JPS62267040A - Working method for external screw - Google Patents

Abstract

PURPOSE:To manufacture the external screw of high accuracy without deterioration of corrosion resistance, inexpensively, with high efficiency by engraving a screw thread with the cold thread rolling die working of the shaft part of the iron external screw base material subjected to the zinc plating in optimum thickness on the surface. CONSTITUTION:The whole body of an iron external screw base material 1 is dipped in a molten zinc melted at about 450 deg.C and the zinc plated layer 4 in 50-70mu thickness is formed on the surface. A screw thread is cut with the cold work of the shaft part 3 thereof between a pair of thread rolling dies 6. The rolling screw thread part becomes black and looks like the zinc plated layer 4 being separated apparently, but there is no separation via the alloy layer 5 of the plating boundary part and no deterioration in the corrosion protection is caused. The screw part is therefore made a good anti-corrosion and the product of high screw precision and yet can be manufactured inexpensively with high efficiency. A silver powder, etc. may be painted on the rolling discoloring screw part for increasing the commodity value.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for easily and accurately processing male screws of all sizes whose surfaces are galvanized to provide anti-corrosion properties. .

[Conventional technology]

Iron screws whose surfaces are plated with zinc have been increasingly used in recent years because of their good anti-corrosion properties.

Conventionally, in order to process an iron screw with a zinc-plated surface into a male screw, for example, a male thread is formed using a die method or the like on a male iron screw base material with a head and a shank formed, or only the shank without a head. After forming a zinc deposit on the surface by infiltrating into a tank containing molten zinc, the excess molten zinc is removed by passing it through a centrifugal separator before it solidifies. The most optimal method is to shake off the zinc and form a thin zinc plating layer on the iron surface.

In addition, before the molten zinc on the iron surface solidifies, compressed air is sprayed to shake off the excess molten zinc and form a thin galvanized layer on the iron surface.When carving threads using the zigzag method or die method, pre-standard dimensions are used. Process it into a smaller size,
There is a method in which a zinc plating layer is formed on the iron surface and then die processing is performed again to obtain standard dimensions, and there is also a method in which the threaded portion is wrapped and a zinc plating layer is formed on the iron surface.

[Problem that the invention seeks to solve]

However, due to the limitations of the capacity of the centrifugal separator, the method of applying a centrifugal separator is limited to objects weighing 2 to 3 kg and within 500 mm in length by heavy tapping with a male screw; It is difficult to form a uniform zinc plating layer on threads with complex surface shapes using the method of blowing compressed air, and the accuracy is poor after processing, making it difficult to screw female threads together. If you use the die method to carve threads into smaller holes, form a zinc layer on the surface, and then re-dice to finish, the internal iron base will be exposed and the desired eThere are problems in that the anti-corrosion effect cannot be expected, and it is troublesome to package and galvanize threaded parts, and the temperature of molten zinc is approximately 450°C, so there are restrictions on the material quality of the package. Each exists.

In view of these conventional problems, it is an object of the present invention to make it possible to easily and accurately process male screws of all sizes whose surfaces are galvanized to provide anti-corrosion properties. shall be.

[Means for solving problems]

In order to achieve this object, the present invention has the following contents.

That is, in the present invention, between the rolling dies arranged in parallel at intervals,
This method of processing a male screw comprises positioning the shaft of an iron male screw base material whose surface is galvanized and carving threads on the shaft by cold working.

[For production]

However, according to the present invention, after galvanizing the iron male screw base material, the screw threads are carved into the shaft portion by a rolling method, so that the machining is simple and the male screw with good accuracy is formed. The screws can be replaced.

〔Example〕

Hereinafter, the male thread processing method of the present invention will be explained in more detail based on the accompanying drawings.

First, a male threaded iron base material is machined from an iron cylindrical body having a desired length, on which a head 2 of a desired shape shown as 1 in the figure and a shaft portion 3 for carving threads are formed.

The entire male threaded iron base material 1 is placed into a tank containing molten zinc at about 450 DEG C. according to the hot-dip plating method, and a zinc i-claw metal layer 4 having a thickness of about 5 to 7 microns is formed on the surface.

5 in the figure is an alloy layer generated at the boundary between iron and zinc during the process of forming the zinc plating layer 4.

The shaft portions 3 of the male threaded iron base material 1 having the zinc plating layer 4 formed on the surface thereof are arranged side by side at intervals that allow the threads to be carved on the shaft portions 3, and each is connected to an appropriate drive source. The second rolling die is placed between 6 and 6 by cold working.
The threads are formed by rotating the rolling die 6.6 as shown by the arrow in the figure. In addition, 7 in the figure is a support plate.

The male screw processed in this way is made of iron/
It is formed by pressing the zinc plating layer 4 to a substantially uniform thickness onto the ff screw base material 1 via the alloy layer 5, and the appearance is blackish and gives the impression that the zinc plating layer 4 has peeled off. However, since there was a zinc i-metal layer 4 of approximately uniform thickness on the surface, the corrosion resistance was comparable to that of the conventional one.

As mentioned above, this processing method results in a blackish appearance, so one method is to coat the surface of the zinc plating layer 4 with silver powder in order to increase its commercial value.

Here, the iron male screw base material l having only the shaft portion 3 without the head 2 can be similarly processed into a headless male screw having the zinc plating layer 4 formed on the surface.

Further, if a rolling tap is used in addition to machining male threads as in the illustrated embodiment, machining of female threads can be performed in the same manner as the male thread machining method of the present invention.

[Effects of the Invention] In the male screw processing method of the present invention as described above, the shaft portion of the iron male screw base material whose surface is galvanized is placed between the rolling dies arranged in parallel at intervals. Since the threads are carved into the shaft part by positioning and cold working, the male threads of all sizes can be machined easily and accurately with zinc plating on the iron surface to provide anti-corrosion properties. In addition, there is no problem in the subsequent process when screwing the screws together.

Furthermore, since the rolling method is used, not only is it possible to produce stronger products without generating chips, but production efficiency is also extremely high.

[Brief explanation of drawings]

The drawings show embodiments of the male screw processing method of the present invention. Fig. 1 is a sectional view showing a state in which an iron male screw base material is galvanized, and Fig. 2 is a cross-sectional view showing a state in which an iron male screw base material is plated with zinc. A simplified explanatory diagram showing a state in which a male thread is galvanized and then a thread is carved on the shaft using a rolling die. Figure 3 is a cross-sectional view of the male screw after the thread is carved. . 2: Head, 3: Shaft, 4: Zinc plating layer, 5: Alloy layer,
6: Rolled die, 7: Support temporary. Figure 3 s 1 Amendment to Figure Procedures August 12, 1986 Commissioner of the Patent Office Black 1) Yu Akihiro Patent Application No. 110130/1982 2 Title of Invention Method for Processing Male Threads 3? Relationship with the person who makes corrections; Patent applicant Kondo Tekko Co., Ltd. 4, Agent ■ 533 Higashi Rostion Building 5, 1-20-14 Higashinakajima, Higashiyodoyo-ku, Osaka City, Date of amendment order 7, Amendment In the 4th page, line 14 of the description of contents, the phrase "approximately 5 to 7 microns thick" is corrected to "approximately 50 to 70 microns thick."that's all

Claims (1)

[Claims] 1) The shaft of a male threaded iron base material whose surface is galvanized is positioned between rolling dies arranged in parallel at intervals, and a thread is carved into the shaft by cold working. How to process screws.