Single-tooth continuous induction hardening method for discontinuous tooth profile gear

Abstract

The invention relates to a single-tooth continuous induction quenching method for a non-continuous tooth-shaped gear, and belongs to the technical field of induction quenching heat treatment.The method comprises the steps that an electromagnetic inductor is adopted for conducting induction quenching on a workpiece, and the electromagnetic inductor conducts continuous quenching on gear teeth of the workpiece gear one by one; comprising the following quenching steps that a single gear tooth is divided into a plurality of quenching tooth sections in the tooth width direction according to the shape of a workpiece gear; according to the divided quenching tooth sections, the single gear tooth quenching process is divided into a plurality of quenching time periods, and the quenching time periods correspond to the quenching tooth sections one to one, so that the quenching heat of each quenching time period is matched with the gear tooth volume and structure of the quenching tooth sections; according to the tooth width size of each divided quenching tooth section, for two adjacent quenching time periods, the switching position of the quenching time periods is determined; an electromagnetic inductor is controlled to conduct single-tooth quenching along the tooth width according to the quenching time period; and the steps are repeated until all the gears are quenched. The induction quenching method is low in quenching difficulty and high in part quenching quality.

Description

Technical Field

[0001] This invention relates to the field of induction hardening heat treatment technology, specifically to a method for continuous induction hardening of a single tooth of a discontinuous gear. Background Technology

[0002] Induction hardening utilizes the principle of electromagnetic induction to generate an alternating magnetic field on the surface of a workpiece, causing eddy currents to form inside the workpiece. Due to the skin effect of alternating current, the eddy currents concentrate on the surface layer of the workpiece, causing the surface to heat up rapidly to the hardening temperature, thus achieving surface hardening. It is widely used for strengthening mechanical parts, such as gears, shafts, and pins, to improve surface hardness and fatigue strength.

[0003] In the current field of induction hardening, induction hardening is widely used for strengthening the teeth of gear rings. Conventional gear rings have a continuous and consistent tooth profile across their entire tooth width, making the induction hardening process relatively easy to control. However, due to structural design requirements, there are gear rings with discontinuous tooth profiles, such as... Figure 1 As shown. In the gear ring of the discontinuous tooth profile gear, the tooth 5 along the tooth width direction, according to assembly requirements, part of the tooth width needs to be removed from the tooth tip to the tooth root at a certain height, so that the tooth profile is discontinuous throughout the entire tooth width range.

[0004] In the existing machining of gear rings, there are two main machining processes for this type of gear ring: P1: Forging → Pre-heat treatment → Machining (without turning the steps) → Gear cutting → Induction hardening → Turning the steps at the top of the gear. P2: Forging → Preliminary heat treatment → Machining (machining out steps) → Gear cutting → Induction hardening.

[0005] Comparing the two processing routes, route P1 involves induction hardening followed by machining the tooth tip step. Route P2, on the other hand, involves machining the tooth tip step first, then cutting the tooth into shape. Figure 1 The structure is then induction hardened. Compared to the two process routes, the P1 process requires intermittent turning after hardening, resulting in higher machining costs. While the P2 process has a cost advantage, the induction hardening control is more difficult. In the P2 route, using the conventional two-segment continuous induction hardening process, the hardened layer is discontinuous at the junction of the two segments due to changes in the coupling interface between the product and the inductor. Furthermore, at the beginning of the second segment's hardening, the area at the junction with the first segment resembles a step, making the hardened tooth surface of the first segment susceptible to induction tempering by adjacent teeth, leading to a decrease in tooth surface hardness and failing to meet technical requirements. Therefore, a single-tooth continuous induction hardening method for discontinuous gear teeth is needed to address the problems of high induction hardening control, discontinuous hardened layer at the junction of the two teeth, and low tooth surface hardness in the existing two-segment continuous induction hardening process for discontinuous gear teeth. Summary of the Invention

[0006] The purpose of this invention is to provide a method for continuous induction hardening of a single tooth of a discontinuous gear, so as to solve the problems mentioned in the background art.

[0007] To achieve the above objectives, the present invention provides the following technical solution: a method for continuous induction hardening of a single tooth of a discontinuous gear, which uses an electromagnetic inductor to perform induction hardening on the workpiece, and the electromagnetic inductor performs continuous hardening of each tooth of the gear, including the following hardening steps: S1. Divide a single gear tooth into several quenched tooth segments along the tooth width direction according to the shape of the workpiece gear. S2. Based on the quenching tooth segments divided in S1, the quenching process of a single tooth is divided into several quenching periods. Each quenching period corresponds one-to-one with the quenching tooth segments in S1, so that the quenching heat of each quenching period is adapted to the tooth volume and structure of the quenching tooth segment. S3. Based on the tooth width dimension of each quenching tooth segment divided in S1, determine the switching position of the quenching period for two adjacent quenching periods. S4. Control the electromagnetic inductor to perform single-tooth quenching along the tooth width according to the quenching period in S2. S5. Repeat step S4 until all gears have been quenched.

[0008] Preferably, the electromagnetic inductor is equipped with an inductor head whose shape is adapted to the tooth groove of the workpiece gear. The electromagnetic inductor inserts the inductor head into the tooth groove of the workpiece gear along the tooth width direction to continuously quench each tooth of the workpiece gear. Spraying components are symmetrically installed on both sides of the inductor head of the electromagnetic inductor to spray and cool the teeth on the adjacent sides of the quenched tooth groove.

[0009] Preferably, in S1, according to the shape of the workpiece gear, a single tooth is divided into two quenched tooth segments along the tooth width direction according to the tooth tip height. The two quenched tooth segments are defined as the first tooth segment and the second tooth segment, and the tooth tip height of the first tooth segment is greater than that of the second tooth segment.

[0010] Preferably, in S2, a numerical control program is set to control the electromagnetic inductor to continuously quench a single tooth. According to the quenching tooth segments divided in S1, the quenching process of a single tooth is divided into a first-stage tooth quenching period and a second-stage tooth quenching period. The numerical control program is divided into a first-stage tooth quenching program and a second-stage tooth quenching program according to the quenching period.

[0011] Preferably, in S3, based on the tooth width of the first tooth segment as defined in S1, when the lower end face of the sensing head moves more than 10mm beyond the end of the first tooth segment during the quenching process, the control system of the electromagnetic sensor switches to a two-stage tooth quenching program for quenching.

[0012] Preferably, the attached spray assembly includes a spray plate and spray pipes; the spray plate is arranged parallel to the tooth tips, and spray pipes are evenly distributed on the plate; when the electromagnetic inductor quenches the tooth groove, the attached spray assemblies on both sides spray and cool the tooth tips on both sides of the quenched tooth groove through the spray pipes.

[0013] Preferably, the size of the spray plate along the tooth width direction is at least twice the thickness of the sensor head; the upper end face of the spray plate is 3-5 mm away from the upper end face of the sensor head.

[0014] Preferably, when the spray pipe sprays the tooth tip, the spray area is the tooth tip area between the end of the tooth tip away from the quenched tooth groove and the tooth tip chamfer 1-2mm adjacent to the quenched tooth groove.

[0015] Preferably, when the electromagnetic inductor performs the two-stage tooth quenching process, the attached spray assembly is turned off, and the quenching power of the electromagnetic inductor is 50%-80% of the quenching power of the first stage tooth, and the moving speed of the inductor head is 1.3-1.8 times that of the first stage tooth.

[0016] Preferably, the spray flow rate of the attached spray assembly is 5-10 L / min. Beneficial effects

[0017] This invention divides a single gear tooth into several quenching segments along the tooth width direction according to the shape of the workpiece gear. Based on the divided quenching segments, the quenching process of a single gear tooth is divided into several quenching periods, with each quenching period corresponding to a quenching segment. This ensures that the quenching heat of each quenching period is adapted to the tooth volume and structure of the quenching segment. Based on the tooth width dimension of each divided quenching segment, the switching position of the quenching period is determined for two adjacent quenching periods. The electromagnetic induction device is controlled to continuously quench each tooth one by one along the tooth width according to the quenching period until the quenching of the entire gear is completed. This invention is based on the P2 process route. By dividing a single gear tooth into several quenched tooth segments along the tooth width direction, and further dividing the quenched tooth segments into several quenching periods, the quenching heat of each quenching period is adapted to the tooth volume and structure of the quenched tooth segment. Furthermore, by determining the tooth width dimension of each quenched tooth segment, this invention determines the switching position of the quenching period for two adjacent quenching periods. This solves the technical problem of discontinuous hardened layer and easy tempering of adjacent tooth surfaces of the first segment at the junction of two tooth segments during continuous induction quenching of non-continuous tooth structure gears, which leads to a decrease in tooth surface hardness.

[0018] Based on the foregoing, the electromagnetic inductor of this invention is equipped with an inductor head whose shape is adapted to the tooth grooves of the workpiece gear. The electromagnetic inductor inserts the inductor head into the tooth grooves of the workpiece gear along the tooth width direction to continuously quench each tooth of the workpiece gear. Spraying components are symmetrically installed on both sides of the inductor head of the electromagnetic inductor for spraying and cooling the teeth on adjacent sides of the quenched tooth grooves. This invention uses an inductor head whose shape is adapted to the tooth grooves of the workpiece gear, inserting it into the tooth grooves along the tooth width direction for continuous quenching of each tooth. Since non-continuous tooth profile gears have sharp corners and irregular structures during quenching, which is detrimental to product quality during continuous induction quenching, the tooth groove quenching of this invention allows the inductor head to conform to the shape and approach the tooth surface for heating and quenching, resulting in uniform heating of the tooth surface and improving the quenching effect. Furthermore, to reduce the heat tempering of adjacent teeth during quenching, spraying components are symmetrically arranged on both sides of the inductor head to increase the surface hardness of adjacent teeth.

[0019] Based on the foregoing, this invention, according to the tooth profile structure of the gear ring, divides a single gear tooth along the tooth width direction into two quenched tooth segments according to the tooth tip height. These two quenched tooth segments are defined as the first segment and the second segment, with the tooth tip height of the first segment being greater than that of the second segment. A CNC program is set to control the electromagnetic inductor for continuous quenching of a single gear tooth. Based on the divided quenched tooth segments, the quenching process of a single gear tooth is divided into a first-segment quenching period and a second-segment quenching period. The CNC program is further divided into a first-segment quenching program and a second-segment quenching program based on the quenching period. This achieves precise control of the electromagnetic inductor to perform induction quenching on discontinuous gear teeth, ensuring that the hardened layer is continuous and the tooth surface hardness meets the processing requirements.

[0020] Based on the foregoing, this invention, according to the tooth width of the first tooth, switches to a two-stage tooth quenching program when the lower end face of the induction head moves more than 10mm beyond the end of the first tooth during the quenching process. During the two-stage tooth quenching program, the auxiliary spray assembly is turned off, and the quenching power of the electromagnetic induction is 50%-80% of the quenching power of the first tooth, while the induction head movement speed is 1.3-1.8 times that of the first tooth. This avoids discontinuity in the hardened layer caused by changes in the coupling interface between the gear and the induction at the junction of the two tooth segments. Since the tooth profiles of the first and second teeth differ at the junction, two quenching periods are used to ensure that the quenching heat matches the tooth profile. Since the junction surface of the two teeth is a stepped surface, the coupled magnetic field changes in the stepped surface area compared to tooth groove quenching. Therefore, this invention uses the quenching program of the first tooth for continuous quenching to ensure hardening of the tooth surfaces on both sides of the stepped position and to ensure the continuity of the hardened layer. When the induction head extends a certain distance beyond the first tooth, the object to be quenched enters the second tooth completely. At this point, quenching is performed by switching to the second-stage tooth quenching program. Since the auxiliary spray shut-off can cause severe tempering on adjacent teeth in the second stage, reducing power and increasing the operating speed significantly improves the reduction in hardness of adjacent teeth due to tempering. Experimental calculations show that switching to the second-stage tooth quenching program when the induction head extends 10mm beyond the first tooth maximizes the quenching quality.

[0021] Building upon the foregoing, to precisely control the spray volume and improve the spraying effect of the attached spray assembly, the attached spray assembly of this invention includes a spray plate and a spray pipe. The spray plate's dimensions along the tooth width direction are at least twice the thickness of the induction head to increase the spray area and improve the spray cooling effect. Simultaneously, the spray plate is 3-5 mm lower than the induction head to ensure the continuity of the hardened layer at the spray pipe's outlet end. Furthermore, due to the limited space of the electromagnetic sensor, the spray pipe of the attached spray assembly needs to be angled towards the induction head to ensure that the spray area matches the tooth tips of adjacent teeth on both sides. If the spray area covers the tooth surface of the hardened tooth groove, the spray will hit the tooth surface undergoing induction hardening, resulting in insufficient hardness of the tooth groove surface. Conversely, if the spray area completely covers the tooth tips of adjacent tooth grooves, there will be no hardened layer near the tooth tip of the hardened tooth groove, causing discontinuity in the hardened layer of the two tooth tips. Experiments have shown that, while ensuring that the hardened layers at the tips of the first tooth segment do not overlap, the hardened layers at the tips of the second tooth segment are continuous. When the spray pipe of this invention sprays the tips of the gear teeth, the spraying area is the tip area between the end of the gear tooth tip away from the quenched tooth groove and the tip area of ​​the tooth tip with a chamfer of 1-2 mm adjacent to the quenched tooth groove. The spray flow rate of the attached spraying component is 5-10 L / min, which can protect the hardness of the adjacent teeth at the tip of the first tooth segment and maintain the continuity of the hardened layer at the tip of the second tooth segment. Attached Figure Description

[0022] Figure 1This is a schematic diagram of the structure of a discontinuous toothed gear ring in the prior art; Figure 2 This is a schematic diagram of the structure of an electromagnetic inductor used in an embodiment to perform single-tooth continuous induction hardening on a non-continuous toothed gear ring. Figure 3 This is a schematic diagram of the structure of the electromagnetic inductor when performing single-tooth continuous induction hardening on a non-continuous toothed gear ring as an example, and the electromagnetic inductor operates to the intersection position of two tooth segments. Detailed Implementation

[0023] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings, but the scope of protection of the present invention is not limited to the embodiments.

[0024] Please see Figures 1-3 This embodiment provides a method for continuous induction hardening of a single tooth of a discontinuous toothed gear. An electromagnetic inductor is used to perform induction hardening on gear 1 of the discontinuous toothed gear ring, and an electromagnetic inductor 2 performs continuous tooth-by-tooth hardening on the gear of the discontinuous toothed gear ring. The method includes the following hardening steps: S1. Based on the gear shape of the non-continuous toothed gear ring, a single tooth is divided into two quenched tooth segments along the tooth width direction according to the tooth tip height. The two quenched tooth segments are defined as the first segment tooth 1-1 and the second segment tooth 1-2, and the tooth tip height of the first segment tooth is greater than the tooth tip height of the second segment tooth. S2. Based on the first tooth segment 1-1 and the second tooth segment 1-2 divided in S1, the quenching process of a single tooth is divided into a first tooth quenching period and a second tooth quenching period. Each quenching period corresponds one-to-one with the quenching tooth segment in S1, so that the quenching heat of each quenching period is adapted to the tooth volume and structure of the quenching tooth segment. In this embodiment, a numerical control program is set to control the electromagnetic inductor to continuously quench a single tooth. The numerical control program is divided into a first tooth quenching program and a second tooth quenching program according to the quenching period. S3. According to the tooth width of the first tooth segment as defined in S1, when the lower end face of the sensing head of the electromagnetic sensor 2 moves more than 10mm beyond the end of the first tooth segment during the quenching process, the control system of the electromagnetic sensor switches to the two-stage tooth quenching program for quenching. S4. Control the electromagnetic inductor to perform single-tooth quenching along the tooth width according to the quenching period in S2. S5. Repeat step S4 until all gears have been quenched.

[0025] In this embodiment, the electromagnetic inductor has an inductor head whose shape is adapted to the tooth groove of the discontinuous toothed gear ring. The electromagnetic inductor inserts the inductor head into the tooth groove of the discontinuous toothed gear ring along the tooth width direction to continuously quench each tooth. A spray assembly 3 is symmetrically installed on both sides of the inductor head to spray and cool the teeth on adjacent sides of the quenched tooth groove. The spray assembly in this embodiment includes a spray plate and spray pipes. The spray plate is arranged parallel to the tooth tips, and spray pipes are evenly distributed on its surface. When the electromagnetic inductor quenches the tooth groove, the spray assemblies on both sides spray and cool the tooth tips on both sides of the quenched tooth groove through the spray pipes.

[0026] Furthermore, in this embodiment, the size of the spray plate along the tooth width direction is at least twice the thickness of the induction head; the upper end face of the spray plate is 3-5 mm away from the upper end face of the induction head. When the spray pipe sprays the tooth tip, the spray area is the tooth tip region between the end of the tooth tip away from the quenched tooth groove and the tooth tip chamfer adjacent to the quenched tooth groove (1-2 mm). Additionally, the spray flow rate of the attached spray assembly in this embodiment is 5-10 L / min.

[0027] In this embodiment, when the electromagnetic sensor performs the two-stage tooth quenching process, the attached spray assembly is turned off, and the quenching power of the electromagnetic sensor is 50%-80% of the quenching power of the first stage tooth, and the moving speed of the sensing head is 1.3-1.8 times that of the first stage tooth.

[0028] Working Principle: In this embodiment of the discontinuous toothed gear single-tooth continuous induction hardening method, during hardening, the operator first needs to preset the CNC program parameters and preset the switching position of the second-stage tooth hardening program based on the tooth width of the first stage tooth. Next, the auxiliary spray assembly is selected and installed. The length of the auxiliary spray plates on both sides is selected to be at least twice the thickness of the induction head. When installing the auxiliary spray plates, the upper surface of the spray plate is adjusted to be 3-5mm lower than the upper surface of the induction head. Then, the spray area is adjusted by adjusting the water hole angle of the spray pipes on the auxiliary spray plates on both sides. In this embodiment, the control angle of the spray pipes is offset towards the hardened tooth groove side by 0-5°, so that when the spray pipe sprays the tooth tip, the spray area is the tooth tip area between the end of the tooth tip away from the hardened tooth groove and the tooth tip chamfered 1-2mm adjacent to the hardened tooth groove. Finally, the spray flow rate is adjusted to 5-10L / min.

[0029] In this embodiment, the electromagnetic inductor uses a sensing head inserted along the tooth width direction into the tooth groove of the discontinuous tooth profile gear ring for continuous tooth quenching. During quenching, when the lower end face of the sensing head moves more than 10mm beyond the end of the first tooth, the electromagnetic inductor switches to a two-stage tooth quenching program. At this time, the auxiliary spray assembly is turned off. Under the control of the two-stage tooth quenching program, the electromagnetic inductor selects a quenching power of 50%-80% of the quenching power of the first tooth and a sensing head movement speed of 1.3-1.8 times that of the first tooth until the two-stage tooth quenching process is completed. The CNC program then automatically proceeds to the quenching process of the next tooth until the entire gear ring is quenched.

[0030] This invention proposes a method for continuous induction hardening of a single tooth of a discontinuous toothed gear. Since the presence of sharp corners and irregular structures during the quenching process of discontinuous toothed gears is detrimental to product quality during continuous induction hardening, this invention divides the quenching tooth segments according to the tooth shape to define the quenching time periods. Based on the tooth width of the divided quenching tooth segments, the switching position between two adjacent quenching time periods is determined. Furthermore, preset CNC program parameters are used to control the quenching heat during each quenching time period. This effectively solves the technical problems of maintaining the continuity of the hardened layer and reducing the hardness of the tooth surface during the single-tooth induction hardening of discontinuous toothed gears, providing greater operational adjustment space for process engineers and operators.

[0031] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for continuous induction hardening of a single tooth of a discontinuous toothed gear, comprising using an electromagnetic inductor to perform induction hardening on the workpiece, characterized in that: The electromagnetic inductor performs continuous quenching of each tooth of the workpiece gear, including the following quenching steps: S1. Divide a single gear tooth into several quenched tooth segments along the tooth width direction according to the shape of the workpiece gear. S2. Based on the quenching tooth segments divided in S1, the quenching process of a single tooth is divided into several quenching periods. Each quenching period corresponds one-to-one with the quenching tooth segments in S1, so that the quenching heat of each quenching period is adapted to the tooth volume and structure of the quenching tooth segment. S3. Based on the tooth width dimension of each quenching tooth segment divided in S1, determine the switching position of the quenching period for two adjacent quenching periods. S4. Control the electromagnetic inductor to perform single-tooth quenching along the tooth width according to the quenching period in S2. S5. Repeat step S4 until all gears have been quenched.

2. The method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 1, characterized in that, The electromagnetic inductor is equipped with an inductor head whose shape is adapted to the tooth groove of the workpiece gear. The electromagnetic inductor inserts the inductor head into the tooth groove of the workpiece gear along the tooth width direction to continuously quench each tooth of the workpiece gear. Spraying components are symmetrically installed on both sides of the inductor head of the electromagnetic inductor to spray and cool the teeth on the adjacent sides of the quenched tooth groove.

3. The method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 2, characterized in that, In S1, according to the shape of the workpiece gear, a single tooth is divided into two quenched tooth segments along the tooth width direction according to the tooth tip height. The two quenched tooth segments are defined as the first tooth segment and the second tooth segment, and the tooth tip height of the first tooth segment is greater than the tooth tip height of the second tooth segment.

4. The method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 3, characterized in that, In S2, a numerical control program is set to control the electromagnetic inductor to continuously quench a single tooth. According to the quenching tooth segments divided in S1, the quenching process of a single tooth is divided into a first-stage tooth quenching period and a second-stage tooth quenching period. The numerical control program is divided into a first-stage tooth quenching program and a second-stage tooth quenching program according to the quenching period.

5. The method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 4, characterized in that, In S3, based on the tooth width dimensions of the first tooth segment as defined in S1, when the lower end face of the sensing head moves more than 10mm beyond the end of the first tooth segment during the quenching process, the control system of the electromagnetic sensor switches to a two-stage tooth quenching program for quenching.

6. The method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 3, characterized in that, The attached spray assembly includes a spray plate and spray pipes; the spray plate is arranged parallel to the tooth tips, and spray pipes are evenly distributed on the plate; when the electromagnetic inductor quenches the tooth groove, the attached spray assemblies on both sides spray and cool the tooth tips on both sides of the quenched tooth groove through the spray pipes.

7. The method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 6, characterized in that, The size of the spray plate along the tooth width direction is at least twice the thickness of the sensor head; the upper end face of the spray plate is 3-5mm away from the upper end face of the sensor head.

8. The method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 6, characterized in that, When the spray pipe sprays the tooth tip of the gear tooth, the spraying area is the tooth tip area between the end of the tooth tip away from the quenched tooth groove and the tooth tip chamfer of 1-2mm adjacent to the quenched tooth groove.

9. A method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 4, characterized in that, When the electromagnetic inductor performs the two-stage tooth quenching process, the auxiliary spray assembly is turned off, and the quenching power of the electromagnetic inductor is 50%-80% of the quenching power of the first stage tooth, and the moving speed of the inductor head is 1.3-1.8 times that of the first stage tooth.

10. A method for continuous induction hardening of a single tooth of a discontinuous gear according to claim 6, characterized in that, The spray flow rate of the attached spray assembly is 5-10 L / min.

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