KR20140013295A

KR20140013295A - Tapping screw for stainless steel object

Info

Publication number: KR20140013295A
Application number: KR1020120079920A
Authority: KR
Inventors: 김창영
Original assignee: 주식회사 아세아볼트
Priority date: 2012-07-23
Filing date: 2012-07-23
Publication date: 2014-02-05

Abstract

The present invention relates to a screw for fastening to a counterpart of a stainless steel material, and more particularly, to a tapping screw for fastening a counterpart of a stainless steel material that can be repeatedly used without using a separate insert when fastening with a stainless steel material.
The present invention is characterized in that the angle between the front flank (flank) and the rear flank forming the retraction direction of the screw thread is 65 ° ~ 85 ° with respect to the center of the screw thread, the entry direction of the thread. Provided are tapping screws for fastening counterparts made of stainless steel.

Description

TAPPING SCREW FOR STAINLESS STEEL OBJECT}

The present invention relates to a screw for fastening to a stainless steel counterpart, and more particularly to a tapping screw for fastening a stainless steel counterpart that can be repeatedly used without a separate insert when fastening with a stainless steel material. .

In the case of a screw for fastening a counterpart of a conventional stainless steel material, a screw having a female thread is usually welded to a screw fastening portion or a female thread is formed on stainless steel.

The male screw fastened to the female screw as described above is called a machine screw. However, the machine screw fastening structure using the insert has been a major factor in the cost increase since additional processing costs such as insert processing cost and insert welding cost are added.

A screw that is fastened by forming a female screw on the counterpart itself without a separate female thread formed on the counterpart is called a tapping screw.

The tapping screw is used only when the counterpart to be fastened is soft, such as an injection molding or a light alloy such as Al, Mg, or Zn.

In the case of stainless steel material, the strength of the material itself is high, and the female acid was not properly formed by tapping screw fastening.

In addition, even when the tapping screw is fastened, an excessive force is required at the time of fastening, and the thread of the screw is worn or broken, thereby having a problem in that there is no repeatability.

Thus, conventional tapping screws cannot be used for counterparts made of stainless steel.

It is an object of the present invention to provide a tapping screw that can be fastened by forming a female thread on a stainless steel counterpart.

Another object of the present invention is to provide a tapping screw that can be repeatedly used in a stainless steel material.

The present invention for achieving this object is based on the center of the screw thread, the angle between the front flank (flank) forming the inclined direction of the thread and the rear flank forming the retraction direction of the screw thread is 65 ° It provides a tapping screw for fastening a counterpart of stainless steel, characterized in that the ~ 85 °.

The front flank and the rear flank of the thread are formed symmetrically with respect to the center of the thread, or the bisectors of the front flank and the rear flank are in the range of 0 ° to ± 2 ° at the center of the thread. desirable.

The tapping screw may use a heat treated carbon steel material in the Vickers hardness range of 550 to 700.

In addition, the tapping screw according to the present invention may further include an induction screw thread having an angle of 45 2 between the front flank surface and the rear flank surface forming the retreat direction inclined direction of the thread at the tip contacting the counterpart. Can be.

In this case, it is preferable that the guide thread is formed in a pitch of 1 to 3, and the guide screw has an angle of 30 ° ± 2 ° of the front flank surface with respect to the center of the screw thread, and the rear flank surface with respect to the center of the screw thread. More preferably, the angle is 15 ° ± 2 °.

In addition, it is preferable that the guide thread has a form in which the height of the screw thread increases from the tip in contact with the counterpart toward the rear side.

The present invention provides a tapping screw fastened to a counterpart of a stainless steel material, thereby eliminating the need to use an insert that was conventionally used when fastening a machine screw, thereby reducing the work time and cost for insert processing and attachment. Bring it.

In addition, the present invention has the effect of providing a tapping screw that can be used repeatedly on a stainless steel counterpart.

1 is a view showing a general machine screw,
2 is a view showing a general tapping screw,
3 is a view showing a tapping screw for fastening a counterpart of a stainless steel material according to the first embodiment of the present invention;
4 is a view showing a tapping screw for fastening a counterpart of a stainless steel material according to a second embodiment of the present invention.

Hereinafter, a preferred embodiment of a tapping screw for fastening a counterpart of a stainless steel material according to the present invention will be described.

BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention, and the manner of achieving them, will be apparent from and elucidated with reference to the embodiments described hereinafter in conjunction with the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. In the following description, well-known functions or constructions are not described in detail since they would obscure the invention in unnecessary detail.

1 is a view showing a general machine screw.

As shown, a typical machine screw 10 is provided with threads having the same height and pitch length along the entire longitudinal section, between the inner and outer diameters of the screws.

The machine screw 10 has an inclined surface that forms a slanted surface at a predetermined angle to the valley with respect to the center of the thread (indicated by a dashed line), and the inclined surfaces are called flank surfaces 12 and 14.

The flanks 12 and 14 are, for convenience of explanation, a front flank 12 arranged in the direction of entry of the screw on the basis of the crest of the thread, and a rear flank 14 disposed in the retraction direction of the screw. It is called).

In the case of the general machine screw 10, the inclination angle between the front flank 12 and the rear flank 14 from the peaks of the thread 10 is formed equal to each other.

The angle of the flank surface of this machine screw 10 is determined at about 30 °, and the sum of these screw angles is determined at about 60 °.

Therefore, in order to fasten the machine screw 10 to the stainless steel counterpart, an insert with a female thread is required beforehand. Therefore, after the insert is manufactured separately, the machine screw 10 is attached to the stainless steel counterpart by welding. Was fastening.

As a result, the insert manufacturing cost, the welding cost, etc., increased in cost, and had a lot of work labor.

When the machine screw 10 is used as a tapping screw on a counterpart of stainless material, the thread angle is narrow to about 60 °, so it is weak to dig into hard stainless steel, so that the thread is destroyed or the thread is compressed. When this phenomenon occurs, the outer diameter of the screw is reduced, the locking rate is reduced, which makes the screw's original function of joining components with axial force difficult.

2 is a view showing a general tapping screw.

The general tapping screw 20 is formed such that the inclination angles of the front flank 22 and the rear flank 24 from the peaks of the thread 10 are equal to each other.

The angle of the front flank 22 of the tapping screw 10 is determined at approximately 22.5-30, and the angle of the rear flank 24 is determined at approximately 22.5-30, and the sum of the screw angles is approximately It is set at 45 degrees-60 degrees.

The tapping screw 20 is generally for fastening to a soft counterpart, and the screw angle has a relatively small value in the range of 45 ° to 60 °.

When the tapping screw 20 is fastened to the counterpart of the stainless steel material, the thread angle is narrow like the machine screw, so that the screw thread is broken when the counterpart is fastened with the counterpart.

3 is a view showing a tapping screw for fastening a counterpart of a stainless steel material according to the first embodiment of the present invention.

The tapping screw 100 for fastening the counterpart of the stainless steel material according to the present invention has a substantially fastening force and includes a top screw thread 120 in which the entire thread is formed at the same height. Herein, the term normal screw thread 120 is for distinguishing from the guide screw thread described later in the second embodiment.

The normal thread 120 has an angle of 65 ° between the front flank 122 forming the entry direction of the thread and the rear flank 124 forming the retraction direction of the thread with respect to the center of the thread. It is characterized by being 85 °. If the angle formed between the front flank 122 and the rear flank 124 is smaller than the angle, the thread is worn or damaged and cannot be used repeatedly,

When the angle formed between the front flank 122 and the rear flank 124 is larger than the angle, the volume of the thread increases, so that the amount of deformation of the counterpart increases, thereby requiring an excessively large torque at the time of tightening. In addition, the angle of the flank surface is small, which brings a problem that the fastening force is lowered.

In the top screw thread 120, the front flank 122 and the rear flank 124 are formed symmetrically with respect to the center of the thread, or each bisector of the front flank and the rear flank is at the center of the thread. It is preferable that it is in the range of 0 ° to ± 2 °.

When the front flank 122 and the rear flank 124 has the large angle difference, the length occupied by the thread becomes longer, resulting in a problem that the number of threads that can be formed per unit length decreases, thereby lowering the tightening force.

In addition, the tapping screw according to the present invention is preferably a heat-treated carbon steel material of Vickers hardness of 550 ~ 700. This is to select a material having a strength and hardness range that can be used repeatedly in consideration of the strength and hardness of the mating stainless steel material.

However, the material is not limited thereto, and other materials having hardness and strength similar to those of stainless steel may be used.

4 is a view showing a tapping screw for fastening a counterpart of a stainless steel material according to a second embodiment of the present invention.

The tapping screw 100 for fastening the counterpart of the stainless steel material according to the second embodiment has a substantial fastening force, and has a top screw thread 120 having an entire thread formed at the same height, and a pitch of 1 to 3 at the distal end contacting the counterpart. Induced screw thread 110 is formed.

The guide screw thread 110 formed at the front end of the normal screw thread has an angle of 45 ° ± between the front flank 112 and the rear flank 114 that forms the oblique side of the thread in the retreat direction of the thread. It is preferably in the range of 2 degrees.

The guide screw thread 110 is intended to induce the formation of the female screw formation seat during initial tightening and to reduce the friction generated during the fastening of the subsequent screw thread portion.

If the guide thread 110 is formed less than 1 pitch, it is not possible to sufficiently obtain the effect of the seat surface formation or the friction reduction effect as described above, and if the guide screw thread 110 is 3 pitch or more, the guide screw thread occupies the entire screw length. The length becomes large and the fastening force falls.

The guide thread 110 has an angle of 30 2 at the front flank 112 based on the center of the thread, and an angle of the rear flank at 15 ° ± 2 ° based on the center of the thread.

In addition, it is preferable that the guide screw thread 110 increases in height from the tip in contact with the counterpart toward the rear side. This is to prevent the damage of the guide screw thread (110) by making the compression of the counterpart gradually and for the formation of smooth female acid.

Example

Hereinafter, an embodiment of a tapping screw for fastening a counterpart of a stainless steel material according to the present invention will be described.

Table 1 shows the results of evaluating the fastening force and reusability by varying the angle between the front flank and the rear flank.

Looking at the results in Table 1,

In the case of the machine screw of the comparative example 1 and the tapping screw of the comparative example 4, the screw thread was broken when the counterpart of the stainless material was fastened.

In the case of the general tapping screw of Comparative Example 2 and Comparative Example 3, it was possible to reuse with 0.00013 outer diameter reduction rate when fastened to the aluminum counterpart. The sex was found to be lacking.

In Example 1, the thread angle was in the range of 65 ° to 85 °, and the outer diameter reduction rate was small, and the torque at the time of tightening was not excessive.

In the above, a preferred embodiment of a tapping screw for fastening a counterpart of a stainless steel material according to the present invention has been described.

It is to be understood that the above-described embodiments are illustrative in all aspects and should not be construed as limiting, and the scope of the present invention is indicated by the appended claims rather than the foregoing description, It is intended that all changes and modifications derived from the meaning and scope of the invention, and from the equivalents thereof, be included in the scope of the present invention.

10: machine screw
12: front flank surface
14: rear flank surface
20: tapping screw
22: front flank surface
24: rear flank surface
100: tapping screw
110: guide thread
112: front flank surface
114: rear flank surface
120: normal thread
122: front flank surface
124: rear flank surface

Claims

Relative to the center of the thread,
Tapping for fastening the counterpart of stainless steel material, characterized in that the angle between the front flank (flank) forming the entry direction of the screw thread and the rear flank forming the oblique direction of the screw thread is 65 ° ~ 85 °. screw.

The method of claim 1,
And the front flank and the rear flank are symmetrical with respect to the center of the thread.

The method of claim 1,
Tapping screws, characterized in that each bisector of the front flank and the rear flank is in the range of 0 to 2 in the center of the thread.

The method of claim 1,
The tapping screw is a tapping screw, characterized in that the carbon steel material of Vickers hardness of 550 ~ 700.

The method of claim 1,
The tapping screw is
And a guide thread having an angle of 45 ° ± 2 ° between a front flank surface and a rear flank surface forming the retreat inclined direction of the screw thread at the tip contacting the counterpart.

The method of claim 5, wherein
The guide thread is a tapping screw, characterized in that formed 1 to 3 pitch.

The method of claim 5, wherein
The guide thread is
The angle of the front flank is 30 ° ± 2 ° from the center of the thread.
Tapping screw, characterized in that the angle of the rear flank surface 15 ° ± 2 ° with respect to the center of the thread.

The method of claim 5, wherein
The guide thread is a tapping screw, characterized in that the height of the thread increases toward the rear side from the tip in contact with the counterpart.