CN112628379A - Electric VVT chain wheel of automobile engine and powder metallurgy preparation method thereof - Google Patents

Electric VVT chain wheel of automobile engine and powder metallurgy preparation method thereof Download PDF

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Publication number
CN112628379A
CN112628379A CN202011378161.6A CN202011378161A CN112628379A CN 112628379 A CN112628379 A CN 112628379A CN 202011378161 A CN202011378161 A CN 202011378161A CN 112628379 A CN112628379 A CN 112628379A
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China
Prior art keywords
chain wheel
electric vvt
sintering
powder metallurgy
bearing cover
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CN202011378161.6A
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Chinese (zh)
Inventor
施昌旭
夏敏
石小荣
张艳伟
刘桦
茆长林
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Jiangsu Zhizao New Material Co ltd
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Jiangsu Zhizao New Material Co ltd
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Priority to CN202011378161.6A priority Critical patent/CN112628379A/en
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/06—Use of materials; Use of treatments of toothed members or worms to affect their intrinsic material properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/10—Metallic powder containing lubricating or binding agents; Metallic powder containing organic material
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/16—Both compacting and sintering in successive or repeated steps
    • B22F3/164—Partial deformation or calibration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F5/08—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product of toothed articles, e.g. gear wheels; of cam discs
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0264—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements the maximum content of each alloying element not exceeding 5%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C33/00—Making ferrous alloys
    • C22C33/02—Making ferrous alloys by powder metallurgy
    • C22C33/0257—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements
    • C22C33/0278—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5%
    • C22C33/0285—Making ferrous alloys by powder metallurgy characterised by the range of the alloying elements with at least one alloying element having a minimum content above 5% with Cr, Co, or Ni having a minimum content higher than 5%
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/12—Ferrous alloys, e.g. steel alloys containing tungsten, tantalum, molybdenum, vanadium, or niobium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/16—Ferrous alloys, e.g. steel alloys containing copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/20—Ferrous alloys, e.g. steel alloys containing chromium with copper
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
    • C23C8/36—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases using ionised gases, e.g. ionitriding
    • C23C8/38—Treatment of ferrous surfaces
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16H—GEARING
    • F16H55/00—Elements with teeth or friction surfaces for conveying motion; Worms, pulleys or sheaves for gearing mechanisms
    • F16H55/02—Toothed members; Worms
    • F16H55/30—Chain-wheels
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/12—Both compacting and sintering
    • B22F3/16—Both compacting and sintering in successive or repeated steps
    • B22F3/164—Partial deformation or calibration
    • B22F2003/166—Surface calibration, blasting, burnishing, sizing, coining

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • General Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electromagnetism (AREA)
  • Thermal Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Gears, Cams (AREA)

Abstract

The invention discloses an electric VVT chain wheel of an automobile engine and a powder metallurgy preparation method thereof. Comprises a sprocket body, a gear part and a bearing cover; the gear part is arranged on the chain wheel body, and the outer edge of the gear part is provided with gear teeth; the middle part of the chain wheel body is provided with a shaft hole; the bearing cover is arranged on one side of the chain wheel body and is of an annular structure; the chain wheel body is provided with a groove, and one end of the groove is communicated with the shaft hole; a notch corresponding to the groove is arranged on the bearing cover and is communicated with the groove; the outer edge of the bearing cover is also provided with a bulge, and the bulge is provided with an assembling hole; a positioning sleeve is arranged on one side of the chain wheel body, which is far away from the bearing cover, and a key is arranged in the positioning sleeve; the chain wheel body, the bearing cover and the positioning sleeve are of an integrated forming structure. Preparation: mixing → warm compaction forming → presintering → shaping slider slot working face to surface densification → machining → sintering → ionic nitriding → inspection and warehousing. The electric VVT chain wheel of the automobile engine has the advantages of higher response speed and more accurate control.

Description

Electric VVT chain wheel of automobile engine and powder metallurgy preparation method thereof
Technical Field
The invention relates to the technical field of automobile engine parts, in particular to an electric VVT chain wheel of an automobile engine and a powder metallurgy preparation method thereof.
Background
The variable timing mechanism (VVT) can effectively improve the fuel economy of an engine and reduce the emission of harmful gases, but the traditional hydraulic VVT is influenced by the temperature and the pressure of engine oil and cannot intervene in the operation at low temperature, low rotating speed and the initial starting stage of the engine. The electric VVT is a motor-driven intelligent variable valve timing system, and the motor-controlled VVT has higher response speed and more accurate control and can realize stepless regulation so that the working range of the variable valve timing system is expanded. The electric VVT can change the timing of an air inlet valve and an air outlet valve under the condition of larger engine speed and lower temperature range of cooling liquid, and improves the air inlet efficiency and the air outlet efficiency, thereby improving the idle speed stability and the low speed smoothness, improving the power and the torque of an engine, reducing the fuel consumption rate of part load and improving the exhaust emission. The application of the electric VVT on an automobile engine can effectively improve the fuel economy of the engine and reduce the emission of harmful gases.
The sprocket is the key functional part of electronic VVT system, and the structure is complicated, and the precision is high, and the working face needs to possess high strength, high wear resistance. Conventional powder metallurgy processes do not allow for the manufacture and batch production of such electric VVT sprockets.
Disclosure of Invention
The invention aims to provide an electric VVT chain wheel of an automobile engine, which has high response speed and high control precision, and designs three components with different functions, namely a chain wheel body, a bearing cover bearing high-strength torque and provided with a slide block groove and a positioning sleeve, into an integral piece formed in one step, thereby improving the assembly precision and the assembly efficiency and reducing the component cost; the invention also aims to provide a simple powder metallurgy preparation method of the electric VVT chain wheel of the automobile engine, which ensures the strength, the wear resistance and the matching size precision of the working surface of the chain wheel and meets the use requirement of the electric VVT by selecting proper powder metallurgy materials and powder metallurgy processes.
The invention is realized by the following technical scheme:
an electric VVT sprocket of an automobile engine is characterized by comprising a sprocket body, a gear part and a bearing cover; the gear part is arranged on the sprocket body, and gear teeth are arranged on the outer edge of the gear part; the middle part of the chain wheel body is provided with a shaft hole for connecting an installation shaft; the bearing cover is arranged on one side of the chain wheel body and is of an annular structure; the chain wheel body is provided with a groove, and one end of the groove is communicated with the shaft hole; the bearing cover is provided with a notch corresponding to the groove, and the notch is communicated with the groove; the outer edge of the bearing cover is also provided with a plurality of bulges, and the bulges are provided with assembly holes; an annular step-shaped positioning sleeve is arranged on one side, away from the bearing cover, of the chain wheel body, and a key for fixing the mounting shaft is arranged in the positioning sleeve; the chain wheel body, the bearing cover and the positioning sleeve are of an integrated forming structure. Specifically, when using this electronic VVT sprocket the shaft hole in connect the installation axle, install epaxial supporting be provided with key complex keyway, realize both key-type connection through the key in the position sleeve and the epaxial keyway of installation, fix the installation axle to prevent in the course of the work the installation axle be in the shaft hole in the drunkenness. According to the electric VVT chain wheel of the automobile engine, the chain wheel body, the bearing cover with the sliding block groove and the positioning sleeve which bear high-strength torque and have different functions are designed into an integral piece which is formed in one step, so that the assembly precision and the assembly efficiency are improved, and the component cost is reduced. The electric VVT chain wheel of the automobile engine works by depending on the motor control assembly, and has higher response speed and more accurate control.
Furthermore, the number of the grooves is two, and the grooves are symmetrically arranged along the radial direction of the chain wheel body; the number of the notches is two, and the notches are symmetrically arranged along the radial direction of the bearing cover; the notch is communicated with the groove to form two slider grooves. Specifically, two grooves are respectively arranged at two ends of the sprocket body (namely the shaft hole) in the diameter direction; the two notches are also respectively arranged at the two ends of the bearing cover in the diameter direction. The groove is arranged on the chain wheel body and is communicated with an axle hole in the chain wheel body, namely the groove is provided with an opening in the axle hole; the bearing cover is provided with a notch, and the notch is positioned above the groove and communicated with the groove to form a sliding block groove.
Further, the inner diameters of the shaft hole, the bearing cover and the positioning sleeve are the same; the width of the groove is the same as that of the notch. Preferably, the inner diameters of the shaft hole, the bearing cap and the positioning sleeve are set to be the same, and the bearing cap is arranged at one side of the chain wheel body and is precisely butted with the shaft hole (namely, the inner wall of the bearing cap with an annular structure is smoothly connected with the inner wall of the shaft hole without steps); meanwhile, the positioning sleeve is arranged on one side, which is far away from the bearing cover, of the chain wheel body and is precisely butted with the shaft hole (namely, the inner wall of the annular step-shaped positioning sleeve is smoothly connected with the inner wall of the shaft hole without steps). Preferably, the width of the recess and the width of the groove are designed to be the same, i.e. to provide a smooth connection between the recess and the recess, i.e. to provide a smooth connection between the recess and the opening of the groove in the shaft bore.
Furthermore, the number of the bulges is 4, and the bulges are uniformly distributed on the peripheral surface of the outer edge of the bearing cover; the assembling hole is a threaded hole; the chain wheel body is also provided with a timing mark. Preferably, a timing mark is arranged on the end face of the chain wheel body, so that positioning during assembly is facilitated.
A powder metallurgy preparation method of an electric VVT chain wheel of an automobile engine is characterized by comprising the following steps:
(1) material preparation and material mixing: preparing a powder metallurgy material of the electric VVT chain wheel of the automobile engine, and uniformly mixing; the powder metallurgy material comprises the following components in percentage by mass; c: 0.5-1.0%, Mo: 0-0.9%, Cr: 0-7.0%, Cu: 0-3.0%, Mn: 0-0.5%, Si: 0 to 0.5 percent of lubricant, 0.3 to 0.6 percent of lubricant, and the balance of Fe and inevitable impurities;
(2) warm-pressing and forming: pressing and forming the uniformly mixed powder metallurgy material in a forming die to obtain an electric VVT sprocket green body; ensuring that the joint of each part of the green compact has no crack, automatically brushing burrs after the green compact is demoulded, and ensuring that the density of the bearing cover, the gear part and the chain wheel body is 6.95-7.05g/cm3The density of the positioning sleeve is 6.85-6.95g/cm3The dividing density of each forming section is less than or equal to 0.2g/cm3(ii) a Heating the powder metallurgy material and the die before forming;
(3) pre-sintering: pre-sintering the formed electric VVT sprocket green body at the temperature of 800-1000 ℃ for 20-60 minutes;
(4) shaping: will be provided withThe pre-sintered electric VVT chain wheel is arranged in a shaping die, and the local extrusion densification is carried out on the groove, and the density of the part is 7.25-7.35g/cm3(ii) a The related dimensional accuracy and the position degree of the chain wheel are ensured through shaping;
(5) machining: after shaping, processing an assembly hole on the bulge;
(6) and (3) sintering: after machining, performing secondary sintering on the electric VVT chain wheel; the sintering temperature is 1100-1150 ℃, and the sintering time is 30-60 minutes;
(7) ion nitriding: performing secondary sintering on the electric VVT sprocket and then performing ion nitriding to obtain the electric VVT sprocket of the automobile engine;
(8) cleaning, inspecting and packaging: after ion nitriding, cleaning, inspecting, packaging and warehousing the product.
In view of the requirement of mechanical property of the working surface of the electric VVT chain wheel of the automobile engine, a plurality of alloy elements are added in the raw material composition design, but the alloy elements can influence the pressing property of the raw materials, and the green density of the product is difficult to improve; the addition of the lubricant can change the surface property of the metal powder, so that the metal powder is in a viscous state during warm pressing, the lubricating effect among powder particles in the pressing process is enhanced, small powder particles are promoted to be filled into gaps among large powder particles, the filling property of the powder particles is improved, the pressing pressure is better transmitted, the friction resistance is reduced, and the pressing property and the green density of the raw material are improved. The electric VVT depends on a motor control assembly to work, the response speed is higher, the control is more accurate, the precision requirement of the chain wheel matching size is high, a slide block needs to reciprocate in a slide block groove and bear high-strength torque, so that the working surface of the slide block groove in the bearing cover of the electric VVT chain wheel needs to have high wear resistance and high strength, the consistency of the size precision is ensured in the production process of the chain wheel, and the deformation is controlled; according to the powder metallurgy preparation method of the electric VVT chain wheel of the automobile engine, the strength, the wear resistance and the matching size precision of the working surface of the chain wheel are ensured by selecting the proper powder metallurgy material and the powder metallurgy process, and the use requirement of the electric VVT chain wheel is met.
Further, the step (1) of batching and mixing: preparing a powder metallurgy material of the electric VVT chain wheel of the automobile engine, and uniformly mixing; the powder metallurgy material comprises the following components in percentage by mass; c: 0.5-0.8%, Mo: 0.4-0.9%, Cr: 4.0-7.0%, Cu: 1.0-3.0%, Mn: 0.2-0.4%, Si: 0.1-0.3%, 0.4-0.6% of lubricant, and the balance of Fe and inevitable impurities.
Further, warm-pressing in the step (2): putting the uniformly mixed powder metallurgy material into a 500-1000-ton CNC forming machine for press forming to obtain an electric VVT sprocket green compact; ensuring that the joint of each part of the green compact has no crack, automatically brushing burrs after the green compact is demoulded, and ensuring that the density of the bearing cover, the gear part and the chain wheel body is 6.95-7.05g/cm3The density of the positioning sleeve is 6.85-6.95g/cm3The dividing density of each forming section is less than or equal to 0.2g/cm3(ii) a And heating the powder metallurgy material and the die to 130-150 ℃ before the press forming.
Further, step (3) presintering: and placing the formed electric VVT sprocket green body into a mesh belt sintering furnace for pre-sintering, wherein the pre-sintering temperature is 850-900 ℃, and the pre-sintering time is 20-60 minutes. Preferably, the pre-sintering temperature is 850 ℃.
Further, sintering in the step (6): after machining, placing the electric VVT chain wheel in a mesh belt type sintering furnace for secondary sintering; the sintering temperature is 1110-1130 ℃, and the sintering time is 30-45 minutes; sintering is carried out in an oxygen-free environment in which nitrogen and hydrogen are mixed, and the volume ratio of the nitrogen to the hydrogen is 9: 1. the oxygen-free environment employs hydrogen as a shielding gas.
Further, step (7) ion nitriding: the temperature of the ion nitriding is 450-550 ℃, and the time is 6-8 hours. The product deformation can be reduced through the ion nitriding treatment, and the wear resistance and the bearing capacity in the wear process of the product can be improved.
The invention has the beneficial effects that:
(1) according to the electric VVT chain wheel of the automobile engine, three components with different functions, namely the chain wheel body, the bearing cover with the sliding block groove and the positioning sleeve, which bear high-strength torque, are designed into an integral piece formed in one step by powder metallurgy, so that the assembly precision and the assembly efficiency are improved, and the component cost is reduced; the electric VVT chain wheel of the automobile engine works by depending on the motor control assembly, and has higher response speed and more accurate control.
(2) The powder metallurgy preparation method of the electric VVT chain wheel of the automobile engine adopts proper powder metallurgy materials, special raw material lubricants, warm compaction forming and the like to improve the pressability of prealloying raw materials, realizes the local densification of the working surface of the slide block groove in the bearing cover by shaping after the pre-sintering to improve the strength of the working surface, has relatively low hardness and rigidity of the product after the pre-sintering, and can improve the shaping and machining efficiency. After secondary sintering, in order to further improve the alternating load resistance and the wear resistance of the working surfaces of the electric VVT chain wheel and the sliding block groove, the chain wheel is subjected to ion nitriding treatment, and compared with conventional carburizing or local high-frequency heat treatment, the ion nitriding treatment can reduce the deformation of the product and improve the wear resistance and the bearing capacity in the wear process of the product.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
FIG. 1 is a front view of an electric VVT sprocket of an automotive engine of the present invention;
FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1;
FIG. 3 is a rear view of the automotive engine electric VVT sprocket of the present invention;
fig. 4 is a schematic structural diagram of an electric VVT sprocket of an automobile engine according to the present invention.
In the figure: 1 sprocket body, 2 gear parts, 3 bearing covers, 4 shaft holes, 5 locating sleeves, 6 keys, 7 timing marks, 8 slider grooves, 11 grooves, 31 notches, 32 protrusions and 321 assembly holes.
Detailed Description
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 only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. 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
An electric VVT sprocket of an automobile engine is characterized by comprising a sprocket body 1, a gear part 2 and a bearing cover 3; the gear part 2 is arranged on the sprocket body 1, and gear teeth are arranged on the outer edge of the gear part 2; the middle part of the chain wheel body 1 is provided with a shaft hole 4 for connecting an installation shaft; the bearing cover 3 is arranged on one side of the chain wheel body 1, and the bearing cover 3 is of an annular structure; a groove 11 is formed in the chain wheel body 1, and one end of the groove 11 is communicated with the shaft hole 4; a notch 31 corresponding to the groove 11 is arranged on the bearing cover 3, and the notch 31 is communicated with the groove 11; the outer edge of the bearing cover 3 is also provided with a plurality of bulges 32, and the bulges 32 are provided with assembly holes 321; an annular step-shaped positioning sleeve 5 is arranged on one side, away from the bearing cover 3, of the sprocket body 1, and a key 6 for fixing the mounting shaft is arranged in the positioning sleeve 5 (namely, the mounting shaft is fixedly connected in the shaft hole 4 through the key connection, so that the mounting shaft is prevented from moving in the shaft hole 4); the chain wheel body 1, the bearing cover 3 and the locating sleeve 5 are integrally formed by powder metallurgy.
Preferably, the number of the grooves 11 is two, and the grooves 11 are symmetrically arranged at two ends along the radial direction of the sprocket body 1 (the shaft hole 4); the number of the notches 31 is also two, and the notches 31 are symmetrically arranged at two ends of the bearing cover 3 along the radial direction; the notch 31 is communicated with the groove 11 to form two slider grooves 8. Preferably, the inner diameters of the shaft hole 4, the bearing cap 3 and the positioning sleeve 5 are the same, the inner diameters of the shaft hole 4, the bearing cap 3 and the positioning sleeve 5 are set to be the same, and the bearing cap 3 is arranged on one side of the sprocket body 1 and is precisely butted with the shaft hole 4, namely, the inner wall of the bearing cap 3 with an annular structure is smoothly connected with the inner wall of the shaft hole 4 without steps; the positioning sleeve 5 is arranged on one side, deviating from the bearing cover 3, of the chain wheel body 1 and is precisely butted with the shaft hole 4, so that the inner wall of the annular step-shaped positioning sleeve 5 is smoothly connected with the inner wall of the shaft hole 4 without steps. The width of the groove 11 is the same as the width of the notch 31. Preferably, the width of the notch 31 and the width of the groove 11 are designed to be the same, i.e. to have a smooth connection between the notch 11 and the groove 31, i.e. to have a smooth connection between the notch 31 and the opening of the groove 11 in the shaft hole 4. Preferably, the number of the protrusions 32 is 4, and the protrusions are uniformly distributed on the outer circumferential direction of the bearing cover 3; the assembling hole 321 is a threaded hole; sprocket body 1 on still be provided with timing sign 7, set up timing sign 7 on sprocket body 1, location when being convenient for assemble.
Example 2
A powder metallurgy preparation method of an electric VVT chain wheel of an automobile engine is characterized by comprising the following steps:
(1) material preparation and material mixing: preparing a powder metallurgy material of the electric VVT chain wheel of the automobile engine, and uniformly mixing; the powder metallurgy material comprises the following components in percentage by mass; c: 0.5%, Mo: 0.6%, Cr: 7.0%, Cu: 2.0%, Mn: 0.2%, Si: 0.2%, 0.6% of lubricant, and the balance of Fe and inevitable impurities;
(2) warm-pressing and forming: putting the uniformly mixed powder metallurgy material into a 500-ton CNC forming machine for press forming, and heating the powder metallurgy material and a die to 135 ℃ before press forming to obtain an electric VVT sprocket green body; ensuring that the joints of all parts of the green body have no cracks, automatically brushing burrs after the green body is demoulded, and ensuring that the density of the bearing cover, the gear part and the chain wheel body is 6.98g/cm3The density of the positioning sleeve is 6.86g/cm3The dividing density of each forming section is less than or equal to 0.2g/cm3；
(3) Pre-sintering: placing the formed electric VVT sprocket green body into a mesh belt sintering furnace for presintering, wherein the presintering temperature is 850 ℃, and the presintering time is 30 minutes;
(4) shaping: placing the pre-sintered electric VVT chain wheel in a shaping die, and locally compacting the groove by extrusion, wherein the density of the part is 7.30g/cm3(ii) a The related dimensional accuracy and the position degree of the chain wheel are ensured through shaping;
(5) machining: after shaping, processing an assembly hole on the bulge;
(6) and (3) sintering: after machining, placing the electric VVT chain wheel in a mesh belt type sintering furnace for secondary sintering; the sintering temperature is 1120 ℃, and the sintering time is 35 minutes; sintering is carried out in an oxygen-free environment in which nitrogen and hydrogen are mixed, and the volume ratio of the nitrogen to the hydrogen is 9: 1; hydrogen is used as protective gas in the oxygen-free environment;
(7) ion nitriding: performing secondary sintering on the electric VVT sprocket and then performing ion nitriding to obtain the electric VVT sprocket of the automobile engine; the temperature of the ion nitriding is 530 ℃, and the nitriding time is 6 hours;
(8) cleaning, inspecting and packaging: after ion nitriding, cleaning, inspecting, packaging and warehousing the product.
The main functional indexes of the qualified product are as follows:
the standard requires that: 0.03-0.10mm of nitrided layer on the surface of the chain wheel and hardness value HV of tooth part0.2Not less than 340, hardness HV of working surface of sliding block slot of bearing cover0.2Not less than 360.
Testing of the automotive engine electric VVT sprocket made in example 2 above: 0.05mm of nitrided layer on the surface of the chain wheel and hardness value HV of tooth part0.2345 bearing cap slider groove working face hardness HV0.2375, all meet the standard requirements.
Example 3
A powder metallurgy preparation method of an electric VVT chain wheel of an automobile engine is characterized by comprising the following steps:
(1) material preparation and material mixing: preparing a powder metallurgy material of the electric VVT chain wheel of the automobile engine, and uniformly mixing; the powder metallurgy material comprises the following components in percentage by mass; c: 0.8%, Mo: 0.8%, Cr: 4.0%, Cu: 3.0%, Mn: 0.4%, Si: 0.3%, 0.5% of lubricant, and the balance of Fe and inevitable impurities;
(2) warm-pressing and forming: putting the uniformly mixed powder metallurgy material into a CNC (computer numerical control) forming machine of 800 tons for press forming, and heating the powder metallurgy material and a die to 140 ℃ before the press forming to obtain an electric VVT sprocket green body; ensuring that the joints of all parts of the green body have no cracks, automatically brushing burrs after the green body is demoulded, and ensuring that the density of the bearing cover, the gear part and the chain wheel body is 6.97g/cm3The density of the positioning sleeve is 6.88g/cm3The dividing density of each forming section is less than or equal to 0.2g/cm3；
(3) Pre-sintering: placing the formed electric VVT sprocket green body into a mesh belt sintering furnace for pre-sintering, wherein the pre-sintering temperature is 1000 ℃, and the pre-sintering time is 20 minutes;
(4) shaping: placing the pre-sintered electric VVT chain wheel in a shaping die, and locally compacting the groove by extrusion, wherein the density of the part is 7.35g/cm3(ii) a The related dimensional accuracy and the position degree of the chain wheel are ensured through shaping;
(5) machining: after shaping, processing an assembly hole on the bulge;
(6) and (3) sintering: after machining, placing the electric VVT chain wheel in a mesh belt type sintering furnace for secondary sintering; the sintering temperature is 1125 ℃, and the sintering time is 30 minutes; sintering is carried out in an oxygen-free environment in which nitrogen and hydrogen are mixed, and the volume ratio of the nitrogen to the hydrogen is 9: 1; hydrogen is used as protective gas in the oxygen-free environment;
(7) ion nitriding: performing secondary sintering on the electric VVT sprocket and then performing ion nitriding to obtain the electric VVT sprocket of the automobile engine; the temperature of the ion nitriding is 450 ℃, and the nitriding time is 8 hours;
(8) cleaning, inspecting and packaging: after ion nitriding, cleaning, inspecting, packaging and warehousing the product.
The main functional indexes of the qualified product are as follows:
the standard requires that: 0.03-0.10mm of nitrided layer on the surface of the chain wheel and hardness value HV of tooth part0.2Not less than 340, bearing cap sliding block groove toolHardness of working surface HV0.2Not less than 360.
Testing of the automotive engine electric VVT sprocket made in example 3 above: surface nitrided layer of 0.04mm of sprocket, tooth hardness number HV0.2355 bearing cap slider groove working surface hardness HV0.2371 all meet the standard requirements.
Example 4
A powder metallurgy preparation method of an electric VVT chain wheel of an automobile engine is characterized by comprising the following steps:
(1) material preparation and material mixing: preparing a powder metallurgy material of the electric VVT chain wheel of the automobile engine, and uniformly mixing; the powder metallurgy material comprises the following components in percentage by mass; c: 0.6%, Mo: 0.4%, Cr: 6.0%, Cu: 1.0%, Mn: 0.3%, Si: 0.1%, 0.5% of lubricant, and the balance of Fe and inevitable impurities;
(2) warm-pressing and forming: putting the uniformly mixed powder metallurgy material into a 1000-ton CNC forming machine for press forming, and heating the powder metallurgy material and a die to 150 ℃ before press forming to obtain an electric VVT sprocket green body; ensuring that the joints of all parts of the green body have no cracks, automatically brushing burrs after the green body is demoulded, and ensuring that the density of the bearing cover, the gear part and the chain wheel body is 7.00g/cm3The density of the positioning sleeve is 6.89g/cm3The dividing density of each forming section is less than or equal to 0.2g/cm3；
(3) Pre-sintering: placing the formed electric VVT sprocket green body into a mesh belt sintering furnace for pre-sintering, wherein the pre-sintering temperature is 900 ℃, and the pre-sintering time is 60 minutes;
(4) shaping: placing the pre-sintered electric VVT chain wheel in a shaping die, and locally compacting the groove by extrusion, wherein the density of the part is 7.34g/cm3(ii) a The related dimensional accuracy and the position degree of the chain wheel are ensured through shaping;
(5) machining: after shaping, processing an assembly hole on the bulge;
(6) and (3) sintering: after machining, placing the electric VVT chain wheel in a mesh belt type sintering furnace for secondary sintering; the sintering temperature is 1110 ℃, and the sintering time is 45 minutes; sintering is carried out in an oxygen-free environment in which nitrogen and hydrogen are mixed, and the volume ratio of the nitrogen to the hydrogen is 9: 1; hydrogen is used as protective gas in the oxygen-free environment;
(7) ion nitriding: performing secondary sintering on the electric VVT sprocket and then performing ion nitriding to obtain the electric VVT sprocket of the automobile engine; the temperature of the ion nitriding is 550 ℃, and the nitriding time is 6 hours;
(8) cleaning, inspecting and packaging: after ion nitriding, cleaning, inspecting, packaging and warehousing the product.
The main functional indexes of the qualified product are as follows:
the standard requires that: 0.03-0.10mm of nitrided layer on the surface of the chain wheel and hardness value HV of tooth part0.2Not less than 340, hardness HV of working surface of sliding block slot of bearing cover0.2Not less than 360.
Testing of the automotive engine electric VVT sprocket made in example 4 above: surface nitrided layer of 0.04mm of sprocket, tooth hardness number HV0.2369 hardness HV of working surface of sliding block slot of bearing cover0.2381 which all meet the standard requirements.
The above-mentioned preferred embodiments of the present invention are provided for illustration only and not for the purpose of limiting the invention. Obvious variations or modifications of the present invention are within the scope of the present invention.

Claims (10)

1. An electric VVT sprocket of an automobile engine is characterized by comprising a sprocket body (1), a gear part (2) and a bearing cover (3); the gear part (2) is arranged on the sprocket body (1), and gear teeth are arranged on the outer edge of the gear part (2); the middle part of the chain wheel body (1) is provided with a shaft hole (4) for connecting a mounting shaft; the bearing cover (3) is arranged on one side of the chain wheel body (1), and the bearing cover (3) is of an annular structure; a groove (11) is formed in the chain wheel body (1), and one end of the groove (11) is communicated with the shaft hole (4); a notch (31) corresponding to the groove (11) is formed in the bearing cover (3), and the notch (31) is communicated with the groove (11); the outer edge of the bearing cover (3) is also provided with a plurality of bulges (32), and the bulges (32) are provided with assembly holes (321); an annular step-shaped positioning sleeve (5) is arranged on one side, away from the bearing cover (3), of the chain wheel body (1), and a key (6) used for fixing the mounting shaft is arranged in the positioning sleeve (5); the chain wheel body (1), the bearing cover (3) and the positioning sleeve (5) are of an integrated forming structure.
2. The electric VVT sprocket of the automobile engine according to claim 1, wherein the number of the grooves (11) is two, and the grooves (11) are symmetrically arranged along the radial direction of the sprocket body (1); the number of the notches (31) is two, and the notches (31) are symmetrically arranged along the radial direction of the bearing cover (3); the notch (31) is communicated with the groove (11) to form two sliding block grooves (8).
3. The automotive engine electric VVT sprocket as claimed in claim 1, wherein the inner diameters of the shaft hole (4), the bearing cap (3) and the positioning sleeve (5) are the same; the width of the groove (11) is the same as that of the notch (31).
4. The electric VVT sprocket of automobile engine according to claim 1, wherein the number of the protrusions (32) is 4, and the protrusions are uniformly distributed on the outer edge of the bearing cover (3); the assembly hole (321) is a threaded hole; the chain wheel body (1) is further provided with a timing mark (7).
5. The powder metallurgy preparation method of the electric VVT sprocket wheel for the automobile engine according to any one of claims 1 to 4, which is characterized by comprising the following steps:
(1) material preparation and material mixing: preparing a powder metallurgy material of the electric VVT chain wheel of the automobile engine, and uniformly mixing; the powder metallurgy material comprises the following components in percentage by mass; c: 0.5-1.0%, Mo: 0-0.9%, Cr: 0-7.0%, Cu: 0-3.0%, Mn: 0-0.5%, Si: 0 to 0.5 percent of lubricant, 0.3 to 0.6 percent of lubricant, and the balance of Fe and inevitable impurities;
(2) warm-pressing and forming: mixing the above powders uniformlyPressing and forming the material in a forming die to obtain an electric VVT sprocket green body; ensuring that the joints of all parts of the green body have no cracks, and the density of the bearing cover, the gear part and the chain wheel body is 6.95-7.05g/cm3The density of the positioning sleeve is 6.85-6.95g/cm3The dividing density of each forming section is less than or equal to 0.2g/cm3(ii) a Heating the powder metallurgy material and the die before forming;
(3) pre-sintering: pre-sintering the formed electric VVT sprocket green body at the temperature of 800-1000 ℃ for 20-60 minutes;
(4) shaping: placing the pre-sintered electric VVT chain wheel in a shaping die, and locally compacting the groove by extrusion, wherein the density of the part is 7.25-7.35g/cm3；
(5) Machining: after shaping, processing an assembly hole on the bulge;
(6) and (3) sintering: after machining, performing secondary sintering on the electric VVT chain wheel; the sintering temperature is 1100-1150 ℃, and the sintering time is 30-60 minutes;
(7) ion nitriding: performing secondary sintering on the electric VVT sprocket and then performing ion nitriding to obtain the electric VVT sprocket of the automobile engine;
(8) cleaning, inspecting and packaging: after ion nitriding, cleaning, inspecting, packaging and warehousing the product.
6. The powder metallurgy preparation method of the automobile engine electric VVT sprocket according to claim 5, characterized in that, the step (1) comprises the following steps: preparing a powder metallurgy material of the electric VVT chain wheel of the automobile engine, and uniformly mixing; the powder metallurgy material comprises the following components in percentage by mass; c: 0.5-0.8%, Mo: 0.4-0.9%, Cr: 4.0-7.0%, Cu: 1.0-3.0%, Mn: 0.2-0.4%, Si: 0.1-0.3%, 0.4-0.6% of lubricant, and the balance of Fe and inevitable impurities.
7. The powder metallurgy preparation method of the automobile engine electric VVT sprocket according to the claim 5, characterized in that, the step (2) warm press forming: the uniformly mixed powder metallurgy material is put into a CNC forming machine of 500-1000 tons for press forming, and the electric VVT chain is obtainedA green wheel body; ensuring that the joints of all parts of the green body have no cracks, and the density of the bearing cover, the gear part and the chain wheel body is 6.95-7.05g/cm3The density of the positioning sleeve is 6.85-6.95g/cm3The dividing density of each forming section is less than or equal to 0.2g/cm3(ii) a And heating the powder metallurgy material and the die to 130-150 ℃ before the press forming.
8. The powder metallurgy preparation method of the automobile engine electric VVT sprocket according to claim 5, characterized in that, the step (3) is pre-sintering: and placing the formed electric VVT sprocket green body into a mesh belt sintering furnace for pre-sintering, wherein the pre-sintering temperature is 850-900 ℃, and the pre-sintering time is 20-60 minutes.
9. The powder metallurgy preparation method of the automobile engine electric VVT sprocket according to claim 5, characterized in that, the step (6) is sintering: after machining, placing the electric VVT chain wheel in a mesh belt type sintering furnace for secondary sintering; the sintering temperature is 1110-1130 ℃, and the sintering time is 30-45 minutes; sintering is carried out in an oxygen-free environment in which nitrogen and hydrogen are mixed, and the volume ratio of the nitrogen to the hydrogen is 9: 1.
10. the powder metallurgy preparation method of the automobile engine electric VVT sprocket according to claim 5, characterized in that, the step (7) is ion nitriding: the temperature of the ion nitriding is 450-550 ℃, and the time is 6-8 hours.
CN202011378161.6A 2020-11-30 2020-11-30 Electric VVT chain wheel of automobile engine and powder metallurgy preparation method thereof Pending CN112628379A (en)

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CN202011378161.6A CN112628379A (en) 2020-11-30 2020-11-30 Electric VVT chain wheel of automobile engine and powder metallurgy preparation method thereof

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Application Number Priority Date Filing Date Title
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Country Link
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113523285A (en) * 2021-07-13 2021-10-22 扬州保来得科技实业有限公司 Preparation method of powder metallurgy high-density multi-row-tooth chain wheel

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113523285A (en) * 2021-07-13 2021-10-22 扬州保来得科技实业有限公司 Preparation method of powder metallurgy high-density multi-row-tooth chain wheel

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