into the second punch sleeve 4, and the protrusion at the front end of the second extrusion punch 3 is sleeved into the center hole at the other end of the ring column blank 22; the first extrusion punch 2 and the second extrusion punch 3 are preheated to 300℃ by acetylene flame, and the first extrusion punch 2 and the second extrusion punch 3 are driven by the hydraulic device to axially extrude the ring column blank 22, and the extrusion stroke is set to 50mm;

[0065] Step four, the first extrusion punch 2 and the second extrusion punch 3 are taken out of the extrusion device together with the fixed outer mold 10, and placed in the rolling forming device, specifically the fixed outer mold 10 is placed vertically on the positioning base 14 and is in tangential contact with the driving wheel 12, and the positioning baffle 15 is adjusted by the hydraulic cylinder 21 to press above the fixed outer mold 10 by 2~4mm from the upper surface; the rolling core roller 13 is placed in the center hole of the ring column blank 22 and is connected with the ring rolling equipment for debugging, the rolling core roller 13 has a diameter of Φ135mm and a length of 1130mm; the electromagnetic induction coil 16 is controlled at a temperature of 300℃;

[0066] Step five, the driving wheel 12 is controlled to rotate by the ring rolling equipment, driving the fixed outer mold 10, the gear mold 9 and the ring column blank 22 to rotate at an angular velocity of 0.1 rad / s, and the electromagnetic induction coil 16 is kept at 300℃; at the same time, the rolling core roller 13 is controlled to rotate by the main shaft of the ring rolling equipment, and the rolling core roller 13 is controlled to translate towards the driving wheel 12 for rolling forming, and the translation speed is uniformly reduced from 0.1mm / s to 0.05mm / s;

[0067] Step six, the gear mold 9 is withdrawn from the rolling forming device, the fixed outer mold 10 is taken off, the gear mold 9 is separated, and a standard spur gear with a module of 22 and a tooth number of 20 is obtained.

[0068] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A rolling forming device for large-module standard spur gears, characterized by: The invention comprises an extrusion device for extruding a ring column blank (22) and a rolling forming device for cooperating with a ring rolling device to roll and form the ring column blank (22) after the extrusion is completed, wherein the ring column blank (22) is mounted on the extrusion device via a fixed outer die (10), a gear die (9) is provided between the ring column blank (22) and the fixed outer die (10), and the ring column blank (22), the gear die (9), and the fixed outer die (10) are coaxially arranged; The extrusion device comprises an extrusion table (8) and an extrusion punch device, wherein the extrusion table (8) is provided with an extrusion base (6) and a first positioning plate (5) and a second positioning plate (7) respectively arranged on both sides of the extrusion base (6) for positioning the extrusion base (6) on the extrusion table (8); the surface of the extrusion base (6) facing away from the extrusion table (8) is a semi-arc-shaped surface matching the fixed outer die (10), and is used for supporting the ring column blank (22) when the extrusion punch device extrudes both sides of the axial direction; The extrusion punch device comprises a first extrusion punch (2) and a second extrusion punch (3) coaxially arranged on both sides of the ring column blank (22), and a first punch sleeve (1) and a second punch sleeve (4) sleeved on the tail ends of the first extrusion punch (2) and the second extrusion punch (3), wherein the first punch sleeve (1) and the second punch sleeve (4) are embedded in the central hole of the ring column blank (22) to extrude the ring column blank (22); The rolling forming device comprises a rolling base plate (20), a positioning base (14) is provided on the rolling base plate (20), and a ring column blank (22), a gear mold (9), and a fixed outer mold (10) are coaxially mounted on the positioning base (14); the rolling forming device is fixed to the ring rolling equipment via the rolling base plate (20); It also includes a driving wheel (12) connected to the ring rolling equipment and a driven wheel (17) mounted on a rolling base plate (20), the driving wheel (12) and the driven wheel (17) both being in tangential contact with a fixed outer mold (10) mounted on a positioning base (14), at least two pillars (18) for mounting the driven wheel (17) are evenly arranged around the outer periphery of the fixed outer mold (10) on the rolling base plate (20), the bottom of the driven wheel (17) being mounted on the pillars (18) via a bearing sleeve, and the driven wheel (17) being used to ensure that the fixed outer mold (10) rotates stably without eccentricity when the fixed outer mold (10) rotates with the driving wheel (12); The invention also includes an electromagnetic induction coil (16) and a support seat (19) for heating the fixed outer mold (10). A hydraulic cylinder (21) is provided on the support seat (19). A positioning pressure plate (15) is fixed on the piston rod of the hydraulic cylinder (21) to prevent the fixed outer mold (10) from rising and being dislocated. The bottom surface of the positioning pressure plate (15) is 2 to 4 mm away from the axial upper surface of the fixed outer mold (10). There is a gap between the inner curved surface of the electromagnetic induction coil (16) and the fixed outer mold (10). The electromagnetic induction coil (16) is fixed to the support seat (19) through a connecting piece.

2. The rolling forming device for large-module standard spur gears according to claim 1, characterized in that: A pair of connecting bosses (81) are provided on the extrusion platform (8), and two grooves for slidingly connecting with the bosses (81) are respectively provided on the bottom surfaces of the first positioning plate (5) and the second positioning plate (7), so as to facilitate the clamping and positioning of the extrusion base (6) by the first positioning plate (5) and the second positioning plate (7).

3. The rolling forming device for large-module standard spur gears according to claim 1, characterized in that: Semicircular grooves are provided at the centers of the surfaces of the first positioning plate (5) and the second positioning plate (7), thereby reserving space for the rotation of the first extrusion punch (2) and the second pressing punch (3).

4. The rolling forming device for large-module standard spur gears according to claim 1, characterized in that: The positioning base (14) is a 3 / 4 cylinder, and a 1 / 4 gap is opened on the side close to the driving wheel (12) to reserve space for the rotation of the driving wheel (12).

5. The rolling forming device for large-module standard spur gears according to claim 1, characterized in that: A plurality of balls are provided on the contact surface between the positioning base (14) and the axial bottom of the fixed outer mold (10) to reduce the frictional force exerted on the fixed outer mold (10) during rotation.

6. The rolling forming device for large-module standard spur gears according to claim 1, characterized in that: The gear mold (9) is composed of four identical gear sub-molds, which are connected and fixed by four positioning pins (11) at the top and bottom. The outer surface of the gear mold (9) and the inner surface of the fixed outer mold (10) are in an interference fit with an angle, and the fit slope is 1° to 2°.

7. A rolling forming method using the rolling forming device for large-module standard spur gears according to any one of claims 1 to 6, characterized in that: The specific steps are as follows: Step 1: Select a blank and determine the size according to the target gear, cut the blank on a band saw to obtain a ring column blank (22), and use an acetylene flame to heat the ring column blank (22) to 800-1000° C. to reduce deformation resistance; Step 2: Install the ring column blank (22) in the gear mold (9), adjust the position with the positioning pin (11), preheat the gear mold (9) to 300-500°C, and then install the gear mold (9) into the fixed outer mold (10), the inner diameter of the fixed outer mold (10) is tapered to match the outer diameter of the gear mold (9); Step 3: The fixed outer die (10) is axially and horizontally placed on the extrusion base (6), and the extrusion base (6) is fixed by a first positioning plate (5) and a second positioning plate (7). After the first extrusion punch (2) and the second extrusion punch (3) of the extrusion punch device are preheated to 300-500° C. by an acetylene flame, the first extrusion punch (2) and the second extrusion punch (3) are driven simultaneously by two hydraulic devices to axially extrude the ring column blank (22) in opposite directions, and the extrusion stroke does not exceed 1 / 4 of the height of the ring column blank (22); Step 4: Remove the first extrusion punch (2) and the second extrusion punch (3) together with the fixed outer die (10) from the extrusion device and place them in a rolling forming device. Specifically, the fixed outer die (10) is placed axially vertically on the positioning base (14) and in tangential contact with the driving wheel (12). The positioning baffle (15) is adjusted by the hydraulic cylinder (21) to be pressed 2 to 4 mm above the axial upper surface of the fixed outer die (10); the rolling core roller (13) is placed in the center hole of the ring column blank (22), connected to the ring rolling equipment for debugging, and the temperature of the electromagnetic induction coil (16) is controlled to 300 to 500°C; Step 5: The ring rolling equipment controls the driving wheel (12) to rotate, driving the fixed outer mold (10), the gear mold (9) and the ring column blank (22) to rotate synchronously, and the driven wheel (17) ensures that the fixed outer mold (10) rotates stably without eccentricity; the electromagnetic induction coil (16) is kept heated; at the same time, the main shaft of the ring rolling equipment controls the rolling core roller (13) to rotate about its own central axis and translate toward the driving wheel (12), thereby gradually rolling the ring column blank (22) into shape; Step six, withdraw the gear mold (9) from the rolling forming device, remove the fixed outer mold (10), separate the gear mold (9), and obtain a standard spur gear.

8. The rolling forming method of large-module standard spur gears according to claim 7, characterized in that: In step 1, the outer diameter of the ring column blank (22) is 1 to 2 mm smaller than the inner diameter of the gear mold (9).

9. The rolling forming method of a large-module standard spur gear according to claim 7, characterized in that: In step three, the first extrusion punch (2) and the second extrusion punch (3) are composed of a cylinder at the tail for clamping and a cone at the head for forming, the inclination angle of the cone is 5 to 15 degrees, and the length of the cylinder does not exceed 2 / 5 of the height of the ring column blank (22).

10. The rolling forming method of large-module standard spur gears according to claim 7, characterized in that: In step five, the outer diameter of the rolling core roller (13) is 0.8-0.9 times the diameter of the center hole of the ring column blank (22); the speed of the rolling core roller (13) moving in the direction of the driving wheel (12) is 0.01-0.03 times the diameter of the rolling core roller (13) per second.

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