CN117696808A - Machining method of steering inner pipe - Google Patents

Abstract

The invention relates to a processing method of a steering inner pipe. The method comprises the following steps: the method comprises the steps of (1) selecting raw materials, (2) carrying out surface treatment on the raw materials, (3) carrying out rotary forging processing, (4) extruding external splines, (5) turning and cutting off and chamfering, (6) extruding internal threads, and (7) cleaning, rust prevention and boxing. The front end reservation material in the second rotary forging process ensures that the thread bottom warp material is enough after the third rotary forging process, and the concave rotary forging diameter is reduced under the supporting effect of the optical stopper rod, so that the A-B jumping value is ensured to be low. In the third rotary forging process, the optical stopper rod is used as a support to prevent the conical surface material from collapsing and keep the conical surface to be well molded. And the joint of the bearing and the mounting switch area can prevent the material in the bearing area from deforming, thereby meeting the outer diameter size requirement of the bearing area.

Description

Machining method of steering inner pipe

Technical Field

The invention relates to the technical field of automobile steering columns, in particular to a processing method of a steering inner tube.

Background

The automobile steering column and intermediate shaft assembly is a connecting part arranged between a steering wheel and a steering gear, and is mainly used for controlling the running direction of an automobile, transmitting torque and absorbing energy during the collision of the automobile. According to the working principle of the product, the steering column can be divided into a mechanical column and an electric adjusting column, and can realize up-down and front-back direction adjustment, and four adjustment items are collectively called, so that the comfort level requirement of a driver can be met.

The structure of the steering inner tube is generally composed of a front-to-back part, namely an external spline 1 area, an internal thread 2 area, a conical surface 3, a combined switch mounting area 4, a bearing 5 area and an internal spline 6 area, as shown in figure 1. In the state of the art, turning to a specific processing method of an inner tube, firstly, performing rotary swaging processing on an inner spline 6 area, secondly, reducing the residual raw material at the other end to enable the outer diameter of the inner tube to be the same as the outer diameter of the inner spline area, thirdly, performing rotary swaging processing on the bottom diameter of an external spline and a conical surface 3 for one-step forming, fourthly, performing rotary swaging processing on a combined switch mounting area 4 for forming, fifthly, performing cold extrusion forming on the external spline 1, and sixthly, performing extrusion tap forming on the internal thread 2.

The processing method has the following defects: 1. the internal thread bottom diameter material is not enough: in the research and development of the actual process, the bearing area and the external spline area are reduced after the internal spline is formed, so that the external diameters of the internal spline area, the bearing area and the external spline area are the same, the pipe wall thickness of the part with the external spline bottom diameter is insufficient, and when the external spline bottom diameter is swaged, the internal thread bottom diameter is larger than the required size under the condition that the external spline bottom diameter size requirement is met, and the material of the thread bottom diameter is insufficient. This problem is normally solved through increasing the wall thickness of tubular product, however, if the wall thickness of material is too big, can lead to the material deformation great when the internal spline shaping, causes certain difficulty, for example equipment vibrations are big, and frock wearing and tearing aggravate, are unfavorable for batch production, and are opposite with modern auto-parts lightweight development moreover. 2. The outer spline bottom diameter end is large in runout: because no light stopper rod is used as a support in the pipe when the external spline bottom diameter is swaged, the external spline bottom diameter is large in runout. 3. Conical surface molding difference: in the prior art processing method, because the external spline bottom diameter and the conical surface 3 are formed by rotary swaging once, and then the combined switch mounting area 4 is formed by rotary swaging, the conical surface material is easy to collapse due to no optical stopper rod support in the pipe, and the conical surface forming is poor.

Disclosure of Invention

The invention aims to provide a processing method of a steering inner pipe, which has high processing precision and good conical surface forming, and can meet the requirements of a thread bottom diameter material.

The technical scheme of the invention is as follows:

a processing method of a steering inner pipe comprises the following steps:

selecting raw materials, (2) carrying out surface treatment on the raw materials, (3) carrying out rotary forging processing, (4) extruding external splines, (5) turning, cutting and chamfering, (6) extruding internal threads, and (7) cleaning, rust preventing and boxing;

the specific processing method comprises the following steps:

(1) Selecting raw materials; selecting a precise seamless cold drawn steel tube with proper outer diameter, wall thickness and length, wherein the steel tube has certain extensibility;

(2) And (3) material surface treatment: the surface phosphating treatment of the seamless steel tube can effectively reduce the extrusion force applied to the working surface of the die and prolong the service life of the clamping fixture;

(3) And (5) rotary forging:

a. rotary forging cold extrusion internal spline: a rotary forging machine is utilized to rotary forge an internal spline at one side of a steel pipe, a proper rotary forging outer diameter die and a core rod are selected, the die is used for extruding the outer surface of the pipe in the processing process, the core rod is supported in the pipe, in the processing process, the material radially and axially flows, and the internal spline is formed after rotary forging;

b: a lathe length-keeping step of reserving the total length of the inner spline part and the inner tube according to requirements by using a numerical control lathe;

c: and (5) rotary forging and diameter reducing: and (3) performing rotary forging and diameter reduction on one side of the steel pipe, which is not extruded by the internal spline, by using a rotary forging machine, performing diameter reduction and rotary forging by using a rotary forging outer diameter die and a light stopper rod in the rotary forging and cold extrusion process of the internal spline, and performing die closing and rotary forging for twice, wherein the diameter reduction is performed on the end part of the steel pipe, which is not extruded by the internal spline, at the first time, the outer diameter after forming is larger than the outer diameter of the internal spline, the diameter reduction is performed on the rest part of the steel pipe after the first time of diameter reduction, the outer diameter after forming is the same as the outer diameter of the internal spline, and the length of the end part of the steel pipe subjected to the first rotary forging is 6% of the length of the internal spline.

d: the method comprises the steps of (1) performing rotary forging on the external spline bottom diameter and the conical surface by using a rotary forging machine, performing rotary forging processing by using a rotary forging external spline bottom diameter die and a light stopper rod in the rotary forging diameter reducing step, wherein the rotary forging is divided into three times of die closing rotary forging, namely, performing first die closing rotary forging on the rotary forging external spline bottom diameter and the conical surface, enabling the head end of the light stopper rod to be positioned at the rear end of the formed conical surface, preventing material collapse during rotary forging, performing second die closing rotary forging, enabling the position of the light stopper rod to be fixed, preventing the conical surface from deforming, performing rotary forging on the front third part of a combined switch installation area, performing third die closing rotary forging, enabling the light stopper rod to move backwards to the joint of a bearing area and the combined switch installation area, and performing second third part of the rotary forging combined switch installation area;

(4) Extruding the external spline; the support rods and the die bench are used for being arranged on the workbench surface of the four-column oil press to perform cold extrusion on external splines, and the extrusion splines are free of missing teeth and piled materials;

(5) Cutting and chamfering; the middle area of the inner tube is held, and the total length of the finished product is reserved by cutting and chamfering and cutting off;

(6) Extruding the internal thread; clamping the middle area of the inner tube by using an air chuck, and cold extruding the threads by using an extruding tap without damaging or breaking the threads;

(7) Cleaning, rust prevention and boxing; checking is carried out before boxing to prevent unqualified products from flowing out.

The invention has the beneficial effects that:

1. the rotary forging die of the internal spline forming process is shared with the second reducing die of the rotary forging process; the second rotary forging process and the third rotary forging process share the optical stopper rod, so that the manufacturing and processing cost of the rotary forging inner pipe tool clamp is indirectly reduced in the rotary forging forming development process. The installation combined switch area is processed in the rotary forging process III, so that one manual feeding processing process is reduced.

2. The external diameter of the front end (one end without an internal spline) of the steering inner tube in the second rotary forging process is larger than the external diameter of the internal spline part region, the tube wall is thick, the size of the internal threaded hole can be ensured to meet the requirement when the external spline bottom diameter is formed in rotary forging, and the internal thread bottom diameter is made of enough materials. And the second diameter reducing step of the rotary forging process uses recessed rotary forging to reduce the diameter under the supporting action of the optical stopper rod, so that the A-B jumping value is ensured to be low. In the third rotary forging process, the optical stopper rod is used as a support to prevent the conical surface material from collapsing and keep the conical surface to be well molded. And the rotary forging is carried out twice in the time division of the combined switch installation area, the position of the optical stopper rod is adjusted back and forth simultaneously, and the front end of the optical stopper rod is arranged at the joint of the bearing area and the combined switch installation area after the optical stopper rod is moved, so that the material in the bearing area can be prevented from being deformed, and the outer diameter size requirement of the bearing area is met.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only embodiments of the present invention, and that other drawings may be obtained according to the provided drawings without inventive effort for a person skilled in the art.

Fig. 1 is a cross-sectional view of a steering inner tube of the present application.

Fig. 2 is a schematic view of the overall structure of the steering inner tube of the present application.

Fig. 3 is a schematic view of the structure of a steel pipe for processing a steering inner pipe.

Fig. 4 is a schematic view of the structure of the workpiece after the first rotary forging process.

Fig. 5 is a schematic view of the structure of the work piece after the length keeping process.

Fig. 6 is a schematic diagram of the structure of the workpiece after the second rotary forging process.

Fig. 7 is a schematic diagram of the structure of the workpiece after the third step of rotary forging.

Reference numerals:

1. an external spline; 2. an internal thread; 3. a conical surface; 4. a combination switch mounting area; 5. a bearing; 6. internal spline, 7, steel pipe; 8. external spline bottom diameter.

Detailed Description

In order to solve the problems in the background technology, the invention particularly provides a processing method of the steering inner pipe, which has high processing precision and good conical surface forming, and can simultaneously meet the size requirements of the thread bottom diameter and the external spline bottom diameter, and the thread bottom diameter is made of enough materials. And the thin-wall raw material pipe is selected as much as possible under the condition of meeting the requirements of internal spline forming and light weight.

The present application is described in detail below with reference to the attached drawing figures:

a processing method of a steering inner pipe comprises the following steps:

selecting raw materials, (2) carrying out surface treatment on the raw materials, (3) carrying out rotary forging processing, (4) extruding external splines, (5) turning, cutting and chamfering, (6) extruding internal threads, and (7) cleaning, rust preventing and boxing;

the specific processing method comprises the following steps:

(1) As shown in fig. 3, a raw material is selected; the precise seamless cold drawn steel tube with proper outer diameter, wall thickness and length is selected, and has certain extensibility.

(2) Surface treatment of raw materials: the surface phosphating treatment of the seamless steel tube can effectively reduce the extrusion force received by the working face of the die and prolong the service life of the clamping fixture.

(3) And (5) rotary forging:

a. as shown in fig. 4, the internal spline is cold-extruded by swaging (swaging process one): and (3) utilizing a rotary forging machine to rotary-forge the internal spline at one side of the steel pipe, selecting a proper rotary-forging outer diameter die and a core rod, extruding the outer surface of the pipe by the die in the processing process, supporting the core rod in the pipe, radially and axially flowing the material in the processing process, and forming the internal spline after rotary forging.

b: the lathe length maintaining process, as shown in fig. 5, is to use a numerical control lathe to maintain the internal spline part and the total inner tube length as required.

c: as shown in fig. 6, the diameter is reduced by swaging (second swaging step): and (3) performing rotary forging and diameter reduction on the part of the steel pipe, which is not extruded by the internal spline, by using a rotary forging machine, performing rotary forging and diameter reduction on the rotary forging outer diameter die and the optical stopper rod in the rotary forging and cold extrusion process of the internal spline, and performing die closing and rotary forging for twice, wherein the diameter reduction is performed on the end part of the side, which is not extruded by the internal spline, of the steel pipe (namely, the corresponding external spline area), the outer diameter of the formed steel pipe is larger than the outer diameter of the internal spline, the diameter reduction is performed on the rest part of the formed steel pipe (corresponding to the bearing area and the combined switch installation area) after the first time of diameter reduction, the outer diameter of the formed steel pipe is identical to the outer diameter of the internal spline, and the length of the end part of the first rotary forged steel pipe is 6% of the length of the internal spline.

d: as shown in FIG. 7, the external spline bottom diameter and the conical surface are swaged by a swaging machine (a swaging process III), the external spline bottom diameter and the conical surface are swaged by a swaging machine, the material is prevented from collapsing during swaging by a die for the external spline bottom diameter and a light stopper rod in the step of swaging the diameter, the die is swaged in three times, the die is swaged in the first time, the external spline bottom diameter and the conical surface are swaged in the die for the first time, the head end of the light stopper rod is positioned at the rear end of the conical surface after molding, the material is prevented from collapsing during swaging, the die is swaged in the second time, the position of the light stopper rod is not moved, the deformation of the conical surface is prevented, the front third part of the mounting area of the swaging combination switch is swaged in the third time, the light stopper rod is moved backwards to the junction of the bearing area and the mounting area of the combination switch, the material is prevented from deforming in the bearing area, and the second part behind the mounting area of the combination switch is swaged in the third order.

(4) Extruding the external spline; the support rod and the die bench are used for being installed on the workbench surface of the four-column oil press to perform cold extrusion on external splines, and the extrusion splines are free of missing teeth and piled materials.

(5) Cutting and chamfering; and (5) adding and holding the middle area of the inner tube, cutting and chamfering, and cutting off to keep the total length of the finished product.

(6) Extruding the internal thread; the middle area of the inner tube is clamped by an air chuck, the threads are formed by cold extrusion of an extrusion tap, and no thread damage or fracture occurs.

(7) Cleaning, rust prevention and boxing; checking is carried out before boxing to prevent unqualified products from flowing out.

Specific examples:

in order to better match the existing steering wheel, the embodiment ensures that the M18 threaded interface is unchanged, the external spline parameters are unchanged, and the diameters of the bearing areas are unchanged. The parameter design requirement of the steering inner tube is as follows: 18 teeth internal spline parameter, M18 internal thread, bearing zone diameterThe rigidity of the structure is superior to that of the inner pipe of the structure with other parameters, so that the service performance of the product is improved, and the driving safety of a vehicle is enhanced. The number of teeth of the internal spline 6 is 18, the diameter is +.>Major diameter->Diameter of reference circleThread 2 is M18X1.5; the number of teeth of the external spline 1 is 86, the tooth socket angle is 30 degrees, and the reference circle is +.>Tip circle->Root circle->

The inner surface and the outer surface of the steering inner pipe cannot be subjected to turning processing in the forming process, otherwise, the metallographic structure of the material is damaged, except for the cutting length and the chamfer angle, the material is formed by cold extrusion, in the processing process, the pipe material is subjected to plastic deformation, the material is hardened in the extrusion process, certain fiber flows, the hardness and the strength of the product can be improved, and accordingly, larger rigidity is obtained, and larger torque is transmitted.

If the prior art method is adopted, there are the following problems,

1. the requirements of the external spline bottom diameter and the internal thread bottom diameter cannot be met at the same time, and the screw extrusion forming condition cannot be met.

2. A, B is taken as a reference, and the runout of the bottom diameter end of the external spline is more than 0.2mm; after the inner pipe is formed by rotary forging, the jump value of the bottom diameter position of the external spline is measured by a dial indicator to be between 0.4 and 1.2, and the requirement of drawing is not more than or equal to 0.2.

3. After the external spline bottom diameter procedure is in rotary swaging, the conical surface is formed poorly.

The specific processing method comprises the following steps:

(1) Selecting raw materials: a precise seamless cold drawn steel tube with the outer diameter of 34.6, the inner diameter of 27.8, the wall thickness of 3.4 and the length of more than or equal to 240 is selected, and the steel tube has certain extensibility.

(1) Surface treatment of raw materials: the method is characterized in that raw materials are prepared for treatment before rotary forging and cold extrusion, and the surface of the seamless steel tube is subjected to phosphating treatment, so that the extrusion force applied to the working surface of the die can be effectively reduced, and the service life of the clamping fixture is prolonged.

(2) And (5) rotary forging:

a. rotary swaging cold extruding internal spline (rotary swaging process one): the HA-40 rotary forging machine is utilized to rotary forge an internal spline at one side of a steel pipe, a rotary forging outer diameter die and 18-tooth core rods are selected, the die extrudes the outer surface of the pipe in the processing process, the 18-tooth core rods are supported in the pipe, in the processing process, radial and axial flow of materials occurs, the 18-tooth internal spline is formed after rotary forging, the length is more than or equal to 240, and the outer diameter is larger than or equal to 240

b: the lathe length keeping step comprises the steps of keeping the inner spline part to be 238 and keeping the total length to 320+/-0.5 by using a numerical control lathe;

c: rotary forging diameter reduction (rotary forging process II): utilize HA-40 rotary forging machine rotary forging diameter reduction, outer diameter mould and in the step of cold extrusion internal spline of rotary forging borrowThe optical stopper rod is subjected to diameter reduction and rotary forging, program parameters are adjusted, the optical stopper rod is subjected to die assembly and rotary forging for two times, the end part of the steel pipe, which is not extruded by the internal spline, is subjected to diameter reduction for the first time, and the outer diameter of the formed optical stopper rod is larger than the outer diameter of the internal spline, namely +_part>Reducing the residual part of the steel pipe after the first diameter reduction for the second time, wherein the outer diameter after molding is the same as the outer diameter of the internal spline, namelyThe length of the end part of the steel pipe subjected to the first rotary forging is 14-16;

d: rotary forging external spline bottom diameter and conical surface (rotary forging process III): utilizing HA-40 rotary forging machine to forge external spline bottom diameter and conical surface, and utilizing rotary forging external spline bottom diameter die and rotary forgingIn the step of reducing the diameterThe optical stopper rod is subjected to rotary forging processing, and is subjected to die closing rotary forging for three times in total, wherein the die closing rotary forging is performed for the first time, and the bottom diameter of an external spline is formed by rotary forging>The head end of the optical stopper rod is positioned at the rear end of the formed conical surface, so that material collapse during rotary forging is prevented, the second die closing rotary forging is performed, the position of the optical stopper rod is fixed, the deformation of the conical surface is prevented, and the size of a mounting area of a rotary forging combined switch is->Front length 10, third die closing and rotary forging, the optical stopper rod moves backwards 30, namely the junction of the bearing area and the combined switch installation area, so that the material deformation of the bearing area is prevented, and the size of the rotary forging combined switch installation area is +.>And (5) length 20, and performing rotary swaging forming in the third order.

(4) Forming an external spline: the support rod and the die bench are used for being installed on the workbench surface of the four-column oil press to perform cold extrusion on external splines, and the extruded splines are free of missing teeth and piled up, so that the requirements are met.

(5) Cutting and chamfering; and (5) adding and holding the middle area of the inner tube, cutting and chamfering, and cutting off to keep the total length of the finished product.

(6) Forming threads; and clamping the middle area of the inner tube by using an air chuck, and cold extruding and forming the threads by using an extruding tap.

(7) Cleaning, rust prevention and boxing. Checking is carried out before boxing to prevent unqualified products from flowing out.

The rotary forging die of the rotary forging cold extrusion 18-tooth internal spline forming process is shared with the second diameter reducing die of the rotary forging process; the second rotary forging process and the third rotary forging process share the optical stopper rod, so that the manufacturing and processing cost of the rotary forging inner pipe tool clamp is indirectly reduced in the rotary forging forming development process. Mounting the combined switch areaThe size is processed in the third step, and one manual feeding processing procedure is reduced.

Front end in rotary forging process IIReserving materials, ensuring that the thread bottom warp materials are enough after the rotary forging process III, and ensuring that the A-B jumping value is less than or equal to 0.2 by recessed rotary forging diameter reduction under the supporting action of a light stopper rod. In the rotary forging process III, the optical stopper rod is used as a support to prevent conical surface materials from collapsing and keep the conical surface to be well molded; and->Size and->The size joint can prevent the material of the bearing area from not deforming and meet the requirement of the bearing area>Requirements.

Description: the length units are in millimeters in this application.

The steering inner tube of the application has an internally splined portion as the rear end and an externally splined portion as the front end.

Finally, it should be noted that the above embodiments are merely illustrative of the technical solutions of the embodiments of the present invention, and are not limiting. Although embodiments of the present invention have been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the corresponding technical solutions.

Claims (2)

1. A processing method of a steering inner pipe is characterized in that: the method comprises the following steps:

selecting raw materials, (2) carrying out surface treatment on the raw materials, (3) carrying out rotary forging processing, (4) extruding external splines, (5) turning, cutting and chamfering, (6) extruding internal threads, and (7) cleaning, rust preventing and boxing;

the specific processing method comprises the following steps:

(1) Selecting raw materials; selecting a precise seamless cold drawn steel tube with proper outer diameter, wall thickness and length, wherein the steel tube has certain extensibility;

(2) And (3) material surface treatment: the surface phosphating treatment of the seamless steel tube can effectively reduce the extrusion force applied to the working surface of the die and prolong the service life of the clamping fixture;

(3) And (5) rotary forging:

a. rotary forging cold extrusion internal spline: a rotary forging machine is utilized to rotary forge an internal spline at one side of a steel pipe, a proper rotary forging outer diameter die and a core rod are selected, the die is used for extruding the outer surface of the pipe in the processing process, the core rod is supported in the pipe, in the processing process, the material radially and axially flows, and the internal spline is formed after rotary forging;

b: a lathe length-keeping step of reserving the total length of the inner spline part and the inner tube according to requirements by using a numerical control lathe;

c: and (5) rotary forging and diameter reducing: and (3) performing rotary forging and diameter reduction on one side of the steel pipe, which is not extruded by the internal spline, by using a rotary forging machine, performing diameter reduction and rotary forging by using a rotary forging outer diameter die and a light stopper rod in the rotary forging and cold extrusion process of the internal spline, and performing die closing and rotary forging for twice, wherein the diameter reduction is performed on the end part of the steel pipe, which is not extruded by the internal spline, at the first time, the outer diameter after forming is larger than the outer diameter of the internal spline, the diameter reduction is performed on the rest part of the steel pipe after the first time of diameter reduction, the outer diameter after forming is the same as the outer diameter of the internal spline, and the length of the end part of the steel pipe subjected to the first rotary forging is 6% of the length of the internal spline.

d: the method comprises the steps of (1) performing rotary forging on the external spline bottom diameter and the conical surface by using a rotary forging machine, performing rotary forging processing by using a rotary forging external spline bottom diameter die and a light stopper rod in the rotary forging diameter reducing step, wherein the rotary forging is divided into three times of die closing rotary forging, namely, performing first die closing rotary forging on the rotary forging external spline bottom diameter and the conical surface, enabling the head end of the light stopper rod to be positioned at the rear end of the formed conical surface, preventing material collapse during rotary forging, performing second die closing rotary forging, enabling the position of the light stopper rod to be fixed, preventing the conical surface from deforming, performing rotary forging on the front third part of a combined switch installation area, performing third die closing rotary forging, enabling the light stopper rod to move backwards to the joint of a bearing area and the combined switch installation area, and performing second third part of the rotary forging combined switch installation area;

(4) Extruding the external spline; the support rods and the die bench are used for being arranged on the workbench surface of the four-column oil press to perform cold extrusion on external splines, and the extrusion splines are free of missing teeth and piled materials;

(5) Cutting and chamfering; the middle area of the inner tube is held, and the total length of the finished product is reserved by cutting and chamfering and cutting off;

(6) Extruding the internal thread; clamping the middle area of the inner tube by using an air chuck, and cold extruding the threads by using an extruding tap without damaging or breaking the threads;

(7) Cleaning, rust prevention and boxing; checking is carried out before boxing to prevent unqualified products from flowing out.

2. The method for machining a steering inner tube according to claim 1, wherein: the specific processing method comprises the following steps:

the internal spline 18 teeth of the steering inner tube, the internal thread M18 and the diameter of the bearing areaThe number of teeth of the external spline is 86,

(1) Selecting raw materials: selecting a precise seamless cold drawn steel tube with the outer diameter of 34.6, the inner diameter of 27.8, the wall thickness of 3.4 and the length of more than or equal to 240, wherein the steel tube has certain extensibility;

(2) Surface treatment of raw materials: raw materials are prepared for treatment before rotary forging and cold extrusion, and the surface of the seamless steel tube is subjected to phosphating treatment, so that the extrusion force applied to the working surface of the die can be effectively reduced, and the service life of the clamping fixture is prolonged;

(3) And (5) rotary forging:

a. rotary forging cold extrusion internal spline: the HA-40 rotary forging machine is utilized to rotary forge an internal spline at one side of a steel pipe, a rotary forging outer diameter die and 18-tooth core rods are selected, the die extrudes the outer surface of the pipe in the processing process, the 18-tooth core rods are supported in the pipe, in the processing process, radial and axial flow of materials occurs, the 18-tooth internal spline is formed after rotary forging, the length is more than or equal to 240, and the outer diameter is larger than or equal to 240

b: the lathe length keeping step comprises the steps of keeping the inner spline part to be 238 and keeping the total length to 320+/-0.5 by using a numerical control lathe;

c: and (5) rotary forging and diameter reducing: utilize HA-40 rotary forging machine rotary forging diameter reduction, outer diameter mould and in the step of cold extrusion internal spline of rotary forging borrowThe optical stopper rod is subjected to diameter reduction and rotary forging, program parameters are adjusted, the optical stopper rod is subjected to die assembly and rotary forging for two times, the end part of the steel pipe, which is not extruded by the internal spline, is subjected to diameter reduction for the first time, and the outer diameter of the formed optical stopper rod is larger than the outer diameter of the internal spline, namely +_part>Reducing the residual part of the steel pipe after the first diameter reduction for the second time, wherein the outer diameter after molding is the same as the outer diameter of the internal spline, namely +.>The length of the end part of the steel pipe subjected to the first rotary forging is 14-16;

d: rotary forging external spline bottom diameter and conical surface: the bottom diameter and the conical surface of the external spline are swaged by utilizing an HA-40 swaging machine, and a die for swaging the bottom diameter of the external spline and the step of swaging and reducing the diameter are utilizedThe optical stopper rod is subjected to rotary forging processing, and is subjected to die closing rotary forging for three times in total, wherein the die closing rotary forging is performed for the first time, and the bottom diameter of an external spline is formed by rotary forging>And the conical surface, the head end of the optical stopper rod is at the rear end position of the conical surface after molding, prevent material collapse during rotary forging, the second die closing rotary forging, the optical stopper rod is fixed in position, prevent conical surface deformation, the rotary forging makes the size of the switch installation area upFront length 10, third die closing and rotary forging, and the optical stopper rod moves backwards to the junction of the bearing area and the combined switch installation area to prevent material deformation of the bearing area, and the dimension of the rotary forging combined switch installation area is +.>Length 20.

(4) Forming an external spline: the support rod and the die bench are used for being installed on the workbench surface of the four-column oil press to perform cold extrusion on external splines, and the extruded splines are free of missing teeth and piled up, so that the requirements are met.

(5) Cutting and chamfering; and (5) adding and holding the middle area of the inner tube, cutting and chamfering, and cutting off to keep the total length of the finished product.

(6) Forming threads; and clamping the middle area of the inner tube by using an air chuck, and cold extruding and forming the threads by using an extruding tap.

(7) Cleaning, rust prevention and boxing: checking is carried out before boxing to prevent unqualified products from flowing out.