JPH0261381B2 - - Google Patents

Abstract

PURPOSE:To bond tubular members at a high productivity by such an arrangement wherein the outer circumference of the tubular members made of synthetic resin is surrounded by 2 different electrodes and a high frequency voltage is impressed between the electrodes, the members are bonded together by heating and melting them from outside without inserting electrodes inside the members. CONSTITUTION:Into the interior of a tubular member 4a made of synthetic resin such as vinyl chloride, etc., another tubular member 4b is inserted and the overlapped part of the two tubular members 4a, 4b is used as a part to be bonded, and next, the outer circumference 6 of the part to be bonded 5 is surrounded by 2 half bodies 2a, 2b composing an electrode 2 so that they are brought to contact, and on the one hand, another electrode 3 is caused to surround the members so that it is not brought to contact with the electrode 2. In other words, the outer circumference 6 of the part to be bonded 5 is surrounded by the electrodes 2, 3 in the axial direction of the member 4 at a fixed interval placed between them. Next, a high frequency voltage is impressed on the electrodes 2, 3 and the part to be bonded 5 is bonded by being heated and melted. EFFECT:It is possible to bond long tubular members together, or tubular members of which the other ends are sealed together.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for joining tubular members made of synthetic resin, and more specifically, to high-frequency dielectric heating of tubular members made of a material with a relatively large dielectric loss coefficient such as polyvinyl chloride. This invention relates to improvements in joining methods by welding.

Conventionally, a joining method using high frequency dielectric heating has been used to join polyvinyl chloride, nylon resin, etc. According to this method, even thick parts can be heated uniformly with no temperature difference between the surface and the inside, and local selective heating is also possible, making the high-frequency dielectric heating welding method for synthetic resins an extremely effective joining method. be. However, the high-frequency dielectric heat welding method involves sandwiching the adhered part between two electrodes and applying a high-frequency voltage between the two electrodes. In the dielectric heat welding method, as shown in FIG. 4, first, a small diameter tubular member 4b is inserted into a large diameter tubular member 4a, and the inside of the adhered portion 5, which is the overlapping portion of the two tubular members 4a and 4b, is removed. The electrode 2 having an outer diameter approximately equal to the inner diameter of the small-diameter tubular member 4b is inserted into the small diameter tubular member 4b, and the outer circumferential surface 6 of the adhered portion 5 is surrounded by the half bodies 3a and 3b of the electrode 3. The process involved applying a high-frequency voltage. However, with this method, the electrode 2 must be inserted into the small-diameter tubular member 4b for each tubular member, which is a very complicated and unproductive joining method. In particular, when welding long tubular members, it is necessary to insert a long electrode 2 with an outer diameter approximately equal to the inner diameter of the tubular member 4b into each welding member, and to pull this electrode out again after welding, which greatly reduces production efficiency. The joining process lacked quality. Further, when joining tubular members whose other ends are sealed, or where the inner diameter of the other end is reduced, it is virtually impossible to insert or remove an electrode.

The present invention provides a joining method using high-frequency dielectric heat welding that provides sufficient joining strength without requiring the step of inserting an electrode into the tubular member, which is the source of the above-mentioned problems.

An embodiment of the present invention will be described below with reference to the drawings.
First, the small diameter tubular member 4b is inserted inside the large diameter tubular member 4a. The two tubular members 4a, 4
The overlapped portion of b is the adhered part 5 of this joining method.
shall be. Next, the outer circumferential surface 6 of the adhered portion 5 is surrounded by the two halves 2a and 2b constituting the electrode 2 so as to be in contact with each other, and the other electrode 3 is placed at a certain distance without contacting the electrode 2. to connect the adhered portion 5 to the electrode 2
Similarly, it is surrounded by the halves 3a and 3b of the electrode 3. That is, two different electrodes 2 and 3 are connected to the outer circumferential surface 6 of the adhered portion 5 at a constant interval in the axial direction of the tubular member 4.
Obtain the state surrounded by . Here, half 2 of electrodes 2 and 3
a, 2b and 3a, 3b are in close contact with each other. Subsequently, electrodes 2 and 3 are spaced apart at a constant interval.
A high frequency voltage is applied from the high frequency oscillator 1 to heat and weld the adhered portion 5. After welding is completed, the electrodes 2 and 3
The halves 2a, 2b and 3a, 3b are separated and the welded tubular member 4 is attached and detached to complete the joining method of the present invention.

If the interval between the electrodes 2 and 3 is too wide, the bonding efficiency will be poor, and if it is too narrow, the electrodes may come into contact with each other and cause a short circuit. This interval varies depending on the outer diameter and wall thickness of the tubular member 4, but considering the above points, it is 0.5
mm to 20 mm is preferred.

The material of the tubular member 4 is preferably a synthetic resin with a large dielectric loss. For example, vinyl chloride, vinylidene chloride, nylon, polyurethane, methacrylic resin, etc. can be efficiently bonded by the high frequency dielectric heating of the present invention. Further, the shape of the tubular member 4 is not limited to a ring-shaped cross section, but may have a polygonal shape as long as the two inserted tubular members are in contact with each other.

In addition, in the joining method of the present invention, if the shapes of the ends of the surfaces of the electrodes facing each other are made into acute angles as shown in FIG. changes. Therefore, if the wall thickness of the large-diameter tubular member is thin, that is, if the point A, which is the part where the two tubular members contact, is located outward from the center of the wall thickness of the two joining members, the electrodes may If the shape of the end of the attracting surfaces is made acute, the part where the electric lines of force are dense will move outward from the center of the wall thickness, and the part that generates the most heat will move to the vicinity of the contacting surface of the two tubular members. Therefore, efficient heat welding and high bonding strength can be achieved.

According to the joining method of the present invention, the electric lines of force work as described above and the joining surfaces can be heated and welded, so that the insertion of an electrode inside the tubular member, which was always required in the conventional high-frequency dielectric heat welding method for this type of tubular member, is possible. It is now possible to eliminate the need for attachment and detachment, and it has become possible to join only by operations from the outside of the tubular member. Furthermore, conventionally, the electrodes to be inserted had to be made according to the inner diameter of the tubular member, but according to the joining method of the present invention, this can be omitted. On the other hand, it is possible to join long tubular members together, which was conventionally impossible to perform high-frequency dielectric heat welding, or to join tubular members whose other ends are sealed.

The present invention involves inserting the other tubular member into one tubular member, and aligning the outer peripheral surface of the one tubular member having overlapping surfaces with each other at a constant interval in the axial direction of the tubular member. This is a joining method for synthetic resin tubular members that are surrounded by two different electrodes and welded by applying a high-frequency voltage between the electrodes. There is no need for two electrodes, and bonding can be achieved by placing two different electrodes only on the outside. Therefore, the welding work can be performed only on the outside of the tubular member, and high-frequency dielectric heating welding can be achieved with very high productivity. On the other hand, the method of the present invention has made it possible to join tubular members whose other ends are sealed, or to join tubular members whose other ends have a reduced inner diameter, although conventional high-frequency dielectric heating welding has not been possible. It is.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment according to the present invention, FIG. 2 is an enlarged view of the electrode portion of FIG. 1, FIG. 3 is an enlarged explanatory diagram showing the flow of electric lines of force in the embodiment, and FIG. The figure is an enlarged view showing a conventional example. DESCRIPTION OF SYMBOLS 1... High frequency oscillator, 2... Electrode, 3... Electrode, 4a... Large diameter tubular member, 4b... Small diameter tubular member, 5... Adhesive part, 6... Outer peripheral surface, 7... Electric force line.

Claims (1)

[Claims] 1. Insert the other tubular member into the inside of one tubular member, and use two different electrodes to connect the outer peripheral surface of one of the tubular members, which has overlapping surfaces of the two tubular members, to the axis of the tubular member. 1. A method for joining synthetic resin tubular members, the method comprising surrounding the electrodes at a constant interval in a direction and welding them by applying a high frequency voltage between the electrodes.