JPH066344B2 - Method for manufacturing a connecting piece such as a branch saddle - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to a method for producing connecting moldings such as branch saddles. In this case, the connecting molding piece is made of thermoplastic resin and is provided with a heating wire, and the heating wire can supply an electric current to form a weld joint between the connecting molding piece and the connection target. Is.

2. Description of the Prior Art A method for producing moldings of this kind for connection is known from European patent application No. 82401203.3.

Generally, when connecting a thermoplastic tube to a connecting molding by welding, a connecting molding with an electric heating element in the form of a spiral wound wire is often used. In order to form such a weld joint between the molded connecting piece and the pipe, an electric current is supplied for a predetermined time by means of a spiral heating wire arranged on the surface of the molded connecting piece. As a result of the heat generation in the heating wire, the material on the mutually facing surfaces of the connecting piece and the tube will melt.

According to the example of the European patent application, the fixing of the spiral heating wire is carried out by embedding the heating wire on one side of one disc. The inner end of the heat wire embedded in a spiral shape is bent, separated from the disk surface by one rotatable lip, and led out to the outside of the disk through the spiral winding. Thus, both ends of the heating wire can be easily connected to the voltage source. However, this method has the following drawbacks. That is, uneven heating of the surface of the connecting molded piece and the surface of the pipe facing each other occurs at the intersection of the bent inner end of the heat wire and the vortex winding, and as a result, the quality of the welded joint is improved. It is significantly impaired.

The problem to be solved by the present invention is to improve the quality of the welded joint in the method described at the outset.

Means for Solving the Problems The present invention has solved such problems as follows. That is, one heating wire is applied to each of the surfaces on both sides of one disk-shaped core.
The core is embedded according to a single spiral groove, and the core thus embedded with the heating wire is joined to the molding piece for connection, in which case the core is made of a material which becomes integral with the material of the molding piece for connection. According to this method, one heat wire is embedded in each of the surfaces on both sides of the disk-shaped core in a spiral shape, and the inner ends of both heat wires are connected to each other at the center of the spiral wire. You can Further, it is possible to embed two heat wires in a spiral shape and to embed one heat wire continuously on one surface of the core and then on the other surface.

It is also possible to embed the heating wire on the surface of each of the two discs, in which case the two discs are brought into contact with one another on the side opposite to the heating side and are joined as one core.

By selecting the embedding type of the hot wire, it is possible to adapt the connecting profile to the respective heating requirements for optimum weld joint formation. The heat wire may be embedded with insulation, or may be embedded without insulation. When embedding the heating wire in a spiral shape, the pitch or number of the spiral winding may be different on both sides of the disk-shaped core, or the diameter of the heating wire itself may be changed. Also, heating wires having different diameters may be used for embedding on both surfaces of the core, and the vortex winding may be left-handed or right-handed.

In any possible embodiment of the connecting profile of the invention, it is advantageous for the disc-shaped core to have hot-wires embedded in both its surfaces, which results in a permanent high-quality welding. In order to form the joint, a more uniform and complete melting of the disk-shaped core and the surface of the connecting molding piece in contact with this core or of the surface to be connected to the connecting molding piece is possible.

The size of the spiral winding formed by embedding the hot wire is related to the size of the surface on which the welded joint is to be formed in the connecting molded piece and the connecting object. As a result, different powers are required depending on the size of the vortex winding to form the optimum weld joint. In the example of the already mentioned European patent application, an electric welding tool for connecting thermoplastic tubes comprises a heating wire and an auxiliary resistor connected in series with this heating wire. In order to define the total resistance of the hot wire and auxiliary resistor, one electrical control and distributor is connected to the electric welding tool, which automatically adjusts to the measured total resistance. An electric current is introduced by the hot wire over the period of time prepared. In this case, as a premise,
A constant total resistance corresponds to a constant period. This resistance measuring method is not accurate for a system that automatically adjusts the welding time in relation to the measured resistance. This is because, depending on the electric welding tool used, even if the expansion of the molding piece for connection is the same, it has a significantly different resistance value with respect to the heating wire. In this case, the tolerance of the resistivity of the hot wire will be significantly different, and thus different resistance values will result.

In order to deal with such a point, in the case of the connection molding piece of the present invention, one auxiliary resistor is provided for the purpose of automatic processing of welding, and this auxiliary resistor, like the heating wire, is provided through a separate conductor. Connected to an electrical control and distributor. The resistance value of this auxiliary resistor can be precisely defined independently of the resistance of the heating wire, and can be applied to any manufacturing system of the connection molding piece of the present invention. As a premise in this case, for example, 100 ohm or 10,000o
A specific resistance value of the auxiliary resistor of less than hm or larger corresponds, for example, to a given welding time of less than 10 seconds or 600 seconds or longer. The auxiliary resistor according to the present invention can be mounted either during or after the molding of the connecting molding piece.

According to a preferred embodiment, the auxiliary resistor is provided with a protective coating and is fastened to the connecting piece via the connecting pin. The welding time required to supply the desired power can be calculated depending on the resistance of the wire and the tolerance of the diameter of the wire, which is the material of the wire, depending on the determination of the resistance of the wire of the connecting piece. Accordingly, a correct auxiliary resistor with a corresponding resistance value can be attached to the connecting piece. This auxiliary resistor serves to supply the required energy during welding for a predetermined period of time via an electrical control and distributor. This makes it possible to minimize the number of defective welded joints in an advantageous manner.

In order to make it possible to visually judge the progress during welding of the connecting molded piece, a place is provided at an arbitrary position of the connecting molded piece, and the wall or bottom of this place partially contacts the heat ray. Then, loosely insert the marked pin made of a material different from that of the connecting molded piece into the housing. The pin with this mark serves as an inspection member of the quality of the welded joint during welding. This is because the thermal expansion of the material to be melted causes an overpressure, which causes the molten material to squeeze out the pins in the chamber. The degree to which the pin is pushed can be read by the mark protruding to the outside, which is a standard for the quality of the welded portion formed. This is because the amount of extrusion of the marked pin depends on the amount of molten material, and this amount of melting causes thermal expansion of the molten area,
This is because the durability of the welded joint between the molded piece for connection and the object to be connected is determined.

Examples The invention will now be described according to the examples shown in the drawings: In FIGS. 1a, 1b and 1c a disc-shaped core 1 is shown in plan and longitudinal section. The spirally wound heating wire 2 is embedded on both surfaces of the core 1. At the center of the disk 1, the inner ends bi, bi 'of the heating wires 2 on both sides are connected to each other, so that as the voltage source is connected, the outer ends bu of one heating wire to the outside of the other heating wire. Current flows to the end bu '. The pitch of the vortex winding of the heating wire 2 is selected according to the required heating amount, in which case the number of windings is less than 10 or 30 or more.

FIG. 2a shows a connecting saddle piece 17 as a branch saddle in a longitudinal section, and FIG. 2b in a transverse section. The heating member consisting of a disk-shaped core 1 has a heating wire 2 leading to an electric connection pin 7, and is bent so as to have a bending radius matching the radius of a connecting molding piece 3 to be molded, Alternatively, it is positioned as an insert piece inside the mold. After the molding of the connecting molding piece 3, this heating member, that is, the heating member made of a material whose disc-shaped core is combined with the material of the connecting molding piece 3, is used together with the molded connecting molding piece 3. Make one. According to another embodiment, a corresponding overhang is formed in the connecting piece 3 and the heating element is subsequently inserted into this overhang.

The auxiliary resistor 4 is also shown in FIGS. 2a and 2b. This auxiliary resistor 4 has an electrical connection pin 8,
It is arranged at an appropriate position in the molding piece 3 for connection during molding of the molding piece 3 for connection, or as a unit consisting of electric connection pins and auxiliary resistors, it is arranged with a protective coating after molding.

An overhang 5 is also visible in FIGS. 2a and 2b. This recess 5 is formed during molding of the connecting molding piece 3 via a suitable mold pin of circular, oval, square or any other cross-sectional shape. After molding the molding piece 3 for connection, loosely insert the pin 6 with the mark, which has been manufactured accordingly, into this recess 5. If necessary, a large number of such recesses 5 and mark pins 6 may be arranged.

[Brief description of drawings]

FIG. 1a is a plan view of a disk-shaped core according to the present invention, FIG.
1a is a longitudinal sectional view of the core of FIG. 1a, FIG. 1c is a bottom view of the core of FIG. 1a, FIG. 2a is a longitudinal sectional view of a molding piece for connection according to the invention, and FIG. 2b is a connection of FIG. 2a. It is a cross-sectional view of a molding piece for. DESCRIPTION OF SYMBOLS 1 ... Core, 2 ... Heat wire, 3 ... Molded piece for connection, 4 ... Auxiliary resistor, 5 ... Overhang area, 6 ... Pin, 7, 8 ... Electrical connection pin

Claims (4)

[Claims] 1. A method for producing a molded piece for connection, wherein the molded piece for connection is made of a thermoplastic and is provided with a heating wire, and the molding wire for connection is connected to the connecting object by the heating wire. In which a current can be conducted to form a welded joint on the core, a heat wire is embedded in the surfaces of both sides of one disk-shaped core according to a spiral groove, and the core embedded with the heat wire is connected to a molding piece for connection. Combined with
A method for producing a molding piece for connection, characterized in that the disk-shaped core is manufactured from a material which is integrated with the material of the molding piece for connection by melting. 2. A heating wire is embedded in the surface of one side of each of the two disks, and both disks are brought into contact with each other on the surface opposite to the side of the heating wire to combine them into the shape of a disk-shaped core. Method according to claim 1 3. A molded piece for connection is provided with one auxiliary resistor, the resistance value of which can be preselected as a parameter of welding time which is automatically adjusted before welding. Claim 1 wherein the regulation is controlled via one electrical control and distribution device connected to the heating wire and the auxiliary resistor via a separate conductor between the voltage source and the connecting strip. Or the method according to item 2 4. The molding piece for connection is formed with a place adjacent to the heating wire, and a pin with a mark made of a material different from that of the molding piece for connection is loosely inserted into this molding place. The method according to any one of 1 to 3