阅读说明：本技术 一种一次性成形多孔偏心台阶螺旋齿轮及加工工艺 (One-time formed porous eccentric step spiral gear and machining process ) 是由 尤天兵 李军 戴德标 谈尚文 赵友宝 李玉 于 2021-07-12 设计创作，主要内容包括：本发明公开了一种一次性成形多孔偏心台阶螺旋齿轮及加工工艺,涉及齿轮加工技术领域。包括轮毂,轮毂由偏心设置的大轮和小轮一体成型,且小轮位于大轮的一侧端面上凸出设置,大轮的外圆周面上设置有轮齿,大轮的两侧端面对称设置有与大轮同心的环形凹槽,小轮位于环形凹槽内设置,且环形凹槽内设置有仅贯穿大轮的销孔,销孔内插接有销轴,大轮的中心设置有贯穿大轮和小轮的通孔,且小轮上的端面上设置有与通孔偏心的环形凸台。通过成型压制、烧结、粗车、滚齿、剃齿、热处理、压PIN、精车、振研、清洗、包装等步骤制得成品齿轮。本发明克服了现有技术的不足,将齿轮一次成型,并通过多种加工工艺提高齿轮的产品性能和品质。(The invention discloses a one-time forming porous eccentric step spiral gear and a processing technology thereof, relating to the technical field of gear processing. The novel wheel hub comprises a wheel hub body, wherein the wheel hub body is formed by integrally forming a large wheel and a small wheel which are arranged eccentrically, the small wheel is arranged on one side end face of the large wheel in a protruding mode, wheel teeth are arranged on the outer circumferential face of the large wheel, annular grooves which are concentric with the large wheel are symmetrically formed in the two side end faces of the large wheel, the small wheel is arranged in the annular grooves, pin holes which only penetrate through the large wheel are formed in the annular grooves, pin shafts are connected in the pin holes in an inserting mode, through holes which penetrate through the large wheel and the small wheel are formed in the center of the large wheel, and annular bosses which are eccentric with the through holes are formed in the end face of the small wheel. The finished gear is prepared by the steps of molding pressing, sintering, rough turning, gear hobbing, gear shaving, heat treatment, PIN pressing, fine turning, vibration grinding, cleaning, packaging and the like. The invention overcomes the defects of the prior art, the gear is molded at one time, and the product performance and the quality of the gear are improved through various processing techniques.)

1. A porous eccentric step helical gear once only takes shape, includes wheel hub (1), its characterized in that: wheel hub (1) is by bull wheel (2) and steamboat (3) integrated into one piece of eccentric settings, and steamboat (3) are located the protrusion setting on the side end face of bull wheel (2), be provided with teeth of a cogwheel (4) on the outer periphery of bull wheel (2), the both sides terminal surface symmetry of bull wheel (2) is provided with bull wheel (2) endocentric annular groove (5), steamboat (3) are located and set up in annular groove (5), and are provided with pinhole (6) that only run through bull wheel (2) in annular groove (5), it has round pin axle (7) to peg graft in pinhole (6), the center of bull wheel (2) is provided with and runs through bull wheel (2) with through-hole (8) of steamboat (3), and be provided with on the terminal surface on bull wheel (3) with through-hole (8) eccentric annular boss (9).

2. A one-time-formed porous eccentric stepped helical gear according to claim 1, wherein: the footpath festival of wheel hub (1) is 28, the number of teeth of wheel hub (1) is 46, the pressure angle of wheel hub (1) is 20, the helix angle of wheel hub (1) is dextrorotation 23, the addendum circle diameter of wheel hub (1) is 47.10-47.25mm, the dedendum circle diameter of wheel hub (1) is 43.13-43.27mm, the PIN footpath of striding of wheel hub (1) is 48.786-48.904mm, the PIN footpath of wheel hub (1) is 2mm, the precision rating of wheel hub (1) is DIN 9.

3. A one-time-formed porous eccentric stepped helical gear according to claim 1, wherein: bull wheel (2) are including mutually perpendicular's horizontal axis (10) and vertical axis (11), the centre of a circle of through-hole (8) with the eccentric contained angle between the extension line of the centre of a circle line of annular boss (9) and horizontal axis (10) of bull wheel (2) is 45.

4. A one-time-formed porous eccentric stepped helical gear according to claim 3, wherein: the small wheel (3) and the pin hole (6) are arranged on a vertical shaft line (11) of the large wheel (2), and the small wheel (3) and the pin hole (6) are arranged at intervals.

5. The machining process of the one-time forming porous eccentric step spiral gear according to claim 1, characterized by comprising the following steps:

s1, forming and pressing: feeding a certain amount of mixed raw material powder into a press, pressing by a die, and forming at one time to obtain a pressed blank;

s2, sintering: placing the formed pressed blank in a high-temperature mesh belt furnace for sintering, introducing a proper amount of nitrogen and hydrogen, and rapidly cooling to normal temperature after sintering is completed to obtain a sintered piece;

s3, rough turning: roughly turning the sintered part by adopting a numerical control lathe, wherein the rough turning comprises the steps of carrying out machining on the contour surfaces of a large wheel (2) and a small wheel (3), drilling a pin hole (6) and a through hole (8) to a finish machining size, and turning an annular groove (5) and an annular boss (9) to obtain a roughly turned part;

s4, hobbing: carrying out roller teeth (4) on the rough turning piece by adopting a numerical control gear hobbing machine to obtain a first gear;

s5, shaving: shaving the tooth surface of the gear tooth (4) of the first gear by using a numerical control gear shaving machine to obtain a second gear;

s6, heat treatment: carrying out carburizing and quenching treatment on the second gear to obtain a third gear;

s7, pressing PIN: a PIN shaft (7) is implanted into the PIN hole (6) of the second gear by adopting a PIN pressing machine to obtain a fourth gear;

s8, finish turning: finish turning is carried out on the through hole (8) of the third gear by adopting a numerical control lathe to obtain a fifth gear;

s9, vibration grinding and cleaning: carrying out vibration grinding on the fifth gear by using a vibration grinding machine for 20-40min to remove burrs, rough edges, flash edges and the like on the surface of the part, and cleaning after the vibration grinding is finished to obtain a finished gear;

s10, packaging: and (5) detecting, packaging and warehousing the finished gear.

6. The one-time forming porous eccentric step helical gear machining process according to claim 5, characterized in that: the pressure at the time of pressing the mold in the step S1 is 200-300 MPa.

7. The one-time forming porous eccentric step helical gear machining process according to claim 5, characterized in that: the sintering process in step S2 is divided into four stages, the first stage is a degreasing stage: keeping the furnace temperature at 600-650 ℃, and keeping the temperature for 10-20 min; the second stage is a preheating stage: keeping the furnace temperature at 750 ℃ for 700-; the third stage is a heat preservation stage: keeping the furnace temperature at 1100-; in the fourth stage, the temperature is kept at 950 and 1000 ℃ for 10-20 min.

8. The one-time forming porous eccentric step helical gear machining process according to claim 5, characterized in that: the high-temperature mesh belt in the step S2 is made of stainless steel 304.

9. The one-time forming porous eccentric step helical gear machining process according to claim 5, characterized in that: the heat treatment process in step S6 is divided into four stages, the first stage is a preheating process: firstly keeping the furnace temperature at 400-; the second stage is carburizing treatment: firstly, the furnace temperature is 900-; the third stage is quenching treatment: keeping the furnace temperature at 900-; the fourth stage is tempering treatment: keeping the furnace temperature at 200-250 ℃, keeping the temperature for 40-60min, and cooling to room temperature.

Technical Field

The invention relates to the technical field of gear machining, in particular to a one-step formed porous eccentric step spiral gear and a machining process.

Background

Gears are wheel-like mechanical parts that transmit torque by virtue of meshing of teeth. The gear can realize the functions of changing the rotating speed and the torque, changing the moving direction, changing the moving form and the like by transmitting with other toothed mechanical parts (such as another gear, a rack and a worm). Because of the advantages of high transmission efficiency, accurate transmission ratio, large power range and the like, the gear mechanism is widely applied to industrial products, and the design and manufacturing level of the gear mechanism directly influences the quality of the industrial products. The mutual buckling of the gear teeth on the gear can drive the other gear to rotate so as to transmit power. The two gears are separated, and a chain, a crawler belt and a belt can be used for driving the gears on the two sides to transmit power.

The whole machining process of the gear is complex, at present, machining of porous eccentric step spiral gears in the market is not one-step forming, the products are generally made into a split type, then the split type gear is changed into a whole in a sintering welding mode, the process is complex, the cost is high, in the prior art, the performance and the quality of the gear obtained through powder metallurgy are general, the surface hardness is low, cracks are prone to being generated in the subsequent grinding machining process, and the service life of the gear is influenced. Therefore, a one-step forming porous eccentric step spiral gear and a machining process are provided.

Disclosure of Invention

Technical problem to be solved

Aiming at the defects of complex processing and general performance and quality of the obtained gear product in the prior art, the invention provides a one-step formed porous eccentric step spiral gear and a processing technology thereof.

(II) technical scheme

In order to achieve the purpose, the invention is realized by the following technical scheme:

the utility model provides a porous eccentric step helical gear once only takes shape, includes wheel hub, wheel hub is by eccentric settings's bull wheel and steamboat integrated into one piece, and the steamboat is located the protrusion setting on the terminal surface of one side of bull wheel, be provided with the teeth of a cogwheel on the outer periphery of bull wheel, the both sides terminal surface symmetry of bull wheel is provided with the annular groove with the bull wheel is endocentric, the steamboat is located the annular groove and sets up, and is provided with the pinhole that only runs through the bull wheel in the annular groove, it has the round pin axle to peg graft in the pinhole, the center of bull wheel is provided with and runs through the bull wheel with the through-hole of steamboat, and be provided with on the terminal surface on the steamboat with the eccentric annular boss of through-hole.

The preferred technical scheme, the diameter section of wheel hub is 28, the number of teeth of wheel hub is 46, the pressure angle of wheel hub is 20 °, the helix angle of wheel hub is dextrorotation 23 °, the addendum circle diameter of wheel hub is 47.10-47.25mm, the dedendum circle diameter of wheel hub is 43.13-43.27mm, the cross PIN footpath of wheel hub is 48.786-48.904mm, the PIN footpath of wheel hub is 2mm, the precision rating of wheel hub is DIN 9.

According to a further preferred technical scheme, the bull wheel comprises a horizontal axis and a vertical axis which are perpendicular to each other, and an eccentric included angle between an extension line of a circle center of the through hole and a circle center connecting line of the annular boss and the horizontal axis of the bull wheel is 45 degrees.

According to a further preferred technical scheme, the small wheel and the pin hole are arranged on a vertical axis of the large wheel, and the small wheel and the pin hole are arranged at intervals.

The optimized technical scheme is that the machining process for the one-time forming porous eccentric step spiral gear comprises the following steps of:

s1, forming and pressing: feeding a certain amount of mixed raw material powder into a press, pressing by a die, and forming at one time to obtain a pressed blank;

s2, sintering: placing the formed pressed blank in a high-temperature mesh belt furnace for sintering, introducing a proper amount of nitrogen and hydrogen, and rapidly cooling to normal temperature after sintering is completed to obtain a sintered piece;

s3, rough turning: roughly turning the sintered part by adopting a numerical control lathe, wherein the rough turning comprises the steps of carrying out turning on contour surfaces of a large wheel and a small wheel, drilling pin holes and through holes to be in a finish-machined size, and turning an annular groove and an annular boss to obtain a roughly-turned part;

s4, hobbing: carrying out roller tooth on the rough turning piece by adopting a numerical control gear hobbing machine to obtain a first gear;

s5, shaving: shaving the tooth surfaces of the gear teeth of the first gear by using a numerical control gear shaving machine to obtain a second gear;

s6, heat treatment: carrying out carburizing and quenching treatment on the second gear to obtain a third gear;

s7, pressing PIN: implanting a PIN shaft into the PIN hole of the second gear by using a PIN pressing machine to obtain a fourth gear;

s8, finish turning: finely turning the through hole of the third gear by using a numerical control lathe to obtain a fifth gear;

s9, vibration grinding and cleaning: carrying out vibration grinding on the fifth gear by using a vibration grinding machine for 20-40min to remove burrs, rough edges, flash edges and the like on the surface of the part, and cleaning after the vibration grinding is finished to obtain a finished gear;

s10, packaging: and (5) detecting, packaging and warehousing the finished gear.

Further preferably, the pressure of the mold in the step S1 is 200-300 Mpa.

In a further preferred embodiment, the sintering process in step S2 is divided into four stages, where the first stage is a degreasing stage: keeping the furnace temperature at 600-650 ℃, and keeping the temperature for 10-20 min; the second stage is a preheating stage: keeping the furnace temperature at 750 ℃ for 700-; the third stage is a heat preservation stage: keeping the furnace temperature at 1100-; in the fourth stage, the temperature is kept at 950 and 1000 ℃ for 10-20 min.

In a further preferable embodiment, the high-temperature mesh belt in step S2 is made of stainless steel 304.

In a further preferred embodiment, the heat treatment process in step S6 is divided into four stages, where the first stage is a preheating process: firstly keeping the furnace temperature at 400-; the second stage is carburizing treatment: firstly, the furnace temperature is 900-; the third stage is quenching treatment: keeping the furnace temperature at 900-; the fourth stage is tempering treatment: keeping the furnace temperature at 200-250 ℃, keeping the temperature for 40-60min, and cooling to room temperature.

(III) advantageous effects

The embodiment of the invention provides a one-step formed porous eccentric step spiral gear and a processing technology thereof. The method has the following beneficial effects:

1. the gear is molded at one time, the production cost is reduced, the molded compact is placed in a high-temperature mesh belt furnace for sintering, the sintering process is divided into a degreasing stage, a preheating stage, a heat preservation stage and a temperature equalization stage, and the temperature and the time are optimized, so that parts can be better and stably combusted in the furnace, and the performance of the gear is improved.

2. The heat treatment process is divided into four stages of preheating treatment, carburizing treatment, quenching treatment and tempering treatment, the temperature and the time are optimized, the mechanical property of the gear is enhanced, and the mechanical strength and the surface hardness of the gear are improved.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

In the description of the present invention, it is to be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present invention.

FIG. 1 is a schematic front view of the present invention;

FIG. 2 is a schematic side sectional view of the present invention.

In the figure: 1 wheel hub, 2 bull wheels, 3 bull wheels, 4 gear teeth, 5 annular grooves, 6 pin holes, 7 pin shafts, 8 through holes, 9 annular bosses, 10 horizontal axis lines and 11 vertical axis lines.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The utility model provides a porous eccentric step helical gear once only takes shape, includes wheel hub 1, wheel hub 1 is by eccentric arrangement's bull wheel 2 and 3 integrated into one piece of steamboat, and steamboat 3 is located the protruding setting on the terminal surface of one side of bull wheel 2, be provided with the teeth of a cogwheel 4 on the outer periphery of bull wheel 2, the both sides terminal surface symmetry of bull wheel 2 is provided with 2 endocentric annular groove 5 with the bull wheel, steamboat 3 is located the setting of annular groove 5, and is provided with the pinhole 6 that only runs through bull wheel 2 in the annular groove 5, it has round pin axle 7 to peg graft in the pinhole 6, the center of bull wheel 2 is provided with and runs through bull wheel 2 with the through-hole 8 of steamboat 3, and be provided with on the terminal surface on the steamboat 3 with through-hole 8 eccentric annular boss 9.

In order to facilitate accurate machining of the gear, the diameter section of the hub 1 is 28, the number of teeth of the hub 1 is 46, the pressure angle of the hub 1 is 20 °, the helix angle of the hub 1 is right-handed 23 °, the addendum circle diameter of the hub 1 is 47.10-47.25mm, the dedendum circle diameter of the hub 1 is 43.13-43.27mm, the cross PIN diameter of the hub 1 is 48.786-48.904mm, the PIN diameter of the hub 1 is 2mm, and the precision grade of the hub 1 is DIN 9.

In order to enable the annular boss 9 and the through hole 8 to be eccentrically arranged, the bull wheel 2 comprises a horizontal axis 10 and a vertical axis 11 which are perpendicular to each other, and an eccentric included angle between an extension line of a circle center connecting line of the through hole 8 and the circle center of the annular boss 9 and the horizontal axis 10 of the bull wheel 2 is 45 degrees.

In order to facilitate the processing of the gear, the small wheel 3 and the pin hole 6 are arranged on a vertical axis 11 of the large wheel 2, and the small wheel 3 and the pin hole 6 are arranged at intervals.

Example 2

A one-time forming porous eccentric step spiral gear machining process comprises the following steps:

s1, forming and pressing: feeding a certain amount of mixed raw material powder into a press, pressing by using a mold, and forming at one step to obtain a pressed blank, wherein the pressure intensity is 200Mpa when the mold is pressed;

s2, sintering: placing the formed pressed compact in a high-temperature mesh belt furnace for sintering, introducing a proper amount of nitrogen and hydrogen, and rapidly cooling to normal temperature after sintering is completed to obtain a sintered piece, wherein the sintering process is divided into four stages, and the first stage is a degreasing stage: keeping the temperature of the furnace at 600 ℃ and keeping the temperature for 10 min; the second stage is a preheating stage: keeping the furnace temperature at 700 ℃ for 10min, and keeping the furnace temperature at 800 ℃ for 10 min; the third stage is a heat preservation stage: keeping the furnace temperature at 1100 deg.C, and keeping the temperature for 30 min; in the fourth stage, temperature equalization is carried out, the furnace temperature is kept at 950 ℃, the heat preservation time is 10min, and the high-temperature mesh belt is made of stainless steel 304;

s3, rough turning: roughly turning the sintered part by adopting a numerical control lathe, wherein the rough turning comprises the steps of carrying out turning on the contour surfaces of the large wheel 2 and the small wheel 3, drilling the pin holes 6 and the through holes 8 to be in a finish-machined size, and turning the annular groove 5 and the annular boss 9 to obtain a roughly-turned part;

s4, hobbing: carrying out roller teeth 4 on the rough turning piece by adopting a numerical control gear hobbing machine to obtain a first gear;

s5, shaving: shaving the tooth surface of the gear tooth 4 of the first gear by using a numerical control gear shaving machine to obtain a second gear;

s6, heat treatment: and (3) carrying out carburizing and quenching treatment on the second gear to obtain a third gear, wherein the heat treatment process is divided into four stages, and the first stage is preheating treatment: keeping the furnace temperature at 400 ℃ for 30min, and then keeping the furnace temperature at 600 ℃ for 50 min; the second stage is carburizing treatment: firstly keeping the furnace temperature at 900 ℃ for 60min, then keeping the furnace temperature at 1000 ℃ for 80min, then cooling to 850 ℃ along with the furnace to perform spheroidizing annealing for 60min, and then air-cooling to room temperature; the third stage is quenching treatment: keeping the temperature of the furnace at 900 ℃, keeping the temperature for 50min, then putting the furnace into quenching oil at 100 ℃, cooling the furnace for 20min, taking out the furnace, and then cooling the furnace to room temperature; the fourth stage is tempering treatment: keeping the furnace temperature at 200 ℃, keeping the temperature for 40min, and cooling to room temperature;

s7, pressing PIN: a PIN shaft 7 is implanted into the PIN hole 6 of the second gear by adopting a PIN pressing machine to obtain a fourth gear;

s8, finish turning: finely turning the through hole 8 of the third gear by using a numerical control lathe to obtain a fifth gear;

s9, vibration grinding and cleaning: carrying out vibration grinding on the fifth gear by using a vibration grinding machine for 20-40min to remove burrs, rough edges, flash edges and the like on the surface of the part, and cleaning after the vibration grinding is finished to obtain a finished gear;

s10, packaging: and (5) detecting, packaging and warehousing the finished gear.

Example 3

A one-time forming porous eccentric step spiral gear machining process comprises the following steps:

s1, forming and pressing: feeding a certain amount of mixed raw material powder into a press, pressing by using a mold, and forming at one step to obtain a pressed blank, wherein the pressure intensity is 300Mpa when the mold is pressed;

s2, sintering: placing the formed pressed compact in a high-temperature mesh belt furnace for sintering, introducing a proper amount of nitrogen and hydrogen, and rapidly cooling to normal temperature after sintering is completed to obtain a sintered piece, wherein the sintering process is divided into four stages, and the first stage is a degreasing stage: keeping the temperature of the furnace at 650 ℃, and keeping the temperature for 20 min; the second stage is a preheating stage: keeping the furnace temperature at 750 deg.C, maintaining for 20min, keeping the furnace temperature at 850 deg.C, and maintaining for 20 min; the third stage is a heat preservation stage: keeping the furnace temperature at 1200 ℃, and keeping the temperature for 40 min; in the fourth stage of temperature equalization, the furnace temperature is kept at 1000 ℃ and the heat preservation time is 20 min;

s3, rough turning: roughly turning the sintered part by adopting a numerical control lathe, wherein the rough turning comprises the steps of carrying out turning on the contour surfaces of the large wheel 2 and the small wheel 3, drilling the pin holes 6 and the through holes 8 to be in a finish-machined size, and turning the annular groove 5 and the annular boss 9 to obtain a roughly-turned part;

s4, hobbing: carrying out roller teeth 4 on the rough turning piece by adopting a numerical control gear hobbing machine to obtain a first gear;

s5, shaving: shaving the tooth surface of the gear tooth 4 of the first gear by using a numerical control gear shaving machine to obtain a second gear;

s6, heat treatment: and (3) carrying out carburizing and quenching treatment on the second gear to obtain a third gear, wherein the heat treatment process is divided into four stages, and the first stage is preheating treatment: keeping the furnace temperature at 500 ℃ for 40min, and keeping the furnace temperature at 700 ℃ for 60 min; the second stage is carburizing treatment: firstly, keeping the furnace temperature at 1000 ℃ for 70min, then keeping the furnace temperature at 1200 ℃, keeping the temperature for 90min, then cooling to 900 ℃ along with the furnace to perform spheroidizing annealing for 120min, and then cooling to room temperature in air; the third stage is quenching treatment: keeping the furnace temperature at 950 ℃, keeping the temperature for 60min, then putting into quenching oil at 120 ℃, cooling for 30min, taking out, and then cooling to room temperature in air; the fourth stage is tempering treatment: keeping the furnace temperature at 250 ℃, keeping the temperature for 60min, and cooling to room temperature;

s7, pressing PIN: a PIN shaft 7 is implanted into the PIN hole 6 of the second gear by adopting a PIN pressing machine to obtain a fourth gear;

s8, finish turning: finely turning the through hole 8 of the third gear by using a numerical control lathe to obtain a fifth gear;

s9, vibration grinding and cleaning: carrying out vibration grinding on the fifth gear by using a vibration grinding machine for 20-40min to remove burrs, rough edges, flash edges and the like on the surface of the part, and cleaning after the vibration grinding is finished to obtain a finished gear;

s10, packaging: and (5) detecting, packaging and warehousing the finished gear.

Example 4

A one-time forming porous eccentric step spiral gear machining process comprises the following steps:

s1, forming and pressing: feeding a certain amount of mixed raw material powder into a press, pressing by using a mold, and forming at one step to obtain a pressed blank, wherein the pressure intensity is 250Mpa when the mold is pressed;

s2, sintering: placing the formed pressed compact in a high-temperature mesh belt furnace for sintering, introducing a proper amount of nitrogen and hydrogen, and rapidly cooling to normal temperature after sintering is completed to obtain a sintered piece, wherein the sintering process is divided into four stages, and the first stage is a degreasing stage: keeping the temperature of the furnace at 625 ℃, and keeping the temperature for 15 min; the second stage is a preheating stage: keeping the furnace temperature at 725 ℃, keeping the temperature for 15min, and keeping the furnace temperature at 825 ℃, keeping the temperature for 15 min; the third stage is a heat preservation stage: keeping the temperature of the furnace at 1150 ℃ and keeping the temperature for 35 min; in the fourth stage, the temperature is kept at 975 ℃ for 15 min;

s3, rough turning: roughly turning the sintered part by adopting a numerical control lathe, wherein the rough turning comprises the steps of carrying out turning on the contour surfaces of the large wheel 2 and the small wheel 3, drilling the pin holes 6 and the through holes 8 to be in a finish-machined size, and turning the annular groove 5 and the annular boss 9 to obtain a roughly-turned part;

s4, hobbing: carrying out roller teeth 4 on the rough turning piece by adopting a numerical control gear hobbing machine to obtain a first gear;

s5, shaving: shaving the tooth surface of the gear tooth 4 of the first gear by using a numerical control gear shaving machine to obtain a second gear;

s6, heat treatment: and (3) carrying out carburizing and quenching treatment on the second gear to obtain a third gear, wherein the heat treatment process is divided into four stages, and the first stage is preheating treatment: keeping the furnace temperature at 450 ℃ for 35min, and keeping the furnace temperature at 650 ℃ for 55 min; the second stage is carburizing treatment: firstly keeping the furnace temperature at 950 ℃ for 65min, then keeping the furnace temperature at 1100 ℃ for 85min, then cooling to 875 ℃ along with the furnace to perform spheroidization annealing for 90min, and then air-cooling to room temperature; the third stage is quenching treatment: keeping the furnace temperature at 925 ℃, keeping the temperature for 55min, then placing the furnace into quenching oil at 110 ℃, cooling the furnace for 25min, taking out the furnace, and then cooling the furnace to room temperature; the fourth stage is tempering treatment: keeping the furnace temperature at 225 ℃, keeping the temperature for 50min, and cooling to room temperature;

s7, pressing PIN: a PIN shaft 7 is implanted into the PIN hole 6 of the second gear by adopting a PIN pressing machine to obtain a fourth gear;

s8, finish turning: finely turning the through hole 8 of the third gear by using a numerical control lathe to obtain a fifth gear;

s9, vibration grinding and cleaning: carrying out vibration grinding on the fifth gear by using a vibration grinding machine for 20-40min to remove burrs, rough edges, flash edges and the like on the surface of the part, and cleaning after the vibration grinding is finished to obtain a finished gear;

s10, packaging: and (5) detecting, packaging and warehousing the finished gear.

Comparative example 1

A one-time forming porous eccentric step spiral gear machining process comprises the following steps:

s1, forming and pressing: feeding a certain amount of mixed raw material powder into a press, pressing by using a mold, and forming at one step to obtain a pressed blank, wherein the pressure intensity is 250Mpa when the mold is pressed;

s2, sintering: placing the formed pressed blank in a high-temperature mesh belt furnace for sintering, introducing a proper amount of nitrogen and hydrogen, and rapidly cooling to normal temperature after sintering is completed to obtain a sintered piece, wherein the furnace temperature in the sintering process is 1150 ℃, and the temperature is kept for 90 min;

s3, rough turning: roughly turning the sintered part by adopting a numerical control lathe, wherein the rough turning comprises the steps of carrying out turning on the contour surfaces of the large wheel 2 and the small wheel 3, drilling the pin holes 6 and the through holes 8 to be in a finish-machined size, and turning the annular groove 5 and the annular boss 9 to obtain a roughly-turned part;

s4, hobbing: carrying out roller teeth 4 on the rough turning piece by adopting a numerical control gear hobbing machine to obtain a first gear;

s5, shaving: shaving the tooth surface of the gear tooth 4 of the first gear by using a numerical control gear shaving machine to obtain a second gear;

s6, heat treatment: carrying out carburizing and quenching treatment on the second gear to obtain a third gear, wherein the temperature of the heat treatment furnace is 1100 ℃, and the temperature is kept for 90 min;

s7, pressing PIN: a PIN shaft 7 is implanted into the PIN hole 6 of the second gear by adopting a PIN pressing machine to obtain a fourth gear;

s8, finish turning: finely turning the through hole 8 of the third gear by using a numerical control lathe to obtain a fifth gear;

s9, vibration grinding and cleaning: carrying out vibration grinding on the fifth gear by using a vibration grinding machine for 20-40min to remove burrs, rough edges, flash edges and the like on the surface of the part, and cleaning after the vibration grinding is finished to obtain a finished gear;

s10, packaging: and (5) detecting, packaging and warehousing the finished gear.

Detection of

The hardness and tensile strength of the gears in examples 2 to 4 and comparative example 1 were determined in accordance with German standard DIN50150, and the results are shown in the following table:

group of	Example 1	Example 2	Example 3	Comparative example 1
					Hardness (HRC)	59.5	60	62	45.8
Tensile strength (N/mm)2）	2280	2255	2350	1850

As can be seen from the table, the hardness and tensile strength of the one-time formed porous eccentric step helical gear prepared by the method are obviously improved.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.