DE2208862B2 - Electrically weldable tapping saddle made of thermoplastic material - Google Patents

Description

The invention relates to a tapping saddle made of thermoplastic material, as described in the preamble of claim 1 and is known for example from DE-GM 7121 715. This property right describes the joining of thermoplastic parts, e.g. B. a tapping saddle with a pipe, through a Star-shaped heating conductor made from a coiled resistance wire. The heating conductor can be made of thermoplastic be covered and connected to the tapping saddle. The manufacture of the heating conductor is, however expensive and also has a relatively large thickness because of the reversible ice, so that when heated the thermoplastic parts have to be pressed hard, which leads to deformation in particular of the pipe can.

A heating conductor for welding thermoplastic plastic parts is also known (DE-OS 14 40 958), which is embedded in a plastic body designed as a support element. The disadvantage is that of the thermoplastic parts separate execution of the heating conductor, through which the heating conductor into the contact zone of the two thermoplastic parts to be welded comes lying, so that the thinner thermoplastic part is softened more and by the acting pressure is deformed. In another known heating conductor (DE-GM 18 49 053), a heat-resistant carrier is used Plastic used so that the heating conductor can be used repeatedly. For welding However, this heating conductor cannot be used for two flat thermoplastic parts.

It is also known to weld the ends of thermoplastic pipes with the aid of sleeves, wherein the heating conductor either on the inside of the socket wall or between the pipe end and the Sleeve is inserted (DE-GM 18 85 743, CH-PS 3 96 536, US-PS 30 94 452). Although with such pipe connections no compressive forces are exerted on the parts to be welded, the parts used there can monofilament or bifilar wound resistance wires existing heating conductors also for welding flat thermoplastic parts are used.

The invention is based on the object of designing a tapping saddle of the type described in the preamble of claim 1 so that the resistance wire used as a heating conductor can be arranged in a simple manner around the connection area of the connecting piece.
This object is achieved according to the invention by the

ίο characterizing features of claim 1 solved. It is thereby achieved that a more uniform and thus better welding in the connection area of the connecting piece, via which forces acting on the connecting piece are introduced onto the saddle part, preferably arises the wire sheathing is part of a sunk into the saddle part and with this, preferably through Fusion, connected, arched plate, the latter being the inner surface of the saddle at most slightly This allows a certain distance between the heating conductor and the mostly thin-walled one Pipe part to which the tapping saddle is welded must be adhered to.

The invention is shown for example in the drawing and described below. It shows

F i g. 1 a schematic representation with a complementary shell body,

F i g. 2 shows a vertical section through an enlarged The section of the tapping clamp shown in FIG. 1 with an embedded, sheathed resistance wire,

F i g. 3 a schematically illustrated development of the inner surface of the saddle with a resistance wire laid in the form of a double-barreled spiral,
F i g. 4 a schematically illustrated development of the inner surface of the saddle with a resistance wire laid in the form of a simple spiral and

5 shows a section of a tapping saddle laid ready for use.
The tapping saddles used in metal pipelines to connect two lines of smaller diameter to existing pipelines are also used in pipelines made of thermoplastic material. Here, a heating conductor is arranged between the tapping clamp and the pipe 1 to be tapped, as shown in FIG. 1 and 2 can be seen. The pipeline 1 is spanned by a saddle part 2 with a connecting piece 2 ′ and a complementary shell body 5. On the connecting piece 2 'is an upper part 3 with a connecting piece 3' and a

so arranged closure 4, preferably afterwards for example on the construction site, permanently or detachably connected to the saddle part 2. The saddle part 2 and the upper part 3 can also be manufactured as one part. The closure shown as a cap has the Task, the opening in the main axis of the upper part for the tapping tool after removal close the same tightly.

From the saddle section in F i g. 2 is the embedding of a heating conductor in the form of a resistor

hi) stand wire 6 on the inner surface of the saddle part 2 evident. The wire 6 is prior to being inserted in the saddle part 2 with the same or a related one Material coated like the material of the saddle part 2, which, as indicated by dashed lines, at least;

iw is partially welded to the saddle part 2. the Sheathing solves the connection of the resistance wire 6 with the saddle part 2 and in a simple manner also ensures a flawless electrical

Contact protection. Because the coated resistance wire 6 is not or at most slightly protrudes beyond the inner surface of the saddle part, this is laid under the inner surface, so that a notch effect in the interface between the pipeline 1 and the saddle part 2, which is highly stressed during operation, is omitted This also increases the risk of excessive or complete softening of the relatively thin-walled Pipeline 1 reduced If the base part is manufactured by injection molding, the heating conductor can from the uiproantelten resistance wire 6 into the form inserted and then the saddle part 2 injected.

In Figure 3 the resistance wire 6 forms a spiral in a square shape with a bifilar arranged resistance wire 6. Inside the spiral can already be at the Manufacture of the saddle part 2 a connection hole 8 can be provided for the branch line. Training the spiral according to Figure 3 is very tight in terms of tightness reliable, albeit because of the bifilar wire guidance there is a risk of short circuits during welding.

In Fig.4 shows the from the sheathed resistance wire 6 formed spiral on a similar execution as in F i g. 3, however, is the resistance wire Arranged in the form of a simple spiral in a circular ring shape, this arrangement offers both electrical Regarding the tightness, a high degree of reliability.

While in the execution according to FIG. 3 the ends of the resistance wire on both sides of the connector 2 'or the connection hole 8 (FIG. 2) is arranged, in the embodiment according to FIG . Correspondingly, in the embodiment according to FIG. 3, wire connections 7, which are arranged at the ends of the resistance wire 6 and are guided to the outside of the saddle part, lie outside the connecting piece, while in the embodiment according to FIG. 4 at the outer end of the resistance wire 6, the wire connection 7 and at the inner end of the wire connection T are arranged. In the execution according to FIG. 4, the connection hole 8 can only be drilled after the saddle part 2 has been welded to the pipeline 1. As can be seen from FIGS. 3 and 4, the spiral only extends at a distance from the center which is at least equal to half the diameter of the connection bore 8. The internal connection according to FIG. 4 is guided in a direct line to the center of the connection bore 8 to be subsequently produced. There are also other shapes of the spiral conceivable, for. B. in the form of a polygon.

In Fig. 5, the tapping saddle consists of a saddle part 2 with the one opening into the tapping axis Nozzle 2 'and a T-shaped upper part J with the connecting piece 3' for the connection of a branch line 10. The upper part 3 is through a commercially available, electrically weldable sleeve 9 with the connecting piece 2 'of the Saddle part 2 connected. Another sleeve 9 with wire connections 9 * connects the branch line 10 mii the connecting piece 3 'of the upper part 3. The complementary shell body is also a saddle part 2, wherein a spiral according to FIG. 3 with the wire connection 7 located outside and inside the connector 2 '

ίο or 7 'is arranged

To connect the branch line 10 to the pipeline 1, the two saddle parts 2 are stretched around the pipeline 1 and welded thereon, the required welding heat being supplied in the form of electrical energy via the wire connections 7 and T, respectively. After the saddle parts 2 have been welded to the pipeline 1, the upper part 3 with the socket 9 is placed on the one socket 2 'and the branch line 10 is connected with a further socket 9 with the connection socket 3'. By charging the welding sleeves 9 with electrical current via the wire connections 9 ', the upper part 3 is firmly connected to the socket 2' on the one hand and the connecting piece 3 'to the branch line 10 on the other hand. A tubular cutting tool is then inserted into the upper part 3 and the connecting bore 8 and a pipe tapping 1 'are drilled with it. When drilling the connection hole 8, the wire connection T arranged inside the connector 2 'is removed by cutting through the wire end leading to this connection, but this is meaningless because the resistance wire 6 has no further task to perform after the saddle part 2 has been welded to the pipeline 1 Has. The upper part 3 is closed from the outside by inserting the locking pin, which has a snap ring 4 "which engages in a groove 3 '. A sealing ring 4' made of rubber-elastic material seals the locking pin 4.
By using saddle parts 2 in pairs, the entire circumference of the pipeline 1, spanned from the inside, can be welded, even if only a single connection is required. As a result, the thrust forces that often occur in practice are symmetrically distributed over two welds. The welding of paired saddle parts 2 to the pipeline 1 is expediently carried out in one operation. The separately produced upper part 3 can also be connected to the connecting piece 2 'with the aid of a welding mirror. Instead of the sheathed resistance wire you can

■> o the spiral in one of the same similar material be embedded as the saddle part 2 existing plate for the manufacture of the saddle part 2 in the Injection mold is inserted and connected to the saddle part 2.

For this purpose 3 sheets of drawings

Claims (2)

Patent claims: 1. Tapping saddle with a saddle part having a socket made of weldable thermoplastic material for connecting to pipes made of the same or similar material by means of electric current, with a resistance wire that converts the electrical energy into heat, is covered with the said material and arranged in a layer in the inner surface of the Saddle part is inserted and at least partially connected to it, characterized in that the resistance wire (6) is designed in the form of a spiral around the connection area of the connecting piece (2 ') and the shape of a simple spiral with a wire connection inside and outside the connecting piece (7, T) or a double-ended spiral with wire connections (7) lying outside the nozzle on both sides 2. tapping saddle according to claim 1, characterized in that the wire sheathing is a component one sunk into the saddle part (2) and connected to it, preferably by fusing, arched plate, the latter protruding at most slightly from the inner surface of the saddle.