KR100800362B1 - Rust preventing lead screw and manufacturing process thereof - Google Patents

Abstract

A method for manufacturing a rust-preventing lead screw using a steel wire is provided to manufacture a lead screw having excellent surface strength and improved corrosion resistance, sticking resistance and heat resistance by nitriding a lead screw using a steel wire workpiece that is processed more easily than a stainless steel wire and is less expensive than a brass wire, thereby forming a nitride layer on a surface of the lead screw. A method for manufacturing a rust-preventing lead screw using a steel wire comprises: a screw manufacturing step of passing steel wire workpieces cut to a predetermined length through a rolling process using a rolling dies or form rolling dies to manufacture lead screws in which screw grooves are formed spirally; a screw injecting and aligning step of injecting a plurality of the manufactured lead screws into a nitriding heat treatment furnace and aligning the lead screws such that the lead screws are vertically set up with being spaced apart from one another in a predetermined distance; a heat treatment step of performing first to third heat treatment processes in the nitriding heat treatment furnace having the plurality of the lead screws set up therein using carbon dioxide gas and nitrogen gas; a nitriding step of performing first to third nitriding processes of the lead screws within the nitriding heat treatment furnace using ammonia gas, carbon dioxide gas and nitrogen gas to form a nitride layer with a thickness range of 0.002 to 0.03 mm on the entire surfaces of the lead screws; and a cooling step injecting nitrogen gas into the nitriding heat treatment furnace and cooling the lead screws to 0 deg.C for 30 to 60 minutes in the nitrogen gas atmosphere.

Description

Rust preventing lead screw and manufacturing process made of steel wire material

1 is an embodiment of a partially enlarged cross-sectional lead screw for explaining the present invention.

2 is a nitriding treatment operation state in the nitriding treatment furnace of the lead screw of the present invention.

Figure 3 is a lead screw manufacturing process of the present invention.

4 is a graph showing a process example of temperature, time, pressure and gas amount for forming a rust-resistant nitriding surface layer on a lead screw of the present invention.

※ Explanation of code for main part of drawing

1: Lead screw 11: Spiral groove

12: first 2: nitride layer

3: nitriding heat treatment 4: screw jig

41: fitting hole

The present invention relates to a method for manufacturing a rust-proof lead screw manufactured from steel wire, and more particularly, to a nitride layer for improving the wear resistance, corrosion resistance, heat resistance, and adhesion resistance of the steel wire. Is formed so that rust does not occur even when exposed to air for a long time, and the deformation is extremely small, which leads a reader to read a compact disc (CD) or a recording and recording tape in electronic products such as computers and audio and video. It provides a small screw called a screw or sled screw, and also relates to a method of manufacturing such that a nitride layer is formed on the surface of the lead screw.

In general, electronic products such as computers, audio, video, DVDs, notebooks, camcorders, cameras, etc., have a variety of small lead screws, including lead screws or sled screws that guide readers to read CDs, recordings, and tapes. The small lead screw mounted on the computer should not be rusted because it is exposed to the air, and the surface should be smooth, and it should be made of metal material with little deformation to prevent frequent breakdown of electronic products. In addition, it is possible to prevent various components of the electronic product from operating or to prevent malfunctions.

In the prior art, in order to satisfy the conditions described above, a lead screw made of a non-ferrous metal stainless steel wire or a brass wire is used. Since the former stainless steel wire has excellent strength, the number of processing steps for manufacturing a screw increases. On the other hand, labor costs continue to rise, resulting in a high production cost of stainless steel wire leadscrews, and the latter brass wire has a weaker strength than stainless steel wires, making it easier to process, thus reducing processing costs. However, since the raw material prices of brass have recently increased, the screw manufacturing industry predicts that the production cost of brass screws will gradually become expensive. Ways In search of

However, since electric and electronic product manufacturers are demanding to lower the cost of supplying lead screws to reduce the production cost of electronic products, rather than understanding the screw manufacturing industry as described above, research and development to lower the production cost of lead screw Investing a lot of money in the situation.

Therefore, the screw manufacturing industry cannot reduce the production cost unless the raw material price of the lead screw used in the electric and electronic products decreases. Therefore, the lead screw manufacturing equipment is moved to a country where labor cost is low, or a new equipment is installed there. By reducing the labor cost of manpower required to manufacture screws by increasing the production of lead screws, this is reducing the production cost of lead screw. This phenomenon causes lead screw manufacturers to get out of countries with low labor costs. As a result, the basic industries of the country are deteriorated, and when screw manufacturing companies are forced to go abroad, jobs are reduced so that unemployment is generated.

Therefore, the present invention was created in order to produce lead screws with self-sustaining power and competitive price in consideration of the above-mentioned matters, and are easier to process than stainless steel wire and are more expensive than brass wire. Lead screw manufactured from cheap steel wire (hereinafter referred to as 'steel wire') is made by nitriding the nitride to form a nitride layer on the surface to improve surface strength and to improve corrosion resistance, adhesion resistance and heat resistance. Lead screw products that are competitive in price against lead stainless steel and brass wires produced in countries where the surface is rust-free and smooth, and where labor costs are low, like lead screws made of conventional stainless steel wires and brass wires. It is invented for the purpose of providing a method for producing the same.

The present invention as a means for achieving the above object,

Lead screw of the present invention,

In a lead screw having a screw groove formed in a spiral shape,

The material of the lead screw is a steel wire, characterized in that the nitride layer is formed to a thickness of 0.005 ~ 0.008mm over the entire surface.

Lead screw manufacturing method of the present invention,

A screw manufacturing step of manufacturing a lead screw having a threaded groove formed in a spiral through a rolling process using a rolling die or a rolling die using a steel wire cut to a predetermined length;

A screw input and alignment step of inserting a plurality of lead screws manufactured in the above step into a nitriding heat treatment, and fixing each of the lead screws to be aligned in a vertically upright state spaced apart from each other at a predetermined interval;

Nitrogen heat treatment in which nitrogen gas (N ₂ ) is introduced into the nitriding heat treatment for 15 to 25 minutes during which the internal temperature is preheated from 0 ° C. to 440 to 490 ° C. by the nitriding heat treatment in which the plurality of lead screws are installed is 0.5 to 0.5 to nitrogen atmosphere. Carbon dioxide gas (CO ₂ ) and nitrogen for 8 to 13 minutes, heating from 440 to 490 ° C to 500 to 580 ° C, where the primary heat treatment process is preheated in a pressure atmosphere of 1.2 bar, and the above-mentioned primary heat treatment process is completed. A secondary heat treatment process in which a gas (N ₂ ) is added at a ratio of 50:50 to continuously heat in a 0.8 to 1.2 bar pressure atmosphere as in the first heat treatment process, and the second heat treatment process as described above. A heat treatment step comprising a third heat treatment step of performing heat treatment for 15 to 25 minutes at a temperature of 550 to 580 ° C. in an atmosphere in which carbon dioxide gas (CO ₂ ) and nitrogen (N ₂ ) are introduced at the same ratio;

While maintaining the same temperature as the tertiary heat treatment step of the heat treatment step, the nitriding treatment by heating in a pressure atmosphere of 1.2 to 3.5 bar, ammonia gas (NH) for 45 to 120 minutes from the completion of the secondary heat treatment process ₃ ) Primary nitriding treatment step of heat treatment by adding 55 to 90%, 5 to 10% of carbon dioxide gas (CO ₂ ), and 5 to 35% of nitrogen gas (N ₂ ); Subsequent to the second nitriding process for releasing the gas introduced into the nitriding heat treatment for 15 to 25 minutes, followed by the first and the second nitriding in the atmosphere where the gas was discharged by nitriding heat treatment for 30 to 60 minutes. Nitriding to form a nitride layer with a thickness of 0.002 to 0.03mm on the entire surface of the lead screw in the third nitriding treatment process in which the heat treatment is performed while gradually lowering the temperature from 500 to 580 ° C to 450-500 ° C. A processing step;

After the nitriding treatment step is completed, a nitrogen gas (N ₂ ) is added to the cooling step to cool to 0 ℃ for 30 to 60 minutes under a nitrogen gas atmosphere; consisting of a nitride layer formed on the surface of the lead screw made of steel wire material Characterized in that it is configured to.

In addition, in the tertiary nitriding treatment step of the nitriding treatment step, oxygen gas (O ₂ ) is introduced to generate an oxide layer on the surface of the nitride layer formed on the lead screw, and then undergoes a cooling step.

In addition, it characterized in that it further comprises a surface polishing step for smoothly processing the surface of the nitride layer formed on the surface of the lead screw through the cooling step.

Further, in the screw input and alignment step, a means of fitting one end of the lead screw into each of the fitting holes formed in the vertically and horizontally on the upper surface of the plate-shaped screw jig which is horizontally installed on the floor by nitriding heat treatment. A structure for fixing a plurality of lead screws vertically one by one, characterized in that the nitriding heat treatment in a state in which the entire surface of the lead screw except for one end inserted into each of the fitting holes is exposed to the nitriding heat treatment furnace.

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

1 is an embodiment of a partially enlarged cross-sectional lead screw for explaining the present invention, Figure 2 is a nitriding treatment state diagram of the lead screw of the present invention in the nitriding treatment furnace, Figure 3 is a lead screw of the present invention 4 is a manufacturing process diagram, and FIG. 4 shows a graph showing a process example of temperature, time, pressure, and gas amount for forming a rust-resistant nitriding surface layer on a lead screw of the present invention.

In the drawing, reference numeral 1 denotes a lead screw, and the lead screw 1 is made of steel wire. That is, when the steel wire is cut to a predetermined length and then the rolling or rolling process of the steel wire using a conventional rolling die or a rolling die, the lead screw 1 having a screw groove 11 having a desired pitch and depth in a spiral shape is formed. The lead screw (1) manufactured as described above is made of a steel wire material, so if it is exposed to air for a long time, rust may be generated, and thus it cannot be used as an electric and electronic component.

Therefore, in the present invention, in order to be able to use the lead screw (1) made of steel wire as a component of an electronic product, while providing corrosion resistance to prevent rusting on the surface thereof, wear resistance, heat resistance can be improved, and surface strength can be improved. The nitride layer 2 which exists is formed.

The nitride layer 2 penetrates and diffuses to a predetermined depth while the generator nitrogen atoms are adsorbed on the surface of the lead screw 1 to harden the surface and to improve corrosion resistance, wear resistance, heat resistance, and the like.

In addition, the nitride layer 2 is formed not only on the surface of the lead screw 1 but also on the threaded groove 11 formed in a spiral shape with a thickness within the range of 0.002 to 0.03 mm (more preferably 0.003 to 0.029 mm), which is very thin. have. When the thickness of the nitride layer 2 is formed to be thinner than 0.002 mm, there is a concern that the generator nitrogen atoms may not be evenly adsorbed on the surface of the lead screw 1 or the rust may not be completely prevented. When formed thicker than 0.03mm, the nitriding heat treatment time is long, the energy consumption is increased and the production cost is increased. Thus, the nitride layer 2 is formed within the range of 0.002 to 0.03mm as described above. It is preferable.

On the other hand, the nitride layer 2 is not formed at one end 12 of the lead screw 1. One of the reasons is that the lead screw (1) is heated in a semi-melt state by high heat when it is put into the nitriding heat treatment furnace (3) to form the nitride layer (2) on the lead screw (1) made of steel wire and nitriding. In order to prevent bending), it is necessary to fix the lead screw (1) upright in a vertical state. For this purpose, one end (12) of the lead screw (1) has a plate-shaped screw jig. This is because one end 12 inserted into each fitting hole 41 is not exposed to the inside of the nitriding heat treatment furnace 3 because it is fixed to each of the plurality of fitting holes 41 formed on the upper surface of (4). At least one end 12 of both leads screw 1 mounted on the cover is concealed so that a magnetic component for imparting rotational power is assembled or attached to a supporting structure such as a bracket so as not to be exposed to air. Is that it is so that the area does not need to form a nitride layer (2).

Next, a manufacturing process for forming the nitride layer 2 in which the generator nitrogen atoms are adsorbed and diffused on the lead screw 1 made of steel wire as described above will be described as follows.

<Screw Manufacturing Steps>

It is made of steel wire, and it is a steel wire cut to a certain length so that it can be used for electronic products by rolling or rolling by using rolling dice or rolling dies that are used to continuously manufacture existing lead screws. Small lead screw such that the screw groove 11 is formed in a spiral shape on the entire body except the 12 or the screw groove 11 is formed in the body except the knurled portion that is knurled at the other end of the other end 12. 1) manufacturing step.

<Screw injection and alignment step>

In the screw manufacturing step, a plurality of lead screws (1) processed to be used for electrical and electronic products are introduced into the nitriding heat treatment furnace (3), and the lead screws (1) are subjected to high heat when nitriding heat treatment. In order to prevent bending even when heated in a semi-melt state, and to allow nitriding heat treatment without interfering between neighboring lead screws (1), the lead screws (1) can be fixed in an upright position. Screw jig 4 is used.

On the upper surface of the screw jig (4) it is possible to fix a plurality of lead screws (1) one end 12, one by one, and to fix each of the lead screws (1) upright in a state spaced at a predetermined interval. A plurality of fitting holes 41 are formed, and the plurality of fitting holes 41 are formed at a suitable interval and spaced apart from each other. Accordingly, when one end 12 of each of the lead screws 1 is inserted into each fitting hole 41 of the screw jig 4 and fixed to be vertical, the screw jig 4 has a plurality of lead screws 1. ) Are arranged in a plurality of rows spaced at appropriate intervals, so that each of the plurality of lead screws (1) introduced into the nitriding heat treatment furnace (3) as shown in Figure 2 to the screw jig (4) Not only can the lead screws 1 be preheated and heated evenly in each of the heat treatment step and the nitriding treatment step which will be described later. Nitrogen atoms are evenly adsorbed and penetrated and diffused on the surface of the heated lead screws to uniformly form the nitride layer 2 with the same thickness (0.002 to 0.03 mm).

And the screw jig (4) is installed in a multi-stage by spaced at appropriate intervals up and down by using a support column, and arranged a plurality of lead screw (1) vertically to each of the screw jig (4) installed in each end When the nitriding treatment is carried out in the nitriding heat treatment furnace 3 in a state, the nitriding layer 2 can be formed on the surface of the lead screw 1 in a larger amount by one nitriding treatment.

<Heat treatment step>

This step is a step of preheating and heating a plurality of lead screws (1) introduced into the nitriding heat treatment furnace in the screw input and alignment step to heat-treat, to form the nitride layer (2) on the surface of the lead screw (1) efficiently In order to make the first to third heat treatment process, the heat treatment conditions are different. In other words,

In the first heat treatment process, the temperature is maintained at a high temperature within the range of 0 ° C to 450 ° C to 490 ° C while maintaining the inside of the nitrification heat treatment furnace 3 under a nitrogen gas (N ₂ ) atmosphere within a pressure range of 0.5 to 1.2 bar. The time period for the primary train separation process is about 15 to 25 minutes.

In the secondary heat treatment process, carbon dioxide gas (CO ₂ ) and nitrogen gas (N ₂ ) are introduced into the nitriding heat treatment furnace 3 at a ratio of 50:50, respectively, based on the percentage (%), and the above-described primary process is performed. As in the heat treatment process, preheating is performed within the pressure range of 0.5 to 1.2 bar, and 8 to 13 minutes from the time when the above-mentioned first heat treatment process is completed to reach the maximum temperature of 500 to 580 ° C. to be preheated. During the preheating process.

The third heat treatment process is performed at the same temperature (500 to 590 ° C.), the same pressure (0,5 to 1.2 bar), and the same gas atmosphere (50% of CO ₂ and N _2, respectively) at the same temperature as the second heat treatment process. It proceeds to the process of heat processing for -25 minutes.

<Nitriding step>

This step is performed continuously after the third heat treatment step of the heat treatment step to form a nitride layer (2) on the surface of the lead screw (1), the nitriding treatment process divided into first to third heating process Will proceed. In other words,

In the first nitriding treatment step, 55 to 90% of ammonia gas (NH ₃ ) and carbon dioxide are used to form a nitride layer on the surface of the lead screw 1 while maintaining the same temperature as in the third heat treatment step of the heat treatment step. In the state in which the gas (C0 ₂ ) 5-10%, the nitrogen gas (N ₂ ) 5-35% at a rate of 1.2 to 3.5 bar at a pressure of 45 to 120 minutes to proceed to the process.

The secondary nitriding treatment proceeds to a heat treatment for 15 to 25 minutes at the same temperature and the same pressure as the first nitriding treatment in the state where the gas introduced during the first nitriding treatment is discharged.

The tertiary nitriding process is carried out for 30 to 60 minutes while the gas is discharged as in the secondary nitriding process, wherein the heat treatment temperature is the lowest temperature of 500 ° C. in the temperature range of the secondary nitriding process. It proceeds to the process of heat treatment in the temperature range of 450 ℃ lower than that.

As described above, the nitrogen gas (N ₂ ), carbon dioxide (CO ₂ ) and ammonia gas (NH ₃ ) introduced in the first nitriding treatment process are catalysts on the surface of the lead screw 1 heated to a high temperature of 500 to 580 ° C. Pyrolysis by the action, the nitrogen element generated during the pyrolysis is adsorbed to the surface of the lead screw (1) to penetrate and diffuse therein to form a nitride layer (2), since the adsorption and diffusion on the surface of the lead screw (1) The nitride layer 2 thus formed is formed to a thickness of approximately 0.002 to 0.03 mm.

In addition, the nitride layer 2 formed by the adsorption and diffusion of the generator nitrogen element generated during the thermal decomposition of the gas introduced in the first nitriding treatment step is stabilized during the second and third nitriding treatment steps. In the third nitriding treatment process, the heat treatment process may be performed in a state in which the entire amount of gas is discharged by nitriding heat treatment, and the heat treatment process may be performed in the state where oxygen gas (O ₂ ) is added. In this case, an oxide layer (Fe ₃ O ₄ ) is formed on the surface of the nitride layer 2 to further improve corrosion resistance, wear resistance, and surface strength of the lead screw 1.

<Cooling stage>

This step is to cool the lead screw (1) after the nitriding treatment step in the nitriding heat treatment furnace (3), in which nitrogen gas is introduced into the nitriding heat treatment furnace (3) to maintain a pressure of 2 to 4 bar. In this state, it is cooled for 30 to 60 minutes.

<Surface Polishing Step>

This step is a process of smoothly polishing the rough surface of the nitride layer 2 formed on the lead screw 1 cooled in the cooling step, and the polishing machine used is a barrel that is easy to polish a large amount of lead screw. A grinder is used.

On the other hand, the small screw (1) made of a steel wire material and nitrided as described above may exhibit a fine thermal expansion phenomenon when the heat treatment in the nitriding heat treatment furnace (3) to form a nitride layer (2) on its surface have. Therefore, the steel wire material of the small screw (1) in consideration of the thermal expansion when forming the nitride layer (2) is a steel wire having a fine diameter smaller than the diameter of the finished product of the lead screw (1) formed with the nitride layer (2) When the lead screw is manufactured from a material and then subjected to nitriding, the lead screw 1 having the same diameter as the finished product can be manufactured, and thus the outer diameter of the nitride layer 2 formed on the outer surface of the lead screw 1 in the surface polishing step. The polishing process time can be shortened by not having to polish and shrink as much as the thermal expansion of the finished product.

According to the present invention as described above, the nitride layer on the surface of the lead screw made of steel wire of the general steel material without the production of various non-ferrous metal wire such as stainless steel and brass of various lead screws used in electrical and electronic products As a means of forming the lead screw, the strength of the lead screw can be improved and corrosion resistance, abrasion resistance, heat resistance, and adhesion resistance can be improved. Therefore, even when the lead screw made of steel wire is used in electronic products, it does not generate rust. Since the lead screw of the present invention can be manufactured at a lower production cost than the lead screw made of expensive non-ferrous metal wire, it is possible to provide a lead screw with a competitive price against the non-ferrous metal lead screw produced in a country where labor costs are low. Major contribution to the development of the screw manufacturing industry To have.

Claims (5)

delete A screw manufacturing step of manufacturing a lead screw having a threaded groove formed in a spiral through a rolling process using a rolling die or a rolling die using a steel wire cut to a predetermined length; A screw input and alignment step of inserting a plurality of lead screws manufactured in the above step into a nitriding heat treatment, and fixing each of the lead screws to be aligned in a vertically upright state spaced apart from each other at a predetermined interval; Nitrogen heat treatment in which nitrogen gas (N ₂ ) is introduced into the nitriding heat treatment for 15 to 25 minutes during which the internal temperature is preheated from 0 ° C. to 440 to 490 ° C. by the nitriding heat treatment in which the plurality of lead screws are placed is 0.5 to Carbon dioxide gas (CO ₂ ) and nitrogen for 8 to 13 minutes, heating from 440 to 490 ° C to 500 to 580 ° C, where the primary heat treatment process is preheated in a pressure atmosphere of 1.2 bar, and the above-mentioned primary heat treatment process is completed. A secondary heat treatment process in which a gas (N ₂ ) is added at a ratio of 50:50 to continuously heat in a 0.8 to 1.2 bar pressure atmosphere as in the first heat treatment process, and the second heat treatment process as described above. A heat treatment step comprising a third heat treatment step of performing heat treatment for 15 to 25 minutes at a temperature of 550 to 580 ° C. in an atmosphere in which carbon dioxide gas (CO ₂ ) and nitrogen (N ₂ ) are introduced at the same ratio; While maintaining the same temperature as the tertiary heat treatment step of the heat treatment step, the nitriding treatment by heating in a pressure atmosphere of 1.2 to 3.5 bar, ammonia gas (NH) for 45 to 120 minutes from the completion of the secondary heat treatment process ₃ ) Primary nitriding treatment step of heat treatment by adding 55 to 90%, 5 to 10% of carbon dioxide gas (CO ₂ ), and 5 to 35% of nitrogen gas (N ₂ ); Subsequent to the second nitriding process for releasing the gas introduced into the nitriding heat treatment for 15 to 25 minutes, followed by the first and the second nitriding in the atmosphere where the gas was discharged by nitriding heat treatment for 30 to 60 minutes. Nitriding to form a nitride layer with a thickness of 0.002 to 0.03mm on the entire surface of the lead screw in the third nitriding treatment process in which the heat treatment is performed while gradually lowering the temperature from 500 to 580 ° C to 450-500 ° C. A processing step; After the nitriding treatment step is completed, a nitrogen gas (N ₂ ) is added to the cooling step to cool to 0 ℃ for 30 to 60 minutes under a nitrogen gas atmosphere; consisting of a nitride layer formed on the surface of the lead screw made of steel wire material Method for producing a rust-proof lead screw made of a steel wire material, characterized in that configured to. The method of claim 2, In the third nitriding treatment step of the nitriding treatment step, oxygen gas (O ₂ ) is introduced to produce an oxidized layer on the surface of the nitride layer formed on the lead screw, followed by a cooling step. Method of producing a preventive lead screw. The method of claim 2 or 3, And a surface polishing step for smoothly processing the surface of the nitride layer formed on the surface of the lead screw through the cooling step. The method of claim 2, In the screw input and alignment step, a plurality of holes in each of the fitting holes are provided by means of fitting one end of the lead screw into each of the fitting holes formed vertically and horizontally on the upper surface of the plate-shaped screw jig which is horizontally installed on the floor by nitriding heat treatment. A structure for fixing lead screws vertically one by one, wherein the entire surface of the lead screw except for one end inserted into each of the fitting holes is heat-nitrided while being exposed to a nitriding heat treatment furnace. Method of manufacturing antirust small screws.

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