CN117900780A - Method for machining annular gear part - Google Patents
Method for machining annular gear part Download PDFInfo
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- CN117900780A CN117900780A CN202410259922.8A CN202410259922A CN117900780A CN 117900780 A CN117900780 A CN 117900780A CN 202410259922 A CN202410259922 A CN 202410259922A CN 117900780 A CN117900780 A CN 117900780A
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Abstract
The invention discloses a machining method of an annular gear part, which comprises the following steps of blank material selection, blanking, basic shot blasting, tooth extrusion, tempering, turning, drilling and tapping, fine gear shaping, nitriding, strengthening shot blasting, gear grinding and the like, wherein a pipe is directly selected as an original blank, the structural performance of a tooth part after strengthening forming is performed by shot blasting, and the structural strength of a tooth root part is optimized, so that the structural performance of the tooth part and other parts of the machined annular gear part is fully improved, and the machining precision of the tooth part is correspondingly optimized. In addition, compared with the prior art, in the whole annular gear part machining process, only single-channel turning operation is needed, and multiple-channel turning processes such as rough turning and finish turning are not needed as in the prior art, so that turning waste generated in the annular gear part machining process in the scheme is less, the material utilization rate in the annular gear part machining process is correspondingly improved, and the overall machining cost is correspondingly reduced.
Description
Technical Field
The invention relates to the technical field of machining and forming of annular gear parts, in particular to a machining method of an annular gear part.
Background
In the current machining field, for machining an annular gear part, a rolled material or a casting blank bar is generally selected as an original blank, the rolled material bar is blanked and then forged into a blank, and after subsequent procedures of rough turning, tempering, finish turning, drilling, tapping, gear shaping and the like are respectively carried out, the blank is machined and formed into the annular gear part.
However, although the above processing method can meet the basic processing requirement of the ring gear part, due to the blank selection and the self process steps, the forging and forming of the rolled bar stock into the blank is selected to be matched with the deep processing of the downstream process, so that the method can ensure the final forming effect of the ring gear part by taking turning processes such as rough turning and finish turning as main blank forming processing means, and a large amount of materials can be removed from the blank in the implementation of the rough turning and finish turning processes, so that the material utilization rate in the processing process is not high, and the overall processing and manufacturing cost of the ring gear part is higher; in addition, the tooth part structure precision of the inner gear ring part processed and molded by the existing technology is not high, and the tooth part structure performance is not good, so that the service life of the inner gear ring part is short, and the working condition tolerance and the adaptability are poor. The situation is more remarkable in mass production of the ring gear parts, and a plurality of adverse effects are caused to processing and manufacturing of the related ring gear parts.
Therefore, how to optimize the processing method of the annular gear part, improve the material utilization rate of the annular gear part, and improve the processing precision and the structural performance of the tooth part of the processed and molded annular gear part is an important technical problem that needs to be solved by the person skilled in the art at present.
Disclosure of Invention
The invention aims to provide a method for processing an annular gear part, which can improve the material utilization rate in the processing process of the annular gear part and improve the processing precision and structural performance of the tooth part of the processed and molded annular gear part.
In order to solve the technical problems, the invention provides a method for processing an inner gear ring part, which comprises the following steps:
selecting blank materials, namely selecting the blank materials according to the performance parameters of the pipe materials, and selecting the pipe material blank materials capable of meeting the machining and forming requirements of the annular gear part;
Discharging, namely removing a section of annular end scraps from the head end and the tail end of the whole pipe blank along the axial direction, ensuring that the head end and the tail end of the pipe blank are perpendicular to the axis of the pipe blank when the annular end scraps are removed, cutting the pipe blank into circular ring blanks according to the turning allowance of the axial direction reserved in the processing drawing of the annular gear part, and ensuring that the parallelism of the two end surfaces of the circular ring blanks meets the process requirements;
Performing basic shot blasting, namely performing shot blasting treatment on the whole annular blank to remove oxide skin on the surface of the annular blank;
tooth extrusion, namely placing a ring blank into a lower die cavity of an extrusion die, enabling one end face of the ring blank to be attached to the inner lower surface of the lower die cavity, enabling the outer surface of the ring blank to be attached to the inner circumferential surface of the lower die cavity, starting an extruder, enabling a tooth-shaped extrusion cutter of the extruder to be pressed into the ring blank downwards, keeping the axis of the extruder coincident with the axis of the ring blank at the moment, and enabling the tooth-shaped extrusion cutter of the extruder to eject out of the lower die cavity after extruding and forming a tooth part on the ring blank, so that the ring blank is processed into a gear ring blank, and enabling a material ejection rod of the lower die cavity to eject out the gear ring blank;
Quenching and tempering, namely quenching and tempering the gear ring blank according to the technical requirements of the processing drawing of the inner gear ring part;
Turning, namely taking a first end face of the gear ring blank as a positioning basis, clamping an outer circular face adjacent to the end face by using a three-jaw chuck, aligning a second end face and the outer circular face of the gear ring blank to enable jumping precision to meet technological requirements, turning the second end face and the outer circular face of the gear ring blank to be formed, turning an orifice chamfer and a spigot at corresponding positions of the second end face to be formed, and chamfering a sharp edge of the second end face of the gear ring blank; then, the machined second end face of the gear ring blank is used as a positioning basis, a three-jaw chuck is used for clamping an outer circular face, a copper sheet is arranged at a clamping position in a cushioning mode, the outer circular face is aligned, so that jumping precision meets technological requirements, the first end face and the outer circular face of the gear ring blank are turned to be formed, an orifice chamfer and a spigot are turned to be formed at the corresponding positions of the first end face, and sharp edges of the first end face of the gear ring blank are blunted;
drilling and tapping, namely, setting out each hole according to a processing drawing of the inner gear ring part by using a proper center drill, and then drilling and tapping each screw hole correspondingly until forming;
The gear ring blank is horizontally placed on a general cushion block, a pressing plate is used for pressing, the upper end face and the outer circular face of the gear ring blank are aligned, the jumping precision meets the technological requirements, and then the gear ring blank is subjected to fine gear shaping according to the processing drawing requirements of the inner gear ring part until the inner teeth are formed;
nitriding, namely placing the gear ring blank subjected to the finish gear shaping treatment on a lifting appliance after cleaning, and then carrying out integral nitriding treatment on the gear ring blank according to the processing drawing requirements of the inner gear ring part;
Strengthening shot blasting is carried out on the tooth root part of the gear ring blank so as to improve the roughness of the tooth root part, and compressive stress is formed on the tooth root part so as to strengthen the structural strength of the tooth root part;
grinding teeth, and grinding and forming the gear ring blank until a finished product of the inner gear ring part is obtained.
Preferably, the step of extruding teeth between the basic shot blasting and the tooth extruding further comprises the steps of:
cleaning preparation, namely cleaning the inner surface and the outer surface of the circular ring blank by adopting scouring pad, and ensuring that the inner surface and the outer surface of the circular ring blank are free of impurities;
Preparing for lubrication, namely uniformly coating high molecular lubricant on the inner surface and the outer surface of the annular blank and the end face of the annular blank;
and (3) drying, namely placing the round-ring blank coated with the polymer lubricant into a drying oven for drying.
Preferably, in the blanking, two ring blanks with different lengths and inner and outer diameter sizes, namely a first ring blank and a second ring blank, are obtained by cutting;
In the tooth extrusion process, the first annular blank and the second annular blank are respectively subjected to tooth extrusion treatment to obtain a first gear ring blank and a second gear ring blank, and the first gear ring blank and the second gear ring blank are pressed into a combined gear ring blank.
Preferably, in the blank material selection, the annealing hardness of the pipe is 150-170 HBW.
Preferably, in the blank material selection, the fluctuation of carbon content of each point of the cross section of the pipe is less than 0.03%.
Preferably, in the blank material selection, the residual magnetic quantity of the pipe is ensured to be not more than 5 gauss.
Preferably, in the blanking, the axial length of the annular end scraps is 1-2 mm.
Preferably, in the blanking, the parallelism of the two end faces of the annular blank is not more than 0.1mm.
Compared with the background technology, the method for processing the annular gear part provided by the invention has the advantages that in the operation and application process, through the steps of blank material selection, blanking, basic shot blasting, tooth extrusion, tempering, turning, drilling and tapping, fine gear shaping, nitriding, strengthening shot blasting, tooth grinding and the like which are sequentially carried out, a pipe is directly selected as an original blank, in the process implementation process, the blank is subjected to surface polishing and cleaning by shot blasting, then the extruded tooth is used as a core treatment process of tooth part processing and forming, and the internal tooth processing and forming are realized by matching with turning and fine gear shaping, on the basis, the structural performance of the tooth part after the shot blasting treatment strengthening forming is utilized, the structural strength of the tooth root part is optimized, and therefore, the structural performance of the tooth part and other parts of the processed annular gear part is fully improved, and the tooth part processing precision of the annular gear part is correspondingly optimized. In addition, compared with the prior art, because the pipe is directly selected as the original blank, the high-precision forming of the annular gear part can be realized only by matching the working procedures of extruding teeth, fine gear shaping, gear grinding and the like in the whole annular gear part processing process in the scheme, and the multi-channel turning treatments such as rough turning, fine turning and the like are not needed as in the prior art, so that less turning waste is generated in the annular gear part processing process in the scheme, the material utilization rate in the annular gear part processing process is correspondingly improved, and the whole processing cost is correspondingly reduced.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a flowchart illustrating steps of a method for machining an annular gear part according to an embodiment of the present invention;
Fig. 2 is a flowchart of steps of a method for machining an annular gear part according to a second embodiment of the present invention.
Detailed Description
The core of the invention is to provide the annular gear part machining method, which can improve the material utilization rate in the annular gear part machining process and improve the machining precision and structural performance of the tooth part of the machined annular gear part.
In order to better understand the aspects of the present invention, the present invention will be described in further detail with reference to the accompanying drawings and detailed description.
Please refer to fig. 1.
In a first embodiment, the method for machining an inner gear ring part provided by the invention includes:
And S101, selecting blank materials.
Selecting materials according to the performance parameters of the pipe, and selecting pipe blanks capable of meeting the machining and forming requirements of the annular gear parts.
Generally, seamless steel pipes are selected as the pipes, and the selection of the pipes in the blank material selection process can comprise parameters such as a forming mode of the pipes, pipe dimensions, pipe bending, material organization performance of the pipes and the like.
Specifically, a tube material formed by heating a rolled material and passing through the tube is selected, the inner wall and the outer wall of the tube material are extruded, sized and subjected to air cooling treatment, and the air cooling treatment is natural cooling in the air; in addition, the tube is annealed after straightening, and the annealing hardness is preferably 150-170 HBW. In the production process, the pipe is stressed and deformed in the axial direction and the radial direction, and the structure performance of the pipe is improved to a certain extent, and the longitudinal and transverse performances are uniform, similar to the forging process after blanking of the pipe; in addition, because the temperature is higher during sizing, air cooling is similar to normalizing treatment after sizing, and the annealing treatment after straightening can not only reduce the hardness of the pipe so as to facilitate the subsequent tooth extrusion processing, but also remove the residual stress caused by the straightening process.
And measuring and selecting the outer diameter, the inner diameter, the wall thickness and the curvature of the pipe, wherein the outer diameter, the inner diameter and the wall thickness are selected according to the reserved machining size and the turning allowance, and the curvature meets the machining technical requirements of the annular gear part. Specifically, the outer diameter measuring part is the head part, the middle part and the tail part of the pipe, the inner diameter and the wall thickness are the head part and the tail part, and the curvature is measured along the axial direction of the pipe. The deviations of the dimensions after measurement were: outer diameter = ±outer diameter/1000, inner diameter = ±inner diameter/1000, wall thickness = ±wall thickness/100, deflection of curvature = ±0.4mm/m.
The material organization property of the pipe is correspondingly checked and selected, and generally, the pipe with uniform chemical composition, the organization property and the brand meeting the requirements of the internal gear ring part processing drawing is selected, wherein the fluctuation Wc of the carbon content of each point of the cross section of the pipe is ensured to be less than 0.03 percent as much as possible. In actual operation, samples of chemical components, metallographic structures, mechanical properties and the like of the pipe are all sampled at the 1/2 wall thickness position. The specific sampling positions are as follows: the strip tissue inspection surface is a longitudinal section and a transverse section at a radius of 1/2 of the wall thickness; the chemical components and nonmetallic inclusions are longitudinal sections with 1/2 radius of the wall thickness; the grain size, hardness and gas content test surface is perpendicular to the axial direction of the pipe. Wherein the number of chemical component samples is not less than 3, and the sampling positions should be uniformly distributed in the circumferential direction of the pipe; the rest requirements of the pipe all meet the enterprise or national standards.
In the blank selection process, UT (acronym for Ultrasonic Testing, i.e., ultrasonic detection) flaw detection and magnetic content detection can be performed on the pipe if necessary. Generally, UT flaw detection can be performed on the pipe according to the standard and grade specified by the processing technical drawing of the ring gear part against the artificial defect standard block so as to select the pipe meeting the requirement. And the magnetic content detection requires that the residual magnetic quantity of the pipe is not more than 5 gauss.
Of course, the specific requirement standards for the relevant parameters, the structure and the material performance of the pipe in the related blank selection can be properly adjusted and flexibly selected according to different specific application working conditions. In principle, any material may be used as long as it can meet the practical requirements of the machining method of the ring gear part.
In the prior art, the original blank is a bar stock, so that the bar stock is usually processed in a single piece in the process of being processed into a circular ring blank through a forging process; in the scheme, the pipe is selected as an original blank, and the processing technologies of pipe penetration, periodic forging and rolling and the like adopted in the pipe processing process are all continuous processing treatment of a plurality of blanks. Therefore, the processing efficiency of adopting the pipe as the original blank is higher, and the process flow is smoother and more efficient.
Step S102, blanking.
And respectively removing a section of annular end scraps from the head end and the tail end of the whole pipe blank along the axial direction, ensuring that the head end and the tail end of the pipe blank are perpendicular to the axis of the pipe blank when the annular end scraps are removed, cutting the pipe blank into circular ring blanks according to the turning allowance of the axial direction reserved in the processing drawing of the annular gear part, and ensuring that the parallelism of the two end surfaces of the circular ring blanks meets the technological requirements.
Generally, the axial length of the annular end scraps removed from the head end and the tail end of the pipe blank is 1-2 mm, and the parallelism of the two end faces of the annular end scraps removed from the annular end scraps should be not more than 0.1mm.
And step S103, basic shot blasting.
And (3) performing shot blasting treatment on the whole annular blank to remove the oxide skin on the surface of the annular blank.
The shot blasting referred to herein is generally a process of blasting out a steel shot at a high speed by using an impeller rotating at a high speed to strike the steel shot onto the surface of a workpiece, thereby cleaning or strengthening the surface of the workpiece. In practice, shot blasting may be used instead of the above-mentioned shot blasting, and in particular, shot blasting is a process of cleaning or strengthening a surface of a workpiece by using compressed air as a motive force and by spraying steel shots onto the surface of the workpiece by a high-speed air flow of the compressed air. In practical application, the shot blasting and shot blasting process can be replaced and changed according to specific working condition requirements, and in principle, the practical process requirements of basic shot blasting and the specific application requirements of the annular gear part machining method can be met.
Step S104, extruding teeth.
Placing the ring blank into a lower die cavity of an extrusion die, enabling one end face of the ring blank to be attached to the inner lower surface of the lower die cavity, enabling the outer surface of the ring blank to be attached to the inner circumferential surface of the lower die cavity, starting an extruder, enabling a tooth-shaped extrusion cutter of the extruder to be pressed into the ring blank downwards, keeping the axis of the extruder coincident with the axis of the ring blank, enabling the tooth-shaped extrusion cutter of the extruder to extrude a tooth part on the ring blank and then exit the lower die cavity, processing the ring blank into a gear ring blank, and enabling a lower die cavity ejector rod to eject the gear ring blank, so that the whole tooth extrusion processing procedure is completed.
Because the conventional rough gear shaping process needs all teeth to be simultaneously formed, compared with the conventional rough gear shaping process in the prior art, the gear shaping process has the advantages of higher gear shaping speed and higher processing efficiency.
It should be understood that the axis of the extruder mentioned above, which is generally referred to as the axis of the extrusion die on the extruder, coincides with the axis of the annular blank, and can sufficiently ensure the accuracy of the extrusion process and the shaping effect of the ring gear blank.
In practical application, the extrusion forming mode can improve the processing efficiency of the annular gear part, and can form a cold work hardening layer distributed along the tooth profile direction on the whole tooth form (comprising a tooth surface, a tooth root and a tooth top), so that the fatigue strength and the service life of the gear are obviously improved.
And step S105, tempering.
And carrying out quenching and tempering treatment on the gear ring blank according to the technical requirements of the processing drawing of the inner gear ring part. For the field, tempering refers to a heat treatment process for improving the comprehensive mechanical properties of steel materials, which is performed by quenching a workpiece to be treated and then tempering the workpiece at a high temperature. The tempering aims to ensure that the steel parts have good matching of strength and toughness, and have higher strength, excellent toughness, plasticity, cutting performance and the like.
And S106, turning.
The first end face of the gear ring blank is used as a positioning basis, an outer circular face adjacent to the end face is clamped by a three-jaw chuck, the second end face and the outer circular face of the gear ring blank are aligned, so that the jumping precision meets the technological requirements, the second end face and the outer circular face of the gear ring blank are turned to be formed, an orifice chamfer and a spigot are turned to be formed at the corresponding positions of the second end face, and the sharp edge of the second end face of the gear ring blank is blunted; then, the machined second end face of the gear ring blank is used as a positioning basis, a three-jaw chuck is used for clamping an outer circular face, a copper sheet is arranged at a clamping position in a cushioning mode, the outer circular face is aligned, the jumping precision meets the technological requirements, the first end face and the outer circular face of the gear ring blank are turned to be formed, an orifice chamfer and a spigot are turned to be formed at corresponding positions of the first end face, and sharp edges of the first end face of the gear ring blank are blunted.
And S107, drilling and tapping.
And (3) lofting all holes according to the processing drawing of the inner gear ring part by using a proper center drill, and then drilling and tapping all screw holes correspondingly until the holes are formed.
Step S108, fine gear shaping.
After the universal cushion block is cleaned up, the gear ring blank is horizontally placed on the universal cushion block, the gear ring blank is pressed by a pressing plate, the upper end face and the outer circular face of the gear ring blank are aligned, the runout precision meets the process requirement, and then the gear ring blank fine gear shaping is processed to the internal tooth forming according to the processing drawing requirement of the internal gear ring part.
Generally, the roughness Ra of the tooth surface of the internal tooth formed by the fine gear shaping treatment is less than or equal to 2.0, so that the consistency of the metallographic structure of the tooth surface after the subsequent nitriding treatment, particularly the uniformity of the thickness of the white bright layer, is convenient, and the falling of the white bright layer when the part is used due to the excessive thickness of the local white bright layer is prevented.
In the scheme, the seamless steel pipe is directly selected as an original blank, so that in the actual processing process, the annular blank can be processed into the gear ring blank only by tooth extrusion, the primary forming of the inner gear ring part is realized, in the whole tooth extrusion process, the blank is only subjected to extrusion forming treatment, no material is removed, the whole material of the blank is free from loss, and then the subsequent single turning process and fine tooth shaping process are matched, so that the high-precision processing forming treatment of the core structures such as the tooth part of the inner gear ring part can be completed. Therefore, the scheme does not need to combine a rough turning process to process the forged blank into a blank, and then further process the blank into a high-precision formed part by matching with a finish turning process, so that a large amount of materials on the blank are eliminated and discarded due to the rough turning and finish turning processes, raw material waste is effectively avoided, and material utilization rate is improved.
Step S109, nitriding.
And (3) after the gear ring blank subjected to the finish gear shaping treatment is cleaned, the gear ring blank is horizontally placed on a lifting appliance, and then the gear ring blank is subjected to integral nitriding treatment according to the processing drawing requirements of the inner gear ring part, so that a final inner gear ring part product has good high-temperature resistance, corrosion resistance and wear resistance and fatigue resistance, and the working condition tolerance of the inner gear ring part is optimized, so that the gear ring part is more durable.
Nitriding treatment referred to herein generally refers to a chemical heat treatment process in which nitrogen atoms are allowed to permeate into the surface layer of a workpiece in a certain medium at a certain temperature. The nitriding treated product has the characteristics of excellent wear resistance, fatigue resistance, corrosion resistance and high temperature resistance.
Step S110, strengthening shot blasting.
And (3) strengthening shot blasting is carried out on the tooth root part of the gear ring blank so as to improve the roughness of the tooth root part, form compressive stress on the tooth root part, and then cooperate with a cold work hardening layer formed in the tooth profile direction in the tooth extrusion process so as to strengthen the structural strength of the tooth root part and optimize the overall structural performance of the inner gear ring part product.
Similar to the basic shot blasting described above, the shot blasting process in the enhanced peening can also be replaced by a shot blasting process, in principle, as long as the actual process requirements of the enhanced peening and the specific application requirements of the ring gear part machining method can be satisfied.
Step S111, grinding teeth.
And (3) polishing and forming the gear ring blank until a finished product of the inner gear ring part is obtained.
Of course, the above steps mainly describe the processing process flow of the straight-barrel ring gear part without flange, in practical application, if the outer circle of the ring gear part has a flange, when the step of extruding teeth is implemented in S104, the flange should be synchronously extruded and molded, specifically, the flange storage position can be reserved at the ring gear flange in the lower die cavity, and the flange can be extruded; the outer circle and the thickness of the flange are finely turned and formed when the turning procedure is implemented in S106; in the S107 drilling and tapping process, corresponding screw holes are drilled and tapped on the flange plate until the flange plate is molded.
The lower die required by the flange molding is an assembly and is divided into a flange molding cavity and a flange upper straight cylinder part molding cavity. After the flange is formed, the forming cavity of the straight cylinder part at the upper part of the flange can be radially expanded to the outer circle size of the flange, and the ring gear blank can be ejected out by the ejector rod.
Please refer to fig. 2.
In a second embodiment, the method for machining an inner gear ring part provided by the invention includes:
step S201, selecting blank materials.
Selecting materials according to the performance parameters of the pipe, and selecting pipe blanks capable of meeting the machining and forming requirements of the annular gear parts.
Generally, seamless steel pipes are selected as the pipes, and the selection of the pipes in the blank material selection process can comprise parameters such as a forming mode of the pipes, pipe dimensions, pipe bending, material organization performance of the pipes and the like.
Specifically, a rolled material or a casting blank is selected and is subjected to tube penetrating molding after being heated, the inner wall and the outer wall of the tube are subjected to extrusion sizing and air cooling treatment, and the air cooling treatment is natural cooling in the air; in addition, the tube is annealed after straightening, and the annealing hardness is preferably 150-170 HBW. In the production process, the pipe is stressed and deformed in the axial direction and the radial direction, and the structure performance of the pipe is improved to a certain extent, and the longitudinal and transverse performances are uniform, similar to the forging process after blanking of the pipe; in addition, because the temperature is higher during sizing, air cooling is similar to normalizing treatment after sizing, and the annealing treatment after straightening can not only reduce the hardness of the pipe so as to facilitate the subsequent tooth extrusion processing, but also remove the residual stress caused by the straightening process.
And measuring and selecting the outer diameter, the inner diameter, the wall thickness and the curvature of the pipe, wherein the outer diameter, the inner diameter and the wall thickness are selected according to the reserved machining size and the turning allowance, and the curvature meets the machining technical requirements of the annular gear part. Specifically, the outer diameter measuring part is the head part, the middle part and the tail part of the pipe, the inner diameter and the wall thickness are the head part and the tail part, and the curvature is measured along the axial direction of the pipe. The deviations of the dimensions after measurement were: outer diameter = ±outer diameter/1000, inner diameter = ±inner diameter/1000, wall thickness = ±wall thickness/100, deflection of curvature = ±0.4mm/m.
The material organization property of the pipe is correspondingly checked and selected, and generally, the pipe with uniform chemical composition, the organization property and the brand meeting the requirements of the internal gear ring part processing drawing is selected, wherein the fluctuation Wc of the carbon content of each point of the cross section of the pipe is ensured to be less than 0.03 percent as much as possible. In actual operation, samples of chemical components, metallographic structures, mechanical properties and the like of the pipe are all sampled at the 1/2 wall thickness position. The specific sampling positions are as follows: the strip tissue inspection surface is a longitudinal section and a transverse section at a radius of 1/2 of the wall thickness; the chemical components and nonmetallic inclusions are longitudinal sections with 1/2 radius of the wall thickness; the grain size, hardness and gas content test surface is perpendicular to the axial direction of the pipe. Wherein the number of chemical component samples is not less than 3, and the sampling positions should be uniformly distributed in the circumferential direction of the pipe; the rest requirements of the pipe all meet the enterprise or national standards.
In the blank selection process, UT (acronym for Ultrasonic Testing, i.e., ultrasonic detection) flaw detection and magnetic content detection can be performed on the pipe if necessary. Generally, UT flaw detection can be performed on the pipe according to the standard and grade specified by the processing technical drawing of the ring gear part against the artificial defect standard block so as to select the pipe meeting the requirement. And the magnetic content detection requires that the residual magnetic quantity of the pipe is not more than 5 gauss.
Of course, the specific requirement standards for the relevant parameters, the structure and the material performance of the pipe in the related blank selection can be properly adjusted and flexibly selected according to different specific application working conditions. In principle, any material may be used as long as it can meet the practical requirements of the machining method of the ring gear part.
In the prior art, the original blank is a bar stock, so that the bar stock is usually processed in a single piece in the process of being processed into a circular ring blank through a forging process; in the scheme, the pipe is selected as an original blank, and the processing technologies of pipe penetration, periodic forging and rolling and the like adopted in the pipe processing process are all continuous processing treatment of a plurality of blanks. Therefore, the processing efficiency of adopting the pipe as the original blank is higher, and the process flow is smoother and more efficient.
Step S202, blanking.
And respectively removing a section of annular end scraps from the head end and the tail end of the whole pipe blank along the axial direction, ensuring that the head end and the tail end of the pipe blank are perpendicular to the axis of the pipe blank when the annular end scraps are removed, cutting the pipe blank into circular ring blanks according to the turning allowance of the axial direction reserved in the processing drawing of the annular gear part, and ensuring that the parallelism of the two end surfaces of the circular ring blanks meets the technological requirements.
Generally, the axial length of the annular end scraps removed from the head end and the tail end of the pipe blank is 1-2 mm, and the parallelism of the two end faces of the annular end scraps removed from the annular end scraps should be not more than 0.1mm.
In the step S202 of blanking, two ring blanks with different lengths and inner and outer diameter sizes are required to be cut, namely a first ring blank and a second ring blank, and each parameter of the two ring blanks needs to meet the following requirements:
① The length of the first annular blank is at least 2mm smaller than that of the second annular blank, and the length of the second annular blank is equal to the sum of the length of the drawing part plus a preset turning allowance;
② The diameter of the reference circle of the part is smaller than or equal to the diameter of the tooth root circle of the part, the inner diameter of which is smaller than or equal to the diameter of the first circular ring blank of the drawing; drawing part tooth root diameter + (2-5) mm < first ring blank outer diameter < second ring blank outer diameter;
③ The diameter of the addendum circle of the drawing part is smaller than the diameter of the dedendum circle of the drawing part, and the inner diameter of the second circular ring blank is smaller than or equal to the diameter of the inner diameter of the second circular ring blank; the diameter of the outer circle of the first circular ring blank is smaller than that of the outer circle of the drawing, and the inner diameter and the outer diameter of the second circular ring blank are smaller than or equal to those of the outer circle of the drawing;
④ The first annular blank and the second annular blank are preferably made of steel materials with the same brand and the same technical requirements; the first annular blank can also be made of similar type steels with similar chemical components and tissue performance equal to or better than that of the second annular blank, so that the subsequent heat treatment mode can be conveniently selected.
And step S203, basic shot blasting.
And (3) performing shot blasting treatment on the whole annular blank to remove the oxide skin on the surface of the annular blank.
The shot blasting referred to herein is generally a process of blasting out a steel shot at a high speed by using an impeller rotating at a high speed to strike the steel shot onto the surface of a workpiece, thereby cleaning or strengthening the surface of the workpiece. In practice, shot blasting may be used instead of the above-mentioned shot blasting, and in particular, shot blasting is a process of cleaning or strengthening a surface of a workpiece by using compressed air as a motive force and by spraying steel shots onto the surface of the workpiece by a high-speed air flow of the compressed air. In practical application, the shot blasting and shot blasting process can be replaced and changed according to specific working condition requirements, and in principle, the practical process requirements of basic shot blasting and the specific application requirements of the annular gear part machining method can be met.
Step S204, cleaning preparation.
The inner and outer surfaces of the circular ring blank are cleaned by adopting the scouring pad, so that the inner and outer surfaces of the circular ring blank are ensured to be free of impurities such as scrap iron and the like.
Step S205, lubrication preparation.
Uniformly coating high molecular lubricant on the inner surface and the outer surface of the circular ring blank and the end surface of the circular ring blank so as to reduce friction force in the extrusion process and prevent die abrasion and defects on the surface of the gear ring;
Step S206, drying.
And (3) putting the circular ring blank coated with the polymer lubricant into an oven, and drying at a proper temperature.
Step S207, extruding teeth.
Placing the ring blank into a lower die cavity of an extrusion die, enabling one end face of the ring blank to be attached to the inner lower surface of the lower die cavity, enabling the outer surface of the ring blank to be attached to the inner circumferential surface of the lower die cavity, starting an extruder, enabling a tooth-shaped extrusion cutter of the extruder to be pressed into the ring blank downwards, keeping the axis of the extruder coincident with the axis of the ring blank, enabling the tooth-shaped extrusion cutter of the extruder to extrude a tooth part on the ring blank and then exit the lower die cavity, processing the ring blank into a gear ring blank, and enabling a lower die cavity ejector rod to eject the gear ring blank, so that the whole tooth extrusion processing procedure is completed.
Compared with the conventional rough gear shaping process, the gear shaping process adopted in the scheme has the advantages of higher gear shaping speed and higher processing efficiency.
It should be understood that the axis of the extruder mentioned above, which is generally referred to as the axis of the extrusion die on the extruder, coincides with the axis of the annular blank, and can sufficiently ensure the accuracy of the extrusion process and the shaping effect of the ring gear blank.
In practical application, the extrusion forming mode can improve the processing efficiency of the annular gear part, and can form a cold work hardening layer distributed along the tooth profile direction on the whole tooth form (comprising a tooth surface, a tooth root and a tooth top), so that the fatigue strength and the service life of the gear are obviously improved.
In specific implementation, the first annular blank and the second annular blank are subjected to tooth extrusion treatment respectively to obtain a first gear ring blank and a second gear ring blank, and the two gear ring blanks after tooth extrusion are required to meet the following conditions:
① The number of teeth of the two gear ring blanks is the same;
② The tooth thickness and the tooth height of the first gear ring blank are smaller than those of the second gear ring blank; the tooth root diameter and the tooth slot width of the first gear ring blank are all larger than those of the second gear ring blank;
③ The diameter of the outer circle of each blank is limited by the lower die cavity and does not change during tooth extrusion.
④ The sum of the thickness of each part of the single tooth of the first gear ring blank and the thickness of each part of the single tooth of the second gear ring blank is larger than or equal to the sum of the thickness of the single tooth of the drawing and the turning allowance, the sum of the height of the single tooth of the first gear ring blank and the height of the single tooth of the second gear ring blank is larger than or equal to the sum of the thickness of the single tooth of the drawing and the turning allowance, and the sum of the volume of the single tooth of the first gear ring blank and the volume of the single tooth of the second gear ring blank is larger than or equal to the sum of the volume of the single tooth of the drawing and the turning allowance.
And pressing the two molded gear ring blanks into one, cleaning up all the foreign matters such as lubricant, greasy dirt and scrap iron on the surface of the first gear ring before pressing, preheating a die to 250-300 ℃, heating the second gear ring blank to 1150-1200 ℃ and preserving heat for a period of time, taking out the second gear ring blank after the second gear ring blank is thoroughly heated, removing oxide skin on the upper end surface of the second gear ring blank, horizontally placing the lower end surface of the second gear ring blank into a lower die cavity, attaching the lower end surface of the lower die cavity to the lower surface of the die cavity, and reserving the finish turning allowance of the diameter of an inner hole of the lower die cavity according to the outer diameter of the gear blank of a drawing part. The upper die tooth-shaped extrusion cutter is arranged according to the tooth shape size of a tooth blank of which the finish turning allowance is reserved in the drawing part, and the tooth-shaped extrusion cutter is coaxial with the first gear ring blank and the second gear ring blank; the first gear ring blank is horizontally arranged on the upper end face of the second gear ring blank, the coaxiality of the first gear ring blank and the second gear ring blank is less than or equal to phi 0.025, each tooth of the first gear ring blank is required to be aligned with the corresponding tooth of the second gear ring blank, and the alignment error is less than or equal to 0.001.
The pressing device is used for pressing the first gear ring blank downwards into the second gear ring blank on the upper end face of the first gear ring blank, and the force applied to the upper end face of the first gear ring blank is uniform and vertically downward when the pressing force is applied. Pressing until the tooth width midpoint of the first gear ring blank coincides with the tooth width midpoint of the second gear ring blank, namely, the two gear ring blanks pass through the tooth width middle part and coincide with a horizontal plane perpendicular to the axis; or pressing the first gear ring blank to the upper end surface of the first gear ring blank, wherein the upper end surface of the first gear ring blank is 1-10mm lower than the upper end surface of the first gear ring blank. The pressing is completed, a pressing blank is obtained, the pressing completion temperature is not less than 950 ℃, the pressing blank is taken out after the pressing is completed, the sand stack is horizontally placed, stacked and cooled to 110-250 ℃ for the next welding procedure, the pressing face is kept downwards during stacking, and the concave cavity is prevented from being cooled too fast. The above operation procedure can be repeatedly implemented until each gear ring blank is pressed into an integral pressed blank, and multiple layers of metal flow direction superposition are formed on the tooth part, so as to strengthen the performance of the tooth part.
Placing the pressed blank on a horizontal plane to enable the pressed end faces of the first gear ring blank and the second gear ring blank to face upwards, polishing a concave cavity formed by the pressed end faces of the first gear ring blank and the second gear ring blank until oxide skin is removed completely, melting welding materials with equivalent or better tissue performance and similar chemical components to those of the second gear ring blank in a welding mode, and filling the concave cavity until the filling materials at all parts of the concave cavity are 0.5-1 mm higher than the end face of the second gear ring blank; the welding mode can be selected from common methods such as overlaying welding or brazing, and the like, and then the pressed blank is heated to a proper temperature below AC1 for a period of time for stress relief annealing, so that the combined gear ring blank is obtained.
And S208, tempering.
And carrying out quenching and tempering treatment on the combined gear ring blank according to the technical requirements of the processing drawing of the inner gear ring part.
Step S209, turning.
The first end face of the gear ring blank is used as a positioning basis, an outer circular face adjacent to the end face is clamped by a three-jaw chuck, the second end face and the outer circular face of the gear ring blank are aligned, so that the jumping precision meets the technological requirements, the second end face and the outer circular face of the gear ring blank are turned to be formed, an orifice chamfer and a spigot are turned to be formed at the corresponding positions of the second end face, and the sharp edge of the second end face of the gear ring blank is blunted; then, the machined second end face of the gear ring blank is used as a positioning basis, a three-jaw chuck is used for clamping an outer circular face, a copper sheet is arranged at a clamping position in a cushioning mode, the outer circular face is aligned, the jumping precision meets the technological requirements, the first end face and the outer circular face of the gear ring blank are turned to be formed, an orifice chamfer and a spigot are turned to be formed at corresponding positions of the first end face, and sharp edges of the first end face of the gear ring blank are blunted.
And S210, drilling and tapping.
And (3) lofting all holes according to the processing drawing of the inner gear ring part by using a proper center drill, and then drilling and tapping all screw holes correspondingly until the holes are formed.
Step S211, fine gear shaping.
After the universal cushion block is cleaned up, the gear ring blank is horizontally placed on the universal cushion block, the gear ring blank is pressed by a pressing plate, the upper end face and the outer circular face of the gear ring blank are aligned, the runout precision meets the process requirement, and then the gear ring blank fine gear shaping is processed to the internal tooth forming according to the processing drawing requirement of the internal gear ring part.
Generally, the roughness Ra of the tooth surface of the internal tooth formed by the fine gear shaping treatment is less than or equal to 2.0, so that the consistency of the metallographic structure of the tooth surface after the subsequent nitriding treatment, particularly the uniformity of the thickness of the white bright layer, is convenient, and the falling of the white bright layer when the part is used due to the excessive thickness of the local white bright layer is prevented.
In the scheme, the seamless steel pipe is directly selected as an original blank, so that in the actual processing process, the annular blank can be processed into the gear ring blank only by tooth extrusion, the primary forming of the inner gear ring part is realized, in the whole tooth extrusion process, the blank is only subjected to extrusion forming treatment, no material is removed, the whole material of the blank is free from loss, and then the subsequent single turning process and fine tooth shaping process are matched, so that the high-precision processing forming treatment of the core structures such as the tooth part of the inner gear ring part can be completed. Therefore, the scheme does not need to combine a rough turning process to process the forged blank into a blank, and then further process the blank into a high-precision formed part by matching with a finish turning process, so that a large amount of materials on the blank are eliminated and discarded due to the rough turning and finish turning processes, raw material waste is effectively avoided, and material utilization rate is improved.
Step S212, nitriding.
And (3) after the gear ring blank subjected to the finish gear shaping treatment is cleaned, the gear ring blank is horizontally placed on a lifting appliance, and then the gear ring blank is subjected to integral nitriding treatment according to the processing drawing requirements of the inner gear ring part, so that a final inner gear ring part product has good high-temperature resistance, corrosion resistance and wear resistance and fatigue resistance, and the working condition tolerance of the inner gear ring part is optimized, so that the gear ring part is more durable.
Nitriding treatment referred to herein generally refers to a chemical heat treatment process in which nitrogen atoms are allowed to permeate into the surface layer of a workpiece in a certain medium at a certain temperature. The nitriding treated product has the characteristics of excellent wear resistance, fatigue resistance, corrosion resistance and high temperature resistance.
In the embodiment, the material of the blank is 42CrMo, and in the specific operation, pre-oxidation is carried out for 1-3 hours under the working condition of 350 ℃ in the initial stage of nitriding treatment; before the nitriding treatment is finished, the nitrogen removing process is carried out for 1-4 hours under the working condition of 520 ℃, and the ammonia decomposition rate during the process is not less than 70 percent, so that the ratio of the white bright layer structure gamma phase (Fe 4 N) to the epsilon phase (Fe 2-3 N) of the tooth surface is more than 8. The process reduces the hardness and brittleness of the white and bright layer by adjusting the proportion of the brittle and hard phases.
Step S213, strengthening shot blasting.
And (3) strengthening shot blasting is carried out on the tooth root part of the gear ring blank so as to improve the roughness of the tooth root part, form compressive stress on the tooth root part, and then cooperate with a cold work hardening layer formed in the tooth profile direction in the tooth extrusion process so as to strengthen the structural strength of the tooth root part and optimize the overall structural performance of the inner gear ring part product.
Similar to the basic shot blasting described above, the shot blasting process in the enhanced peening can also be replaced by a shot blasting process, in principle, as long as the actual process requirements of the enhanced peening and the specific application requirements of the ring gear part machining method can be satisfied.
Step S214, grinding teeth.
And (3) polishing and forming the gear ring blank until a finished product of the inner gear ring part is obtained.
Of course, the above steps mainly describe the processing process flow of the straight-barrel ring gear part without flange, in practical application, if the outer circle of the ring gear part has a flange, when the step of extruding teeth is implemented in S207, the flange should be synchronously extruded and molded, specifically, the flange storage position can be reserved at the ring gear flange in the lower die cavity, and the flange can be extruded; finish turning and forming the outer circle and the thickness of the flange when the turning procedure is implemented in S209; in the S210 drilling and tapping process, corresponding screw holes are drilled and tapped on the flange plate until the flange plate is molded.
The lower die required by the flange molding is an assembly and is divided into a flange molding cavity and a flange upper straight cylinder part molding cavity. After the flange is formed, the forming cavity of the straight cylinder part at the upper part of the flange can be radially expanded to the outer circle size of the flange, and the ring gear blank can be ejected out by the ejector rod.
In a third embodiment, the method for machining an inner gear ring part provided by the invention includes:
step S301, selecting blank materials.
Selecting materials according to the performance parameters of the pipe, and selecting pipe blanks capable of meeting the machining and forming requirements of the annular gear parts.
Generally, seamless steel pipes are selected as the pipes, and the selection of the pipes in the blank material selection process can comprise parameters such as a forming mode of the pipes, pipe dimensions, pipe bending, material organization performance of the pipes and the like.
Specifically, a rolled material or a casting blank is selected and is subjected to tube penetrating molding after being heated, the inner wall and the outer wall of the tube are subjected to extrusion sizing and air cooling treatment, and the air cooling treatment is natural cooling in the air; in addition, the tube is annealed after straightening, and the annealing hardness is preferably 150-170 HBW. In the production process, the pipe is stressed and deformed in the axial direction and the radial direction, and the structure performance of the pipe is improved to a certain extent, and the longitudinal and transverse performances are uniform, similar to the forging process after blanking of the pipe; in addition, because the temperature is higher during sizing, air cooling is similar to normalizing treatment after sizing, and the annealing treatment after straightening can not only reduce the hardness of the pipe so as to facilitate the subsequent tooth extrusion processing, but also remove the residual stress caused by the straightening process.
And measuring and selecting the outer diameter, the inner diameter, the wall thickness and the curvature of the pipe, wherein the outer diameter, the inner diameter and the wall thickness are selected according to the reserved machining size and the turning allowance, and the curvature meets the machining technical requirements of the annular gear part. Specifically, the outer diameter measuring part is the head part, the middle part and the tail part of the pipe, the inner diameter and the wall thickness are the head part and the tail part, and the curvature is measured along the axial direction of the pipe. The deviations of the dimensions after measurement were: outer diameter = ±outer diameter/1000, inner diameter = ±inner diameter/1000, wall thickness = ±wall thickness/100, deflection of curvature = ±0.4mm/m.
The material organization property of the pipe is correspondingly checked and selected, and generally, the pipe with uniform chemical composition, the organization property and the brand meeting the requirements of the internal gear ring part processing drawing is selected, wherein the fluctuation Wc of the carbon content of each point of the cross section of the pipe is ensured to be less than 0.03 percent as much as possible. In actual operation, samples of chemical components, metallographic structures, mechanical properties and the like of the pipe are all sampled at the 1/2 wall thickness position. The specific sampling positions are as follows: the strip tissue inspection surface is a longitudinal section and a transverse section at a radius of 1/2 of the wall thickness; the chemical components and nonmetallic inclusions are longitudinal sections with 1/2 radius of the wall thickness; the grain size, hardness and gas content test surface is perpendicular to the axial direction of the pipe. Wherein the number of chemical component samples is not less than 3, and the sampling positions should be uniformly distributed in the circumferential direction of the pipe; the rest requirements of the pipe all meet the enterprise or national standards.
In the blank selection process, UT (acronym for Ultrasonic Testing, i.e., ultrasonic detection) flaw detection and magnetic content detection can be performed on the pipe if necessary. Generally, UT flaw detection can be performed on the pipe according to the standard and grade specified by the processing technical drawing of the ring gear part against the artificial defect standard block so as to select the pipe meeting the requirement. And the magnetic content detection requires that the residual magnetic quantity of the pipe is not more than 5 gauss.
Of course, the specific requirement standards for the relevant parameters, the structure and the material performance of the pipe in the related blank selection can be properly adjusted and flexibly selected according to different specific application working conditions. In principle, any material may be used as long as it can meet the practical requirements of the machining method of the ring gear part.
In the prior art, the original blank is a bar stock, so that the bar stock is usually processed in a single piece in the process of being processed into a circular ring blank through a forging process; in the scheme, the pipe is selected as an original blank, and the processing technologies of pipe penetration, periodic forging and rolling and the like adopted in the pipe processing process are all continuous processing treatment of a plurality of blanks. Therefore, the processing efficiency of adopting the pipe as the original blank is higher, and the process flow is smoother and more efficient.
Step S302, blanking.
And respectively removing a section of annular end scraps from the head end and the tail end of the whole pipe blank along the axial direction, ensuring that the head end and the tail end of the pipe blank are perpendicular to the axis of the pipe blank when the annular end scraps are removed, cutting the pipe blank into circular ring blanks according to the turning allowance of the axial direction reserved in the processing drawing of the annular gear part, and ensuring that the parallelism of the two end surfaces of the circular ring blanks meets the technological requirements.
Generally, the axial length of the annular end scraps removed from the head end and the tail end of the pipe blank is 1-2 mm, and the parallelism of the two end faces of the annular end scraps removed from the annular end scraps should be not more than 0.1mm.
In the blanking of S302, two ring blanks with different lengths and inner and outer diameter sizes, namely a first ring blank and a second ring blank, need to be cut, and each parameter of the two ring blanks needs to meet the following requirements:
① The length of the first annular blank is at least 2mm smaller than that of the second annular blank, and the length of the second annular blank is equal to the sum of the length of the drawing part plus a preset turning allowance;
② The diameter of the reference circle of the part is smaller than or equal to the diameter of the tooth root circle of the part, the inner diameter of which is smaller than or equal to the diameter of the first circular ring blank of the drawing; drawing part tooth root diameter + (2-5) mm < first ring blank outer diameter < second ring blank outer diameter;
③ The diameter of the addendum circle of the drawing part is smaller than the diameter of the dedendum circle of the drawing part, and the inner diameter of the second circular ring blank is smaller than or equal to the diameter of the inner diameter of the second circular ring blank; the diameter of the outer circle of the first circular ring blank is smaller than that of the outer circle of the drawing, and the inner diameter and the outer diameter of the second circular ring blank are smaller than or equal to those of the outer circle of the drawing;
④ The first annular blank and the second annular blank are preferably made of steel materials with the same brand and the same technical requirements; the first annular blank can also be made of similar type steels with similar chemical components and tissue performance equal to or better than that of the second annular blank, so that the subsequent heat treatment mode can be conveniently selected.
Step S303, basic shot blasting.
And (3) performing shot blasting treatment on the whole annular blank to remove the oxide skin on the surface of the annular blank.
The shot blasting referred to herein is generally a process of blasting out a steel shot at a high speed by using an impeller rotating at a high speed to strike the steel shot onto the surface of a workpiece, thereby cleaning or strengthening the surface of the workpiece. In practice, shot blasting may be used instead of the above-mentioned shot blasting, and in particular, shot blasting is a process of cleaning or strengthening a surface of a workpiece by using compressed air as a motive force and by spraying steel shots onto the surface of the workpiece by a high-speed air flow of the compressed air. In practical application, the shot blasting and shot blasting process can be replaced and changed according to specific working condition requirements, and in principle, the practical process requirements of basic shot blasting and the specific application requirements of the annular gear part machining method can be met.
Step S304, cleaning preparation.
The inner and outer surfaces of the circular ring blank are cleaned by adopting the scouring pad, so that the inner and outer surfaces of the circular ring blank are ensured to be free of impurities such as scrap iron and the like.
Step S305, lubrication preparation.
Uniformly coating high molecular lubricant on the inner surface and the outer surface of the circular ring blank and the end surface of the circular ring blank so as to reduce friction force in the extrusion process and prevent die abrasion and defects on the surface of the gear ring;
step S306, drying.
And (3) putting the circular ring blank coated with the polymer lubricant into an oven, and drying at a proper temperature.
Step S307, extruding teeth.
Placing the ring blank into a lower die cavity of an extrusion die, enabling one end face of the ring blank to be attached to the inner lower surface of the lower die cavity, enabling the outer surface of the ring blank to be attached to the inner circumferential surface of the lower die cavity, starting an extruder, enabling a tooth-shaped extrusion cutter of the extruder to be pressed into the ring blank downwards, keeping the axis of the extruder coincident with the axis of the ring blank, enabling the tooth-shaped extrusion cutter of the extruder to extrude a tooth part on the ring blank and then exit the lower die cavity, processing the ring blank into a gear ring blank, and enabling a lower die cavity ejector rod to eject the gear ring blank, so that the whole tooth extrusion processing procedure is completed.
Compared with the conventional rough gear shaping process, the gear shaping process adopted in the scheme has the advantages of higher gear shaping speed and higher processing efficiency.
It should be understood that the axis of the extruder mentioned above, which is generally referred to as the axis of the extrusion die on the extruder, coincides with the axis of the annular blank, and can sufficiently ensure the accuracy of the extrusion process and the shaping effect of the ring gear blank.
In practical application, the extrusion forming mode can improve the processing efficiency of the annular gear part, and can form a cold work hardening layer distributed along the tooth profile direction on the whole tooth form (comprising a tooth surface, a tooth root and a tooth top), so that the fatigue strength and the service life of the gear are obviously improved.
In specific implementation, the first annular blank and the second annular blank are subjected to tooth extrusion treatment respectively to obtain a first gear ring blank and a second gear ring blank, and during tooth extrusion treatment, the first gear ring blank and the second gear ring blank are preheated to 1150-1200 ℃ and are kept warm for a period of time until the first gear ring blank and the second gear ring blank are thoroughly heated, the die is preheated to 250-300 ℃, and the two gear ring blanks after tooth extrusion are required to meet the following requirements:
① The number of teeth of the two gear ring blanks is the same;
② The tooth thickness and the tooth height of the first gear ring blank are smaller than those of the second gear ring blank; the tooth root diameter and the tooth slot width of the first gear ring blank are all larger than those of the second gear ring blank;
③ The diameter of the outer circle of each blank is limited by the lower die cavity and does not change during tooth extrusion.
④ The sum of the thickness of each part of the single tooth of the first gear ring blank and the thickness of each part of the single tooth of the second gear ring blank is larger than or equal to the sum of the thickness of the single tooth of the drawing and the turning allowance, the sum of the height of the single tooth of the first gear ring blank and the height of the single tooth of the second gear ring blank is larger than or equal to the sum of the thickness of the single tooth of the drawing and the turning allowance, and the sum of the volume of the single tooth of the first gear ring blank and the volume of the single tooth of the second gear ring blank is larger than or equal to the sum of the volume of the single tooth of the drawing and the turning allowance.
And pressing the two molded gear ring blanks into one, cleaning up all the foreign matters such as lubricant, greasy dirt and scrap iron on the surface of the first gear ring before pressing, preheating a die to 250-300 ℃, heating the second gear ring blank to 1150-1200 ℃ and preserving heat for a period of time, taking out the second gear ring blank after the second gear ring blank is thoroughly heated, removing oxide skin on the upper end surface of the second gear ring blank, horizontally placing the lower end surface of the second gear ring blank into a lower die cavity, attaching the lower end surface of the lower die cavity to the lower surface of the die cavity, and reserving the finish turning allowance of the diameter of an inner hole of the lower die cavity according to the outer diameter of the gear blank of a drawing part. The upper die tooth-shaped extrusion cutter is arranged according to the tooth shape size of a tooth blank of which the finish turning allowance is reserved in the drawing part, and the tooth-shaped extrusion cutter is coaxial with the first gear ring blank and the second gear ring blank; the first gear ring blank is horizontally arranged on the upper end face of the second gear ring blank, the coaxiality of the first gear ring blank and the second gear ring blank is less than or equal to phi 0.025, each tooth of the first gear ring blank is required to be aligned with the corresponding tooth of the second gear ring blank, and the alignment error is less than or equal to 0.001.
The pressing device is used for pressing the first gear ring blank downwards into the second gear ring blank on the upper end face of the first gear ring blank, and the force applied to the upper end face of the first gear ring blank is uniform and vertically downward when the pressing force is applied. Pressing until the tooth width midpoint of the first gear ring blank coincides with the tooth width midpoint of the second gear ring blank, namely, the two gear ring blanks pass through the tooth width middle part and coincide with a horizontal plane perpendicular to the axis; or pressing the first gear ring blank to the upper end surface of the first gear ring blank, wherein the upper end surface of the first gear ring blank is 1-10mm lower than the upper end surface of the first gear ring blank. The pressing is completed, a pressing blank is obtained, the pressing completion temperature is not less than 950 ℃, the pressing blank is taken out after the pressing is completed, the sand stack is horizontally placed, stacked and cooled to 110-250 ℃ for the next welding procedure, the pressing face is kept downwards during stacking, and the concave cavity is prevented from being cooled too fast. The above operation procedure can be repeatedly implemented until each gear ring blank is pressed into an integral pressed blank, and multiple layers of metal flow direction superposition are formed on the tooth part, so as to strengthen the performance of the tooth part.
Placing the pressed blank on a horizontal plane to enable the pressed end faces of the first gear ring blank and the second gear ring blank to face upwards, polishing a concave cavity formed by the pressed end faces of the first gear ring blank and the second gear ring blank until oxide skin is removed completely, melting welding materials with equivalent or better tissue performance and similar chemical components to those of the second gear ring blank in a welding mode, and filling the concave cavity until the filling materials at all parts of the concave cavity are 0.5-1 mm higher than the end face of the second gear ring blank; the welding mode can be selected from common methods such as overlaying welding or brazing, and the like, and then the pressed blank is heated to a proper temperature below AC1 for a period of time for stress relief annealing, so that the combined gear ring blank is obtained.
And step S308, tempering.
And carrying out quenching and tempering treatment on the combined gear ring blank according to the technical requirements of the processing drawing of the inner gear ring part.
Step S309, turning.
The first end face of the gear ring blank is used as a positioning basis, an outer circular face adjacent to the end face is clamped by a three-jaw chuck, the second end face and the outer circular face of the gear ring blank are aligned, so that the jumping precision meets the technological requirements, the second end face and the outer circular face of the gear ring blank are turned to be formed, an orifice chamfer and a spigot are turned to be formed at the corresponding positions of the second end face, and the sharp edge of the second end face of the gear ring blank is blunted; then, the machined second end face of the gear ring blank is used as a positioning basis, a three-jaw chuck is used for clamping an outer circular face, a copper sheet is arranged at a clamping position in a cushioning mode, the outer circular face is aligned, the jumping precision meets the technological requirements, the first end face and the outer circular face of the gear ring blank are turned to be formed, an orifice chamfer and a spigot are turned to be formed at corresponding positions of the first end face, and sharp edges of the first end face of the gear ring blank are blunted.
And step S310, drilling and tapping.
And (3) lofting all holes according to the processing drawing of the inner gear ring part by using a proper center drill, and then drilling and tapping all screw holes correspondingly until the holes are formed.
Step S311, fine gear shaping.
After the universal cushion block is cleaned up, the gear ring blank is horizontally placed on the universal cushion block, the gear ring blank is pressed by a pressing plate, the upper end face and the outer circular face of the gear ring blank are aligned, the runout precision meets the process requirement, and then the gear ring blank fine gear shaping is processed to the internal tooth forming according to the processing drawing requirement of the internal gear ring part.
Generally, the roughness Ra of the tooth surface of the internal tooth formed by the fine gear shaping treatment is less than or equal to 2.0, so that the consistency of the metallographic structure of the tooth surface after the subsequent nitriding treatment, particularly the uniformity of the thickness of the white bright layer, is convenient, and the falling of the white bright layer when the part is used due to the excessive thickness of the local white bright layer is prevented.
In the scheme, the seamless steel pipe is directly selected as an original blank, so that in the actual processing process, the annular blank can be processed into the gear ring blank only by tooth extrusion, the primary forming of the inner gear ring part is realized, in the whole tooth extrusion process, the blank is only subjected to extrusion forming treatment, no material is removed, the whole material of the blank is free from loss, and then the subsequent single turning process and fine tooth shaping process are matched, so that the high-precision processing forming treatment of the core structures such as the tooth part of the inner gear ring part can be completed. Therefore, the scheme does not need to combine a rough turning process to process the forged blank into a blank, and then further process the blank into a high-precision formed part by matching with a finish turning process, so that a large amount of materials on the blank are eliminated and discarded due to the rough turning and finish turning processes, raw material waste is effectively avoided, and material utilization rate is improved.
Step S312, nitriding.
And (3) after the gear ring blank subjected to the finish gear shaping treatment is cleaned, the gear ring blank is horizontally placed on a lifting appliance, and then the gear ring blank is subjected to integral nitriding treatment according to the processing drawing requirements of the inner gear ring part, so that a final inner gear ring part product has good high-temperature resistance, corrosion resistance and wear resistance and fatigue resistance, and the working condition tolerance of the inner gear ring part is optimized, so that the gear ring part is more durable.
Nitriding treatment referred to herein generally refers to a chemical heat treatment process in which nitrogen atoms are allowed to permeate into the surface layer of a workpiece in a certain medium at a certain temperature. The nitriding treated product has the characteristics of excellent wear resistance, fatigue resistance, corrosion resistance and high temperature resistance.
In the embodiment, the material of the blank is 42CrMo, and in the specific operation, pre-oxidation is carried out for 1-3 hours under the working condition of 350 ℃ in the initial stage of nitriding treatment; before the nitriding treatment is finished, the nitrogen removing process is carried out for 1-4 hours under the working condition of 520 ℃, and the ammonia decomposition rate during the process is not less than 70 percent, so that the ratio of the white bright layer structure gamma phase (Fe 4 N) to the epsilon phase (Fe 2-3 N) of the tooth surface is more than 8. The process reduces the hardness and brittleness of the white and bright layer by adjusting the proportion of the brittle and hard phases.
Step S313, strengthening shot blasting.
And (3) strengthening shot blasting is carried out on the tooth root part of the gear ring blank so as to improve the roughness of the tooth root part, form compressive stress on the tooth root part, and then cooperate with a cold work hardening layer formed in the tooth profile direction in the tooth extrusion process so as to strengthen the structural strength of the tooth root part and optimize the overall structural performance of the inner gear ring part product.
Similar to the basic shot blasting described above, the shot blasting process in the enhanced peening can also be replaced by a shot blasting process, in principle, as long as the actual process requirements of the enhanced peening and the specific application requirements of the ring gear part machining method can be satisfied.
Step S314, grinding teeth.
And (3) polishing and forming the gear ring blank until a finished product of the inner gear ring part is obtained.
Of course, the above steps mainly describe the processing process flow of the straight-barrel ring gear part without flange, in practical application, if the outer circle of the ring gear part has a flange, when the step of extruding teeth is implemented in S307, the flange should be synchronously extruded and molded, specifically, the flange storage position can be reserved at the ring gear flange in the lower die cavity, and the flange can be extruded; the outer circle and the thickness of the flange are finely turned and molded when the turning procedure is implemented in S309; in the S310 drilling and tapping process, corresponding screw holes are drilled and tapped on the flange plate until the flange plate is molded.
The lower die required by the flange molding is an assembly and is divided into a flange molding cavity and a flange upper straight cylinder part molding cavity. After the flange is formed, the forming cavity of the straight cylinder part at the upper part of the flange can be radially expanded to the outer circle size of the flange, and the ring gear blank can be ejected out by the ejector rod.
The drawings referred to herein generally refer to process drawings on which specific operating parameters and operating condition references for various processes and process details are indicated to ensure proper and smooth performance of the process steps.
In summary, in the operation and application process of the method for machining the annular gear part provided by the invention, through the sequentially performed operation steps of blank material selection, blanking, basic shot blasting, tooth extrusion, tempering, turning, drilling and tapping, fine gear shaping, nitriding, strengthening shot blasting, gear grinding and the like, a pipe is directly selected as an original blank, in the process implementation process, the blank is subjected to surface polishing and cleaning by shot blasting, then the extruded teeth are used as core processing procedures for tooth part machining and forming, and the turning and fine gear shaping are matched to realize the inner tooth machining and forming, on the basis, the structural performance of the tooth part after the shot blasting strengthening and forming is utilized, the structural strength of the tooth part is optimized, and therefore the structural performance of the tooth part and other parts of the machined annular gear part is fully improved, and the tooth part machining precision of the annular gear part is correspondingly optimized. In addition, compared with the prior art, because the pipe is directly selected as the original blank, the high-precision forming of the annular gear part can be realized only by single turning operation and matched with the procedures of tooth extrusion, tooth finish shaping and the like in the processing process of the annular gear part in the scheme, and multiple turning treatments such as rough turning, finish turning and the like are not needed as in the prior art, so that less turning waste is generated in the processing process of the annular gear part in the scheme, the material utilization rate in the processing process of the annular gear part is correspondingly improved, and the overall processing cost is correspondingly reduced.
The method for machining the annular gear part provided by the invention is described in detail above. The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.
Claims (8)
1. The method for machining the inner gear ring part is characterized by comprising the following steps:
selecting blank materials, namely selecting the blank materials according to the performance parameters of the pipe materials, and selecting the pipe material blank materials capable of meeting the machining and forming requirements of the annular gear part;
Discharging, namely removing a section of annular end scraps from the head end and the tail end of the whole pipe blank along the axial direction, ensuring that the head end and the tail end of the pipe blank are perpendicular to the axis of the pipe blank when the annular end scraps are removed, cutting the pipe blank into circular ring blanks according to the turning allowance of the axial direction reserved in the processing drawing of the annular gear part, and ensuring that the parallelism of the two end surfaces of the circular ring blanks meets the process requirements;
Performing basic shot blasting, namely performing shot blasting treatment on the whole annular blank to remove oxide skin on the surface of the annular blank;
tooth extrusion, namely placing a ring blank into a lower die cavity of an extrusion die, enabling one end face of the ring blank to be attached to the inner lower surface of the lower die cavity, enabling the outer surface of the ring blank to be attached to the inner circumferential surface of the lower die cavity, starting an extruder, enabling a tooth-shaped extrusion cutter of the extruder to be pressed into the ring blank downwards, keeping the axis of the extruder coincident with the axis of the ring blank at the moment, and enabling the tooth-shaped extrusion cutter of the extruder to eject out of the lower die cavity after extruding and forming a tooth part on the ring blank, so that the ring blank is processed into a gear ring blank, and enabling a material ejection rod of the lower die cavity to eject out the gear ring blank;
Quenching and tempering, namely quenching and tempering the gear ring blank according to the technical requirements of the processing drawing of the inner gear ring part;
Turning, namely taking a first end face of the gear ring blank as a positioning basis, clamping an outer circular face adjacent to the end face by using a three-jaw chuck, aligning a second end face and the outer circular face of the gear ring blank to enable jumping precision to meet technological requirements, turning the second end face and the outer circular face of the gear ring blank to be formed, turning an orifice chamfer and a spigot at corresponding positions of the second end face to be formed, and chamfering a sharp edge of the second end face of the gear ring blank; then, the machined second end face of the gear ring blank is used as a positioning basis, a three-jaw chuck is used for clamping an outer circular face, a copper sheet is arranged at a clamping position in a cushioning mode, the outer circular face is aligned, so that jumping precision meets technological requirements, the first end face and the outer circular face of the gear ring blank are turned to be formed, an orifice chamfer and a spigot are turned to be formed at the corresponding positions of the first end face, and sharp edges of the first end face of the gear ring blank are blunted;
drilling and tapping, namely, setting out each hole according to a processing drawing of the inner gear ring part by using a proper center drill, and then drilling and tapping each screw hole correspondingly until forming;
The gear ring blank is horizontally placed on a general cushion block, a pressing plate is used for pressing, the upper end face and the outer circular face of the gear ring blank are aligned, the jumping precision meets the technological requirements, and then the gear ring blank is subjected to fine gear shaping according to the processing drawing requirements of the inner gear ring part until the inner teeth are formed;
nitriding, namely placing the gear ring blank subjected to the finish gear shaping treatment on a lifting appliance after cleaning, and then carrying out integral nitriding treatment on the gear ring blank according to the processing drawing requirements of the inner gear ring part;
Strengthening shot blasting is carried out on the tooth root part of the gear ring blank so as to improve the roughness of the tooth root part, and compressive stress is formed on the tooth root part so as to strengthen the structural strength of the tooth root part;
grinding teeth, and grinding and forming the gear ring blank until a finished product of the inner gear ring part is obtained.
2. The method for machining an annular gear part according to claim 1, wherein between the basic shot blasting and the tooth extrusion, further comprising the steps of:
cleaning preparation, namely cleaning the inner surface and the outer surface of the circular ring blank by adopting scouring pad, and ensuring that the inner surface and the outer surface of the circular ring blank are free of impurities;
Preparing for lubrication, namely uniformly coating high molecular lubricant on the inner surface and the outer surface of the annular blank and the end face of the annular blank;
and (3) drying, namely placing the round-ring blank coated with the polymer lubricant into a drying oven for drying.
3. The method for machining an inner gear ring part according to claim 1, wherein in the blanking, two ring blanks with different lengths and inner and outer diameter sizes, namely a first ring blank and a second ring blank, are obtained by cutting;
In the tooth extrusion process, the first annular blank and the second annular blank are respectively subjected to tooth extrusion treatment to obtain a first gear ring blank and a second gear ring blank, and the first gear ring blank and the second gear ring blank are pressed into a combined gear ring blank.
4. The method for machining an annular gear part according to claim 1, wherein the blank material is 150-170 HBW in annealing hardness of the pipe.
5. The method for machining an annular gear part according to claim 1, wherein the carbon content fluctuation of each point of the cross section of the tube is less than 0.03% in the blank material.
6. The method for machining an annular gear part according to claim 1, wherein the blank is selected so as to ensure that the residual magnetic quantity of the pipe is not more than 5 gauss.
7. The method for manufacturing an annular ring gear part according to claim 1, wherein the axial length of the annular end scraps in the blanking is 1-2 mm.
8. The method for machining an annular gear part according to claim 1, wherein in the blanking, the parallelism of both end faces of the annular ring blank is not more than 0.1mm.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410259922.8A CN117900780A (en) | 2024-03-07 | 2024-03-07 | Method for machining annular gear part |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202410259922.8A CN117900780A (en) | 2024-03-07 | 2024-03-07 | Method for machining annular gear part |
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