JPH03149406A - Manufacture of drill thread - Google Patents

Abstract

PURPOSE:To enhance corrosion resistance and drill performance as well at a low cost by plating the whole surface of a drill thread with zinc, tin or solder so as to be heat-treated after the drill has been tempered, removing oxides produced by the aforesaid processes, and thereby forming a corrosion preventive surface film thereafter. CONSTITUTION:After the whole surface of a drill thread 10 has been tempered, which is formed with a drill section 14 at the tip end of a shank 11 and with a thread edge 13 at its outer circumference, it is plated with zinc, tin or solder so as to be successively heat-treated. In the second place, oxides produced by heat treatment are removed so that a corrosion preventive surface film is formed by secondary treatment such as zinc plating and the like. This thereby enables the drill thread 10 furnished with high drill performance and high corrosion preventive properties as well to be manufactured at low cost without impairing corrosion resistance.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention comprises a head screw integrally formed with a drill portion at the tip thereof for drilling a pilot hole in a fastened object. The present invention relates to a method for manufacturing a drill screw.

[Problems to be solved by conventional techniques and inventions] Generally,
For this type of drill screw, for example,
No. 09 (U.S. Pat. No. 3,125,923 specification), U.S. Pat.
As described in Publication No. 6217 (British Patent Publication No. 2063731) or Japanese Utility Model Application No. 62-174111, etc., the drill part is formed by cutting with a milling cutter or the like, and Publication (
U.S. Patent No. 3,463,045), Japanese Patent Publication No. 1983-1
No. 3139 (U.S. Patent No. 3,395,603)
or JP-A-4-1401 (U.S. Patent No. 3683)
436), the drill portion is formed by cold forging.

The drill portion of these various drill screws all have at least two longitudinal grooves formed in the drill portion, and at the tip of the drill portion, a land portion between the two longitudinal grooves is connected from the free end of the drill portion to the shank. forming a pair of inclined entry end surfaces extending obliquely outward toward each other, and by intersecting the entry end surfaces at the free terminal end of the drill part, a chisel edge is formed at the intersection point, and both longitudinal grooves are formed. It is well known that by intersecting one full surface with each of the entry end surfaces, tip cutting edges are formed at the intersections.

As is well known, these drill screws have a head formed at one end of a rod-shaped shank material of an appropriate length, and a drill portion formed at the other end of the shank material by forging or cutting. Next, a thread is formed on the outer periphery of the shank material, followed by carburizing and quenching or carbonitriding and then tempering.Finally, in the case of steel drill screws, for rust prevention, and stainless steel In the case of drill screws, they are manufactured by applying zinc plating or tin plating to finish them.

In addition, the drill performance of these drill screws is measured in seconds required for the drill part to penetrate a metal plate when the drill screw is rotated at a predetermined rotational speed and pressed with a predetermined force against a fully flexed part. It is generally expressed in terms of time (drill time).

However, all of the conventional drill screws described in the above-mentioned prior patent documents are designed to improve the drill performance by devising the shape of the drill part. In order to improve drill performance through the shape of the drill part, if the cutting edge of the drill part is damaged when drilling into a broken line filler, or if the drill part is forged, the shape of the forging mold should be There are limitations in that the lifespan is extremely reduced, or when the drill portion is formed by cutting, the cost required for the cutting process increases significantly.

Therefore, with conventional drill screws, in order to shorten the time required for the drill part to penetrate the metal plate (drill time), the pressing force against the gold xi must be increased, so the metal plate is a thin metal plate. In this case, the thin metal plate will be deformed by the pressing force of the drill screw,
Alternatively, in the case of a thick metal plate, operator fatigue will increase.

Therefore, the present inventor focused on the fact that the performance of a drill screw in a drill screw is greatly influenced by the surface properties of the drill part, and filed an earlier patent application (Japanese Patent Application No. 63-2333).
No. 28), by plating the entire surface of the drill screw with zinc and then heat-treating it at an appropriate temperature,
We have proposed a method for manufacturing drill screws in which a zinc-iron alloy layer is formed on the surface of the drilled portion of the drill screw.

According to this manufacturing method, a zinc-iron alloy layer can be formed on the surface of the drill part, so the performance of the drill is improved by adding zinc or iron to the entire surface of the drill screw for rust prevention. This was a significant improvement over the conventional case of simply plating tin.

However, on the other hand, in the method of the prior invention, when forming a zinc-iron alloy layer on the surface of the drill part,
Since the method of plating the entire surface of the drill screw with zinc and then heating it to an appropriate temperature was used, it was found that the following problems occurred.

That is, when the entire surface of the drill part is plated with zinc and then heated to an appropriate temperature, a part of the zinc layer of the zinc plated on the entire surface of the drill screw becomes alloyed with iron and becomes zinc. -Although an iron-based alloy layer is formed, the remaining zinc layer reacts with oxygen in the atmosphere and becomes a blackened zinc oxide layer, which flakes off from the surface of the drill screw. As a result, the commercial value is significantly lowered, and it has been observed that the rust resistance is also lower than that of simply electroplating the entire surface of the drill screw with zinc. .

The present invention is based on the method of the earlier invention, and solves the problem of the earlier invention, that is, the reduction in commercial value and rust prevention properties due to heat treatment after plating with zinc etc. Another object of the present invention is to provide a method for manufacturing a screw, and another object of the present invention is to provide a method for manufacturing a drill screw having high drilling performance and high rust resistance at a low cost.

[Means and operations for solving the problem] In order to achieve this object, claim 1 provides a method in which a drill portion is formed at the tip of a shank having a head at one end, a thread is formed on the outer periphery of the shank, and then carburized and quenched. Alternatively, in a method for manufacturing a drill screw in which a tempering treatment is performed after a carbonitriding quenching treatment, the entire surface of the drill screw is plated with zinc, tin, or solder after the tempering treatment, and then heat treatment is performed. After removing the oxides generated by this heat treatment, we decided to form a surface coating for rust prevention.

In this case, the means for plating the entire surface of the drill screw with zinc, tin, or solder is not limited to electroplating with the various metals mentioned above, but also by dipping it in a molten bath of the various metals and then pulling it up. Methods such as hot-dip plating, or thermal spray plating, in which the above-mentioned various metals are sprayed in a melted state, can be employed.

In addition, as means for forming a surface coating for rust prevention, it is possible to adopt plating of the various metals mentioned above by the above-mentioned electroplating, hot-dip plating, thermal spray plating, etc. For example, "Z Coat" from NCZ Co., Ltd. or products sold under the name "Dacrotized" by Dacro Shamrock Co., Ltd.
Other means may be employed, such as coating the entire surface of the drill screw with powder of a rust-resistant metal such as zinc.

As mentioned above, by plating the entire surface of the drill screw with zinc, tin, or solder after carburizing and quenching or carbonitriding and then tempering, the entire surface of the drill screw is heated. Since it is possible to form an alloy layer of the above-mentioned various metals and iron, the drill performance when drilling a metal plate with the drill part can be improved by simply adding zinc or tin to the entire surface of the drill screw as in the conventional method. This makes it possible to dramatically improve the quality of the material compared to those that are simply plated with gold.

Oxides are generated on the surface of the zinc, tin, or solder plated on the entire surface of the drill screw due to the heat treatment described above, but after removing these oxides, a surface coating for rust prevention as described above is applied. By forming a rust-preventing surface film on the surface of the alloy layer of various metals and iron without any metal oxide intervening therebetween, in other words, the rust-preventing surface film is The surface coating can be reliably formed under conditions where the surface coating does not peel off.

Therefore, by heat treatment to form an alloy layer of various metals such as zinc and iron on the entire surface of the drill screw, it is possible to prevent the commercial value of the drill screw from being significantly reduced, and furthermore, Since a double coating of the alloy layer and the surface coating is formed on the entire surface of the drill screw, the rust prevention of the drill screw cannot be improved as compared to the conventional method. This is certainly an improvement over something that simply has the surface plated with zinc or tin.

Next, in claim 2, a drill part is formed at the tip of the shank having a head at one end, and a thread is formed on the outer periphery of the shank,
In the method for manufacturing a drill screw, the entire surface of the drill screw is subjected to the carburizing and quenching or carbonitriding and quenching treatment, and then before being subjected to the tempering treatment. After plating with zinc, tin, or solder, and then performing the above-mentioned tempering treatment and removing the zinc oxide coating generated by the tempering treatment, a rust-preventing surface coating was formed.

This claim 2 is such that between the carburizing quenching or carbonitriding quenching and tempering treatment in claim 1, plating with zinc, tin, or solder is performed, and the tempering is performed after the step of plating with zinc, etc. By processing,
Since the alloy layer can be formed at the same time, in other words, the alloy layer can be formed simultaneously by the tempering process, so the heat treatment process in claim 1 can be omitted.

Further, in claim 3, a drill portion is formed at the tip of the shank having a head at one end, and a thread is formed on the outer periphery of the shank,
In the method for producing a drill screw, the entire surface of the drill screw is then subjected to the tempering treatment, and then plated with zinc, tin, or solder.
Next, a heat treatment was performed in a substantially oxygen-free atmosphere such as a nitrogen gas atmosphere, and then a surface coating for rust prevention was formed.

When performing heat treatment after plating with zinc, tin, or solder, this heat treatment is performed as in claim 3,
If the heat treatment is carried out in an oxygen-free atmosphere such as a nitrogen gas atmosphere, the metal such as zinc may change color, but is it possible to prevent the generation of metal oxides? Alternatively, since the generation of oxides can be kept to a very small amount, the step of removing oxides in claims 1 and 2 can be omitted, and furthermore, the metal oxides can be removed during the heat treatment. In addition to being able to prevent the generation of oxides or to keep the generation of oxides to an extremely small amount, and to maintain the thickness of the metal layer such as zinc, there may be an additional barrier layer on the surface. Since a surface coating for rust is formed, the rust prevention property is much improved compared to the case of the first aspect.

Furthermore, claim 4 provides that a drill part is formed at the tip of the shank having a head at one end, and a screw thread is formed on the outer periphery of the shank, and then the process is carried out through carburizing and quenching or carbonitriding and quenching and then to tempering. In the method for manufacturing a drill screw, the entire surface of the drill screw is plated with zinc, tin, or solder after the carburizing quenching or carbonitriding quenching treatment and before the tempering treatment, and then plating the entire surface of the drill screw with zinc, tin, or solder in a nitrogen gas atmosphere, etc. After performing the above-mentioned tempering treatment in a substantially oxygen-free atmosphere, a surface treatment for rust prevention was performed.

This claim 4 is to perform plating with zinc, tin, or solder between the carburizing quenching or carbonitriding quenching and tempering treatment in claim 3, and the tempering treatment after the step of plating this zinc etc. Accordingly, the alloy layer can be formed at the same time. In other words, the alloy layer can be formed simultaneously by the tempering process, so the heat treatment process in the third aspect can be omitted.

According to a fifth aspect of the present invention, a drill portion is formed at the tip of a shank having a head at one end, and a screw thread is formed on the outer periphery of the shank, and then a carburizing and quenching process or a carbonitriding and quenching process is performed, followed by a tempering process. In the method for manufacturing a drill screw, the entire surface of the drill screw is subjected to the tempering treatment, then plated with zinc, tin, or solder, further plated with a heat-resistant metal such as copper, and then subjected to heat treatment. , it was decided to form a surface coating for rust prevention.

According to claim 5, by plating with zinc, tin, or solder and further plating with a heat-resistant metal such as copper, it is possible to prevent the zinc, tin, or solder from oxidizing during heat treatment. Since this can be prevented by the plating layer of heat-sensitive metal, it is possible to avoid creating a substantially oxygen-free atmosphere as in claim 3 during the heat treatment.

Further, in claim 6, a drill portion is formed at the tip of the shank having a head at one end, and a thread is formed on the outer periphery of the shank,
In the method for manufacturing a drill screw, the entire surface of the drill screw is subjected to the carburizing and quenching or carbonitriding and quenching treatment, and then before being subjected to the tempering treatment. After plating with zinc, tin, or solder, and then plating with a heat-resistant metal such as copper, and then performing the above-mentioned tempering treatment, a surface coating for rust prevention is formed.

According to the sixth aspect, the heat treatment for forming the alloy layer can be performed at the same time as the tempering process, so the heat treatment process in the fifth aspect can be omitted.

In the cases of claims 2 to 6, the means for plating the entire surface of the drill screw with zinc or the like may be electroplating, hot-dip plating, thermal spray plating, etc., as in the case of claim 1. Further, as a means for forming a rust-preventive surface coating, in addition to zinc plating, coating with rust-preventive metal powder such as zinc can be used. Needless to say, other means can be used.

[Effects of the Invention] As described above, according to claim 1, a drill screw having excellent drilling performance and rust prevention can be manufactured, and according to claim 2, Since the heat treatment step can be omitted, it is possible to reduce the manufacturing cost of a drill screw having excellent drilling performance and rust prevention. Further, according to claim 3, it is possible to manufacture a drill screw having higher rust prevention properties than in the case of claim 1, and furthermore, according to claim 4, it is possible to manufacture a drill screw with higher rust prevention than in the case of claim 3. Costs can be lowered.

According to claim 5, it is possible to avoid creating a substantially oxygen-free atmosphere as in claims 3 and 4 during the heat treatment, so that manufacturing costs can be reduced in the case of claims 3 and 4. Furthermore, according to claim 6, there is an effect that the manufacturing cost can be lowered more than in the case of claim 5.

[Embodiment 1] The steel drill bit 10 shown in FIGS. 1 to 4 has a drill part 14 that is integrated with a shank 11 with a drill bit 13 extending integrally from a head 12, for example. 62-17411
It is formed by cutting into the shape disclosed in Publication No. 1. However, in this figure, the number 15
16 indicates a pair of left and right longitudinal grooves provided in the drill portion 14, and 16 indicates two land portions 17 between the longitudinal grooves 15.
A pair of inclined entry end surfaces are provided to extend obliquely outward toward the shank 11 from the free end of the drill portion 14, and reference numeral 18 indicates that the two entry end surfaces 16 intersect at the free end of the drill portion 14. The reference numeral 20 indicates a chisel edge formed by this, and the reference numeral 20 indicates a tip cutting edge formed at the intersection of one groove surface 19 constituting both longitudinal grooves 15 and the entry end surface 18.

The drill screw lO with the drill portion 14 formed as described above is placed in a carburizing furnace and heated and carburized, then quenched by immersion in oil to be carburized and quenched, and then heated at a temperature of about 350° C. for 60 minutes. After that, tempering treatment is performed by air cooling, and then first zinc electroplating is applied to the entire surface of the drill screw lO (the process up to this point is the same as before), and this first zinc electroplating is applied to the entire surface of the drill screw lO. The electroplated product is placed in a lint furnace and heat-treated at a temperature of about 400°C for about 60 minutes in the presence of atmospheric air. After removing the oxides by shot blasting, secondary zinc electroplating was applied to the entire surface.

In addition, when applying the second zinc electroplating after removing the oxide, it is important not to perform pickling as a preliminary step. In other words, when pickling is performed as a pre-process to the second zinc electroplating, the zinc in the alloy layer formed on the entire surface of the drill screw due to the previous heat treatment disappears due to the pickling. Therefore, as a step before applying the second zinc electroplating,
It is not acid-washed.

The thread diameter (D) manufactured as described above was 4.
A Drill Neshiku product of the present invention of size W size) and a Drill Neshiku conventional product of the size W size with the same screw thread diameter (D) manufactured by a conventional method) were rotated at a rotation speed of 2500 revolutions per minute. At a speed of 13.
When screwing with a pressing force of 6 kg, and when the thickness is 3.2 -
The time required for the drill part 14 to penetrate the steel plate (drill time) was measured in two cases: one is screwed into the steel plate with a pressing force of 18.1 kg, and the time for the drill part 14 to penetrate the steel plate was measured.
The results of the test to find the average value per O unit are as follows:
As shown in the table, the time required for the drill part to penetrate the steel plate is approximately 4 times longer than that of the conventional manufacturing method.
It was also possible to shorten the time.

Table 1 Thickness 1.6 Theory In the case of iron plate with thickness 3.2 mm Average value of conventional product 2.30 seconds 3.68 seconds Average value of inventive product 1.32 seconds 2.02 seconds Further, a drill screw of the present invention manufactured by the method described above, and a first intermediate drill screw that has only been heat-treated in the manufacturing method described above,
A corrosion resistance test was conducted by spraying salt water on four screws: the second intermediate drill screw from which oxides were removed by shot blasting after heat treatment in the manufacturing method described above, and the drill screw manufactured by the conventional manufacturing method.

The result is approximately 150~150 for conventional drill screws.
Red rust occurred after 200 hours, about 100 hours in the case of the first intermediate drill screw, and about 70 hours in the case of the second intermediate drill screw. , in the case of the drill screw of the present invention, 400
It was observed that red rust appeared only after ~500 hours, and the rust prevention was more than double that of conventional products.

Further, in the drill screw having the shape shown in FIGS. 1 to 3, after carburizing and quenching, zinc is electroplated and then heat treated, and the oxides generated during this heat treatment are removed by shot blasting. Instead of applying the second zinc electroplating, we coated it with zinc powder using "Dacrotized" sold by Dacro Shamrock Co., Ltd., and the drill performance and rust prevention properties of this product were as described above. After removal of the oxide, there was almost no inferiority compared to the second zinc electroplating.

Furthermore, the screw thread diameter (
D) is carburized and quenched in 4 Tsuru's drill bit IO,
Next, instead of applying the first zinc electroplating, tin was electroplated and then heat treated, and the oxides generated during this heat treatment were removed by shot blasting.
Drills made with secondary zinc electroplating are as follows:
In the case of the tin-plated product of the present invention) and in the case of
Drill screw IO with the shape shown in the figure and a thread diameter (D) of 4 mm
Instead of carburizing and quenching and then applying the first zinc electroplating, the solder was electroplated and then heat treated, and the oxides generated during this heat treatment were removed by shot blasting. Both drills (hereinafter referred to as solder-plated products of the present invention) made by applying secondary zinc electroplating have the shapes shown in FIGS. 1 to 4 and have a thread diameter (D). A conventional drill screw in which the entire surface of the drill screw is simply electroplated with tin (hereinafter referred to as a conventional tin-plated product), and a screw thread with the shape shown in FIGS. 1 to 4 above. A pressing force of 18-1 kg was applied to a conventional drill that simply electroplated solder on the entire surface of a drill screw with a diameter (D > 4 + va). The results of a test comparing the time required to penetrate a steel plate with a thickness of 3.2 mm are shown in Table 2. In either case, drill performance can be significantly improved. It was.

(Hereinafter, blank space) 2. Time required to penetrate a steel plate with a thickness of 3.2 fi 1. Tin-plated product of the present invention 1-1.56 seconds 1. In addition, in a corrosion resistance test by spraying salt water, The product of the present invention and the solder-plated product of the present invention had rust prevention properties that were more than twice as high as those of the conventional tin-plated product and the conventional solder-plated product.

On the other hand, the results of an experiment on the relationship between the heating temperature and the time required to penetrate the iron plate during the heat treatment after the first zinc electroplating are shown in Figure 5. This is true, and it was confirmed that the drill performance could be sufficiently improved even if the heating temperature was 300° C. when the heating time was 60 minutes.

In this way, the heating temperature (300
°C) and heating time (60 minutes) are close to the heating temperature and heating time in the tempering treatment after hardening the drill screw, so the primary plating treatment of zinc, tin, or solder is By performing the tempering process after the quenching process and the first plating process, the tempering process and the alloying of the plated zinc, tin, or solder can be performed simultaneously. It can be done.

In this Example 1, instead of applying secondary zinc liquid gold or forming the surface coating with [Dacrotized], tin plating or solder plating, or other methods such as "Z coating" etc. A surface coating may also be formed.

[Example 2] Next, the present inventor placed the drill bit IO formed as shown in FIGS. 1 to 4 in a carburizing furnace to heat and carburize it, and then quenched it by immersing it in oil. The drill screw 10 is carburized and quenched, then heated to a temperature of about 350° C. for 60 minutes and then air cooled to perform a tempering treatment, and then the entire surface of the drill screw 10 is subjected to primary zinc electroplating. Up to this point, the process is the same as before), and the first zinc electroplated product is placed in a lint furnace, and nitrogen gas is blown into the lint furnace to create an almost oxygen-free atmosphere. After this heat treatment, secondary zinc electroplating was applied to the entire surface.

Then, the 611 size drill Neshiki manufactured in this way (the invention product) and the same 6-tsuru size drill Neshiki conventional product manufactured by the conventional method were rotated at a rotation speed of 2500 revolutions per minute. When screwing with a pressing force of 20.4 against an iron plate with a thickness of 1.6 at a rotation speed of
The drill part 1 was tested in two cases: when screwing into a steel plate with a thickness of 4.5 fi with a pressing force of 27.2 mm.
Table 3 shows the results of a test to measure the time it takes for the drill part to penetrate the steel plate (drill time) and find the average value per 1O of each. The time required for manufacturing can be considerably reduced compared to drilling screws produced using conventional manufacturing methods.

Table 3 In the case of an iron plate with a thickness of 1.6M and a thickness of 4.5 meters, the average value of the invented product was 1 0.87 seconds 1.83 seconds 1 Also, in a corrosion resistance test by spraying salt water, The product of the present invention produced by the method described above did not develop red rust even after 1000 hours.

In addition, in this Example 2, as in the case of Example 1, the tempering treatment is performed after the first zinc electroplating, so that the electroplated zinc is alloyed. Of course, it is possible to omit the heat treatment for oxidation, and instead of the first zinc plating, tin plating or solder plating may be used, and furthermore, the second zinc plating may be applied. Alternatively, tin plating or solder plating may be applied, or other surface coatings such as the above-mentioned "Z coat" or "dacrotized" may be formed.

[Example 3] Furthermore, the present inventor put the drill screw lO formed as shown in FIGS. Carburizing and quenching, followed by tempering by heating to a temperature of about 350°C for 60 minutes and air cooling, and then applying first zinc electroplating to the entire surface of the drill screw lO. The zinc surface obtained by this first plating is further electroplated with copper, and then placed in a lint furnace and heated in the presence of atmospheric air. After heat treatment at a temperature of 400° C. for about 60 minutes, secondary zinc electroplating was applied to the entire surface.

In this way, after performing the first zinc plating and before performing the heat treatment, by applying copper plating to the surface of the zinc formed by the first plating, during the heat treatment,
Since the copper plating layer can prevent the zinc formed by the first plating from being oxidized, during the heat treatment, as in Example 2, an oxygen-free method such as blowing nitrogen gas into the lint furnace may be used. There is no need to create an atmosphere,
In addition, when the copper is heat-treated after being plated, some oxides are generated on the surface of the copper, so a surface coating such as secondary zinc electroplating is formed after the heat treatment. In the previous step, it is necessary to remove oxides on the surface of the copper by pickling or the like, and instead of plating the copper, a heat-resistant metal such as nickel or chromium may be plated. It's good.

The drill performance and rust prevention properties of the drill screw manufactured as described above could be improved compared to the case of Example 2.

In addition, in this Example 3, as in the case of Example 1 and Example 2, the tempering treatment was performed after the first zinc electroplating and then the plating with a heat-resistant metal such as copper. Of course, by doing so, it is possible to omit the heat treatment for alloying zinc in the first plating, and in place of the first zinc plating, tin plating or solder can be used. Furthermore, instead of applying the second zinc plating, tin plating or solder plating may be applied, or the above-mentioned "two coat" or "
Other surface coatings such as "dacrotized" may also be formed.

[Brief explanation of the drawing]

Figure 1 is a front view of the drill screw, Figure 2 is a side view of Figure 1, Figure 3 is an enlarged bottom view of Figure 1, Figure 4 is an enlarged perspective view of the drill part of the drill screw, and Figure 5 is an enlarged perspective view of the drill part of the drill screw. The figure is a diagram showing the relationship between heat treatment temperature and drill performance. 10...Drill, 11...Shank, 12
...Head, 13...Screw thread, 14...Drill part.

Claims (6)

[Claims] (1) A drill screw in which a drill part is formed at the tip of a shank with a head at one end, and a screw thread is formed on the outer periphery of the shank, followed by carburizing and quenching or carbonitriding and quenching, and then tempering. In the manufacturing method, the entire surface of the drill screw is plated with zinc or tin or solder after the tempering treatment, followed by heat treatment to remove oxides generated by this heat treatment, and then rust preventive. A method for producing a drill screw, the method comprising forming a surface film for use in the drill screw. (2) A drill screw in which a drill part is formed at the tip of the shank with a head at one end, and a screw thread is formed on the outer periphery of the shank, and then the process proceeds to a tempering process through carburizing and quenching or carbonitriding and quenching. In the manufacturing method, the entire surface of the drill screw is plated with zinc or tin or solder after the carburizing quenching or carbonitriding quenching treatment and before the tempering treatment, and then the tempering treatment is performed, and by this tempering treatment. A method for manufacturing a drill screw, characterized in that a surface film for rust prevention is formed after removing a generated zinc oxide film. (3) A drill screw in which a drill part is formed at the tip of a shank with a head at one end, and a screw thread is formed on the outer periphery of the shank, and then the process proceeds to a tempering process through carburizing and quenching or carbonitriding and quenching. In the manufacturing method, the entire surface of the drill screw is plated with zinc, tin, or solder after the tempering treatment, and then heat treated in a substantially oxygen-free atmosphere such as a nitrogen gas atmosphere. , a method for manufacturing a drill screw characterized by forming a surface coating for rust prevention. (4) A drill screw in which a drill part is formed at the tip of a shank with a head at one end, and a screw thread is formed on the outer periphery of the shank, and then the process proceeds to a tempering process through carburizing and quenching or carbonitriding and quenching. In the manufacturing method, the entire surface of the drill screw is plated with zinc, tin, or solder after the carburizing quenching or carbonitriding quenching treatment and before the tempering treatment, and then in a substantially oxygen-free environment such as a nitrogen gas atmosphere. A method for manufacturing a drill screw, which comprises forming a surface coating for rust prevention after the above-mentioned tempering treatment in an atmosphere of (5) A drill screw in which a drill part is formed at the tip of a shank with a head at one end, and a screw thread is formed on the outer periphery of the shank, and then the process proceeds to a tempering process through carburizing and quenching or carbonitriding and quenching. In the manufacturing method, the entire surface of the drill screw is subjected to the tempering treatment, then plated with zinc or tin or solder, further plated with a heat-resistant metal such as copper, then heat treated, and then rust-proofed. A method for producing a drill screw, the method comprising forming a surface film for use in the drill screw. (6) A drill screw in which a drill part is formed at the tip of the shank with a head at one end, and a screw thread is formed on the outer periphery of the shank, and then the process proceeds to a tempering process through carburizing and quenching or carbonitriding and quenching. In the manufacturing method, the entire surface of the drill screw is plated with zinc, tin, or solder after the carburizing quenching or carbonitriding quenching treatment and before the tempering treatment, and further plated with a heat-resistant metal such as copper, A method for manufacturing a drill screw, characterized in that, after the tempering treatment is performed, a surface coating for rust prevention is formed.