CN1073924C - Method for producing end fittings on plastic pipes and device for carrying out the method - Google Patents

Abstract

A method of manufacturing a pipe end fitting (2) on a plastic pipe (1) made of a thermoformed plastic, in particular made of polyolefin or PVC, is disclosed. In a heating station, a pipe end, which has approximately the length of the pipe connection, is heated to or above its deformation temperature, in which state the pipe connection (2) is formed by means of a pipe connection machining tool (5) inserted from the pipe end (3), and the pipe end is cooled to below the heat distortion temperature before and/or after the pipe connection machining tool (5) is removed. Clamping means (13, 14) allowing insertion of the pipe joint machining tool (5) and contacting the pipe wall from both the inside and the outside secure the pipe (1) by the outer end of the pipe joint part (2) allowing the pipe joint machining tool (5) to be inserted into the pipe, in such a way that the pipe joint part is pulled through the pipe joint machining tool (5) instead of being pushed through it. An apparatus for carrying out the method is also disclosed.

Description

Method for producing end fittings on plastic pipes and device for carrying out the method

The invention relates to a method for producing pipe end fittings on plastic pipes made of thermoformed plastics, in particular polyolefin plastic pipes or PVC pipes, wherein a pipe end whose length is substantially equal to the length of the pipe joint is heated The station is heated to or above the deformation temperature. In this case, the pipe end is deformed by a pipe joint processing tool inserted from the pipe end, and the pipe end is cooled below the heat deformation temperature before and/or after the pipe joint processing tool is withdrawn.

The invention also relates to a device for carrying out the method, said device having a pipe joint processing station in which a pipe joint processing tool such as a pipe joint processing mandrel designed to taper its insertion end can be Inserted with relative longitudinal adjustment into a pipe end which has a length approximately equal to the pipe connection and which is heated in a heating station to its deformation temperature or above its deformation temperature and where Tube ends are machined into tube joints with deformation and enlargement.

Materials for the manufacture of such plastic pipes include, for example, polyolefins such as high- and low-pressure polyethylene, polypropylene and other thermoformable plastics (thermoplastics) and especially PVC. The possible deformation properties depend to a large extent on the respective processing material and the temperature used for deformation, wherein the deformation performance is not only mainly affected by the processing material, but also by the type, amount and consistency of the additives used, such as grain size. In general, the lower the pipe tension required to form the pipe joint, the thinner the pipe wall and the shorter the extent of the pipe joint to be machined, the simpler the manufacture of the pipe joint. Depending on the material, such pipe joints can therefore be produced efficiently and continuously close to their limit dimensions, so that, for example, in the case of certain pipes which require pipe joints whose diameter and extent exceed the above-mentioned limit dimensions, it is necessary to use a small amount of material for the entire pipe. Additive and expensive process material with enhanced thermoformability. Special shapes such as pipe end fittings for connecting thick-walled or large pipes can usually only be produced by machining the pipe fitting and connecting the pipe fitting to the pipe in a separate injection molding operation or by bonding the pipe directly after the injection molding operation. The fittings are molded onto the ends of existing pipes. This is especially the case when the basic shape of the accessory, such as a fitting, differs significantly from that of the pipe, for example when a square fitting is to be connected to a round pipe. In this case, common methods consist of designing the parts to be connected as pipe fittings with circular sleeves which are inserted into ordinary pipe end fittings, or, as described above, redesigning the parts during mass production. Designed as injection molded parts.

Even in the case of relatively easily deformable materials, serious problems arise when the diameter and length of the pipe connection is relatively large compared to the pipe diameter. It is known hitherto to clamp the pipe at the pipe end remote from the pipe joint processing zone and to press the pipe joint processing tool into the heated pipe end, or conversely, to immobilize the pipe joint processing tool such as the corresponding shaft and to press the pipe Push onto the fixed fitting machining axis to machine fittings. In both cases, the sockets which receive or exert thrust are produced in unheated or only slightly heated tube parts. When the pipe joint part is heated strongly for large deformation, inserting the pipe joint processing tool may cause ripples to be formed in this heated pipe end, but the pipe joint processing tool has not processed the pipe joint when the pipe joint processing tool is inserted. This is undesirable and this actually results in defective products. The very flat tapered slope of the fitting tool at the front end facilitates and facilitates the insertion of the fitting tool into the pipe, but this creates an undesired long distance between the normal pipe and the fitting portion having the entire pipe end diameter. Transition zone. A partial solution to these problems has so far been successful in long pipe joints, where the ends of the pipes designed to form the pipe joint are heated to different temperatures based on many empirical calculations, i.e. the outer end is heated much higher than the inner end, so that the inner end of the pipe joint that is in contact with the pipe joint processing tool has a higher rigidity than the end portion before the pipe joint processing operation. As a result, however, the deforming force to be applied is again increased due to the stronger shape memory of the cold part. In addition, a disadvantage in almost all plastics used and tubes made of them is the so-called "memory effect", ie parts that have been pre-processed by thermoforming try to return fully or partially when heated or at normal temperature original shape. The memory effect is stronger if the heat distortion temperature has to be kept lower relative to the melting point, because other conditions are observed during the production of the pipe joint. In the above example of a long fitting, the memory effect is stronger near the inner end of the fitting, so due to this shape memory effect, a higher deformation over time occurs at the inner end than at the end.

The object of the present invention is to improve the above-mentioned method, thereby simplifying the production of dimensionally accurate pipe joints, the production of large long pipe joints and avoiding to a large extent or completely in pipes made of corresponding materials compared with the existing methods. Dimensional fluctuations caused by the so-called memory effect. Another object of the present invention is to provide a simple device for carrying out the improved method described above.

According to the present invention, the above object is solved in that the pipe is fixed at the outer end of the pipe joint portion for insertion of the pipe joint processing tool by a clamping device which allows the insertion of the pipe joint processing tool and clamps the pipe wall from both inside and outside.

The basic idea of the invention (which is first of all particularly simple) consists in pulling an elastic pipe joint to a Much easier on the mandrel. The tube can be heated not only to a temperature that allows deformation, but also to a much higher temperature, at which more crystals that produce said memory effect The temperature melts in the crystal structure of thermoplastic materials. As a result, the pipe section becomes more elastic and more easily deformable, so that longer and larger pipe joint sections can be produced from the same material than with prior methods. In addition, subsequent deformation of the material due to memory effects is largely avoided, since the vast majority of the crystals have already melted and thus lose their "memory" of their original shape. Many structures for these holding devices can be conceived by following the condition that the holding devices must allow insertion of a pipe joint processing tool. They may basically have jaws that are radially adjustable from the starting diameter to the final diameter, or the jaws may have variable-diameter inner parts like expanding or hinged mandrels, which should be designed so that they The clamping areas protrude only slightly beyond the inside of the tube or they are pressed into the inside of the tube so that a pipe joint processing tool can pass therethrough.

A preferred device for carrying out the method according to the invention is characterized in that a clamping device is provided for the outer end of the pipe joint portion, which clamping device has jaws with extensions for clamping the pipe wall from the inside, said The expansion piece can be adjusted outwards from its basic position corresponding to the original pipe diameter to a clamping position that allows the pipe joint processing tool to pass through it and press the outer surface of the pipe end onto the opposite clamping seat when the tube is expanded. .

Often a separate extension drive can be used. However, it is particularly advantageous and simple to obtain the adjustment of the expansion piece directly from the adjustment of the fitting tool relative to the pipe. It is therefore also possible to equip an existing pipe joint processing station with a corresponding clamping device. From a structural point of view, this offers a particularly simple solution, since the clamping device has an outer sleeve, through which the pipe connection tool is inserted all the way into the pipe end, wherein the outer sleeve has a An annular seat for expanding the end of the tube with a clamping portion for the outer side of the tube. On the outer sleeve, at a distance from the annular seat and outside the insertion path of the pipe connection processing tool, on the insertion side, an expansion arm is provided, the free end of which can be positioned at a flattened angle of attack in the rest position. It protrudes from the inside into the longitudinal region of the annular seat and clamps the undeformed pipe end there. In the case of enlarged pipe ends, the inserted pipe joint processing tool expands the expansion arms that together constitute the insertion auxiliary part of the pipe joint processing tool, so that the expanded arms open the pipe joint processing tool from the inside of the pipe through its free end. The end presses against the opposite clamping seat of the annular seat and holds the tube in place during the continued processing of the tube joint. Preferably, the opposing clamping seats are arranged in such a way that they reach at most one annular bead designed to accommodate the sealing ring in the respective pipe connection. The annular bead can be produced in a manner known per se, either by additionally using a separable outer mold and by blowing the bead part into the outer mold or by using an articulated mandrel with an embedded tool .

According to one embodiment, said extension arm is formed by reeds fastened to the outer sleeve at an angle of attack and evenly distributed around the outer sleeve. The advantage of using a reed as the extension arm is that the desired nozzle expansion movement can be achieved without a joint and that flats can be used that either simply fit inside the union or are placed there for insertion into the union processing tool. Thin reeds in slots.

At least one annular comb is provided as the opposite clamping seat of the annular seat, which likewise presses into the heated pipe in the clamping position, like the ends of the spreading arms. The coupling end is thus securely held and has a clean appearance similar to the outer edge of a crown cork.

Due to the basic requirements of the present invention, special shapes of pipe joints can also be processed. In the case of a correspondingly arranged spreader arm, in order to form the corresponding pipe connection, the pipe connection processing tool and the outer sleeve have a cross-sectional shape different from the basic cross-sectional shape of a rotating body, such as a quadrilateral or a polygon, at least in the edge region. .

In the above example of processing HD-PE long pipe joints, if a pipe joint with an inner pipe end diameter of 112mm and a length of 400mm needs to be used for a pipe with an inner diameter of 104mm and a wall thickness of 5mm, heating to different temperatures is necessary. Difficult, where the temperature at the inner end of the pipe joint will reach a maximum of 120°C, and the temperature at the outer end will reach a maximum of 140°C. In the method of the invention, the same tube is maintained over its entire length above 140°C and the tube is preferably heated to a temperature in the range of 200°C, ie very close to the melting point, and then deformed.

Further details and advantages of the inventive subject matter can be obtained from the following description of the drawings.

In the figures, the subject-matter of the invention is shown by way of example, in which:

Figure 1 shows a view of a pipe with a pipe end fitting manufactured according to the method of the present invention;

Fig. 2 shows a cross-sectional view of the clamping device of the pipe joint embedding station of the present invention with an inserted pipe end before the pipe joint processing process;

FIG. 3 shows the clamping device in the same view as FIG. 2 when the pipe end is stationary and the pipe joint processing shaft of the processing station is partially inserted into the pipe.

As shown in FIG. 1, a pipe joint 2 is formed on the end of the pipe 1, which is long compared with the diameter of the pipe and which has a large diameter. During the processing of the pipe joint, the pipe end 3 of the pipe joint is fixed and the pipe joint supports at a certain distance from the pipe end 3 an annular roll formed, for example, by blowing gas into the outer mold and used to accommodate a sealing ring side 4. During the processing of the pipe joint, the pipe joint part 2, 3, 4 is heated to a high temperature over its entire length, so that even if it is made of sensitive materials, the memory effect of the finished pipe joint is excluded .

The pipe joint processing station shown in FIGS. 2 and 3 is equipped with known clamping or feeding devices for pipes 1 and with a pipe joint processing mandrel 5 extending longitudinally relative to the pipe and having a conical end 6, This pipe joint processing mandrel 5 can be provided with nozzles in the area that subsequently forms the annular bead 4, said nozzles blowing the corresponding pipe joint area into a separate outer mold, which after forming the annular bead It can also be disassembled to loosen the ring curl. In order to produce the ring bead, it is also possible to use hinged cores in the pipe joint machining mandrel 5 .

Essential to the invention in this embodiment is the clamping device 7 as shown in FIGS. 2 and 3 . This clamping device mainly is made of an outer sleeve 8, makes the diameter of the outer sleeve near the annular seat 10 of the outer end 9 and the inner end 11 slightly larger than the diameter of the pipe joint processing mandrel 5, and the outer sleeve is drawn from the inner The end 11 widens slightly conically towards a recess 12 .

The recess 12 is an annular groove with a triangular cross-section, the outer edge of which is inclined towards 12 . On the hypotenuse of the recess 12 sloping towards the end 11 there is provided a reed 13 serving as an extension arm, said tongue having an angle of attack which in the rest state is inclined straight towards the end 11 and the ring seat 10 . The free ends of the tongues 13 lie close to each other on a circle. For example, the reed width may be in the range of 10 mm and the reed thickness may be in the range of 1 mm.

As shown in FIG. 2 , the respective end of the heated tube 1 is inserted into the outer sleeve 8 so that the tube end edge slightly protrudes beyond the annular seat 10 , wherein the end of the reed 12 is inserted into the tube end 3 . Now, the pipe joint processing mandrel 5 is inserted from the right and thus the reeds 13 are spread out until they almost touch the inner wall of the outer sleeve 8, wherein the reeds or the leaf springs 13 respectively inserted in the pipe end 3 The free end widens the tube end and presses it into the annular seat 10 . In the ring seat 10 there is arranged parallel to the edge at least one ring-shaped comb 14 , which, with the tongue 13 fully extended, presses from the outside into the pipe end 3 which is now the pipe connection end. The reed end is also pressed into the nipple end 3 from the outside. From this position upwards, anyway, the end of the pipe connection enlarged by the swinging of the reed is fixed on the outer sleeve 8, so that the further inserted pipe connection processing mandrel not only has an insertion aid via the reed 13, but also has When the part is pulled onto the pipe joint processing mandrel 5, it is reliably prevented from extruding the pipe joint part. After finishing the pipe joint processing process and setting the annular bead 4 in the above-mentioned way, it is best to pre-cool the pipe joint part until the pipe joint 2 has the necessary strength, and then pull out the pipe joint processing mandrel or pull out the pipe joint. Extract the pipe 1 with the pipe joint finished product 2 in the joint processing mandrel.

Claims (6)

1. method of making the pipe end joint on by thermoforming plastic and the plastic tube especially made by polyolefin or PVC, wherein in a heater station, one section tube end that roughly has pipe joint length is heated on its deformation temperature or its deformation temperature, under this state, form pipe joint by a pipe joint machining tool that inserts from pipe end, before extracting the pipe joint machining tool out and/or afterwards pipe end is cooled to below the heat distortion temperature, it is characterized in that, in order to insert pipe joint machining tool (5), by allow to insert pipe joint machining tool (5) and from the clamping device (13,14) of inside and outside contact both sides tube wall at the place, outer end of pipe joint portion (2) fixing tube (1).

2. device of implementing the described method of claim 1, it has a pipe joint processing station, one for example is designed to can be inserted in such plastic tube end under carrying out the situation of relatively vertically regulating in this worker station at the pipe joint machining tool of the tapered pipe joint processing mandrel that dwindles of insertion end, be that described tube end has the length that is substantially equal to pipe joint and it is heated to its deformation temperature in a heater station or it is processed to pipe joint more than deformation temperature and under this tube end distortion and condition of enlarged, it is characterized in that, for the outer end (3) of the pipe joint portion (2) of pipe (1) is provided with a clamping device (7), this clamping device has the jaw (13 that has from the extension (13) of inboard clamping tube wall, 14), described extension is on can outwards being adjusted under the tubing expansion situation that a permission pipe joint machining tool (5) passes wherein from its home position corresponding to the pipe end green diameter and pipe end (3) lateral surface being pressed onto clip position on the relative grip slipper (14).

3. device as claimed in claim 2, it is characterized in that, clamping device (7) has an outer sleeve (8), pipe joint machining tool (5) inserts in the pipe end (3) by this outer sleeve always, wherein this outer sleeve has end (a 3) and annular seating (10) that have the clamping part (14) that is used to manage lateral surface relatively that is used to expand pipe (1) in that side near pipe, on described outer sleeve, be provided with exhibition arm (13) in the inserting side from annular seating one segment distance ground and outside pipe joint machining tool insertion route, the free end of described exhibition arm can be on resting position be charged in vertical district of annular seating (10) also the still undeformed pipe end of clamping there with the angle of attack that flattens from the inboard, under the extended situation of pipe end, the exhibition arm (13) that the pipe joint machining tool (5) that inserts makes common formation pipe joint machining tool insert assisted parts launches, thereby described exhibition arm open pipes joint machining tool path ground is gone up the relative grip slipper (14) that pipe end is pressed in annular seating (10) and fixing tube (1) the process that continues the processing tube joint from managing the inboard by its free end.

4. device as claimed in claim 3 is characterized in that, described exhibition arm is by being stretched on the outer sleeve (8) with the angle of attack and reed (13) that be evenly distributed on around the outer sleeve constitutes.

5. as claim 3 or 4 described devices, it is characterized in that, be provided with at least one annular broach (14) as the relative grip slipper of annular seating (10), they also with the same on clip position, being pressed in the heated tubing in exhibition arm (13) end.

6. as the described device of one of claim 2-5, it is characterized in that, correspondingly arranging under the situation of exhibition arm, in order to form corresponding pipe joint, pipe joint machining tool and outer sleeve have the shape of cross section such as a quadrangle or the polygon that are not equal to the basic shape of cross section of a rotary body at least in the marginal zone.

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