A processing technology for ball sliding shaft in automobile steering system

Abstract

The present invention discloses a process for processing ball sliding shafts for automotive steering systems. The process utilizes a three-ball groove asymmetric extrusion process to ensure, after a single extrusion, the values ​​of the torsion, fitting circle, and line profile, straightness, and the taper of the fitting circle after extrusion. The specific steps include: 1) manufacturing the part; 2) machining the part's outer circle; 3) machining the part's slots; 4) surface treatment; and 5) testing the finished product. Through the above-described method, the present invention provides a process for processing ball sliding shafts for automotive steering systems. By ensuring, after a single extrusion, the values ​​of the torsion, fitting circle, and line profile, straightness, and the taper of the fitting circle after extrusion, the process not only improves part utilization but also reduces the amount of machining required.

Description

Technical Field

[0001] The invention relates to the field of automobile parts, in particular to a processing technology for a ball sliding shaft in an automobile steering system. Background Art

[0002] The existing steering column is composed of a ball sliding shaft and a ball sliding tube. The ball sliding shaft and the ball sliding tube use a steel ball retainer to reduce friction, which can affect the torque of the steering system and greatly improve the vehicle's handling performance.

[0003] An arc groove is set on the outer wall of the ball sliding shaft at a circumferential interval of every 120°. The corners of the three arc grooves are all arc-shaped. The surface of the ball groove needs to be high-frequency treated to reach HRC50-55. The high-frequency treatment itself will generate great stress and cause a large amount of deformation. The dimensional change after high-frequency treatment will be unstable. At present, some domestic companies use honing or secondary extrusion to process the three ball grooves after high-frequency treatment to meet the requirements of the drawings. Although this processing form can meet the requirements of the drawings, the efficiency and cost will be very high, and the economy and competitiveness are very poor. After extrusion, there will be taper due to the difficulty of the flow of the parts, which is not suitable for mass production. Summary of the Invention

[0004] The main technical problem solved by the present invention is to provide a processing technology for a ball sliding shaft in an automobile steering system, which can improve the utilization rate of parts and reduce the number of machining operations.

[0005] To solve the above technical problems, the present invention adopts a technical solution: providing a processing technology for a ball sliding shaft in an automobile steering system, using a three-ball groove asymmetric extrusion process for the ball sliding shaft, ensuring the torsion, the numerical value of the fitting circle and line profile, the straightness, and the taper of the fitting circle after extrusion after one extrusion. The specific steps include:

[0006] 1) Parts manufacturing: The raw material is analyzed for composition by infrared spectrometer, and then cut and annealed according to the required size on an automatic sawing machine to obtain the required parts;

[0007] 2) Part outer circle processing: centerless grinding of the outer circle and turning of the outer circle end surface of the part obtained in step 1);

[0008] 3) Part slot processing: cold extrusion of ball slots and drilling and boring of the parts processed in step 2);

[0009] 4) Surface treatment: performing high-frequency quenching and straightening on the parts processed with the slots in step 3);

[0010] 5) Finished product inspection: The parts processed in step 4) are cleaned and inspected for cracks to obtain finished products.

[0011] In a preferred embodiment of the present invention, the parts obtained in step 1) are placed in a shot blasting machine for shot blasting before processing in step 2).

[0012] In a preferred embodiment of the present invention, the part is subjected to external finishing before drilling and boring in step 3).

[0013] In a preferred embodiment of the present invention, after step 3) cold extrusion of the ball groove, the taper of the fitting circle is ensured to meet 0.005 mm, the torsion and straightness meet 0.02 mm, and the line profile meets 0.03 mm.

[0014] In a preferred embodiment of the present invention, the parts after high-frequency quenching are subjected to dephosphorization treatment before straightening in step 4).

[0015] In a preferred embodiment of the present invention, the parts are engraved before cleaning in step 5).

[0016] The beneficial effects of the present invention are as follows: the present invention provides a processing technology for a ball sliding shaft in an automobile steering system, which not only improves the utilization rate of parts but also reduces the amount of machining by ensuring the value of the torsion, the fitting circle and the line profile, the straightness and the taper of the fitting circle after extrusion after one extrusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a three-dimensional diagram of the finished product after processing a ball sliding shaft for an automobile steering system according to the present invention;

[0018] Figure 2 The present invention is a process flow chart of a process for processing a ball sliding shaft in an automobile steering system. DETAILED DESCRIPTION

[0019] The preferred embodiments of the present invention are described in detail below with reference to the accompanying drawings so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby making a clearer and more precise definition of the protection scope of the present invention.

[0020] See also Figure 1 and Figure 2 , embodiments of the present invention include:

[0021] A processing technology for a ball sliding shaft in an automobile steering system adopts a three-ball groove asymmetric extrusion process for the ball sliding shaft. After a single extrusion, the torsion, the numerical values ​​of the fitting circle and line profile, the straightness, and the taper of the fitting circle after extrusion are guaranteed, thereby avoiding the use of honing or secondary extrusion to process the three ball grooves after high-frequency processing, reducing the processing steps, and overcoming the problem that high-frequency processing itself will generate extremely large stress and cause a large amount of deformation, and the dimensional change after high-frequency processing will be less stable.

[0022] The specific steps include:

[0023] Manufacturing of parts: The composition of the whole raw material is analyzed by infrared spectrometer, and then it is cut and annealed according to the required size on an automatic sawing machine to obtain the parts required for processing.

[0024] Put 25 raw materials into the jaws of the CNC sawing machine, clamp them after laying the plane flat, weld the roots of the raw materials firmly, calibrate the raw materials to be perpendicular to the saw blade, and start processing. First, saw off the part of the head that is smaller than the drawing requirement after cold drawing (due to the different lengths, at least 180mm of the head should be sawed off), and then process according to the drawing size requirements (if it is found that the end face of the blanked part is not vertical, it should be adjusted in time), and finally stop processing at 60mm-80mm away from the welding point, put the welding part and the head part into the isolation area, the blanking length is 161+1mm, and then heat it to 780° and keep it warm for 4 to 6 hours, then cool it out of the furnace, and put the parts obtained after taking out of the furnace into the shot blasting machine for shot blasting to remove the oxide scale on the surface of the parts.

[0025] Part outer circle processing: the part obtained in step 1) is subjected to centerless outer circle grinding and outer circle end surface turning.

[0026] Dress the grinding wheel and guide wheel on the centerless grinder, check the position of the guide blocks at both ends, the guide block surface should be 0.05mm lower than the guide wheel surface, adjust the drag block to ensure the part size, grind the parts continuously, place the parts one by one on the guide plate of the centerless grinder, and then slowly push the parts forward. If the parts are found to have stopped, remove the stopped parts and measure whether there is a drop in the outer diameter of the parts, isolate the parts with the drop, be careful to avoid scratching each part (already processed) that slides out of the guide plate, place one end face of the part after grinding the outer diameter against the screw plane inside the spring chuck of the CNC double-sided lathe, adjust the screw and fix it, place the part in the spring chuck, clamp it against the limit reference inside, and turn the plane and outer diameter to the required size in the drawing.

[0027] Part slot processing: cold extrusion ball grooves and drilling and boring are performed on the part with the outer circle processed in step 2), and the part is subjected to outer circle finishing processing before the drilling and boring.

[0028] Install the upper and lower molds on the hydraulic press, adjust the size of the ejector rod, adjust the height limit, adjust the pressure of the hydraulic press to 12-20Mpa, insert the small end of the part into the mold barrel, press the start button, extrude the hydraulic press to the limit, and then press the start button to eject it. After cold extrusion of the ball groove, ensure that the taper of the fitting circle meets 0.005mm, the torsion and straightness meet 0.02mm, and the line profile meets 0.03mm. Load the extruded part into the three-jaw clamping tooling installed in the spindle of the CNC lathe, calibrate the runout <0.02, clamp it against the limit reference inside, process the two end faces and the outer circle, replace the tool after processing, and perform drilling and boring again.

[0029] The parts are subjected to phosphorus saponification in the cold extrusion ball groove, which is beneficial to material flow and facilitates cold extrusion.

[0030] Surface treatment: The parts processed by the slots in step 3) are subjected to high-frequency quenching and straightening. Before the straightening, the parts after high-frequency quenching are subjected to dephosphorization treatment.

[0031] After high-frequency quenching, the hardness is guaranteed to be HRC: 50-55. The quenching is only performed on the ball groove position, and the outer circle is not subjected to high-frequency quenching treatment. The quenching depth is: 0.65-1.2mm. The heat treatment quality should comply with the specification GB / T 34882-2017. The deformation of φ21.4 after heat treatment is: 0.03mm-0.04mm. Then dephosphorization treatment is carried out to avoid the formation of oxide scale in the heat treatment area. The parts after dephosphorization are placed on the straightening fixture, and their runout is measured with a lever meter. The places where the tolerance is exceeded are tapped with a copper rod.

[0032] Finished product inspection: The parts after step 4) are cleaned and inspected for cracks to obtain a finished product. The parts are engraved before cleaning.

[0033] Use an ultrasonic cleaning machine to clean the parts after engraving, and then use a flaw detector to detect cracks.

[0034] Different from the existing technology, the present invention is a processing technology for a ball sliding shaft in an automobile steering system. This technology can not only improve the utilization rate of parts but also reduce the amount of machining by ensuring the torsion, the numerical value of the fitting circle and the line profile, the straightness and the taper of the fitting circle after extrusion after one extrusion.

[0035] In the description of the present invention, it should be noted that the components are all universal standard parts or components known to those skilled in the art, and their structures and principles are known to those skilled in the art through technical manuals or conventional test methods. The directions or positional relationships indicated by the terms "upper", "lower", "left", "right", "inside", "outside", etc. are based on the directions or positional relationships shown in the accompanying drawings, or are the directions or positional relationships in which the invented product is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention.

[0036] The above descriptions are merely embodiments of the present invention and are not intended to limit the patent scope of the present invention. Any equivalent structure or equivalent process transformation made using the contents of the present invention's description and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A process for processing a ball sliding shaft in an automobile steering system, characterized in that: The ball sliding shaft adopts a three-ball groove asymmetric extrusion process to ensure the torsion, the numerical value of the fitting circle and line profile, the straightness and the taper of the fitting circle after extrusion after one extrusion. The specific steps include: 1) Parts manufacturing: The raw material is analyzed for composition by infrared spectrometer, and then cut and annealed according to the required size on an automatic sawing machine to obtain the required parts; 2) Part outer circle processing: centerless grinding of the outer circle and turning of the outer circle end surface of the part obtained in step 1); 3) Part slot processing: cold extrusion ball slots and drilling and boring are performed on the parts processed in step 2). After cold extrusion of the ball slots, the taper of the fitting circle is ensured to meet 0.005mm, the torsion and straightness meet 0.02mm, and the line profile meets 0.03mm. 4) Surface treatment: performing high-frequency quenching and straightening on the parts processed with the slots in step 3); 5) Finished product inspection: The parts processed in step 4) are cleaned and inspected for cracks to obtain finished products.

2. The processing technology for the inner ball sliding shaft of the automobile steering system according to claim 1 is characterized in that: Before step 2), the parts obtained in step 1) are placed in a shot blasting machine for shot blasting.

3. The processing technology for the inner ball sliding shaft of the automobile steering system according to claim 1 is characterized in that: Before drilling and boring in step 3), the part is subjected to external finishing.

4. The processing technology for the inner ball sliding shaft of the automobile steering system according to claim 1 is characterized in that: In step 4), the parts after high-frequency quenching are subjected to dephosphorization treatment before straightening.

5. The processing technology for the inner ball sliding shaft of the automobile steering system according to claim 1 is characterized in that: The parts are engraved before cleaning in step 5).

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