KR102562536B1 - Manufacturing method of locknut for steering system of vehicle - Google Patents

Abstract

The present invention relates to a manufacturing method of a locknut for a steering system of a vehicle. More specifically, the manufacturing method of a locknut for a steering system of a vehicle comprises: molding an approximate shape of the locknut by a hot forging step, which is an upsetting step, a blocking step, and a trimming step; increasing strength and removing inner stress of a semi-manufactured product molded in the locknut shape by a heat processing step; and performing heat processing one more time by a cold forging step after molding the shape of the locknut, then removing the inner stress, and then manufacturing the product having a right size by a cutting processing step. Accordingly, the present invention may reduce production time and costs by reducing processes by cutting processing, and enable mass production.

Description

Manufacturing method of locknut for steering system of vehicle {Manufacturing method of locknut for steering system of vehicle}

The present invention relates to a method for manufacturing a lock nut used in a steering device of a vehicle, and more particularly, by forming a lock nut into an approximate shape through a hot forging step, that is, an upsetting step, a blocking step, and a trimming step, and The semi-finished product formed by heat treatment increases the strength and removes internal stress. Then, it is molded into the shape of a lock nut by cold forging, and heat treatment is performed once more to remove internal stress. It is a method of manufacturing a lock nut for a steering device of a vehicle, which can reduce production time and cost by reducing the cutting process by manufacturing a product of, and mass production is possible.

The vehicle's steering system rotates the wheels of the vehicle by organically combining various parts, including the steering wheel, steering column, electronic control unit (ECU), and rack bar. There is a lock screw as a part having a similar function.

The lock nut or lock screw is usually provided on one side of a ball nut installed for the movement of a tie rod connected to a wheel and installed on one side of a bearing supporting rotation of the ball nut, and must be processed to precise dimensions and have durability. It is difficult to manufacture with general casting because it must be relatively higher than general parts, and when a product is produced by machining, there are many parts to be cut from raw materials, resulting in severe material waste, which leads to excessive production cost and production time. There was a problem with consumption.

As a prior art related to such a lock nut or lock screw, there is a rack-driven power-assisted steering device proposed in Patent Registration No. 10-1809774.

The above patent has an outer circumferential screw groove formed on an outer circumferential surface, and a rack bar located in a rack housing; An inner circumferential screw groove corresponding to the outer circumferential screw groove is formed on an inner circumferential surface so as to be coupled to the rack bar via a ball, a bearing is coupled to one side of the outer circumferential surface, and a drive pulley connected to a shaft of an electric motor and a drive belt are connected to the other outer circumferential surface. A ball nut to which a driven pulley is coupled; An annular lock having a protruding end protruding inward in a radial direction on one side of an inner circumferential surface to support one side of the bearing and a separation prevention part protruding axially from the protruding end portion, the outer circumferential surface of which is supported on the inner surface of the rack housing. screw; and an annular elastic support coupled between the protruding end of the lock screw and the bearing, wherein when the elastic support is damaged, the separation preventing part limits the radial movement of the elastic support, and the protruding end of the lock screw A rack-driven power-assisted steering device is proposed, characterized in that a flow prevention portion protruding radially inward is formed on the inner circumferential surface adjacent to the elastic support to prevent radial flow of the elastic support, which is only shown for the approximate shape of the lock screw. However, the specific manufacturing method is not specified.

Another prior art related to a lock nut or lock screw is a lock screw assembly of a rack-driven steering device disclosed in Patent Publication No. 10-2016-0102742.

The patent includes a ball nut for linearly reciprocating a rack bar while being rotated by a drive motor; Unit lock screw bodies separated from each other while facing each other on the outside of the ball nut to be inserted into the seating groove of the reducer in a state where the ball nut is seated in the reducer; And a lock screw assembly of a rack-driven steering device including a coupling pin inserted into an insertion groove formed inside a separated end of the unit lock screw body to maintain the unit lock screw body in an assembled state with each other. , Since the lock screw is composed of two bodies and coupled through a coupling pin, there may be a problem with the durability of the lock screw itself being low, and this is also shown only for the approximate shape and structure of the lock screw, and the specific manufacturing method is not specified for

Republic of Korea Patent Registration No. 10-1809774 (2017. 12. 15. Notice) Republic of Korea Patent Publication No. 10-2016-0102742 (published on August 31, 2016)

Therefore, the present invention is formed into the shape of a lock nut by the hot forging step, that is, the upsetting step, the blocking step, and the trimming step, and then formed into the exact shape of the lock nut except for the face or corner to be cut by the cold forging step. The purpose is to provide a method of manufacturing a lock nut for a steering device of a vehicle that can reduce production time and cost by reducing the process by cutting process and mass production is possible by manufacturing it as a product of fixed number through the subsequent cutting process step. .

In addition, the semi-finished product made through the upsetting, blocking, and trimming steps, which are the hot forging steps, has its hardness increased through the heat treatment step, and the cold forging step is performed in a state in which the hardness has increased, thereby preventing distortion or deformation of the material and improving durability. Another object is to provide a method for manufacturing a lock nut for a steering device of a vehicle that has been raised.

In addition, the size of the through hole drilled through the trimming step is to have a smaller diameter by 1 to 3 mm than the size of the through hole to be made, so that a sufficient amount of cutting can be secured when cutting the inner diameter, preventing damage to cutting tools such as bites, Another object is to provide a method for manufacturing a lock nut for a steering device of a vehicle capable of producing a product with high dimensional accuracy by preventing vibration that may occur during cutting.

A method of manufacturing a lock nut for a steering device of a vehicle according to the present invention includes a raw material preparation step (S10) of cutting a rod-shaped material into a certain size, and the prepared raw material The heating step (S 20) of heating, the hot forging step (S 30) of plastically transforming the raw material in the heated state into the shape of a lock nut using a press and a mold (S 30), in order to increase the hardness of the material made in the shape of the lock nut A first heat treatment step (S 40) of performing heat treatment, a cold forging step (S 60) of plastic deformation using a press and a mold to adjust the shape of the heat treated material to a fixed number (S 60), and removing the stress remaining inside the material It is characterized by consisting of a secondary heat treatment step (S 70) for processing and a cutting step (S 90) of cutting the outer and inner surfaces of the material.

A method for manufacturing a lock nut for a steering device of a vehicle according to the present invention is formed into a lock nut shape through hot forging steps, that is, an upsetting step, a blocking step, and a trimming step, and then a surface or corner to be cut by a cold forging step. After molding into the exact shape of the lock nut except for the cutting process, it is produced as a product of fixed number through the cutting process, which reduces the process by cutting process to reduce production time and cost, and has a remarkable effect that enables mass production. Semi-finished products made through forging steps such as upsetting, blocking, and trimming are hardened through a heat treatment step, and cold forging is performed in a state where the hardness is increased to prevent distortion or deformation of the material and increase durability. , The size of the through-hole drilled through the trimming step should have a diameter that is 1 to 3 mm smaller than the size of the through-hole to be made, so that a sufficient amount of cutting can be secured when cutting the inner diameter, preventing damage to cutting tools such as bites and cutting It has a remarkable effect of producing products with high dimensional accuracy by preventing vibration that may occur during processing.

1 is a perspective view of the configuration of a lock nut according to the present invention
Figure 2 is a perspective view of the configuration of the lock nut after the finishing step before the piercing step of the present invention
3 is a flowchart of the overall configuration of the present invention
Figure 4 is a partial process description of the present invention
Figure 5 is a plan view of the lock nut after the piercing step

The present invention relates to a method for manufacturing a lock nut used in a steering device of a vehicle, and more particularly, by forming a lock nut into an approximate shape through a hot forging step, that is, an upsetting step, a blocking step, and a trimming step, and The semi-finished product formed by heat treatment increases the strength and removes internal stress. Then, it is molded into the shape of a lock nut by cold forging, and heat treatment is performed once more to remove internal stress. It is a method of manufacturing a lock nut for a steering device of a vehicle, which can reduce production time and cost by reducing the cutting process by manufacturing a product of, and mass production is possible.

1 is a perspective view of the configuration of a lock nut according to the present invention, and FIG. 2 is a perspective view of a lock screw that has finished the finishing step before the piercing step of the present invention. A total of six slots 11 are formed in a non-continuous manner along, a through hole is formed in the center, and a screw thread is formed on the circumferential surface of the outer rim of the body 10.

The lock nut shown in FIG. 2 is a lock nut that has completed the finishing step before the piercing step, and the bottom part 12 remains in the center.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

3 is a flowchart of the overall configuration of the present invention, FIG. 4 is a partial process description of the present invention, and FIG. 5 is a plan configuration diagram of a lock nut after the piercing step is completed. In the method for manufacturing a lock nut used in a steering device of a vehicle, a raw material preparation step of cutting a rod-shaped material into a certain size (S 10), a heating step of heating the prepared raw material (S 20), and a heated state A hot forging step of plastically deforming the raw material into a lock nut shape using a press and a mold (S30), and a first heat treatment step of performing heat treatment to increase the hardness of the material made in the shape of a lock nut (S40); A cold forging step (S 60) of plastic deformation using a press and a mold to adjust the shape of the heat treated material to a constant number, a second heat treatment step (S 70) to remove the stress remaining inside the material, and the material It is characterized by consisting of; a cutting step (S90) of cutting the outer and inner surfaces of.

First, the raw material preparation step (S 10) is a step of cutting and preparing a rod-shaped material according to the weight of the lock nut 1 to be made. You can prepare for the loss that occurs.

The heating step (S 20) is a step of softening the organization by heating the prepared raw material with high frequency, the heating temperature is heated between 1100 ~ 1300 ℃, and the material in the heated state is hot forged in the step (S 30) with a press It is plastically deformed using a mold.

The semi-product molded into the shape of the lock nut through the hot forging step (S 30) is moved to the first heat treatment step (S 40) to be heat treated, and the first heat treatment step (S 40) is quenching and loosening. (Annealing) is performed sequentially to increase the hardness of the material and to remove internal cracks in the material hardened by quenching.

The material that has been heat treated through the first heat treatment step (S 40) is plastically transformed in shape and dimension through the cold forging step (S 60) to be made into a product of fixed number, and is plasticized through the cold forging step (S 60). The deformed semi-finished product is subjected to heat treatment once again through the second heat treatment step (S70) to remove internal stress, and then transferred to the machine tool that performs the cutting step (S90) to perform cutting on the outer and inner surfaces. do.

In addition, the hot forging step (S 30) includes an upsetting step (S 31) of plastically deforming the raw material in a heated state to reduce the height and increase the width using a press and a mold, and press the material after the upsetting. It consists of a blocking step (S 32) of plastic deformation into the shape of a lock nut using a mold and a trimming step (S 33) to remove burrs remaining on the outside of the material and drill a through hole, and the material is upsetting (S 31), blocking step (S 32) and trimming step (S 33) are sequentially processed.

The upsetting step (S31) is a step of putting a rod-shaped material heated by a high-frequency heater into a mold and pressing it using a press to make it into a disc shape, and the blocking step (S32) is the upsetting step (S31 ) is a step of molding a disc-shaped material into a rough shape of a lock nut using a press and a mold, and the trimming step (S33) is for removing burrs remaining on the outside of the molded semi-finished product and drilling a through hole. It is fair.

The upsetting step (S 31), the blocking step (S 32), and the trimming step (S 33) are all hot forging steps, so that the material is molded while the temperature of the material is higher than a certain temperature. A chute is installed, and the material in a heated state is discharged along the supply chute, and the supply chute is installed in a closed state except for the side where the material is discharged, so that the temperature of the material rapidly decreases during the transfer of the material prevent that

In addition, a temperature sensor is attached to one side of the forging mold used in the upsetting step (S 31), blocking step (S 32) and trimming step (S 33), and the material is pressed into the forging mold on one side of the forging mold. A release agent spraying device is installed to spray the release agent to prevent sticking, and after the material is injected into the mold and one product is molded and ejected, the release agent is automatically sprayed toward the surface of the mold to prevent the material from sticking, and the amount of release agent sprayed It is automatically adjusted according to the temperature of the silver forging mold.

That is, when the temperature of the forging mold is higher than the set temperature value, the temperature of the forging mold can be lowered by increasing the amount of injection of the release agent, thereby preventing the temperature of the mold from rising rapidly to increase the lifespan of the mold, It is possible to further increase the dimensional accuracy of the molded product by preventing thermal deformation of the molded product.

Here, the blocking step (S 32) is a hot forging process in which the material is formed into the shape of the lock nut using a press and a mold in a state where the temperature of the material is higher than room temperature. The bottom part 12 is formed in the body 10 of the lock nut, the thickness of the bottom part 12 is 1 to 3 mm, and the size of the through hole drilled through the trimming step (S 33) is the size of the through hole to be made. It has a diameter smaller than 1-3 mm.

That is, in the blocking step (S 32), the product is plastically deformed without removing the bottom portion 12, and then the through hole 13 is drilled in the trimming step (S 33), and in the trimming step (S 33) The size of the through hole 13 to be drilled has a smaller diameter by about 1 to 3 mm than the size of the through hole to be finally made.

In addition, referring to Figure 4, the blocking step (S 32) can be divided into two processes, in this case, the first blocking step (S 32-1) and the second blocking step (S 32-2) The second blocking step (S32-2) is a finisher step, and if it is difficult to make a complete shape by one blocking step, the process can be separated into two steps. That is, the second blocking step (S32-2) is a finisher step, and the product molded in the first blocking step (S32-1) is once again molded.

Referring to FIG. 5, if the diameter (D) of the through hole of the lock nut to be made is 60 mm, the diameter (d) of the through hole 13 drilled in the trimming step (S33) is drilled with a diameter between 56 and 59 mm, and then Through the cutting process, the diameter of the through hole 13 is drilled to 60 mm, whereby the exact size of the through hole 13 can be matched.

In addition, between the first heat treatment step (S 40) and the cold forging step (S 60), a shot blasting step (S 50) is further performed to remove the oxide film attached to the surface of the material, and the second heat treatment step (S 70) and the cutting process step (S90), a shot blasting step (S80) is further performed to remove the oxide film.

That is, the shot blasting step (S50, S80) uses a shot blaster device to spray small steel balls toward the heat-treated material with strong pressure to remove foreign substances such as oxide film or rust attached to the surface of the material. In addition, no burr is left on the outside of the material by the two shot blasting steps (S 50 and S 80), and thus, a separate trimming process or cutting process for the outside of the material, especially the corner part, is not required.

In addition, the cutting step (S 90) consists of a first cutting step (S 91) of cutting the inner diameter and end face, and a second cutting step (S 92) of machining the outer diameter and screw. In the cutting process step (S91), while the outer diameter of the lock nut semi-finished product is chucked, the lock nut is rotated to cut the inner diameter and end surface, and in the second cutting process step (S92), the outer diameter of the lock nut is rotated while the inner diameter is chucked. and screws are processed.

That is, in the cutting step, the inner diameter and cross section of the lock nut are processed through the first cutting step (S91). Since the outer surface of the lock nut is circular, the lock nut is rotated while the outer surface is chucked to perform a CNC lathe-like operation. The inner diameter and the end face are cut using a machine, and then the outer diameter is machined through the through hole, that is, the inner surface is chucked through the second cutting step (S92), and the screw is machined if necessary.

Here, in the blocking step (S 32), the outer edge and inner edge of the slot portion 11 are formed to have a lower curvature than the product to be finally made, and then in the cold forging step (S 60), the outer edge and inner edge of the slot portion 11 and By forming the inner corner with the same high curvature as the final product, the usage time of the mold can be further increased.

The forged product of the lock nut manufactured through the shot blasting step (S80) goes through an inspection step (S85) before being sent to the cutting step (S90). The inspection step (S85) is a magnetic particle inspection step ( S 86) and appearance and dimension inspection step (S 87).

In the magnetic particle inspection step (S 86), the magnetic particle concentration is 015 ~ 0.258mm / 100ml, the magnetic particle type is LY-40, the magnetization current is 2000 ~ 3000A / m, and the lock screw sample is inspected at an ultraviolet intensity of 800 Lux or more Cracks should not occur in the internal structure and leakage magnetic field should not occur, and in the external appearance and dimension inspection step (S87), cracks or overlapping phenomena should not occur in the external appearance.

As a result, in the manufacturing method of a lock nut for a steering device of a vehicle according to the present invention, the hot forging step, that is, the upsetting step, the blocking step, and the trimming step are formed into the shape of a lock nut, and then the cold forging step is performed to cut the surface or After molding into the exact shape of the lock nut except for the corners, it is produced as a product of fixed number through the cutting process, which reduces the process by cutting, thereby reducing production time and cost, and has a remarkable effect of mass production. The half-finished product made through the upsetting, blocking, and trimming steps, which are the hot forging steps, has an effect of preventing distortion or deformation of the material and enhancing durability by increasing the hardness through the heat treatment step and performing the cold forging step in a state in which the hardness is increased. In addition, the size of the through hole drilled through the trimming step is to have a smaller diameter by 1 to 3 mm than the size of the through hole to be made, so that a sufficient amount of cutting can be secured when cutting the inner diameter, preventing damage to cutting tools such as bites. It has a remarkable effect of producing products with high dimensional precision by preventing vibration that may occur during cutting.

1. Locknut
10. Body 11. Slot part
12. Bottom part 13. Through hole
S 10; raw material preparation step S 20; heating step
S 30; Hot forging step S 31; upsetting step
S32; Blocking step S 33; trimming step
S40; 1st heat treatment step S 50; shot blasting step
S 60; Cold forging step S 70; 2nd heat treatment step
S80; Shot blasting step S 85; inspection step
S90; Cutting process step S 91; 1st cutting process step
S92; 2nd cutting process step

Claims (5)

In the method of manufacturing a lock nut used in a steering device of a vehicle,
A raw material preparation step of cutting the rod-shaped material into a certain size (S 10), a heating step of heating the prepared raw material (S 20), and firing the heated raw material into a lock nut shape using a press and a mold. The hot forging step of deforming (S 30), the first heat treatment step of performing heat treatment to increase the hardness of the material made in the shape of the lock nut (S 40), and the press and mold to match the shape of the heat treated material to the fixed number A cold forging step of plastic deformation using (S60), a secondary heat treatment step for removing stress remaining inside the material (S70), and a cutting step of cutting the outer and inner surfaces of the material (S90) ; is made up of,
The hot forging step (S 30) includes an upsetting step (S 31) of plastically deforming the raw material in a heated state using a press and a mold to reduce the height and increase the width, and the press and mold of the raw material after the upsetting process. It consists of a blocking step (S 32) of plastic deformation into the shape of a lock nut by using , a trimming step (S 33) to remove burrs remaining on the outside of the material and drill a through hole, and the material is upset (S 32). 31), the blocking step (S 32) and the trimming step (S 33) are processed sequentially,
The blocking step (S32) is a hot forging process in which the material is formed into the shape of the lock nut using a press and a mold in a state where the temperature of the material is higher than room temperature. A bottom portion 12 is formed on the body 10, the thickness of the bottom portion 12 is 1 to 3 mm, and the size of the through hole drilled through the trimming step (S 33) is 1 greater than the size of the through hole to be made. It has a diameter as small as ~3 mm,
The upsetting step (S 31), blocking step (S 32), and trimming step (S 33) are all hot forging steps, in which the material is molded while the temperature of the material is higher than a certain temperature, and is supplied to one side of the high frequency heater. A chute is installed, and the material in a heated state is discharged along the supply chute, and the supply chute is installed in a closed state except for the side where the material is discharged, so that the temperature of the material rapidly decreases during the transfer of the material prevent it,
A temperature sensor is attached to one side of the forging mold used in the upsetting step (S 31), blocking step (S 32) and trimming step (S 33), and one side of the forging mold is so that the material does not stick to the forging mold. A release agent spraying device is installed to spray the release agent. After the material is injected into the mold and one product is molded and discharged, the release agent is automatically sprayed toward the surface of the mold to prevent the material from sticking, so the amount of release agent injected is monotonous. It is automatically adjusted according to the temperature of the mold,
The blocking step (S 32) consists of a first blocking step (S 32-1) and a second blocking step (S 32-2), and the second blocking step (S 32-2) is a finisher step. A method of manufacturing a lock nut for a steering device of a vehicle, characterized in that the product molded in the blocking step (S32-1) is once again molded.
delete delete According to claim 1,
Between the first heat treatment step (S 40) and the cold forging step (S 60), a shot blasting step (S 50) is further performed to remove the oxide film attached to the material surface, and a second heat treatment step (S 70) A method of manufacturing a lock nut for a steering device of a vehicle, characterized in that a shot blasting step (S80) for removing an oxide film is further performed between the and the cutting process step (S90).
According to claim 1,
The cutting step (S 90) consists of a first cutting step (S 91) of cutting the inner diameter and end face, and a second cutting step (S 92) of machining the outer diameter and the screw. Step (S91) rotates the lock nut while chucking the outer diameter of the lock nut semi-finished product to cut the inner diameter and end face, and the second cutting step (S92) rotates the lock nut while chucking the inner diameter to cut the outer diameter and screw A method of manufacturing a lock nut for a steering device of a vehicle, characterized by processing.