JPS6141649B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for manufacturing a threadless coupling which has no internal thread on the inner wall of the pipe but has a set screw hole passing through the pipe wall, and is used to connect pipes such as electrical conduits, for example.

One method of processing such a threadless coupling is to cut it from the hoop material along a cutting line that includes a protrusion that is wider at the tip than the base, and to form a pair of cut rings with a protrusion on one end surface and a recess on the other end surface. A processing method has been developed in which a square plate material with set screw holes is formed, the square plate material is bent, and a convex part is fitted into a concave part to form a tube. In this processing method, when forming a pipe joint by bending and fitting a convex part into a concave part,
There is a problem in that there is a gap in the pipe joint, and so-called galling occurs between the end surfaces of the convex portion and the end surfaces of the concave portion.

The present invention was made in view of this background,
The following will explain the embodiments shown in the drawings.

Figure 1 is a schematic diagram showing the skeleton of continuous sheet metal processing and its manufacturing equipment, which is the first stage of the processing method, Figure 2 is a sectional view showing the tube forming process, which is the second stage of the processing method, and Figure 3 is the above-mentioned FIG. 4 is an enlarged cross-sectional view of the main part of the second stage of processing, and is a perspective view showing a threadless coupling obtained by the above-mentioned processing method.

First, the first step of the processing method will be explained with reference to FIG. Figure 1a shows the set screw hole 1 in the hoop material A.
FIG. 1b shows the burring process of the set screw hole 1, and FIG. 1c shows the threading process of the set screw hole 1 using a tap. Figure 1d shows a preliminary machining process for cutting the uneven joints of the pipe, which will be described later.The tip has a rounded part 2a (a flat surface in the figure, but a rounded surface may also be used), and an inclination angle of 2θ shown in the figure. V punch 2 with
At this step, a V-groove 3 is formed that reaches halfway through the thickness of the hoop material A (depth h as shown). FIG. 1e shows a cutting and sizing process using a punch 5 and a die 4 having a shearing blade 4a and an inclined surface 4b behind the shearing blade 4a. The state of cross-sectional change in this process is as shown in Fig. 2a, first, a cutting line passing through the inner flat surface 3a of the V-groove 3 by the shearing cutting blade 4a (the position of this cutting line varies depending on what is called mold alignment). Then, as shown in FIG. 2b, the sheared end surface 6a of the material is pressed against the inclined surface 4b, so that the flat surface 3a of the V-groove 3 disappears, and the material is sheared approximately from one side to the other side of the sheared surface. It is sized to have a uniform inclination angle (θ in the drawing). Next, the cut end surface 6b corresponding to the sheared material end surface 6a is also sized using a mold, although not shown, in the same way as the die 4 and punch 5 in FIG. 1e. After passing through the first stage of this processing method, the convex portions 7, 7 are formed on one end surface generated by the shearing process, and the convex portions 7 are formed on the other end surface.
A square plate material 9 having recesses 8, 8 into which the two are to be fitted is obtained. The width of the front surface of the convex portions 7, 7 is narrower than that of the back surface. Also, the width of the back side of the recesses 8, 8 is narrower than the front side, but the recesses 8,
The narrower width of the back surface of 8 and the wider width of the back surfaces of the protrusions 7, 7 are approximately equal.

Next, the second stage of the processing method is shown in Figure 3 a, b,
The explanation will be given in the order of processing c and d. FIG. 3a shows a pre-bending band 10 having a curvature of the inner diameter (r in the figure) of the finished pipe product (r in the figure) and a curvature angle (α in the figure) near one end surface of the sheared end surface of the square plate material 9. This figure shows a step of providing a preliminary bending band 11 having the same specifications as the above-mentioned preliminary bending band 10 near the end face. Fig. 3b shows the process of bending the cylindrical core material 12 having a radius (r in the figure) corresponding to the radius of the finished pipe product into a U-shape using pushers 13, 13; One preliminary bending band 10 is brought into close contact with the cylindrical core material 12, and the reverse 6
The step of bending the tube into a shape of a letter, FIG. The process of forming 14 finished products is shown. Although not shown, it is preferable in the present invention to carry out so-called sizing to reduce the diameter of the tube 14 using a cylindrical core material having a slightly smaller diameter than the cylindrical core material 12 to further reduce the fitting gap created by the chamfering. Let's take an example.

FIG. 4 is an enlarged sectional view showing a continuously changing state corresponding to FIG. 3 d and FIG. The width of the concave portions 8, 8 is narrower, and on the other hand, due to the chamfering effect in which the width of the back surface in the rounding direction of the concave portions 8, 8 that receive the concave portions is wider than the width of the front surface of the convex portions 7, 7 (of course, the pre-bending band 11 is In other words, this shows a state in which the convex portion 7 is smoothly fitted into the concave portion 8 without galling (combined with the effect of transitioning parallel to the cross section of the pre-bending band 10).

Through this processing method, a threadless coupling 14 as shown in FIG. 5 is obtained, in which pipes 16 and 16' are fitted into the tube 14, and set screws 17 that are screwed into the set screw holes 1 are fitted to the pipes 16 and 16'. is pressed to connect the pipes 16, 16'.

FIG. 6 shows a different embodiment of the present invention, in which the inclination angles of the V-groove 3 are not equal on both sides (θ ₁ <θ ₂ in the figure) and the hoop material A is sheared along a line close to the small inclination angle. There is. Such embodiments show that V in the shearing step
Burrs generated on the deep flat surface 3a of the groove 3 (see figure 1)
8) is superior in that it can be made smaller than the previous embodiment. As described above, the method for processing a threadless coupling of the present invention involves forming a V-groove reaching halfway through the thickness of a hoop material using a V-punch having a rounded portion at the tip, shearing the hoop material along the V-groove, and then shearing the hoop material along the V-groove. The square plate material is formed by sizing a sheared surface having a substantially uniform inclination angle on the inner wall surface of the V groove from one side of the sheared surface to the other side. It has the following effects.

(b) A V-groove is formed with a V-punch that has a rounded part at the tip, and a square plate material is formed by cutting along the bottom of the V-groove, so when using a V-punch with a sharp tip, In comparison, the life of the punch is long and the precision of so-called mold matching, in which the cut line of the shearing die is matched to the depth of the V-groove with a sharp tip, is no longer required.

(b) Furthermore, due to sizing, the width of the front (or back) side of the convex part in the rounding direction becomes narrower, while the width of the back (or front) side of the concave part that receives it in the rounding direction becomes wider. When rounding and fitting the convex portion and the concave portion, there is an advantage that the narrow convex surface is smoothly inserted into the concave portion wider than the convex surface, and the fitting is performed without galling.

[Brief explanation of the drawing]

1 to 5 show examples of the present invention, and FIG. 1 is a schematic diagram showing a skeleton of continuous sheet metal processing and its manufacturing equipment, which is the first stage of the processing method;
Figure 2 is an enlarged cross-sectional view of the main processing parts in the first stage, Figure 3 is a cross-sectional view sequentially showing the tube forming process in the second stage of the processing method, and Figure 4 is an enlarged view of the main processing parts in the second stage. The sectional view and FIG. 5 are perspective views showing a threadless coupling obtained by the above processing method.
FIG. 6 shows a different embodiment of the present invention, and is an enlarged sectional view of the main part at the first stage of processing. 1 is a set screw hole, 2 is a V punch, 2a is a fitting part, 3 is a V groove, 4 is a die, 4a is a shearing cutting blade,
4b is an inclined surface, 5 is a punch, 6a is a material end surface, 6
b is a cut end surface, 7 is a convex portion, 8 is a concave portion, 9 is a square plate material, 10 is a preliminary bending band, 11 is a preliminary bending band, 12
13 is a cylindrical core material, 13 is a push arrow, 14 is a tube, 15 is a coupling, 16 is a pipe, and 17 is a set screw.

Claims (1)

[Claims] 1 Separate the hoop material along a cutting line that includes a protrusion that is wider at the tip than the base, and make a square plate material that has a protrusion on one end surface, a recess on the other end, and a pair of set screw holes. In the method of processing a threadless coupling, which forms a pipe by bending the square plate material and fitting a convex part into a concave part, a V having a rounded part at the tip is used.
After forming a V-groove that reaches halfway through the thickness of the hoop material with a punch and shearing the hoop material along the V-groove, approximately the inner wall surface of the V-groove is cut from one side of the sheared surface to the other side. A method for processing a threadless coupling, characterized by forming a square plate material by sizing a sheared surface with a uniform inclination angle.