GB2316097A - Hardened structural steel containing cementite - Google Patents
Hardened structural steel containing cementite Download PDFInfo
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- GB2316097A GB2316097A GB9716992A GB9716992A GB2316097A GB 2316097 A GB2316097 A GB 2316097A GB 9716992 A GB9716992 A GB 9716992A GB 9716992 A GB9716992 A GB 9716992A GB 2316097 A GB2316097 A GB 2316097A
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- structural steel
- members
- sliding
- differential
- subjected
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- 229910000746 Structural steel Inorganic materials 0.000 title claims abstract description 64
- 229910001567 cementite Inorganic materials 0.000 title claims abstract description 24
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 230000005540 biological transmission Effects 0.000 claims abstract description 23
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 19
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 19
- 239000002344 surface layer Substances 0.000 claims abstract description 19
- 238000005256 carbonitriding Methods 0.000 abstract description 26
- 229910000831 Steel Inorganic materials 0.000 abstract description 14
- 239000010959 steel Substances 0.000 abstract description 14
- 229910052804 chromium Inorganic materials 0.000 abstract description 12
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 abstract description 11
- 229910052750 molybdenum Inorganic materials 0.000 abstract description 7
- 238000010438 heat treatment Methods 0.000 abstract description 3
- 238000001816 cooling Methods 0.000 abstract 1
- 239000000463 material Substances 0.000 description 8
- 238000010000 carbonizing Methods 0.000 description 7
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 6
- 239000010410 layer Substances 0.000 description 6
- 238000003672 processing method Methods 0.000 description 6
- 238000010586 diagram Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 238000007796 conventional method Methods 0.000 description 4
- 230000007246 mechanism Effects 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- FBPFZTCFMRRESA-JGWLITMVSA-N D-glucitol Chemical compound OC[C@H](O)[C@@H](O)[C@H](O)[C@H](O)CO FBPFZTCFMRRESA-JGWLITMVSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- 229910052748 manganese Inorganic materials 0.000 description 2
- 229910000734 martensite Inorganic materials 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 2
- 238000001556 precipitation Methods 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 229910052710 silicon Inorganic materials 0.000 description 2
- 239000000758 substrate Substances 0.000 description 2
- 229910000851 Alloy steel Inorganic materials 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910001141 Ductile iron Inorganic materials 0.000 description 1
- 229940123973 Oxygen scavenger Drugs 0.000 description 1
- 206010040844 Skin exfoliation Diseases 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 229910001566 austenite Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004299 exfoliation Methods 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 150000002500 ions Chemical group 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 238000005121 nitriding Methods 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 238000010791 quenching Methods 0.000 description 1
- 230000000171 quenching effect Effects 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 208000024891 symptom Diseases 0.000 description 1
- 238000005496 tempering Methods 0.000 description 1
Classifications
-
- 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
- C23C8/28—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 more than one element being applied in one step
- C23C8/30—Carbo-nitriding
- C23C8/32—Carbo-nitriding of ferrous surfaces
Landscapes
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Mechanical Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Gears, Cams (AREA)
- Retarders (AREA)
- Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
- Heat Treatment Of Articles (AREA)
Abstract
To further improve the surface pressure resistance and the wear resistance of power transmission members and sliding members under a high surface pressure structural steel with cementite precipitated on a surface layer is provided. For this purpose. Side gears made of steel comprising Cr, Mo and having a carbon content of 0.23% are subjected to carbo-nitriding processing. By using structural steel having such a structure that cementite is precipitated on the surface layer in a flake form, members of the power transmission unit or sliding unit are formed. The rementite structure is produced by using a particular heating and cooling regime as illustrated in fig 3. In the carbonitriding ammonia gas is supplied simultaneously with the timing of carburising.
Description
2316097
TITLE OF THE INVENTION
STRUCTURAL STEEL AND STRUCTURAL STEEL MEMBER USED UNDER HIGH SURFACE PRESSURE BACKGROUND OF THE INVENTION FIELD OF THE INVENTION
The present invention relates to structural steel members subjected to surf ace hardening processing. More particularly, the present invention relates to structural steel subjected to surface hardening and having a structure with cementite precipitation and relates to a structural steel member having such a structure.
DESCRIPTION OF THE RELATED ART is As described in, for example, "automobile technique" journal, Vol. 47, No. 5, 1993, pp. 17-22, there is a conventional carbonizing and carbo-nitriding processing method as shown in FIG. 1A and FIG. 1B. In the case of gas carbonizing processing of FIG. 1A, however, there is a problem that a sof t abnormal layer (intergranular oxidation layer) is generated on the surface of the member. In the case of carbo-nitriding processing of FIG. 1B, there is a problem that a lowered hardening layer resulting from a Cr nitride is generated on the surface of the member. Furthermore, in the conventional typical carbo-nitriding processing method as shown in, for example, FIG. 1B, a gear is heated in an atmosphere obtained by supplying carbonizing atmosphere gas into an air current of an inert gas (Rx), held and carbonized at 9300 C for 3 hours, thereafter held and nitrided 1 in an air current of ammonium gas (NH3) of 2.5% at 8400 C for 90 minutes. In these heat treatments, the pitching resistance of the gear under a low surf ace pressure is improved, but the pitching resistance under a high surface pressure is not sufficient. In general, the high surface pressure means at least 0. 2 MPa. Even if there is no problem in wear resistance under a low surface 1 pressure, the wear resistance is significantly degraded under a high surface pressure in some cases.
From these facts, it is desired that a member sliding under a high surface pressure is improved in surface pressure resistance and wear resistance as compared with a member sliding under a low surface pressure.
SUMMARY OF THE INVENTION
In order to solve the above described problems, an object of the present invention is to provide structural steel having a structure capable of Improving the surface pressure resistance and the wear resistance in the case where power transmission or sliding is conducted under a high surf ace pressure by using structural steel. 15 Another object of the present invention is to provide a structural steel member capable of f urther improving the surf ace pressure resistance and the wear resistance of the member conducting power transmission or sliding under a high surface pressure. 20 A further object of the present invention Is to provide a differential gear having the surface pressure resistance and the wear resistance of a structural steel member conducting power transmission or sliding under a high surface pressure. In order to accomplish the above described objects, in accordance with a first aspect of the present invention, structural steel to be used in a power transmission unit under a high surf ace pressure includes structural steel subjected to surf ace hardening processing, and a structure having cementite precipitated on a surface layer in a flake form.
In accordance with a second aspect of the present invention, structural steel members to be used in a power transmission unit under a high surface pressure include both members or either of members of the power transmission unit being subjected to surface hardening, and a structure having cementite precipitated on a 2 surface layer of the members in a flake form.
In accordance with a third aspect of the present invention, the structural steel members have a carbon content of 0.23% or less. In accordance with a f ourth aspect of the present invention, the structural steel members are disposed in a differential gear for distributing a torque inputted to a differential case between a pair of output side gears, and the structural steel members are used as sliding members for limiting a differential movement by sliding with respect to a power transmitting gear or the differential case.
In accordance with a f if th aspect of the present invention, structural steel to be used in a sliding unit sliding under a high surface pressure includes structural steel subjected to surface hardening processing, and a structure having cementite precipitated on a surface layer in a flake form.
In accordance with a sixth aspect of the present invention, structural steel members to be used in a sliding unit under a high surface pressure include both members or either of members of the sliding unit being subjected to surf ace hardening, and a structure having cementite precipitated on a surface layer of the member (s) in a flake form.
In accordance with a seventh aspect of the present invention, the structural steel members have a carbon content of 0.23 or less. In accordance with an eighth aspect of the present invention, the structural steel members are disposed in a differential gear for distributing a torque inputted to a differential case between a pair of output side gears, and the structural steel members are sliding members sliding with respect to a power transmitting gear or the differential case.
Here, as the structural steel, an alloy steel containing alloy elements such as Si, Mn, Cr, P, or S, and further containing alloy elements such as Ni, Mo, or Al, and having a good hardening property, or carbon steel having a controlled carbon content can be mentioned. As f or the materials corresponding to the chemical 3 components, in the case of steel comprising Cr,Mo, the C content in the range of 0. 12 to 0. 23%, the Si content in the range of 0. 15 to 0.35%, the Mn content in the range of 0.55 to 0.90%, the Cr content in the range of 0. 85 to 1. 25%, the Mo content in the range of 0. 15 to 0. 35%, the P content of 0. 030-W or less, and the S content of 0. 030% or less are preferred. In the case of steel comprising Cr, the C content in the range of 0. 12 to 0. 23%, the Si content in the range of 0. 15 to 0. 35%, the Mn content in the range of 0. 55 to 0. 90-W, the Cr content in the range of 0. 85 to 1. 25%, the P content of 0. 030-W or less, and the S content of 0. 030-W or less are pref erred.
In both cases, the carbon content is 0. 23-% or less. Furthermore, in the present invention, fine workability is obtained because the carbon content is 0.23% or less. By applying the carbo nitriding processing to the surf ace af ter working, the operation and ef f ect such as the surface pressure resistance of the power transmission unit or the sliding unit are obtained. The carbon content of 0.23% or more is not desirable because carbonizing hardening is caused too excessively and cementite is not precipitated in the flake form, but is precipitated totally, and theref ore there is a f ear of exf oliation due to sliding. Although Si and Mn are ef f ective as oxygen scavenger of steel, the toughness is impaired if the quantity of them is large. Although Cr increases the hardening property and the tempering resistance, it is not desirable because a carbide or a nitride is f ormed if the quantity thereof is large. Alihough Mo increases the hardening property, it is expensive.
The "flake form" is neither global nor a shape similar to a global shape, but it takes the shape of a thin leaf or takes such a complicated shape that a thin leaf is spread into branches.
The expression "precipitated in the flake form" means that these cementite f lakes are mixedly present in the surf ace layer substrate.
The "power transmission" means transmission of power from a prime mover to a work device or running gears. As the power 4 transmission unit, change gears, reduction gears, or the like having a gear drive mechanism or a friction drive mechanism can be mentioned. In addition, a clutch or the like can be mentioned. As the clutch in this case, a clutch f orming a multiple disc clutch which is jointed by thrust force generated in the rotation direction by receiving the input from the differential case and which performs power transmission, for example, can be mentioned. The "sliding" means moving while rubbing on something in the contact state. As the sliding unit, washers disposed between relative rotary members used in change gears or reduction gears can be mentioned.
The ndifferential gear is a device for distributing the driving force while permitting the differential rotation by using an internal differential member installed on the left and right driving wheels or the front and rear driving axles for running a vehicle. The differential limit" means providing rotational resistance by using the sliding friction of the rotary member (sliding member) in the differential gear installed between the lef t and right driving wheels or between the f ront and rear driving axles, and thereby limiting the differential rotation. As the dif f erentail limit system, there are a system in which the differential member directly slides on the differential case with friction, a system in which a member linked with the dif f erential case and supporting the differential member slides on the dif f erential member with friction, and a system in which an additional member such as a multiple disc clutch slides with friction. These members sliding with friction are the sliding members.
The present invention makes it possible to significantly improve the surface pressure resistance (the seizure resistance) and the wear resistance of the power transmission unit or the sliding portion by applying the carbo-nitriding processing to the surface of the power transmission unit or the sliding portion and providing such a structure that hard cementite is precipitated on the surface layer in the flake form.
According to the present invention, therefore, surfaces of the gears of the power transmis s ion unit of the dif f erent ial gear or surfaces of the clutch discs of the sliding member are subjected to the carbo-nitriding processing, and thereby a structural steel member to be used in the dif f erential gear, having high surf ace pressure resistance and wear resistance and having excellent workability can be obtained without impairing the toughness and the shock resistance of the substrate.
According to the present invention, surf ace hardening processing using a gas carbo-nitriding material is conducted and a power transmission member or sliding member having a structure with hard cementite precipitated on the surf ace layer in the f lake f orm is used, and thereby the surf ace pressure resistance (seizure resistance) and the wear resistance of the power transmission member or the sliding member can be significantly improved, as evident from the foregoing description. Furthermore, according to the present invention, the surface of the steel having the carbon content of 0.23% or less is subjected to carbo-nitriding processing, and thereby the effect of improved surface pressure property is obtained and the workability can be improved due to the low carbon content. Furthermore, according to the present invention, the surface of the power transmission unit or the sliding unit of the differential gear is subjected to the carbo-nitriding processing, and thereby a member having the surface pressure resistance can be obtained.
Other many objects of the present invention will become clear by understanding preferred embodiments described later and are shown in claims. By actually practicing the present invention, persons skilled in the art ought to derive many benefits which are not described here.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1A is a diagram showing a conventional carbonizing 6 processing method and FIG. 1B is a diagram showing a conventional carbo-nitriding processing method; FIG. 2 is a sectional view of a differential gearhaving a member subjected to carbo-nitriding processing according to a embodiment 1; FIG. 3 is a diagram illustating the carbo-nitriding processing method of the embodiment 1 and a test result thereof; FIG. 4 is a schematic diagram showing the surface layer of the member of the embodiment 1; FIG. 5 is a sectional view of a differential gear according to an embodiment similar to the embodiment 1; FIG. 6 is a sectional view of a differential gear having a member subjected to carbo-nitriding processing according to a embodiment 2; and is FIG. 7 is a sectional view of a differential gear having a member subjected to carbo-nitriding processing according to a embodiment 3.
Each of numerals 1, 101 and 201 denotes a dif f erential case.
Numeral 7 denotes a female cone portion. Numeral 15 denotes a pinion gear. Each of numerals 17, 19, 107 and 109 denotes a side gear (structural steel member). Numeral 23 denotes a male cone portion. Numeral 25 denotes a cone clutch. Numeral 26 denotes a multiple disc clutch (structural steel member). Each of 101a, 101b, 101c and 101d denotes a differential case internal wall.
Each of numerals 103 and 105 denotes a pinion gear (structural s teel member). Each of numerals 111 and 113 denote a housing hole.
Each of 201a and 201b denotes an internal wall surface of a differential case. Each of 203 and 205 denotes a worm wheel (structural steel member). Each of numerals 207 and 209 denotes a worm gear (side gear, structural steel member). Each of 207a and 209a denotes an outward end face of a worm gear. Each of numerals 211 and 213 denotes an output shaft. Each of numerals 215 and 217 denotes a washer.
7 DETAILED DESCRIPTION OF THE INVENTION (Embodiment 11
A embodiment 1 of the present invention will now be described by referring to FIGS. 2 through 5. FIG. 2 is a sectional 5 view of a differential gear having gears subjected to carbonitriding processing of the present embodiment. FIGS. 3 and 4 are illustration diagrams. FIG. 5 is a sectional view of a differential gear of an embodiment similar to the present embodiment.
A differential case 1 is formed by uniting a main body 3 and a cover 5 in a body by using bolts 6. The dif f erential case 1 is driven and rotated by an engine via a ring gear which is f ixed to the differential case 1 and which is not illustrated. In the internal circumference of the differential case 1, female cone portions 7 taking the shape of a frustum of a cone and reduced in diameter outward in the axis direction of the differential case 1 are formed.
Furthermore, a pinion shaf t 11 is united to the dif f erential case 1 by a spring pin 13. Two pinion gears 15 are supported on the pinion shaf t 11 so as to be rotatable. The two pinion gears 15 are engaged with output side gears 17 and 19 serving as a pair of left and right structural steel members disposed so as to be opposed to each other. To internal circumferences of the side gears 17 and 19, lef t and right output shaf ts which are not illustrated are liked in spline forms, respectively. The thrust of the pinion gear 15 is received by a spherical washer 21 disposed behind it.
On the external circumferences of the side gears 17 and 19, male cone portions 23 and 23 each taking the shape of a frustum of a cone are f ormed. These male cone portions 23 and 23 become sliding surfaces rubbing on the female cone portions 7 and of the differential case 1. Thus, cone clutches 25 and 25 serving as differential limiting mechanisms are formed.
The side gears 17 and 19 are made of steel comprising Cr,Mo 8 or steel comprising Cr serving as structural steel. Out of these materials, SCM420H stipulated in the JIS standards is selected for the memeber of the present invention. On the other hand, the dif f erential case 1 is made of spheroidal graphite cast iron. The differential case 1 may be subjected to the carbo-nitriding processing together with the side gears 17 and 19. Since the differential case also directly becomes the sliding member sometimes, a structural steel member subjected to processing in the same way as the present Invention can be used.
FIG. 3 shows a carbo-nitriding processing method of the present embodiment applied to this material.
Enriched propane gas and ammonia gas (NH3) are supplied to inert gas (Rx) at timing indicated by an arrow in FIG. 3. The material is heated in resulting environment, and kept at 9000 C for 2 hours. Subsequently, the material is kept at 850" C for 15 minutes. Thereafter, the material is rapidly cooled so as to come in the range of 130 to 150 0 C and is subjected to oil quenching.
Unlike the pattern of the above described conventional technique, in which carbonizing is conducted and then nitriding is conducted by using ammonia gas, ammonia gas is supplied simultaneously with the timing of carbonizing shown in FIG. 3. By doing so, the partial pressure of oxygen is lowered, and consequently bonding between iron and active carbon is facilitated. Furthermore, by decomposition of ammonia, active nitrogen is generated and acts upon the precipitation of cementite. By such ammonia gas supply timing, the carbon concentration on the steel surfaceis prevented from becoming excessively high. It aims at preventing all from becoming cementite because of excessively high carbon concentration. On the other hand, nitrogen is diffused and subjected to solid solution on the surface at the same time.
Subsequently, the material is kept at 180 to 2000 C for 2 hours, and then cooled in the air and then tempered.
9 As for the surface structure thus obtained, there is such a structure that cementite is precipitated on a surf ace layer A located at 32 ú m from the surf ace so as to take the shape of shapes with rounded edges as shown in FIG. 4. Structures located around the cementite and located in an underlying layer B are mixed structures of tempered martensite + troostite + sorbite + residual austenite + diffused solved nitrogen. By the flake structures of cementite precipitated on the surf ace layer, the surface hardness is in the range of HRC 58 to 63, and the carbo-nitrided layer depth is in the range of 0. 3 to 1. 5 mm, and pref erably in the range of 0. 7 to 1. 1 mm. It is not especially limited to the metallographic structure of the underlying layer B. For obtaining the toughness, a structure such as tempered martensite or sorbite is desirable. A seizure resistance test was conducted on test articles subjected to the above described carbo-nitriding processing. As a result, such a phenomenon that the torque rose to 1.5 times or more the stationary torque obtained until then as shown in FIG. 3 was not found even if the pressing pressure was raised to 7,000 N. Furhtermore, in such a state that this pressing pressure was loaded, the sliding surface was observed. As a result, appropriate wear was f ound, but any symptom of galling was not noticed.
According to the present embodiment, very hard f lake structures of cementite are obtined on the surface layer of steel member comprising Cr, Mo or steel member comprising Cr subjected to carbo- n1triding processing. Therefore, the surface pressure resistance (the seizure resistance) and the wear resistance are significantly improved as compared with the above described conventional technique. In the present embodiment, the side gears 17 and 19 of the dif f erential gear of bevel gear type have been described. However, the structural steel member of the present invention is not limited to this.
FIG. 5 shows a differential gear in which the multiple disc clutch is f astened by the contact reaction force between the pinion gears and the side gears. In the multiple disc clutch, two discs are coupled to the case side and one disc is coupled to the side gear side. For the pinion gears 15 and the spherical washer 21, structural steel members subjected to carbo-nitriding processing of the same method can be used. Furthermore, f or each clutch disc of the multiple disc clutch or on either of the case side and the side gear side, structural steel members subjected to carbo-nitriding processing of the same method can be used.
Since the carbon content is 0.23% or less, the workability is improved. [Embodiment 21 A second embodiment of the present invention will now be described by referring to FIG. 6. FIG. 6 is a sectional view of a differential gear of parallel shaft type having gears subjected to carbo-nitriding processing of the present embodiment.
Within a differential case 101, pinion gears 103 and 105 and side gears 107 and 109 are supported so as to be rotatable.
The pinion gears 103 and 105 serve as a plurality of pairs of structural steel members. Each pair is formed by a long member and a short member. The side gears 107 and 109 serve as a pair of structural steel members on the output side separately engaging with the pinion gears 103 and 105. The driving f orce of the engine inputted to the dif f erential case 101 is transmitted f rom the side gears 107 and 109 to the left and right output shafts, which are not illustrated, via the pinion gears 103 and 105. These gears are f ormed by helical gears. At the time of drive f orce transmission, therefore, the thrust in the shaft direction is also generated together with the reaction f orce in a direction perpendicular to the shaft.
If there occurs a driving resistance difference between the lef t and right output shaf ts, a dif f erential movement is permitted between the output shafts by the rotation of the pinion gears 103 and 105. At the time of this dif f erential movement, tooth crests of the pinion gears 103 and 105 slide with receipt holes 111 and 11 113 of the differential case 101. Upon receiving the thrust, end faces of them slide with internal wall surfaces 101a, 101b, and 101c of the dif f erentlal case 101. Furthermore, opposed surf aces of the side gears 107 and 109 slide with respect to each other.
In addition, outward end faces 107a and 109a slide with internal wall surfaces 101a and 101d. By this sliding friction, the differential movement is limited.
In order to sufficiently resist the power transmission and sliding friction, the pinion gears 103 and 105 and the side gears 107 and 109 are made of steel comprising Cr,Mo or steel comprising Cr serving as structural steel in the same way as the embodiment 1. In both of them, the carbon content is 0. 23 or less. These gears 103, 105, 107 and 109 have been subjected to carbo-nitriding processing in the same way as the embodiment 1. The heat treatment of the dif f erential case 101 is the same as the dif f erential case 1 of the embodiment 1.
Owing to such a configuration, very hard flake structures of cementite are obtained on the surf ace layers of the tooth crests and tooth flanks of the gears 103, 105, 107 and 109 in the present embodiment. Therefore, the surface pressure resistance (the seizure resistance) and the wear resistance are significantly improved as compared with the conventional technique in the same way as the embodiment 1.
Since the carbon content is 0. 23% or less, the workability is improved.
[Embodiment 31 A embodiment 3 of the present invention will now be described by referring to FIG. 7. FIG. 7 is a sectional view of a differential jear having worm gears subjected to carbo nitriding processing of the present embodiment.
Within a dif f erential case 20 1, a plurality of worm wheel pairs 203 and 205 are incorporated. The worm wheel pair 203 and 205 serve as a pair of structural steel members engaging with each other. In addition, worm gears (side gears) 207 and 209 are 12 supported so as to be rotatable and be displaceable in the shaft direction. The worm gears (side gears) 207 and 209 serve as a pair of structural steel members on the output side separately engaging with the worm wheels 203 and 205. The driving force of the engine inputted to the differential case 201 via a ring gear 202 fixed to the differential case 201 is transmitted from the worm gears 207 and 209 to left and right output shafts 211 and 213 via the worm wheels 203 and 205.
If there occurs a driving resistance difference between the left and right output shafts 2 11 and 213, a dif f erential movement is permitted between the output shaf ts 211 and 213 by the rotation of the worm wheels 203 and 205. At the time of this differential movement, opposed faces of the worm gears 207 and 209 slide with respect to each other via a set of three washers 215 sandwiched in between them. In addition, outward end faces 207a and 209a slide with respect to internal wall surfaces 201a and 201b of the differential case 201 via a set of two washers 217. By this sliding friction, the differential movement is limited.
In order to suf f lciently resist the power transmi-ssion-and sliding friction, the worm wheels 203 and 205 and the worm gears 207 and 209 are made of steel comprising Cr,Mo or steel comprising Cr serving as structural steel in the same way as the f irst embodiment. In both of them, the carbon content is 0. 23% or less.
The worm wheels and worm gears have been subjected to carbo nitriding processing in the same way as the embodiment 1.
Owing to such a configuration, very hard flake structures of cementite are obtained on the surf ace layers of the tooth f lanks of the worm wheels 203 and 205 and the worm gears 207 and 209 in the present emb6diment. Therefore, the surface pressure resistance (the seizure resistance) and the wear resistance are significantly improved as compared with the conventional technique in the same way as the embodiment 1.
Since the carbon content is 0.23% or less, the workability is improved.
13 The present invention can be implemented as a large number of forms without departing from its essential characteristics. Therefore, the embodiments are solely descriptive'and are not restrictive. Furthermore, the present invention is defined by claims. Therefore, changes or equivalents of requirements in the claims are incorporated in the claims.
14
Claims (9)
- WHAT IS CLAIMED IS:Structural steel to be used in a power transmission unit under a high surface pressure, said structural steel comprising:structural steel subjected to surface hardening processing; and a structure having cementite precipitated on a surf ace layer in a flake form.
- 2. Structural steel members to be used in a power transmission unit under a high surf ace pressure, said structural steel members comprising: both members or either of members of said power transmission unit being subjected to surface hardening; and 20 a structure having cementite precipitated on a surf ace layer of said members in a flake form.
- 3. Structural steel members according to claim 2, wherein said structural steel members have a carbon content of 0. 23 or less.
- 4. Structural steel members according to claim 3, wherein said 2,
- 5 structural steel members are disposed in a differential gear for distributing a torque inputted to a differential case between a pair of output side gears, and said structural steel members are sliding members for limiting a differential movement by sliding with respect to apower transmitting gear or the differential )o case. 5. Structural steel to be used in a sliding unit sliding under a high surface pressure, said structural steel comprising:structural steel subjected to surface hardening processing; and is a structure having cementite precipitated on a surface layer in a flake form.
- 6. Structural steel members to be used in a sliding unit under a high surface pressure, said structural steel members comprising: both members or either of members of said sliding unit being subjected to surface hardening; and a structure having cementite precipitated on a surface layer of said members in a flake form.
- 7. Structural steel members according to claim 6, wherein said structural steel members have a carbon content of 0. 23% or less.
- 8. Structural steel members according to claim 7, wherein said structural steel members are disposed in a differential gear for distributing a torque inputted to a differential case between a pair of output side gears, and said structural steel members are sliding members sliding with respect to a power transmitting gear or the differential case.
- 9. A structural steel or structural steel member substantially as hereinbefore described with reference to Figures 2 to 7 of the accompanying drawings.16
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21392496A JPH1060619A (en) | 1996-08-13 | 1996-08-13 | Member made of structural steel |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB9716992D0 GB9716992D0 (en) | 1997-10-15 |
| GB2316097A true GB2316097A (en) | 1998-02-18 |
| GB2316097B GB2316097B (en) | 1999-06-23 |
Family
ID=16647308
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9716992A Expired - Fee Related GB2316097B (en) | 1996-08-13 | 1997-08-11 | Structural steel and structural steel member used under high surface pressure |
Country Status (3)
| Country | Link |
|---|---|
| JP (1) | JPH1060619A (en) |
| DE (1) | DE19734901C2 (en) |
| GB (1) | GB2316097B (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1243815A3 (en) * | 2001-03-23 | 2007-08-22 | Nissan Motor Company, Limited | High strength gear and method of producing the same |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100304049B1 (en) * | 1999-06-30 | 2001-09-24 | 황해웅 | A Method of Surface Hardening using Carbide |
| KR100386300B1 (en) * | 1999-08-16 | 2003-06-02 | 주식회사 경남열처리 | Surface hardening method of a roll using carbide |
| KR20010059687A (en) * | 1999-12-30 | 2001-07-06 | 이계안 | Differential pinion shaft having the improved abrasion resistance and bending strength and preparation method thereof |
| KR100475942B1 (en) * | 2001-12-18 | 2005-03-10 | 현대자동차주식회사 | Heat treatment for bearings of an automobile |
| US7468107B2 (en) | 2002-05-01 | 2008-12-23 | General Motors Corporation | Carburizing method |
| KR100766773B1 (en) | 2006-09-30 | 2007-10-17 | 현대 파워텍 주식회사 | A method of heat treatment for gears in an automatic transmission |
| KR101371225B1 (en) * | 2012-12-26 | 2014-03-10 | 동명대학교산학협력단 | Auto focusing adjustment apparatus for x-ray test automation |
| CN105855812A (en) * | 2016-03-31 | 2016-08-17 | 杭州科技职业技术学院 | Machining process of automobile transmission gears |
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| WO1993017146A1 (en) * | 1992-02-25 | 1993-09-02 | Ina Wälzlager Schaeffler Kg | Process for the thermochemical-heat treatment of case-hardened steels |
| US5310432A (en) * | 1992-06-30 | 1994-05-10 | Sumitomo Metal Industries, Ltd. | Toothed wheel for use in automobiles and its manufacturing method |
| EP0601451A1 (en) * | 1992-12-10 | 1994-06-15 | Adam Opel Ag | Process for hardness increasing and possibly for smoothing of work pieces and work pieces made by this process |
| US5352303A (en) * | 1992-11-25 | 1994-10-04 | Nsk Ltd. | Rolling bearing |
| EP0626468A1 (en) * | 1993-05-26 | 1994-11-30 | SKF Industrial Trading & Development Co, B.V. | Process for carbonitriding steel |
| US5427457A (en) * | 1991-07-18 | 1995-06-27 | Nsk Ltd. | Rolling bearing |
| JPH07242994A (en) * | 1994-03-09 | 1995-09-19 | Daido Steel Co Ltd | Steel for gear excellent in tooth surface strength, gear, and production of gear |
| US5454883A (en) * | 1993-02-02 | 1995-10-03 | Nippon Steel Corporation | High toughness low yield ratio, high fatigue strength steel plate and process of producing same |
| FR2722212A1 (en) * | 1994-07-07 | 1996-01-12 | Solo Fours Industriels Sa | Carburisation or carbonitriding with min. carbon di:oxide and no cyanide emissions |
-
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- 1996-08-13 JP JP21392496A patent/JPH1060619A/en active Pending
-
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- 1997-08-11 GB GB9716992A patent/GB2316097B/en not_active Expired - Fee Related
- 1997-08-12 DE DE1997134901 patent/DE19734901C2/en not_active Expired - Fee Related
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|---|---|---|---|---|
| GB2138028A (en) * | 1983-04-14 | 1984-10-17 | Lucas Ind Plc | Corrosion resistant steel components and method of manufacture thereof |
| US5427457A (en) * | 1991-07-18 | 1995-06-27 | Nsk Ltd. | Rolling bearing |
| WO1993017146A1 (en) * | 1992-02-25 | 1993-09-02 | Ina Wälzlager Schaeffler Kg | Process for the thermochemical-heat treatment of case-hardened steels |
| US5310432A (en) * | 1992-06-30 | 1994-05-10 | Sumitomo Metal Industries, Ltd. | Toothed wheel for use in automobiles and its manufacturing method |
| US5352303A (en) * | 1992-11-25 | 1994-10-04 | Nsk Ltd. | Rolling bearing |
| EP0601451A1 (en) * | 1992-12-10 | 1994-06-15 | Adam Opel Ag | Process for hardness increasing and possibly for smoothing of work pieces and work pieces made by this process |
| US5454883A (en) * | 1993-02-02 | 1995-10-03 | Nippon Steel Corporation | High toughness low yield ratio, high fatigue strength steel plate and process of producing same |
| EP0626468A1 (en) * | 1993-05-26 | 1994-11-30 | SKF Industrial Trading & Development Co, B.V. | Process for carbonitriding steel |
| JPH07242994A (en) * | 1994-03-09 | 1995-09-19 | Daido Steel Co Ltd | Steel for gear excellent in tooth surface strength, gear, and production of gear |
| FR2722212A1 (en) * | 1994-07-07 | 1996-01-12 | Solo Fours Industriels Sa | Carburisation or carbonitriding with min. carbon di:oxide and no cyanide emissions |
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| WPI Accession no 95-355548/46 & JP 07 242 994 A * |
| WPI Accession no 96-059416/07 & FR 2 722 212 A1 * |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1243815A3 (en) * | 2001-03-23 | 2007-08-22 | Nissan Motor Company, Limited | High strength gear and method of producing the same |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2316097B (en) | 1999-06-23 |
| DE19734901A1 (en) | 1998-02-19 |
| JPH1060619A (en) | 1998-03-03 |
| GB9716992D0 (en) | 1997-10-15 |
| DE19734901C2 (en) | 2000-11-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20080811 |