JPS5815675B2 - Gouseijiyushi savenkikantsugiteno settsugohouhou - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of joining a synthetic resin main pipe and a synthetic resin branch pipe fitting having a saddle, which enables complete contact between the heater surface and the main pipe surface, and eliminates poor contact areas. The purpose is to prevent the formation of cavities and unfused portions during fusion by removing the porosity and making heating uniform.

Generally, in the case of a pipe having low rigidity, such as a polyethylene pipe, it is difficult to maintain the cross section of the pipe always in a perfect circle at any point.

In particular, taking advantage of its low rigidity, pipes are wound into coils of 40 meters, 120 meters, 300 meters, etc., and stored or transported as long tubes, and when used, the coils are unwound. In this case, the cross section of the tube becomes elliptical, and the curls remain.

Conventionally, when attaching a semi-cylindrical shape to a pipe like this, when fusion-bonding a synthetic resin branch pipe fitting with a saddle, the pipe is not a perfect circle, so it cannot be melted uniformly at the desired location, making it impossible to complete the fusion-bonding. There wasn't.

In other words, in order to fusion-bond a branch pipe joint with a saddle to the main pipe, a heater plate 3b1 is installed between the main pipe 1 and the saddle-shaped joint 2, as shown in FIGS. A heater 3 consisting of surfaces 3a and 3c is arranged,
The joint surfaces of both are heated and melted by contact heating with a heater 3, and after a predetermined period of time has elapsed, the heater 3 is quickly removed, the molten surfaces of both are brought together, and pressure bonding is continued until the molten portion is hardened.

Then, after at least two minutes have elapsed, a special cutter set in an electric drill is inserted into the upper straight pipe part of the joint 2 to make a hole in the main pipe 1.

However, if the main pipe 1 is curved as shown in Fig. 3 due to the coil winding as described above, and the pipe cross section is distorted into an elliptical shape as shown by the two-dot chain line, the four corners of the heater surface 3c are attached to the main pipe 1. Because of the local contact, (1) the R concave surface of the heater surface 3c and the surface of the main pipe 1 cannot be in complete contact with each other over the entire surface.

(2) If the surface of the main pipe 1 is heated by the heater 3 in the state of (1) above, the heating will be uneven, and degassing during melting will be inhibited, resulting in air pockets.

For these reasons, unmelted portions 6 to 9 as shown in FIG. 4 are generated on the tube surface, making uniform and complete melting impossible.

On the other hand, even if a good contact surface is obtained with the saddle due to the contact heating of the joint 2 with the heater surface 3a, this melting surface and the melting surface of the main pipe 1 are not completely attached due to the same reason as in the case of the heater surface 3c. It is difficult to adhere to the surface, and it is easy to peel off due to poor bonding, leading to the risk of unexpected accidents.

Therefore, conventionally, when joining the joint 2 to the elliptically distorted part of the main pipe 1, a clip 5 for straightening the pipe shape was attached to the heater to ensure the roundness of the main pipe 1, as shown in FIG. Although the tubes are set apart on both sides of the tube, it is still not possible to completely correct the curls and flatness of the tube.

Therefore, since the main pipe 1 could not be uniformly melted, incomplete fusion bonding was inevitable.

Furthermore, as the diameter of the main pipe 1 increases and the saddle of the joint 2 increases, this tendency becomes even worse.

According to this invention, by using a heater for heating the main pipe with chamfered four corners of the heater surface, it is possible to easily and completely contact the main pipe joint surface at any point, and promote uniform heating. A method of joining synthetic resin branch pipe fittings is provided which provides an extremely good welding surface and allows an extremely strong fusion bond, and if necessary, semi-cylindrical installation of branch pipe fittings is possible. If the four corners of the saddle are also chamfered in advance and then melted, all of the above-mentioned problems can be solved, such as making fusion bonding easier.

The heater to be used in the method of this invention is similar to the conventional heater 3 shown in FIGS. The heater surface 3a formed into an R convex surface that can be adapted to the curved surface of the bottom and the heater surface 33c formed into an R concave surface that can be adapted to the surface of the main pipe 1 are combined together, or the heater surface 3a and the heater surface 3a are not limited to this. 3c may be used, but the heater for heating the main pipe has four heaters on the heater surface 13c, as an example shown in FIGS. 7 and 8.
The corner 13d is symmetrically cut out and chamfered.

However, the shape of the chamfer is not limited to this, and may be chamfered in any shape, such as a curved surface with an appropriate radius according to the size of the heater.

For example, the four corners of the heater surface can be curved with large radius, making the entire heater surface circular or elliptical.

The material of the heater is mainly aluminum, and the surface should be treated with anti-adhesion treatment such as Teflon coating.

On the other hand, as shown in Figs. 9 and 10, when installing the branch pipe joint 12, the saddle should be of the most suitable shape so that it does not protrude from the melting surface caused by the contact heating of the main pipe heater. Chamfering allows for extremely good fusion bonding.

Of course, this saddle can also be circular or oval like the heater surface.

Example: coiled with a diameter of 1.8 meters, density 0.940
9/cm3. Polyethylene resin with melt index (MI) 0.2 nominal diameter 50A (outer diameter D 60mm, wall thickness 5
．． 5m, m) pipe with nominal diameter 50AX25A, d=48m, m as shown in Figures 9 and 10.

dO=34mmXh=94m, m, 7=70m, m, w
= 55m, prepare a thick m branch pipe joint 12 of m and a 25A pipe connected to this branch joint 12, and as shown in Figs. 5 and 6, W1 = 60 mm, L medium 133 mm.
, H1=30m, size of m, 1/2D=30mmR
A heater plate 13b integrally formed with a heater surface 13a (mounted for saddle heating) having a convex curved surface, W2=60 mm, L size 133 mm as shown in FIGS. 7 and 8,
A heater with a size of H2 x 35 mm, a concave curved surface of 1/2D = 30 mmR, and a heater surface 13c for heating a polyethylene pipe with chamfered four corners 13b, which is integrally connected with bolts, is almost the same as this heater. By using two types of products, the conventional product and the one in which the four corners of the heater surface 13e are not chamfered due to size and shape, the same fusion conditions, that is, the temperature of the heater surface 260°C.
The conventional method and the method of the present invention were used to melt the pipes and fittings with a heating time of 45 to 50 seconds and a pressure of 30 kg, then remove the heater, continue crimping with a pressure of 30 kg for 1 minute, and finish cooling after 2 minutes. Welding was performed.

At this time, the conventional method requires 0.5 mm at each of the four corners of the saddle.
In the method of the present invention, a branch pipe joint with R chamfers and chamfers of 10 imH at each of the four corners was used.

Next, the test was repeated using a bending test apparatus as shown in FIG. 11 under conditions of a temperature of 20 DEG C. and a bending speed of 50 mm/min with a load P applied thereto.

At this time, the internal dimension of pipe 1 with both ends fixed is 400 m, m, pipe 1
The distance to the fixed inner end of the connecting pipe was 300 mm, and the load P was maintained at a position of 150 mm from the fixed inner end.

In addition, a hot internal pressure creep test was also conducted, and the performance comparisons are as shown in the following table.

In addition, we observed the melting state of the surface of the main pipe melted by the conventional method and the method of the present invention. As shown in FIG. 2, it was found that extremely uniform melting could be achieved by the method of the present invention.

As is clear from the description of the above embodiments, the feature of the joining method of the synthetic resin branch pipe joint according to the present invention is that the semi-cylindrical fitting is a synthetic resin branch pipe joint with a saddle and a synthetic resin main pipe joint. In this method, the joining surface of the main pipe is melted by a main pipe heating heater whose four corners of the heater surface are chamfered, and the saddle is also melted during the installation. Since the two melting surfaces are brought into contact and joined, compared to the case of using a conventional heater for heating the main pipe where the four corners of the heater surface are not chamfered, the heater surface is closer to the joint surface of the main pipe. Since it is possible to make the contact extremely easy and maintain complete contact, an extremely good and even melting surface can be obtained.

Therefore, a complete installation can be done by fusion bonding with the saddle.
Prevents peeling and improves durability.

In addition, if the four corners of the saddle are chamfered during installation, the molten surfaces can be better kept in contact with each other.

[Brief explanation of the drawing]

Figures 1 and 2 are a partial cross-sectional front view and side view showing the contact heating state in the conventional method, Figure 3 is an explanatory diagram of an example where curls remain due to coil winding, and Figure 4 is the case of the conventional method. 5 and 6 are front views and partial plan views showing an example of the mounting of the heater surface for heating the saddle, and FIGS. 7 and 8 are illustrations of the unmelted portions generated in the method of the present invention. Front view and bottom view showing an example of a heater for heating mains, No. 9
10 is a partially sectional front view and a plan view of the branch joint, and FIG. 11 is an explanatory view showing a bending test. In the figure, 1...Main pipe, 2, 12...Branch pipe joint, 3...Stomach heater, 3a, 13a, 3c, 13c...Hitor side, 3b,
13b... Heater plate, 4... Wiring, 5... Clip, 6
~9...Unmelted portion.

Claims (1)

[Claims] 1 Semi-cylindrical mounting is a method of fusion joining a synthetic resin branch pipe joint with a saddle and a synthetic resin main pipe by contact heating with a heater, and the four corners of the heater surface are chamfered for heating the main pipe. A method for joining synthetic resin branch pipe joints, characterized in that the joining surfaces of the main pipes are melted by a heater, while the saddle is also melted during the installation, and then both melted surfaces are brought into contact and joined.