JPH05138439A - Tapped thin tube and method and tool for tapping - Google Patents

Abstract

PURPOSE:To facilitate the tapping to the peripheral wall of a thin tube, and secure the sufficient fastening force of a bolt or the like. CONSTITUTION:A cylindrical-burr or a cylindrical piece-shape burr 4 is formed on the inner surface of the peripheral wall 2 of a thin tube 1, and the tapping is performed to the inner periphery thereof. In this tapping process, a processing tool such as a tap 6, in which a point angle alpha of a blade tip part 6b is formed into an acute angle and a processing part 6g for reducing the cutting function of an edge part having the cutting function is formed, or a drill or the like is pushed for abutment, and while the burr 4 is formed by the plastic deformation to drill a down hole.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin-walled pipe tapped, a tapping method therefor, and a machining tool.

[0002]

2. Description of the Related Art Conventionally, for example, when a metal plate or plate having a thickness of 1, 5 to 2 mm is tapped with a diameter of 4 to 6 mm, it is necessary to maintain the tightening force of bolts and screws with the above thickness relative to the bolt diameter. Since the lead of the screw pitch cannot be secured, the pre-drilling of the pre-tapping hole is performed by punching with a punching die to form a cylindrical skirt that projects on one side of the plate material around the pilot hole. , Secure the lead of the nut by threading on the inner circumference of the skirt,
The tightening force of bolts, etc., which bears the load of the mounting part was maintained.
However, when tapping on the peripheral wall of a square pipe, etc., the die that receives the punch for punching cannot be housed in the pipe, so punching is impossible, and the lead of the thread on the pipe surface is insufficient. A method of welding a thick plate and then tapping after drilling a lower hole, or drilling a bolt insertion hole in the peripheral wall of the pipe and welding a nut has been adopted.

[0003]

However, the welding of parts as described above requires a great deal of labor and processing cost for the welding work, and also causes a drop in the environment such as a food machine or a physics and chemistry machine, and adhesion of various bacteria. There is a drawback that welding flux and oxidative debris must be removed and cleaning work must be performed in order to leave no possible flux, and that the structural materials such as the frame of the equipment must also be treated to correct welding distortion. there were. The present invention provides a tapped thin-walled pipe, a machining method and a machining tool for tapping which solve these problems.

[0004]

In order to solve the above problems, a thin-walled pipe has a cylindrical or cylindrical piece-like burr 4 protrudingly formed on the inner surface of a thin peripheral wall 2 and tapped on the burr 4. It has a feature. Similarly, in the tapping method, the peripheral hole 2 of the thin-walled pipe 1 is provided with the pilot hole 3a by burring to form a burr 4 in the inner wall side in the thickness direction to compensate for the lack of the screw pitch. The tap hole is formed in the pilot hole 3a. Furthermore, the processing tools are
It is characterized in that the point angle α is made acute and the cutting edge is subjected to a processing 6g for reducing or diminishing the cutting function, and at least the outer diameter of the lower end portion is formed with the conical portion 6b having the diameter of the tapped hole.

[0005]

When the tip of the cutting edge portion 6b (8a) of the rotating tap 6 (or drill 8) is pressed against the center position of the pilot hole 3a and pressed, the peripheral wall of the outer periphery of the center is rubbed by the processing portion 6g (8c). 2 plastically deforms into a mortar, tap 6
When the tip is further pushed in, the tip of the cutting edge portion 6b (8a) penetrates and a cylindrical or cylindrical piece-like burr 4 is sequentially formed inside the peripheral wall 2 to form or bore a pilot hole 3a. The sharp edge angle α (θ) of the cutting edge portion 6b of the tap 6 or the like reduces the spread resistance during the burring process and facilitates the spread of the peripheral wall 2 into the cylindrical shape. The processing of the tapped hole 3 is completed by passing the taps 6 and (9) through the pilot hole 3a continuously or in another step. The burr 4 secures a sufficient lead for bolts which is not sufficient only by the wall thickness of the peripheral wall 2 of the thin-walled tube 1 and holds sufficient fastening force to withstand an expected load.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross section of a thin-walled pipe of the present invention, which has been tapped. A tap hole 3 is formed in the center of a peripheral wall 2 of the thin-walled pipe 1, and the tap hole 3 is on the inner surface side of the peripheral wall 2. A burr 4 having a cylindrical shape or a cylindrical piece is formed in a protruding manner, and the inner surface thereof is processed by threading. The burr 4 has a tap diameter (for example, 6 m) with respect to the thickness of the peripheral wall 2 (for example, 2 mm).
When performing tapping of m), the purpose is to compensate for lack of threads for securing the tightening force of the bolt.
Stainless steel material (SOS304) by burr 4
Therefore, at least a lead of 6 mm or more is secured.

The lower hole 3a of the tap hole 3 and the burr 4 are formed by burring, and the tap 6 shown in FIGS. 1 and 2 is a burring tap for performing burring and tapping at the same time. That is, in this example, the tap 6 is a cutting edge portion (conical portion) of the tapered portion (chamfer portion) 6a.
The point angle α of 6b is formed by grinding so as to form a conical shape of, for example, about 45 °, and is formed between the relief groove 6d formed obliquely at the lower end of the tap groove 6c and the cutting blade side of the screw portion 6e. The edge (blade) portion 6f has a machining portion 6 which is abraded so as not to have a cutting function when rotated rightward (when rotated leftward with a left-hand screw), or polished so as to reduce it.
g, and a relief portion 6h is also formed by polishing on the edge portion (relief side) on the opposite side of the relief groove 6d.

To perform tapping with the burring tap 6 as described above, first, the thin-walled tube 1 is set on a drilling machine, the tap hole 3 is positioned by a center punch, and the tip of the rotating tap 6 is tapped. While pressing the center position of 3 and adding cutting oil and the like, the pressure is sequentially lowered. Then, the peripheral wall 2 is plastically deformed into a mortar shape while being pushed outward from the tap hole center position and is depressed,
Next, the tip of the cutting edge penetrates the peripheral wall and taps around it.
As it descends, it is gradually expanded into a cylindrical shape. At this time the lower end of the chamfer portion 6a of the tap 6 forms a tap pilot hole diameter D _1, the tap cutting work in the chamfer portion 6a bottom diameter by the lower end passes is ensured and the tap outer diameter D ₂ However, it will be continuously performed until the inner surface of the burr 4. After the tap cutting is completed, the tap 6 is pulled out to complete the tap processing. The burr 4 is preferably cylindrical, but if the material is sticky and soft, the burr 4 is close to a cylinder, and if the burr 4 is hard, the burr 4 is formed into a cylindrical piece.

FIG. 3 (A) shows a burring drill. The drill 8 has a sharp tip angle θ of the blade portion 8a of about 60 ° and a blade edge 8b which is the tip of the groove 8d and the blade edge 8e.
The polishing process (processed portion 8c) is performed so as to reduce or reduce the cutting function of the drill 8, and the drill 8 has the same diameter as the prepared hole diameter D ₁ of the tap 9. The drilling with the drill 8 is performed by rotating the drill 8 in the same manner as described above, pressing the tip of the blade tip 8a to the center position of the tap hole 3 and pressing down. A cutting hole is not formed in the cutting edge portion 8a of the drill 8 because the cutting function is diminished by the processing portion 8c. Four
Is formed, and the pilot hole of the burr 4 is bored. Then Fig. 3
The tap 9 as shown in (B) is passed through to complete the tapping process.

In the above example, the tapping of the thin-walled pipe 1 is shown as a square stainless steel pipe, but the scope of application of the present invention is not limited to a square pipe, and other polygonal circular cross-section pipes, and the material is suitable for burring. As long as it is plastically deformable, its material is not limited to other metal pipes or synthetic resin pipes.

[0011]

According to the thin-walled pipe and the processing method thereof of the present invention configured as described above, even a thin-walled pipe in which the pilot hole skirt portion for tapping by press working cannot be formed. It does not require post-processing such as welding of auxiliary plate for thread cutting, flux removal after welding, cleaning, and blunting in the case of iron, and easy preparation of holes and taps by pre-work such as marking and center punching. You can As a result, it becomes extremely economical in terms of work efficiency and processing cost.

Further, the machining tool of the present invention forms a cylindrical or cylindrical piece-like burr by lowering or diminishing the cutting function of the cutting edge portion so as to push the peripheral wall of the thin-walled pipe from the center at the time of drilling. However, it is possible to secure a lead that is not sufficient only by the distortion of the thin peripheral wall, and there is an effect that the above-described tapping is possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional perspective view showing an example of a tapped thin-walled pipe of the present invention and a tapping method thereof.

FIG. 2 is a partially enlarged view of a tap which is a processing tool of the present invention.

3 (A) and 3 (B) are partially enlarged views of a drill, which is a processing tool of the present invention, and a tap.

[Explanation of symbols]

 1 Thin-walled tube 2 Circumferential wall 3 Tap hole 3a Lower hole 4 Burr 6 Tap 6b, 8a Blade edge (cone) 6g, 8c Processed part

Claims (3)

[Claims] 1. A burr (4) having a cylindrical shape or a cylindrical piece is formed on the inner surface side of the thin peripheral wall (2) so as to project therefrom, and the burr (4) is formed.
Thin-walled pipe tapped on. 2. A pilot hole is formed by a burring process which forms a cylindrical or tubular piece-like burr (4) in the thickness direction on the inner surface side of the peripheral wall (2) of the thin-walled pipe (1) to make up for a lack of screw pitch. A method of tapping a thin-walled pipe, characterized in that (3a) is bored and tapped into the pilot hole (3a). 3. A sharpened angle (α) is used as an acute angle, and the cutting edge is processed (6g) to reduce or reduce the cutting function, and at least the outer diameter of the lower end portion is formed with a conical portion (6b) having the diameter of the tap pilot hole. Tool for burring process.