CN115839399B - Harmonic reducer rigid gear and preparation method and application thereof - Google Patents
Harmonic reducer rigid gear and preparation method and application thereof Download PDFInfo
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- 239000003638 chemical reducing agent Substances 0.000 title claims abstract description 128
- 238000002360 preparation method Methods 0.000 title claims abstract description 29
- 229910001141 Ductile iron Inorganic materials 0.000 claims abstract description 107
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 67
- 229910002804 graphite Inorganic materials 0.000 claims abstract description 45
- 239000010439 graphite Substances 0.000 claims abstract description 45
- 238000010438 heat treatment Methods 0.000 claims abstract description 39
- 239000000463 material Substances 0.000 claims abstract description 38
- 238000003754 machining Methods 0.000 claims abstract description 33
- 239000002994 raw material Substances 0.000 claims abstract description 18
- 238000011081 inoculation Methods 0.000 claims abstract description 10
- 239000011265 semifinished product Substances 0.000 claims description 55
- 229910001018 Cast iron Inorganic materials 0.000 claims description 35
- 229910001567 cementite Inorganic materials 0.000 claims description 29
- KSOKAHYVTMZFBJ-UHFFFAOYSA-N iron;methane Chemical compound C.[Fe].[Fe].[Fe] KSOKAHYVTMZFBJ-UHFFFAOYSA-N 0.000 claims description 29
- 229910001562 pearlite Inorganic materials 0.000 claims description 29
- 229910000859 α-Fe Inorganic materials 0.000 claims description 27
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 20
- 238000001816 cooling Methods 0.000 claims description 19
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims description 17
- 238000000498 ball milling Methods 0.000 claims description 15
- 229910052698 phosphorus Inorganic materials 0.000 claims description 15
- 239000011574 phosphorus Substances 0.000 claims description 15
- 229910001563 bainite Inorganic materials 0.000 claims description 12
- 238000005266 casting Methods 0.000 claims description 11
- 230000005496 eutectics Effects 0.000 claims description 11
- 239000002054 inoculum Substances 0.000 claims description 9
- 230000009466 transformation Effects 0.000 claims description 9
- 238000004321 preservation Methods 0.000 claims description 7
- 230000015572 biosynthetic process Effects 0.000 claims description 5
- 239000000758 substrate Substances 0.000 claims description 3
- 238000002844 melting Methods 0.000 claims 1
- 230000008018 melting Effects 0.000 claims 1
- 229910052799 carbon Inorganic materials 0.000 abstract description 24
- 230000001050 lubricating effect Effects 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 33
- 230000008569 process Effects 0.000 description 25
- 229910052751 metal Inorganic materials 0.000 description 18
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- 239000011572 manganese Substances 0.000 description 15
- 230000000052 comparative effect Effects 0.000 description 13
- 230000033001 locomotion Effects 0.000 description 12
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 11
- 239000011651 chromium Substances 0.000 description 11
- 229910052748 manganese Inorganic materials 0.000 description 11
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 10
- 229910000831 Steel Inorganic materials 0.000 description 10
- 239000011159 matrix material Substances 0.000 description 10
- 229910052710 silicon Inorganic materials 0.000 description 10
- 239000010703 silicon Substances 0.000 description 10
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- 230000005540 biological transmission Effects 0.000 description 9
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- 238000010791 quenching Methods 0.000 description 9
- 230000000171 quenching effect Effects 0.000 description 9
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 8
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 8
- 229910052804 chromium Inorganic materials 0.000 description 8
- 239000012071 phase Substances 0.000 description 8
- 230000008859 change Effects 0.000 description 7
- 238000004519 manufacturing process Methods 0.000 description 7
- 230000009467 reduction Effects 0.000 description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
- 230000009286 beneficial effect Effects 0.000 description 6
- 229910052802 copper Inorganic materials 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
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- 229910052742 iron Inorganic materials 0.000 description 6
- 238000005461 lubrication Methods 0.000 description 6
- 230000002035 prolonged effect Effects 0.000 description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 5
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- 239000000126 substance Substances 0.000 description 5
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- 239000011593 sulfur Substances 0.000 description 5
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 4
- 229910018619 Si-Fe Inorganic materials 0.000 description 4
- 229910008289 Si—Fe Inorganic materials 0.000 description 4
- 239000003795 chemical substances by application Substances 0.000 description 4
- 239000000320 mechanical mixture Substances 0.000 description 4
- 150000002736 metal compounds Chemical class 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000005011 phenolic resin Substances 0.000 description 4
- 229920001568 phenolic resin Polymers 0.000 description 4
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- 230000007547 defect Effects 0.000 description 3
- 238000012994 industrial processing Methods 0.000 description 3
- 238000007670 refining Methods 0.000 description 3
- 229910000954 Medium-carbon steel Inorganic materials 0.000 description 2
- 241000519995 Stachys sylvatica Species 0.000 description 2
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- -1 bullseye structure Inorganic materials 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
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Classifications
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
- Y02P70/10—Greenhouse gas [GHG] capture, material saving, heat recovery or other energy efficient measures, e.g. motor control, characterised by manufacturing processes, e.g. for rolling metal or metal working
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Abstract
The invention relates to a rigid wheel of a harmonic reducer and a preparation method and application thereof. According to the harmonic reducer rigid wheel, the base material is spheroidal graphite cast iron, carbon is precipitated in spheroidal graphite through spheroidization and inoculation, more granular graphite is obtained, and the lubricating performance is better, so that the harmonic reducer rigid wheel has good castability, wear resistance and machinability. Compared with the existing materials, the rigid wheel of the harmonic speed reducer has excellent mechanical property and machining process property under the specific raw material proportion, and the mechanical property can be further improved through heat treatment, so that the rigid wheel of the harmonic speed reducer is finally ensured to have good mechanical property. The invention also provides a preparation method and application of the harmonic reducer rigid wheel.
Description
Technical Field
The invention belongs to the technical field of speed reducers, and particularly relates to a harmonic speed reducer rigid wheel, a preparation method and application thereof.
Background
The harmonic reducer has the advantages of compact structure, small volume, light weight, large transmission ratio and bearing capacity, high transmission precision and the like, and is widely applied to industries such as electronics, aerospace, robots, automation and the like. The main structure of the harmonic speed reducer comprises three basic components of a wave generator, a flexible gear and a rigid gear. The wave generator consists of a flexible bearing and a cam. The flexible gear is a flexible external gear, and the rigid gear is a rigid annular gear.
The harmonic reducer transmits motion through tooth-to-tooth engagement. In the whole motion process, the meshing area of the inner teeth and the outer teeth is larger, the meshing tooth pair ratio is about 30%, the inner teeth of the rigid gear are meshed with the outer teeth of the flexible gear, the meshing number of the teeth is related to working conditions, the larger the torque is, the larger the number of the meshed teeth is, because the flexible gear is of a thin-wall structure and is in the same shape as a cam after the wave generator is assembled, the end face of the flexible gear is in a periodical bell mouth deformation form in the running process of the wave generator, the end face of the flexible gear is a curved surface, the tooth face of the flexible gear and the rigid gear have meshing relative motion, namely tangential relative motion and tooth direction movement caused by flexible gear deformation, the meshing bearing of the flexible gear and the rigid gear realizes the transmission of harmonic speed reducer force and motion, the contact between the teeth is similar to line contact, and experiments show that the lubrication state between the rigid gear and the flexible gear is mixed lubrication, so that the rigid gear and the flexible gear are required to have higher wear resistance. In the related art, the wear resistance of the rigid wheel is not ideal enough.
Disclosure of Invention
The present invention aims to solve at least one of the above technical problems in the prior art. Therefore, the invention provides the harmonic speed reducer rigid wheel, which has higher wear resistance and mechanical strength through the ball-milling cast iron with specific raw material proportion.
The invention also provides a method for preparing the rigid wheel of the harmonic speed reducer.
The invention also provides a harmonic reducer.
The invention also provides an industrial robot.
The invention provides a rigid gear of a harmonic speed reducer, wherein a base material of the rigid gear of the harmonic speed reducer is spheroidal graphite cast iron, and the spheroidal graphite cast iron comprises Fe and the following components in percentage by mass:
C：3.0％～4.0％，
Si：2.0％～3.0％，
Cu：0.5％～1.0％，
Mn：≤1.0％，
Cr：≤0.1％，
P：≤0.1％，
S：≤0.06％，
In the spheroidal graphite cast iron, the graphite spheroidization rate of a metallographic structure is more than or equal to 95 percent.
The invention relates to a technical scheme of a rigid wheel of a harmonic speed reducer, which has at least the following beneficial effects:
The base material of the rigid wheel of the harmonic reducer is spheroidal graphite cast iron, and the graphite spheroidization rate of a metallographic structure in the spheroidal graphite cast iron is more than or equal to 95 percent, thereby conforming to the primary spheroidization standard specified in GB/T9441-2009. The spheroidal graphite cast iron is cast iron in which carbon obtained through spheroidization and inoculation is precipitated as spheroidal graphite, and has good castability, wear resistance and machinability. The harmonic reducer rigid wheel has excellent mechanical property and technological property under specific raw material proportion, and can further improve the mechanical property through heat treatment, so that the spheroidal graphite cast iron can be used for manufacturing parts with larger load and more complex stress, such as crankshafts, connecting rods, gears, machine tool spindles and the like, and is particularly suitable for the harmonic reducer rigid wheel.
According to the harmonic reducer rigid wheel, the base material is spheroidal graphite cast iron, carbon is an element for crystallizing and separating out spheroidal graphite in the preparation raw material, and the carbon content in the range of 3.0-4.0% enables the spheroidal graphite to crystallize and separate out. Silicon is also an element for crystallizing and precipitating spheroidal graphite, and the silicon content in the range of 2.0% to 3.0% is advantageous for crystallizing and precipitating spheroidal graphite and can also suppress the occurrence of dross defects and graphite floating. Copper can inhibit carbide and is favorable for obtaining spheroidal graphite. Manganese is an element that functions to refine graphite and strengthen a pearlite structure, and manganese in the range of 1.0% or less is favorable for exerting the effect. The chromium has the functions of promoting the growth of pearlite, improving the toughness and refining the matrix. Phosphorus and sulfur are unavoidable impurities in the spheroidal graphite cast iron, and the content of the phosphorus and the sulfur can be reduced as much as possible.
According to some embodiments of the invention, the ductile iron comprises 3.2-4.0% carbon by mass.
According to some embodiments of the invention, the ductile iron comprises 3.5-4.0% carbon by mass.
According to some embodiments of the invention, the ductile iron comprises 3.8-4.0% carbon by mass.
According to some embodiments of the invention, the ductile iron comprises 2.2-3.0% silicon by mass.
According to some embodiments of the invention, the ductile iron comprises 2.5-3.0% silicon by mass.
According to some embodiments of the invention, the ductile iron comprises 2.7-3.0% silicon by mass.
According to some embodiments of the invention, the ductile iron comprises 0.6-1.0% copper by mass.
According to some embodiments of the invention, the ductile iron comprises 0.7-1.0% copper by mass.
According to some embodiments of the invention, the mass percentage of manganese in the spheroidal graphite cast iron is less than or equal to 1.0%.
According to some embodiments of the invention, the mass percentage of manganese in the ductile iron may be 0.7%.
According to some embodiments of the invention, the mass percentage of manganese in the ductile iron may be 0.5%.
According to some embodiments of the invention, the mass percentage of manganese in the ductile iron may be 0.2%.
According to some embodiments of the invention, the mass percentage of chromium in the spheroidal graphite cast iron is 0.03-0.06%.
According to some embodiments of the invention, the mass percentage of chromium in the spheroidal graphite cast iron may be 0.05%.
According to some embodiments of the invention, the mass percentage of chromium in the spheroidal graphite cast iron may be 0.04%.
According to some embodiments of the invention, in the ductile iron, P: less than or equal to 0.1 percent, and phosphorus is an unavoidable impurity in the spheroidal graphite cast iron, so that the content of the phosphorus can be reduced as much as possible.
According to some embodiments of the invention, in the ductile iron, S: sulfur is an unavoidable impurity in the spheroidal graphite cast iron and the content thereof can be reduced as much as possible, which is less than or equal to 0.06%.
The proportion range is suitable for the proportion range of the raw materials for preparing the spheroidal graphite cast iron.
According to some embodiments of the invention, the metallographic structure in the ductile iron comprises cementite and phosphorus eutectic.
Cementite is a metal compound formed by iron and carbon, has a complex orthorhombic crystal structure, is a main strengthening phase in spheroidal graphite cast iron, and has great influence on the performance of steel due to the shape and distribution of the cementite. In the ball-milled cast iron, cementite appears in the structure in different forms and sizes of crystals, and the mechanical properties of the spheroidal graphite cast iron are greatly affected.
In general cast iron, phosphorus eutectic formed by phosphorus with carbon and iron increases brittleness of cast iron, and therefore phosphorus is treated as an impurity element. However, in the wear-resistant cast iron, the phosphor eutectic is beneficial to improving the wear resistance of the cast iron under certain conditions.
According to some embodiments of the invention, the cementite comprises free cementite.
Free cementite refers to cementite that is present as a separate phase from a mechanical mixture (structure) such as ledeburite (eutectic structure) after pearlite (eutectoid structure). Free cementite has a negative effect on material properties and it is necessary to control the free cementite content by controlling the cooling rate. The free cementite in the present invention mainly refers to primary cementite.
According to some embodiments of the invention, the tensile strength of the ductile iron is not less than 1100MPa.
The tensile strength of the spheroidal graphite cast iron is more than or equal to 1100MPa, and the rigid wheel of the harmonic speed reducer is ensured to have higher mechanical strength.
The second aspect of the invention provides a method for preparing the harmonic reducer rigid wheel, which comprises the following steps:
S1: rough machining is carried out on the ball-milling cast iron base material to obtain a semi-finished product of the rigid wheel;
S2: and carrying out heat treatment on the semi-finished product of the rigid wheel, and then carrying out finish machining to obtain the rigid wheel of the harmonic speed reducer.
The invention relates to a technical scheme in a preparation method of a rigid gear of a harmonic reducer, which has at least the following beneficial effects:
According to the preparation method of the harmonic reducer rigid wheel, firstly, the ball-milling cast iron base material is subjected to rough machining to obtain a semi-finished product of the rigid wheel, then, after the semi-finished product of the rigid wheel is subjected to heat treatment, the spheroidal graphite cast iron base material is reinforced, the base material has better toughness, and finally, the finish machining is carried out, so that the harmonic reducer rigid wheel with composite requirements on performance and precision can be obtained. The heat treatment process is a key process in the preparation of the harmonic reducer, and the hardness after heat treatment directly influences the wear resistance of the rigid wheel.
The preparation method of the rigid wheel of the harmonic reducer does not need expensive equipment and complicated process control, and the preparation process is relatively simple and easy to control.
According to the preparation method of the rigid wheel of the harmonic reducer, firstly, the ball-milling cast iron base material is subjected to rough machining, and then is subjected to finish machining after heat treatment, so that on one hand, the dimensional change of the precision of the rigid wheel possibly caused in the heat treatment process is avoided; on the other hand, the performance of the finally prepared harmonic reducer rigid wheel is more excellent through the combination of rough machining and finish machining.
According to some embodiments of the invention, the metallographic structure in the semi-finished rigid wheel comprises spheroidal graphite, pearlite and ferrite.
The spherical graphite can minimize the cracking effect on the cast iron matrix, so that the stress concentration effect in the cast iron is minimized, and therefore, the strength of the spheroidal graphite cast iron is very high and can be comparable to that of medium carbon steel. The ductile cast iron can be used as a base material for manufacturing a workpiece with high strength and toughness requirements and complex shape. When the method is used for processing the rigid wheel of the harmonic speed reducer, the performance of the spheroidal graphite cast iron matrix can be fully exerted, so that the rigid wheel of the harmonic speed reducer prepared has certain plasticity and good toughness.
Under casting conditions, the ductile cast iron undergoes solid phase transformation according to a stable system and a metastable system in a eutectoid transformation stage, and ferrite and pearlite nucleation and growth occur.
According to some embodiments of the invention, the ball-milled cast iron substrate may be self-prepared. The preparation method comprises the following steps: the metal raw materials are melted according to the proportion, and then the molten metal is spheroidized. The spheroidizing treatment has the effect that graphite forms spheres during crystal growth, more granular graphite has better lubricating property and can improve the mechanical property of castings.
According to some embodiments of the invention, the spheroidizing agent consists of 30-70% metal magnesium powder, 18-60% MgO, and 10-12% binder (e.g., phenolic resin). Wherein, the particle size of the metal magnesium powder is 0.05 mm-0.145 mm.
According to some embodiments of the invention, the roughing comprises pouring molten metal into a mold, adding inoculant for inoculation, wherein the purpose of the inoculation is to eliminate white spots, increase eutectic cells, graphite nodules and refine, eliminate segregation, eliminate tendency to crystallization supercooling, etc. The inoculant can be Si-Fe, etc. And cooling and obtaining the semi-finished product of the rigid wheel from the casting mould.
Before heat treatment, the metallurgical structure of the semi-finished product of the rigid wheel consists of spheroidal graphite and a matrix structure. Wherein the matrix structure comprises pearlite and ferrite. Ferrite is a single-phase structure, is a interstitial solid solution formed by dissolving carbon in alpha-Fe, and has low strength and hardness, but good plasticity and toughness. Pearlite is a two-phase structure and is a mechanical mixture composed of ferrite and cementite, wherein the cementite is a metal compound formed by iron and carbon, and the chemical general formula of the pearlite is Fe 3 C, and the pearlite has high strength and hardness. The semi-finished product of the rigid wheel with the metallographic structure can balance strength and plasticity through ferrite and pearlite.
According to some embodiments of the invention, the graphite spheroidization rate of the metallographic structure in the rigid wheel semi-finished product is more than or equal to 70%.
According to some embodiments of the invention, the metallurgical structure of the semi-finished steel wheel prior to heat treatment comprises spheroidal graphite, bullseye structure, and ferrite. Wherein, the graphite spheroidization rate is more than 80 percent, and the ferrite content is less than 25 percent. The bullseye structure is a structure similar to a bullseye shape formed by surrounding ferrite with spherical graphite and pearlite with ferrite periphery, wherein the ferrite content in the bullseye structure is below 25%, and the ferrite content in the whole metallographic structure is below 25%. The semi-finished product of the rigid wheel with the metallographic structure before heat treatment has good strength and hardness performance, is favorable for preparing the wear-resistant rigid wheel, and is particularly suitable for the rigid wheel for the harmonic speed reducer.
In the semi-finished product of the rigid wheel, the graphite spheroidization rate of the metallographic structure is more than or equal to 70%, so that the mechanical properties of the rigid wheel of the harmonic speed reducer after finish machining are ensured, and particularly, the impact strength, fatigue performance, corrosion resistance and wear resistance of the spheroidal graphite cast iron are improved.
According to some embodiments of the invention, the heat treatment comprises a normalizing treatment.
According to some embodiments of the invention, the normalizing process comprises: firstly, heating a semi-finished product of the rigid wheel to a certain temperature above eutectoid temperature, and preserving heat for a period of time, wherein the spheroidal graphite cast iron base material is austenitized; then cooling to a bainite transformation area in a cooling chamber at a cooling speed higher than that of pearlite formation to isothermal, and transforming an austenitized part into bainite at the moment, wherein the strength and toughness of the bainite are higher. The cooling mode can be water quenching.
According to some embodiments of the invention, the quenching temperature of the normalizing treatment is 830 ℃ to 950 ℃, which temperature range is "a temperature above eutectoid temperature".
According to some embodiments of the invention, the quenching temperature of the normalizing treatment is 870 ℃ to 950 ℃.
According to some embodiments of the invention, the quenching temperature of the normalizing treatment is 900 ℃ to 950 ℃.
According to some embodiments of the invention, the incubation time for the normalizing treatment is from 1h to 4h.
According to some embodiments of the invention, the incubation time for the normalizing treatment is from 2 hours to 4 hours.
According to some embodiments of the invention, the incubation time for the normalizing treatment is from 3 hours to 4 hours.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the strength, the hardness and the wear resistance of the spheroidal graphite cast iron are improved.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the surface hardness of the semi-finished product of the rigid wheel is 330-360 HBW.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the surface hardness of the semi-finished product of the rigid wheel is 340 HBW-360 HBW.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the surface hardness of the semi-finished product of the rigid wheel is 350-360 HBW.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the tensile strength of the semi-finished product of the rigid wheel is more than or equal to 1100MPa.
The hardness and the tensile strength show that the heat-treated semi-finished product of the rigid wheel has better wear resistance.
When the thermal deformation test is carried out on the heat-treated semi-finished product of the rigid wheel under the condition of heat preservation at 170 ℃ for 24 hours, the dimensional change is measured to be below 0.01%, which shows that the obtained semi-finished product of the rigid wheel has higher thermal stability before finish machining after heat treatment.
According to some embodiments of the invention, the finishing includes grinding the heat treated semi-finished rigid wheel to form a finished rigid wheel.
A third aspect of the invention provides a harmonic speed reducer in which the harmonic speed reducer rigid wheel of the invention is provided.
The invention relates to a technical scheme of a harmonic reducer, which has at least the following beneficial effects:
The main structure of the harmonic speed reducer comprises three basic components of a wave generator, a flexible gear and a rigid gear. In the harmonic reducer, the steel wheel has higher wear resistance and mechanical strength by using the ball-milling cast iron with specific raw material proportion, and is more durable, so that the service life, stability and reliability of the harmonic reducer are prolonged.
A fourth aspect of the invention provides an industrial robot in which the harmonic reducer rigid wheel of the invention or the harmonic reducer of the invention is provided.
The invention relates to a technical scheme of an industrial robot, which has at least the following beneficial effects:
The industrial robot is a multi-joint manipulator or a multi-degree-of-freedom machine device widely used in the industrial field, has certain automaticity, and can realize various industrial processing and manufacturing functions by means of self power energy and control capability. Industrial robots are widely used in various industrial fields such as electronics, logistics, chemical industry, and the like. As the speed reducer is used as one of important parts of the industrial robot, the speed reducer is provided with the harmonic speed reducer rigid wheel or has better comprehensive performance, so that the service life of the speed reducer is directly prolonged, and the failure rate of the industrial robot is also reduced.
Drawings
Fig. 1 is a schematic diagram of the structure of a rigid wheel of a harmonic speed reducer.
Fig. 2 is a flowchart for preparing a rigid wheel of a harmonic speed reducer.
Fig. 3 is a metallographic structure diagram of a rigid wheel of a harmonic speed reducer prepared in the embodiment.
Fig. 4 is a schematic surface view of a freshly toothed surface prepared in the example before wearing.
Fig. 5 is a schematic surface view of the example prepared with the tooth surface worn.
FIG. 6 is a schematic surface view of a comparative example prepared just prior to wear of the tooth face.
FIG. 7 is a schematic surface view of a comparative example after wear of the face of a rigid gear.
Detailed Description
The following are specific embodiments of the present invention, and the technical solutions of the present invention will be further described with reference to the embodiments, but the present invention is not limited to these embodiments.
In some embodiments of the invention, the invention provides a rigid gear of a harmonic speed reducer, wherein a base material of the rigid gear of the harmonic speed reducer is spheroidal graphite cast iron, and the spheroidal graphite cast iron comprises Fe and the following components in percentage by mass:
C：3.0％～4.0％，
Si：2.0％～3.0％，
Cu：0.5％～1.0％，
Mn：≤1.0％，
Cr：≤0.1％，
P：≤0.1％，
S：≤0.06％，
in the spheroidal graphite cast iron, the graphite spheroidization rate of a metallographic structure is more than or equal to 95 percent.
It can be understood that the rigid wheel of the harmonic reducer is made of ductile cast iron. The spheroidal graphite cast iron is cast iron in which carbon obtained through spheroidization and inoculation is precipitated as spheroidal graphite, and has good castability, wear resistance and machinability. The harmonic reducer rigid wheel has excellent mechanical property and technological property under specific raw material proportion, and the mechanical property of the harmonic reducer rigid wheel can be further improved through heat treatment, so that the spheroidal graphite cast iron can be used for manufacturing parts with larger load and more complex stress, such as crankshafts, connecting rods, gears, machine tool spindles and the like, and is particularly suitable for the harmonic reducer rigid wheel of the invention.
It is also understood that the rigid wheel of the harmonic reducer is made of spheroidal graphite cast iron as the base material, carbon is a required element for crystallizing and separating out spheroidal graphite in the preparation raw material, and the carbon content in the range of 3.0-4.0% enables the spheroidal graphite to crystallize and separate out. Silicon is a necessary element for crystallizing and precipitating spheroidal graphite, and the silicon content in the range of 2.0% to 3.0% is advantageous for crystallizing and precipitating spheroidal graphite and can suppress the occurrence of dross defects and graphite floating. Copper can inhibit carbide and is favorable for obtaining spheroidal graphite. Manganese is an element having a function of refining graphite and strengthening a pearlite structure, and the above-mentioned range of not more than 1.0% contributes to the effect. The chromium has the functions of promoting the growth of pearlite, improving the toughness and refining the matrix. Phosphorus and sulfur are unavoidable impurities in the spheroidal graphite cast iron, and the content of the phosphorus and the sulfur can be reduced as much as possible.
In some embodiments of the invention, the mass percent of carbon in the spheroidal graphite cast iron is 3.2 to 4.0 percent.
Further, in some embodiments of the invention, the mass percent of carbon in the spheroidal graphite cast iron is 3.5 to 4.0 percent.
Further, in some embodiments of the invention, the mass percent of carbon in the spheroidal graphite cast iron is 3.8 to 4.0 percent.
In some embodiments of the invention, the mass percentage of silicon in the spheroidal graphite cast iron is 2.2 to 3.0%.
Further, in some embodiments of the invention, the mass percent of silicon in the spheroidal graphite cast iron is 2.5 to 3.0 percent.
Further, in some embodiments of the invention, the mass percent of silicon in the spheroidal graphite cast iron is 2.7 to 3.0 percent.
In some embodiments of the invention, the ductile iron has a copper content of 0.6% to 1.0% by mass.
Further, in some embodiments of the invention, the ductile iron has a copper content of 0.7% to 1.0% by mass.
In some embodiments of the invention, the mass percent of manganese in the spheroidal graphite cast iron is less than or equal to 1.0%.
Further, in some embodiments of the present invention, the mass percentage of manganese in the ductile iron may be 0.7%.
Further, in some embodiments of the present invention, the mass percent of manganese in the spheroidal graphite cast iron may be 0.5%.
Further, in some embodiments of the present invention, the mass percentage of manganese in the ductile iron may be 0.2%.
In some embodiments of the invention, the mass percent of chromium in the spheroidal graphite cast iron is 0.03 to 0.06%.
Further, in some embodiments of the invention, the mass percent of chromium in the spheroidal graphite cast iron may be 0.05%.
Further, in some embodiments of the present invention, the mass percent of chromium in the spheroidal graphite cast iron may be 0.04%.
The proportion range is suitable for the proportion range of the raw materials for preparing the spheroidal graphite cast iron.
In some embodiments of the invention, the metallographic structure in the spheroidal graphite cast iron comprises cementite and phosphorus eutectic.
It is understood that cementite is a metal compound formed by iron and carbon, has a complex orthorhombic crystal structure, is a main strengthening phase in spheroidal graphite cast iron, and has a great influence on the performance of steel due to the shape and distribution of cementite. In the ball-milled cast iron, cementite appears in the structure in different forms and sizes of crystals, and the mechanical properties of the spheroidal graphite cast iron are greatly affected.
In general cast iron, phosphorus eutectic formed by phosphorus with carbon and iron increases brittleness of cast iron, and therefore phosphorus is treated as an impurity element. However, in the wear-resistant cast iron, the phosphor eutectic is beneficial to improving the wear resistance of the cast iron under certain conditions.
In some embodiments of the invention, the cementite comprises free cementite.
Specifically, free cementite refers to cementite that is present as a separate phase from a mechanical mixture (structure) such as ledeburite (eutectic structure) after pearlite (eutectoid structure). Free cementite has a negative effect on material properties and it is necessary to control the free cementite content by controlling the cooling rate. The free cementite in the present invention mainly refers to primary cementite.
In some embodiments of the invention, the tensile strength of the spheroidal graphite cast iron is greater than or equal to 1100MPa.
It can be understood that the tensile strength of the spheroidal graphite cast iron is more than or equal to 1100MPa, and the rigid wheel of the harmonic speed reducer is ensured to have higher mechanical strength.
In other embodiments of the present invention, the present invention provides a method of preparing a harmonic reducer rigid wheel, comprising the steps of:
S1: rough machining is carried out on the ball-milling cast iron base material to obtain a semi-finished product of the rigid wheel;
S2: and (3) carrying out finish machining after carrying out heat treatment on the semi-finished product of the rigid wheel to obtain the rigid wheel of the harmonic speed reducer.
It can be understood that the preparation method of the rigid wheel of the harmonic reducer comprises the steps of firstly carrying out rough machining on a ball-milling cast iron base material to obtain a semi-finished product of the rigid wheel, then carrying out heat treatment on the semi-finished product of the rigid wheel, strengthening the base material of the spheroidal graphite cast iron, enabling the base material to have better toughness, and finally carrying out finish machining to obtain the rigid wheel of the harmonic reducer with composite requirements on performance and precision. The heat treatment process is a key process in the preparation of the harmonic reducer, and the hardness after heat treatment directly influences the wear resistance of the rigid wheel.
It can also be appreciated that the method for preparing the rigid wheel of the harmonic reducer does not need expensive equipment and complex process control, and the preparation process is relatively simple and easy to control.
It can be further understood that the preparation method of the rigid wheel of the harmonic reducer comprises the steps of firstly carrying out rough machining on the ball-milling cast iron base material, carrying out finish machining after heat treatment, and avoiding the dimensional change of the rigid wheel precision possibly caused in the heat treatment process; on the other hand, the performance of the finally prepared harmonic reducer rigid wheel is more excellent through the combination of rough machining and finish machining.
In some embodiments of the invention, the metallographic structure in the semi-finished steel wheel comprises spheroidal graphite, pearlite, and ferrite.
Specifically, the spheroidal graphite can minimize the splitting effect on the cast iron matrix, so that the stress concentration effect in the cast iron is minimized, and therefore, the spheroidal graphite cast iron has high strength and can be comparable to medium carbon steel. The ductile cast iron can be used as a base material for manufacturing a workpiece with high strength and toughness requirements and complex shape. When the method is used for processing the rigid wheel of the harmonic speed reducer, the performance of the spheroidal graphite cast iron matrix can be fully exerted, so that the rigid wheel of the harmonic speed reducer prepared has certain plasticity and good toughness.
Under casting conditions, the ductile cast iron undergoes solid phase transformation according to a stable system and a metastable system in a eutectoid transformation stage, and ferrite and pearlite nucleation and growth occur.
In some embodiments of the invention, the cast iron base material may be self-prepared. The preparation method comprises the following steps: the metal raw materials are melted according to the proportion, and then the molten metal is spheroidized. The spheroidizing treatment has the function of forming the graphite into spheres during crystal growth so as to improve the appearance of the base material and improve the mechanical property of the casting.
In some embodiments of the invention, the spheroidizing agent is composed of 30-70% metal magnesium powder, 18-60% MgO, and 10-12% binder (e.g., phenolic resin). Wherein, the particle size of the metal magnesium powder is 0.05 mm-0.145 mm.
In some embodiments of the invention, roughing comprises pouring molten metal into a mold, adding inoculant for inoculation, wherein the purpose of inoculation is to eliminate white spots, increase eutectic cells, graphite nodules and refine, eliminate segregation, eliminate tendency to crystallization supercooling, etc. The inoculant can be Si-Fe, etc. And cooling and obtaining the semi-finished product of the rigid wheel from the casting mould.
Specifically, before heat treatment, the metallurgical structure of the semi-finished product of the rigid wheel consists of spheroidal graphite and a matrix structure. Wherein the matrix structure comprises pearlite and ferrite. Ferrite is a single-phase structure, is a interstitial solid solution formed by dissolving carbon in alpha-Fe, and has low strength and hardness, but good plasticity and toughness. Pearlite is a two-phase structure and is a mechanical mixture composed of ferrite and cementite, wherein the cementite is a metal compound formed by iron and carbon, and the chemical general formula of the pearlite is Fe 3 C, and the pearlite has high strength and hardness. The semi-finished product of the rigid wheel with the metallographic structure can balance strength and plasticity through ferrite and pearlite.
In some embodiments of the invention, the graphite spheroidization rate of the metallographic structure of the semi-finished steel wheel is greater than or equal to 70%.
In some embodiments of the invention, the metallurgical structure of the green wheel prior to heat treatment comprises spheroidal graphite, bullseye structure, and ferrite. Wherein, the graphite spheroidization rate is more than 80 percent, and the ferrite content is less than 25 percent. The bullseye structure is a structure similar to a bullseye shape formed by surrounding ferrite with spherical graphite and pearlite with ferrite periphery, wherein the ferrite content in the bullseye structure is below 25%, and the ferrite content in the whole metallographic structure is below 25%. The semi-finished product of the rigid wheel with the metallographic structure before heat treatment has good strength and hardness performance, is favorable for preparing the wear-resistant rigid wheel, and is particularly suitable for the rigid wheel for the harmonic speed reducer.
The graphite spheroidization rate of the metallographic structure in the semi-finished product of the rigid wheel is more than or equal to 70%, the mechanical property of the rigid wheel of the harmonic speed reducer after finish machining is ensured, and the impact strength, fatigue property, corrosion resistance and wear resistance of the spheroidal graphite cast iron can be improved.
In some embodiments of the invention, the heat treatment comprises a normalizing treatment.
In some embodiments of the invention, the normalizing process comprises: firstly, heating a semi-finished product of the rigid wheel to a certain temperature above eutectoid temperature, and preserving heat for a period of time, wherein the spheroidal graphite cast iron base material is austenitized; then cooling to a bainite transformation area in a cooling chamber at a cooling speed higher than that of pearlite formation to isothermal, and transforming an austenitized part into bainite at the moment, wherein the strength and toughness of the bainite are higher.
In some embodiments of the invention, the quenching temperature of the normalizing treatment is 830 ℃ to 950 ℃, i.e. the heating to a temperature above the eutectoid temperature in the process described above.
In some embodiments of the invention, the quenching temperature of the normalizing treatment is 870 ℃ to 950 ℃.
Further, in some embodiments of the invention, the quenching temperature of the normalizing treatment is 900 ℃ to 950 ℃.
In some embodiments of the invention, the incubation time for the normalizing treatment is from 1h to 4h.
Further, in some embodiments of the invention, the incubation time for the normalizing treatment is from 2 hours to 4 hours.
Further, in some embodiments of the invention, the incubation time for the normalizing treatment is from 3 hours to 4 hours.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the strength, the hardness and the wear resistance of the spheroidal graphite cast iron are improved.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the surface hardness of the semi-finished product of the rigid wheel is 330-360 HBW.
Further, after the spheroidal graphite cast iron is subjected to the normalizing treatment process, the surface hardness of the semi-finished product of the rigid wheel is 340 HBW-360 HBW.
Further, after the spheroidal graphite cast iron is subjected to the normalizing treatment process, the surface hardness of the semi-finished product of the rigid wheel is 350-360 HBW.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the tensile strength of the semi-finished product of the rigid wheel is more than or equal to 1100MPa.
It will be appreciated that the hardness and tensile strength indicated above indicate that the heat treated semi-finished steel wheel has better wear resistance.
When the thermal deformation test is carried out on the heat-treated semi-finished product of the rigid wheel under the condition of heat preservation at 170 ℃ for 24 hours, the dimensional change is measured to be below 0.01%, which shows that the obtained semi-finished product of the rigid wheel has higher thermal stability before finish machining after heat treatment.
In some embodiments of the invention, finishing includes grinding the heat treated semi-finished rigid wheel to form a finished rigid wheel.
In other embodiments of the invention, the invention provides a harmonic speed reducer, wherein the harmonic speed reducer rigid wheel is arranged.
It can be understood that the main structure of the harmonic reducer comprises three basic components of a wave generator, a flexspline and a rigid spline. In the harmonic reducer, the steel wheel has higher wear resistance and mechanical strength by using the ball-milling cast iron with specific raw material proportion, and is more durable, so that the service life, stability and reliability of the harmonic reducer are prolonged.
Specifically, the harmonic speed reducer is a precise transmission part and mainly comprises a cam, a flexible bearing, a flexible gear, a rigid gear and a crossed roller bearing, the transmission principle of the harmonic speed reducer is small-tooth-difference transmission, and the harmonic speed reducer can be used as a speed reduction torque-increasing or speed increase torque reduction device. The assembly relation of the harmonic speed reducer is that, taking a top hat type harmonic speed reducer as an example, a cam is assembled on a flexible bearing in a small interference way to form a wave generator, the wave generator can be used as an input end, a flexible gear is assembled on an outer ring of a crossed roller bearing, the wave generator is assembled on the inner wall of the flexible gear, the inner wall of the flexible gear and the outer ring of the flexible bearing are friction pairs, a rigid gear is assembled on an inner ring of the crossed roller bearing, relative motion between the rigid gear and teeth of a flexible gear part is the friction pairs, the meshing rate of the teeth is related to working conditions, the rigid gear is fixed, the flexible gear can be used as an output end, and the reduction ratio i= (number of teeth of the flexible gear-number of rigid gear)/number of teeth of the flexible gear. The tooth surface of the flexible gear and the tooth surface of the rigid gear of the harmonic speed reducer are in line contact friction pairs, relative motion between the tooth surfaces is tangential meshing and tooth direction scraping, wherein the meshing speed is related to the rotating speed of an output end and the size of the flexible gear, the axial relative speed is related to the rotating speed of an input end, the torque and the rigidity of the flexible gear, the axial movement is caused by the periodic buckling deformation of the flexible gear, and the lubrication state of the tooth surface friction pairs is mixed lubrication.
In other embodiments of the present invention, the present invention provides an industrial robot having the inventive harmonic reducer rigid wheel or the inventive harmonic reducer disposed therein.
It can be understood that the industrial robot is a multi-joint manipulator or a multi-degree-of-freedom machine device widely used in the industrial field, has certain automaticity, and can realize various industrial processing and manufacturing functions by means of self power energy and control capability. Industrial robots are widely used in various industrial fields such as electronics, logistics, chemical industry, and the like. As the speed reducer is used as one of important parts of the industrial robot, the speed reducer is provided with the harmonic speed reducer rigid wheel or has better comprehensive performance, so that the service life of the speed reducer is directly prolonged, and the failure rate of the industrial robot is also reduced.
The technical solution of the present invention will be better understood by combining the following specific embodiments.
Examples
This embodiment prepares a harmonic speed reducer rigid wheel, the structure of which is shown with reference to fig. 1. The base material of the rigid wheel of the harmonic speed reducer is spheroidal graphite cast iron, and the preparation raw materials of the spheroidal graphite cast iron comprise Fe and the following components in percentage by mass:
C：3.9％，
Si：2.5％，
Cu：0.7％，
Mn：0.8％，
Cr：0.1％，
P：0.1％，
S：0.03％。
The ball-milling cast iron base material is self-prepared. The preparation method comprises the following steps: the metal raw materials are melted according to the proportion, and then the molten metal is spheroidized. The spheroidizing agent used for spheroidizing consists of 50% of metal magnesium powder, 39% of MgO and 11% of phenolic resin. Wherein, the particle size of the metal magnesium powder is about 0.1 mm.
The preparation flow of the rigid wheel of the harmonic speed reducer is shown by referring to fig. 2, and the specific preparation method comprises the following steps:
S1: rough machining is carried out on the ball-milling cast iron base material to obtain a semi-finished product of the rigid wheel;
S2: and (3) carrying out finish machining after carrying out heat treatment on the semi-finished product of the rigid wheel to obtain the rigid wheel of the harmonic speed reducer.
The rough machining method comprises the following steps: pouring the melted spheroidal graphite cast iron base material into a casting mould, adding an inoculant for inoculation, wherein the inoculant is commercially available Si-Fe, and cooling to obtain a semi-finished product of the rigid wheel from the casting mould.
The normalizing treatment process comprises the following steps: firstly, heating the semi-finished product of the rigid wheel to over 860 ℃, and preserving heat for about 2.5 hours, wherein the spheroidal graphite cast iron base material is austenitized; then, the mixture is cooled to a bainite transformation region in a cooling chamber at a cooling rate higher than that of pearlite formation, and isothermal temperature is carried out at about 340 ℃, and at this time, an austenitized portion is transformed into bainite.
The quenching temperature of the normalizing treatment is about 890 ℃.
The heat preservation time of the normalizing treatment is 3 hours.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the surface hardness of the semi-finished product of the rigid wheel is 345HBW.
After the spheroidal graphite cast iron is subjected to the normalizing treatment process, the tensile strength of the semi-finished product of the rigid wheel is more than or equal to 1100MPa.
When the thermal deformation test is carried out on the heat-treated semi-finished product of the rigid wheel under the condition of heat preservation at 170 ℃ for 24 hours, the dimensional change is measured to be below 0.01%, which shows that the obtained semi-finished product of the rigid wheel has higher thermal stability before finish machining after heat treatment.
And finally, polishing the semi-finished product of the rigid wheel after the heat treatment through finish machining to obtain a finished product of the rigid wheel.
Comparative example
This comparative example prepares a harmonic speed reducer rigid wheel, the structure of which is shown with reference to fig. 1. The base material of the rigid wheel of the harmonic speed reducer is spheroidal graphite cast iron, and the preparation raw materials of the spheroidal graphite cast iron comprise Fe and the following components in percentage by mass:
C：3.9％，
Si：2.5％，
Mn：0.8％，
P：0.1％，
S：0.03％。
The ball-milling cast iron base material is self-prepared. The preparation method comprises the following steps: the metal raw materials are melted according to the proportion, and then the molten metal is spheroidized. The spheroidizing agent used for spheroidizing consists of 50% of metal magnesium powder, 39% of MgO and 11% of phenolic resin. Wherein, the particle size of the metal magnesium powder is about 0.1 mm.
The preparation flow of the rigid wheel of the harmonic reducer is shown with reference to fig. 2. The specific preparation method comprises the following steps:
S1: rough machining is carried out on the ball-milling cast iron base material to obtain a semi-finished product of the rigid wheel;
S2: and (3) carrying out finish machining after carrying out heat treatment on the semi-finished product of the rigid wheel to obtain the rigid wheel of the harmonic speed reducer.
The rough machining method comprises the following steps: pouring the melted spheroidal graphite cast iron base material into a casting mould, adding an inoculant for inoculation, wherein the inoculant is commercially available Si-Fe, and cooling to obtain a semi-finished product of the rigid wheel from the casting mould.
The normalizing treatment process comprises the following steps: firstly, heating the semi-finished product of the rigid wheel to over 860 ℃, and preserving heat for about 2.5 hours, wherein the spheroidal graphite cast iron base material is austenitized; then, the mixture is cooled to a bainite transformation region in a cooling chamber at a cooling rate higher than that of pearlite formation, and isothermal temperature is carried out at about 340 ℃, and at this time, an austenitized portion is transformed into bainite.
The quenching temperature of the normalizing treatment is about 890 ℃.
The heat preservation time of the normalizing treatment is 3 hours.
When the thermal deformation test is carried out on the heat-treated semi-finished product of the rigid wheel under the condition of heat preservation at 170 ℃ for 24 hours, the dimensional change is measured to be below 0.01%, which shows that the obtained semi-finished product of the rigid wheel has higher thermal stability before finish machining after heat treatment.
And finally, polishing the semi-finished product of the rigid wheel after the heat treatment through finish machining to obtain a finished product of the rigid wheel.
Test case
The metallographic structure of the rigid wheel prepared in the example is observed according to GB/T9441-2009 national Standard for ductile iron metallographic examination, as shown in FIG. 3. In FIG. 3, the black spheres are graphite, the maximum size is 48.1 μm, the average size is 11.7 μm, the spheroidization rate is not less than 95%, and particularly 99.3%, and the pearlite ratio is more than 95% according to the national standard grade 1 standard.
According to GB/T230.1-2018, part 1 of Rockwell hardness test of Metal Material: test method the surface hardness of the rigid wheels prepared in the examples and comparative examples was measured. Wherein, the surface hardness of the rigid wheel prepared in the embodiment is between 330HBW and 360 HBW. The surface hardness of the rigid wheel prepared in the comparative example is about 280 HBW.
According to GB/T228.1-2021 section 1 Metal Material tensile test: room temperature test method tensile strength of the rigid wheels prepared in the examples and comparative examples was measured. Wherein, the tensile strength of the rigid wheel prepared in the embodiment reaches 1120MPa. The tensile strength of the rigid wheel prepared in the comparative example is about 900MPa.
In addition, the surface conditions before and after abrasion of the tooth surfaces of the steel teeth prepared in examples and comparative examples were also observed. The rigid wheels prepared in the examples and the comparative examples are used in a top-hat type harmonic speed reducer (25 model, 80 reduction ratio) and run for 500 hours under the rated working condition of the speed reducer, and the abrasion condition of the tooth surface of the rigid wheels is observed. As shown in fig. 4 to 7. Fig. 4 is a schematic surface view of the example prepared just before the wear of the tooth surface, and fig. 5 is a schematic surface view of the example prepared just after the wear of the tooth surface. Fig. 6 is a schematic surface view of the surface of the rigid gear prepared in the comparative example before abrasion, and fig. 7 is a schematic surface view of the surface of the rigid gear prepared in the comparative example after abrasion. As can be seen from comparing fig. 4 to 7, the rigid wheels prepared in the examples have no significant change before and after the tooth surface wear, and no defects such as chipping are observed. The tooth surface of the rigid wheel prepared in the comparative example is cracked after abrasion.
In other embodiments of the present invention, the present invention further provides a harmonic speed reducer, in which the harmonic speed reducer rigid wheel of the present invention is disposed.
It can be understood that the main structure of the harmonic reducer comprises three basic components of a wave generator, a flexspline and a rigid spline. In the harmonic reducer, the steel wheel has higher wear resistance and mechanical strength by using the ball-milling cast iron with specific raw material proportion, and is more durable, so that the service life, stability and reliability of the harmonic reducer are prolonged.
Specifically, the harmonic speed reducer is a precise transmission part and mainly comprises a cam, a flexible bearing, a flexible gear, a rigid gear and a crossed roller bearing, the transmission principle of the harmonic speed reducer is small-tooth-difference transmission, and the harmonic speed reducer can be used as a speed reduction torque-increasing or speed increase torque reduction device. The assembly relation of the harmonic speed reducer is that, taking a top hat type harmonic speed reducer as an example, a cam is assembled on a flexible bearing in a small interference way to form a wave generator, the wave generator can be used as an input end, a flexible gear is assembled on an outer ring of a crossed roller bearing, the wave generator is assembled on the inner wall of the flexible gear, the inner wall of the flexible gear and the outer ring of the flexible bearing are friction pairs, a rigid gear is assembled on an inner ring of the crossed roller bearing, relative motion between the rigid gear and teeth of a flexible gear part is the friction pairs, the meshing rate of the teeth is related to working conditions, the rigid gear is fixed, the flexible gear can be used as an output end, and the reduction ratio i= (number of teeth of the flexible gear-number of rigid gear)/number of teeth of the flexible gear. The tooth surface of the flexible gear and the tooth surface of the rigid gear of the harmonic speed reducer are in line contact friction pairs, relative motion between the tooth surfaces is tangential meshing and tooth direction scraping, wherein the meshing speed is related to the rotating speed of an output end and the size of the flexible gear, the axial relative speed is related to the rotating speed of an input end, the torque and the rigidity of the flexible gear, the axial movement is caused by the periodic buckling deformation of the flexible gear, and the lubrication state of the tooth surface friction pairs is mixed lubrication.
In other embodiments of the present invention, the present invention provides an industrial robot having the inventive harmonic reducer rigid wheel or the inventive harmonic reducer disposed therein.
It can be understood that the industrial robot is a multi-joint manipulator or a multi-degree-of-freedom machine device widely used in the industrial field, has certain automaticity, and can realize various industrial processing and manufacturing functions by means of self power energy and control capability. Industrial robots are widely used in various industrial fields such as electronics, logistics, chemical industry, and the like. As the speed reducer is used as one of important parts of the industrial robot, the speed reducer is provided with the harmonic speed reducer rigid wheel or has better comprehensive performance, so that the service life of the speed reducer is directly prolonged, and the failure rate of the industrial robot is also reduced.
The present invention has been described in detail with reference to the embodiments, but the present invention is not limited to the embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present invention.
Claims (5)
1. The harmonic reducer rigid wheel is characterized in that a base material of the harmonic reducer rigid wheel is spheroidal graphite cast iron, and the spheroidal graphite cast iron comprises Fe and the following components in percentage by mass:
C：3.0％～4.0％，
Si：2.0％～3.0％，
Cu：0.5％～1.0％，
Mn：≤1.0％，
Cr：≤0.1％，
P：≤0.1％，
S：≤0.06％，
In the spheroidal graphite cast iron, the graphite spheroidization rate of a metallographic structure is more than or equal to 95 percent, the metallographic structure comprises cementite and phosphorus eutectic, the tensile strength of the spheroidal graphite cast iron is more than or equal to 1100Mpa,
The preparation method of the rigid wheel of the harmonic speed reducer comprises the following steps:
S1: performing rough machining on a ball-milling cast iron base material conforming to element proportions to obtain a semi-finished product of the rigid wheel, wherein a metallographic structure comprises spherical graphite, pearlite and ferrite, and the graphite spheroidization rate of the metallographic structure in the semi-finished product of the rigid wheel is more than or equal to 70%;
s2: carrying out heat treatment on the semi-finished product of the rigid wheel, and then carrying out finish machining to obtain the rigid wheel of the harmonic reducer;
The heat treatment comprises normalizing treatment, wherein the normalizing treatment comprises heating the semi-finished product of the rigid wheel to above eutectoid temperature for heat preservation, austenitizing a spheroidal graphite cast iron base material, and then cooling the semi-finished product of the rigid wheel to a bainite transformation area at a cooling speed which is higher than that of pearlite formation for isothermal, so that an austenitized part is transformed into bainite.
2. The harmonic reducer rigid wheel according to claim 1, wherein the preparation raw materials of the spheroidal graphite cast iron comprise Fe and the following components in percentage by mass:
C：3.5％～4.0％，
Si：2.5％～3.0％，
Cu：0.7％～1.0％，
Mn：≤1.0％，
Cr：≤0.1％，
P：≤0.1％，
S：≤0.06％。
3. the harmonic reducer rigid wheel of claim 1, wherein the roughing comprises melting the ball-milled cast iron substrate and injecting the melted ball-milled cast iron substrate into a casting mold, and adding an inoculant to perform inoculation.
4. A harmonic speed reducer, characterized in that the harmonic speed reducer is provided with the harmonic speed reducer rigid wheel as claimed in claim 1 or 2.
5. An industrial robot, wherein the harmonic reducer rigid wheel according to claim 1 or 2 or the harmonic reducer according to claim 4 is provided in the industrial robot.
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