DE2241657B1 - Welding process and device for producing a permanent connection between a plastic pipe and a plastic sleeve - Google Patents

Description

tion temperature with simultaneous termination of the plasticizing process is still ensured, that at the beginning of the telescoping of the pipe and socket, their contact surfaces are the same Temperature and thus the plasticized material has the same toughness and hardness, so that tough Do not push the material of the one part less tough material of the other part in front of you or can displace and thus incorrect welds can be avoided.

For this purpose, the plastic pipe and the Plastic sleeve with a constant relative translation speed of about 0.3 cm / sec to 0.75 cm / sec pushed into each other.

In order to avoid any bulging on the outside of the sleeve and thus to ensure that the entire plasticized material takes part directly in the actual welded joint the plastic pipe and the plastic sleeve rotated with respect to one another during the insertion process. Through this the plasticized materials are drawn between the contact surfaces, similar to a lubricant, whereby the plasticized material always seeks the path of least resistance and thus Existing tolerance deviations, especially on the outer circumference of the extruded tube, between Compensates pipe and socket. During this turning process, the relative peripheral speed of the plastic pipe to the plastic sleeve advantageously approximately equal to the relative translational speed of both Parts selected in order to avoid tearing off the plasticized "film" of both parts.

In the meantime, tests have shown that the plasticizing temperature of a pipe or a sleeve, if both parts are made of polybutene, if possible between 250 ° C and 350 ° C, preferably but should be at 330 ° C. When choosing the right plasticizing temperature are under among other things, the enthalpy differences between the parts to be plasticized and the environment are essential, because with increasing enthalpy difference the heat transfer to the environment increases.

At a plasticizing temperature of at least 280 ° C., the plasticizing time has been found to be advantageous a tube made of polybutene with an outside diameter of 20 mm and a wall thickness from 2 mm to about 4 seconds and a sleeve made of polybutene with an outer diameter to be pushed over it of 30 mm and a wall thickness of 5 mm is to be measured in about 10 seconds. Included The plasticizing temperature and plasticizing time must always be coordinated so that with increasing Plasticizing temperature, the plasticizing time decreases.

A device with good thermal conductivity is advantageously used as the device for carrying out the method described above Metal piece with a mandrel corresponding to the inner diameter of the sleeve and one made from the metal piece outstanding bushing, the inner diameter of which corresponds to the outer diameter of the Plastic tube corresponds, with the heat transfer resistances between the metal piece and the The mandrel and the socket are the same size. Only such metals are to be used for the bushing and the mandrel be that no disadvantageous, z. B. catalytic, effects on the plastic concerned exercise.

Some devices and welded joints, on which the above-described procedure is explained in more detail are shown in the drawings. It shows

F i g. 1 shows the cross section through a welding device with an inserted plastic tube and a pushed-on Sleeve,

Fig. 2 shows the cross section through a pipe and a Socket, while sliding into one another,

ίο Fi g. 3 shows the cross section through a further embodiment a socket connection and

Fi g. 4 shows the cross section through an electrically operated Welding machine with detachably inserted socket and mandrel.

In the individual figures, 1 denotes the plastic pipe and 2 denotes the sleeve.

In Fig. 1, the welding device for plasticizing the contact surfaces Γ and 2 'consists of a highly thermally conductive Metal piece 3, which in about its middle with

such an opening 3 'for receiving a thermometer and on one of its side surfaces with a bore 3 "for receiving a handle. The socket 4 for plasticizing the plastic pipe 1 and the mandrel 5 for plasticizing the contact surface 2' of the plastic sleeve 2 are in the present Case integrally connected to the metal piece 3. The bushing 4 is provided at its end facing the metal piece 3 with a thermal insulation layer 4 'and the mandrel 5 at its corresponding end also with a thermal insulation layer 5', thus softening the end faces 1 "of the plastic pipe 1 and the corresponding end face 2 "of the plastic sleeve 2. To achieve the same heat flow per unit of time from the metal piece 3 into the socket 4 or into the mandrel 5, in particular the annular area 4" of the socket 4 is just as large as the circular area 5 " of the dome 5 and - the same material of the socket and mandrel and thus the same thermal conductivity Assuming λ and the same specific heat C _P - the masses of bushing 4 and mandrel 5 participating in the plasticization are dimensioned to be the same. In the case shown, the metal piece 3 is heated by a gas flame 6 until the thermometer located in the opening 3 'shows the temperature which is analogous to the plasticizing temperature. Then that part with the greater wall thickness, in the present case the sleeve 2, is pushed over the mandrel 5 and, after a corresponding period of time, the tube 1 is inserted into the socket 4. The insertion of the plastic pipe 1 must take place at such a point in time that the required plasticization of the sleeve 2 and the pipe 1 are completed at the same time. If, for example, the sleeve 2 requires a plasticizing time of 10 seconds at the specified plasticizing temperature and the pipe 1 requires a heating time of only 4 seconds at the same temperature, the sleeve 2 must first be placed on the mandrel 5 and after 6 seconds the pipe 1 into the socket 4, so that after 10 seconds the plasticization of both parts 1 and 2 is completed at the same time. Then the plastic pipe 1 and the sleeve 2 according to FIG. 2 pushed together. Here, either the sleeve 2 on the stationary pipe 1 or the pipe 1 on the stationary sleeve 2 or both parts 1, 2 are moved coaxially towards one another at the same time. The relative translation speed v, of both parts to each other should

5 6

between about 0.3 and 0.75 cm / sec. In order to measure the plasticizing times equally long. Front side 2 ″ of the sleeve 2 no bulges, that is, none and the mandrel 5 releasably more the entire plasticized © material between the 5 connected to the metal piece 3, which pull through a contact surface Γ and 2 ', the sleeve 2 resistance wire on the required PlastifMe and / or the pipe 1 during the insertion device The relative insulating layer 3 ′ ″ is to be prevented from emitting too much heat from both parts 1, 2 to the surroundings. In the upper part of the contact surfaces 1 ', 2' approximately as large as the relative 10 Fig. 4, the bushing 4 and the mandrel 5 are in the mean translation speed v _t . In this way part 3 is screwed in while it is fitted in the lower part of the plasticized material of the tube 1 to the attachment surface 1 'and the plasticized material of the conical insert surface 1' by means of a bayonet lock. In this way, the socket 4 sleeve 2 on its contact surface 2 'like a lubricating film and the mandrel 5 drawn against other corresponding parts, so that any excess 15 for welding larger or smaller pipes tolerances of the sleeve 2 or the more frequently occurring can be replaced without the entire sub-tolerances of the tube 1 being compensated for, the welding device must be redesigned. You can do this too. Furthermore, this increases the surface pressure at the heat transfer surfaces between the contact surfaces 1 'and 2', which is what the middle part 3 and the socket 4 on the one hand and the strength and quality of the welded joint on the other hand see the middle part 3 and the mandrel 5 is useful. "to be dimensioned so that the heat flow per unit of time Fig. 3 shows a" socket connection "in which the middle part 3 in both parts 4, 5 is the same size or pipe 1 with another pipe 7 of the same wall - in other words, the heat flow resistance is connected between the two thicknesses, the front end of which has been widened to form a central part 3 and the two parts 4 and 5 sol sleeve 2. This widening can be dimensioned in such a way that the same heat transfer is ensured both before the actual plasticizing process In the middle part 3, two temperature sensors 8 are also arranged during the plasticizing process, which are carried out to achieve the required plasticizing temperature via a suitable expanding tool are large, 30 operator will be able to display in this case.

1 sheet of drawings

Claims (7)

1 2 adorns as well as immediately after the simultaneous termination. 1. Welding process for producing an un- There is a process of this type known for its detachable connection of a plastic pipe with 5 implementation a for either butt or a plastic sleeve, both of which are made from a poly socket weld of polyethylene pipes olefin and is used in each case on their contact surface device. This device consists of a Chen thermally plasticized as well as directly provided with plane-parallel surfaces heated after simultaneous completion of the plasticizing plate, which serves as a carrier for attachable on both sides, The heating process is quickly pushed into one another, and they are heated, exchangeable, ring-shaped the, characterized in that with sockets or mandrels to the outside or. Internal heating the same plasticizing temperature the plasticizing of the pipe or the socket is formed. To the Approximation times of the plastic pipe (1) and the implementation of the welding process is this Plastic sleeve (2) heated approximately in a directly proportional welding machine to about 250 ° C, then the end Ratio of their wall thicknesses can be chosen. 15 of the tube in the slightly conical interior of the 2. Welding method according to claim 1, characterized in that the bushing is inserted up to the point of contact with the ground, characterized in that the plastic pipe (1) and while at the same time the sleeve over a mandrel up the plastic sleeve (2) is pushed against the plate with a constant force. Through this The pipe and the socket are at their circumference 0.3 to 0.75 cm / sec. 20 and plasticized at their end faces. After leaving 3. Welding method according to claims 1 pulling the pipe and the socket from the welding and 2, characterized in that the art- icals are pressed into one another, creating an all-material pipe (1) and the plastic sleeve (2) occur during side welding in the area of the sleeve should be turned towards each other during the insertion process. As it turned out in the meantime, is the. 25 this previously known method only with a high 4. Welding method according to claim 3, thereby performing reject rate. This is characterized by its origin that the relative circumferential distance on the one hand in the different heat overspeed (v ") of the plastic pipe (1) to the went from the heating plate to the plastic sleeve (2) of different sizes during the turning process and on the other hand is roughly equal to the relative translational speed in the low temperature of the external heating element (v ₍ ) of both parts. The area for the sleeve as a result of the strong convection 5. Welding method according to claims 1 of the outside air flowing around them and in the higher to 4, characterized in that the plasticizing temperature of the inner heating surface for the tion temperature of a pipe (1) or a pipe outer jacket. Another cause are insbe-muffe (2) made of polybutene, depending on the height of the surrounding area, special in the case of small pipes, the relatively large ones Usage temperature between 250 ° C and 350 ° C, the extrusion process decreasing tolerances preferably at 330 ° C. the wall thickness, which means that the pipe and socket over their 6. Welding method according to claim 5, characterized in that the scope is plasticized to different depths. That characterized that with a plasticizing leads to either the plastic pipe being too strong temperature of at least 280 ° C, the plasticizing 40 and / or the plastic sleeve is insufficiently plasticized ration time of a pipe (1) made of polybutene with egg. On the one hand, the consequence is a collapse nem outer diameter of 20 mm and one of the excessively heated pipe and on the other hand one Wall thickness of 2 mm for about 4 seconds and a displacement of the less tough plasticized material to be pushed over it Sleeve (2) made of polybutene rials of the plastic pipe through the tougher plastifim with an outside diameter of 30 mm and an embellished material of the sleeve, so that the in this way With a wall thickness of 5 mm for about 10 seconds, welded joints created according to Modisen will. fication time performed compression, flexural and 7. Device for carrying out the process did not withstand the tensile test. the claims ibis 6, consisting of a well The invention is based on the object a heat-conducting metal piece with one of the internal 50 welding process of the type mentioned create the corresponding mandrel diameter of the socket, which, while avoiding the and one of the disadvantages that stand out from the piece of metal, with simple means, a uniform socket, whose inner diameter gives the outer bend a good and permanently durable connection safe diameter of the plastic pipe corresponds to. characterized in that the heat transfer ₅₅ This object is achieved according to the invention by resistances between the metal piece (3) and solves that at the same plasticizing temperature the plasticizing times of the plastic pipe and the plastic tube are the same for the mandrel (5) and the socket (4). Plastic sleeve approximately in directly proportional ver ratio of their wall thicknesses can be selected. The welded connections produced with this process genes have produced completely uniform welds, that passed all stress tests. This is surprising insofar as experts in this field The invention relates to a welding method and has hitherto taken the view that a lower one Device for producing an inseparable 65 different wall thickness of the parts to be plasticized Connection of a plastic pipe with an artificial one due to the poor thermal conductivity of the material sleeve, both of which are made of a polyolefin, plastics generally have no effect on the plasticizing and should each have a thermal plasticization depth on their contact surfaces. Through the same plasticizing