KR20220157244A - Method for forming subframe mounting pipe bolts for electric vehicle platform using standard forging technology - Google Patents

Abstract

The present invention relates to a method for forming subframe mounting pipe bolts for an electric vehicle platform using a standard forging technology, and more specifically, to a technology which employs a high-precision multi-stage cold former to enable high-strength difficult forming, to enable process optimization considering the amount of volume change through a distributed process design, and to improve the life of a mold through a process design that minimizes work hardening.

Description

Method for forming subframe mounting pipe bolts for electric vehicle platform using standard forging technology}

The present invention relates to a method for forming a subframe mounting pipe bolt for an electric vehicle platform to which a formal forging technology is applied, and more particularly, enables a pipe bolt to have high rigidity while reducing weight, and durability through heat treatment at each step of the process to prevent work hardening. It is a skill that can enhance

Recently, demand for and research on future vehicles, centered on eco-friendly electric vehicles and self-driving vehicles, is rapidly increasing, and there is no choice but to limit the performance of electric vehicles produced on the existing internal combustion engine platform. is going

By establishing a dedicated platform for electric vehicles, it is possible to lay the groundwork for developing pure electric vehicle technology, secure competitiveness, and improve completeness as an electric vehicle. In line with these changes in the market environment, prepare for the common use of parts for exclusive use of electric vehicles through the development of a platform for electric vehicles. are doing

On the other hand, pipe bolts are used for fastening for sub frame mounting (SUB FRAME MOUNTING) applied to a platform dedicated to electric vehicles.

First, looking at the conventional technologies,

Registration No. 10-0815529 (Special) Upsetting molding to expand the diameter by pressurizing the material using the punch pin on the punch side mold side while placing the material cut to a certain length on the die side mold side equipped with the die pin The first step of doing; In the state in which the front part of the material upset in the first step is supported by a punch pin, the material is extruded backward by a drawing processing method of the material using a die pin inserted into the die sleeve to form a rear groove on the rear side of the material Step 2; In the second step, the front part of the material extruded backwards is upset using the punch sleeve and punch pin of the punch-side mold, and at the same time, backward extrusion is performed using the die-side mold using the die pin, so that the front part of the material A third step of forming a flange portion and forming a front groove in the center of the flange portion; A mounting pipe forming method including a fourth step of shaping the material molded in the third step into a pipe shape through a piercing process in which the die pin of the die-side mold completely penetrates the rear groove and the front groove of the material.

Registration No. 10-0908919 (Special) An upsetting process of reducing the length of the cut material and enlarging the diameter by manufacturing the mounting pipe in the following order using a forming machine for the entire process; A preforming process of forming a preliminary groove with a low depth on the front and rear surfaces of the material; A simultaneous backward extrusion process of forming a groove on one side of the material to extrude the tubular body and forming a groove of a lower depth on the opposite side at the same time; A piercing process of making a complete tubular shape by penetrating between a groove on one side and a groove on the other side; A forward extrusion step of forming a reduced portion and an inclined portion by reducing an outer diameter and an inner diameter of one side; Forming a step and simultaneously forming a diameter expansion portion in the reduced portion to complete the manufacturing process; This is a technology related to a method for manufacturing a mounting pipe for a vehicle in which manufacturing is completed in the above six steps sequentially.

The prior art described above mainly describes a method of molding into a required shape by using a separate processing machine or processing device.

That is, pipe bolts are not formed by hot forging or cold forging, but pipe bolts are formed by using molds in each step, and the pipe bolts are finally formed by using a processing machine or a processing device as needed in each step. In addition to the extremely low productivity of the pipe bolts, since the final molding of the mounting pipe bolts is only possible when a processing machine or processing device is necessarily provided, economic efficiency is inevitably reduced.

The present invention has been devised to solve the problems of the prior art, and enables high-strength difficult molding by applying high-precision cold multi-step former technology, enabling process optimization in consideration of volume change through process dispersion design, and processing It was completed as a technical task with an emphasis on providing a method of forming subframe mounting pipe bolts for electric vehicle platforms using formal forging technology that can improve mold lifespan through process design that minimizes hardening.

Therefore, in the present invention, in the method of forming a subframe mounting bolt for an electric vehicle platform to which formal forging technology is applied, a cutting step of cutting a circular round bar into a predetermined length while forming using a mold in each step for formal forging ( S100); An upsetting step (S200) of molding the lower part of the material 1 cut in the cutting step (S100), forming a groove of a certain depth in the upper part, and gradually forming a smaller diameter in the lower direction; a first preforming step (S300) of forming the upper and lower total lengths longer than the material formed after the upsetting step (S200) and protruding at a smaller diameter than the outer circumference of the upper part; A second preforming step (S400) of forming a protrusion with a diameter smaller than the central portion on the upper part of the material formed after the first preforming step (S300), and forming a slightly longer lower part; A third preliminary step in which the entire upper and lower lengths of the material formed after the second preliminary forming step (S400) are formed shorter, and the upper outer circumference excluding the outer uppermost part forms a boundary in the downward direction and is sequentially formed with small diameters. molding step (S500); The upper and lower total lengths of the material formed after the third preliminary forming step (S500) are formed longer, and the material formed after the third preliminary forming step (S500) has more boundaries in the downward direction than the material formed, and is sequentially reduced in diameter. A fourth preliminary forming step (S600) to be continuously formed; a protruding frame forming step (S700) of forming shorter overall upper and lower lengths of the material formed after the fourth preforming step (S600) and forming a protruding frame having a larger diameter than the upper portion at the central portion; It is a technical feature that includes.

According to the method of forming a subframe mounting pipe bolt for an electric vehicle platform to which the forging technology of the present invention is applied, the original purpose of forming the mounting bolt is maintained, and at the same time, productivity is maximized as process optimization is possible through securing a single flow line. , It is possible to prevent breakage during molding due to stress concentration, thereby securing reliability through suppression of defective rate, and furthermore, as mold life is extended by minimizing work hardening, it is a useful invention with very high economic efficiency.

1 is a flow chart showing a preferred embodiment of the present invention
2 is a process chart showing a preferred embodiment of the present invention
3 is a view showing the cutting step and the upsetting step of the present invention
4 is a view showing the upsetting step and the first preforming step of the present invention.
5 is a view showing a first preforming step and a second preforming step of the present invention.
6 is a view showing the second preforming step and the third preforming step of the present invention.
7 is a view showing a third preforming step and a fourth preforming step of the present invention.
8 is a view showing a fourth preliminary forming step and a protruding frame forming step of the present invention.

Due to the current strengthening of international environmental and fuel efficiency regulations and rising prices of energy resources, advanced automobile countries such as North America, Europe, and Japan have developed power-based vehicles in order to break away from the existing internal combustion engine-centered automobile market and preemptively respond to the 4th industrial revolution. It is a trend that is expanding.

In the power-based vehicle, the structure of the entire lower platform is changed due to the installation of a large-capacity battery that replaces the internal combustion engine, and the change in the center of gravity due to the battery changes the geometry of the vehicle, and the structure and suspension system close to the lower platform changes are also made.

Here, power-based vehicles tend to be completed by fastening a number of parts, and at this time, pipe bolts are used for fastening. Conventional pipe bolts for fastening take a lot of processing time, have a high defect rate, and have very low economic efficiency and productivity, such as having to be equipped with other processing facilities. As the durability of the finished pipe bolts also deteriorates, , frequent breakage occurred frequently.

Accordingly, a method of forming a subframe mounting pipe bolt for an electric vehicle platform using a form forging technology capable of reducing weight and having high rigidity and increasing durability through heat treatment at each process step to prevent work hardening is provided.

Hereinafter, a preferred configuration and operation of the present invention for achieving the above object will be described with reference to FIGS. 1 to 8 with reference to the accompanying drawings.

As shown in FIG. 1 or 2, the present invention In the method of forming a subframe mounting bolt for an electric vehicle platform to which formal forging technology is applied, a mold is used in each step for formal forging, and the material formed in each step is heat-treated and molded in each or single step, and the cutting step (S100 ), upsetting step (S200), first preliminary forming step (S300), first preliminary forming step (S400), first preliminary forming step (S500), first preliminary forming step (S600), protruding frame forming step ( S700).

As shown in FIG. 2 or 3, the cutting step (S100) is a step of cutting a round bar to a predetermined length, and cutting the round bar formed long in the longitudinal direction to fit the size and shape of the pipe bolt to be formed. At this time, in the case of cutting, it can be cut using a device or tool for normal cutting.

At this time, in the case of the size of the round bar, it is to optimize process conditions for improving dimensional accuracy and material yield.

Here, as described above, the present invention also requires different molds to be provided in each step in the upsetting step (S200) and the first, second, third, and fourth preforming steps (S300, S400, S500, and S600), , The cold forging operation is performed with the molds provided in each step, and in the present invention, the molds are not separately shown.

As shown in FIG. 3 or 4, in the upsetting step (S200), the lower part of the material 1 cut in the cutting step (S100) is molded, but a groove of a certain depth is formed in the upper part and downwardly. This step is to gradually form to have a smaller diameter.

In other words, the upsetting step (S200) is to make molding more smooth during molding in the first preliminary molding step (S300), and when the material is suddenly deformed, each step is By making it sequentially rough, it is possible to perform cold forging under optimal conditions.

In the first preforming step (S300), as shown in FIG. 4 or 5, the upper and lower total lengths are longer than those of the material formed after the upsetting step (S200), and the lower part is smaller than the outer circumference of the upper part. This step is to make it protrude with a diameter.

As shown in FIG. 5 or 6, in the second preforming step (S400), the upper portion of the material formed after the first preforming step (S300) is formed to protrude with a smaller diameter than the central portion, and the lower portion is slightly larger. This is the long forming step.

As shown in FIG. 6 or 7, in the third preliminary forming step (S500), the entire upper and lower lengths of the material formed after the second preliminary forming step (S400) are formed shorter, and the upper portion except for the outer uppermost portion is formed. It is a step of forming a boundary from the outer circumference in the downward direction and sequentially forming small diameters continuously.

As shown in FIG. 7 or 8, in the fourth preforming step 600, the upper and lower entire lengths of the material formed after the third preforming step S500 are formed longer, It is a step of forming more boundaries in the lower direction than the material formed after step (S500) and sequentially forming a small diameter continuously.

As shown in FIG. 8, in the protruding frame forming step (S700), the entire upper and lower lengths of the material formed after the fourth preforming step (S600) are formed shorter, and the central portion has a larger diameter than the upper portion. This is the step of forming the protrusion frame.

Here, in the present invention, the final mounting through the cutting step (S100), the upsetting step (S200), the first, second, third, and fourth preliminary forming steps (S300, S400, S500, S600) and the protruding frame forming step (S700) Pipe bolts are molded, but if the volume change in each step (process) is excessive, cracks or bursts occur during the serration molding of the expansion part. It is possible to overcome the above problems by sequentially forming through steps such as preforming.

In addition, on the other hand, after the materials for each step are molded, a heat treatment process may be performed at each step to prevent work hardening.

According to the method of forming a subframe mounting bolt for an electric vehicle platform to which the forging technology of the present invention is applied, productivity is maximized as it is possible to optimize the process by securing a single flow line while maintaining the original purpose of forming the mounting bolt, It is possible to prevent breakage during molding due to stress concentration, thereby securing reliability through suppression of defective rate, and furthermore, as mold life is extended by minimizing work hardening, it is a useful invention with very high economic efficiency.

S100: cutting step S200: upsetting step
S300: First Preliminary Forming Step S400: Second Preliminary Forming Step
S500: Third Preliminary Forming Step S600: Fourth Preliminary Formation Step
S700: 5th preforming step

Claims (1)

In the method of forming a subframe mounting bolt for an electric vehicle platform to which the forging technology is applied,
In each step for forming forging, a mold is used and the material formed in each step is heat-treated and molded in each or single step,
A cutting step (S100) of cutting a round bar into a predetermined length;
An upsetting step (S200) of molding the lower part of the material 1 cut in the cutting step (S100), forming a groove of a certain depth in the upper part, and gradually forming a smaller diameter in the lower direction;
a first preforming step (S300) of forming the upper and lower total lengths longer than the material formed after the upsetting step (S200) and protruding at a smaller diameter than the outer circumference of the upper part;
A second preforming step (S400) of forming a protrusion with a diameter smaller than the central portion on the upper part of the material formed after the first preforming step (S300), and forming a slightly longer lower part;
A third preliminary step in which the entire upper and lower lengths of the material formed after the second preliminary forming step (S400) are formed shorter, and the upper outer circumference excluding the outer uppermost part forms a boundary in the downward direction and is sequentially formed with small diameters. molding step (S500);
The upper and lower total lengths of the material formed after the third preliminary forming step (S500) are formed longer, and the material formed after the third preliminary forming step (S500) has more boundaries in the downward direction than the material formed, and is sequentially reduced in diameter. A fourth preliminary forming step (S600) to be continuously formed;
a protruding frame forming step (S700) of forming shorter overall upper and lower lengths of the material formed after the fourth preforming step (S600) and forming a protruding frame having a larger diameter than the upper portion at the central portion; A method of forming a subframe mounting pipe bolt for an electric vehicle platform using a form forging technology, characterized in that it comprises a.

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