DE4218910C1 - Extruder installation for plastic pipe - Google Patents

Abstract

An extruder installation for plastic pipes includes an extruder with a connected calibration sleeve, in a vacuum tank, and a cooling chamber with a wall thickness measurement unit consisting of measurement heads. The calibration sleeve extends in the extruder direction beyond the vacuum tank, and the front end has a connected intensive cooling ring. The wall thickness measurement device is located between the intensive cooling ring and the vacuum tank outside the tank.

Description

The invention relates to an extrusion system for Plastic pipes, consisting of an extruder, one on it subsequent, arranged in a vacuum tank and with a water cooling calibration sleeve, which the pulling extruded tube against the inside of its wall, and a downstream flow cooling chamber, wherein a wall thickness measuring device with one or more radial aligned to the extruded tube, after the Ultra sound principle working measuring heads is provided.

A generic extrusion system is in the DE 40 33 443 A1 described; in the known Extrusion system is the wall thickness measuring device in one  between the vacuum tank holding the calibration sleeve and the associated after-cooling chamber arranged separately Chamber installed so that the wall thickness measurement after Exit of the extruded tube from the calibration sleeve and after leaving the one receiving the calibration sleeve Vacuum tank is done.

With the known extrusion system, there is already one Reduction of the dead time between the measurement of the wall thickness of the extruded pipe and thus possible determination of wall thickness deviations exceeding the tolerance range and a subsequent correction of the Adjustment of the extruder possible, but this is sufficient Shortening the dead time with regard to one if possible error-free and inexpensive production process is not out. Furthermore, during the cooling of the ex trudged tube in the calibration sleeve differ about the wall thickness, which is a falsification the results of ultrasound measurements.

The invention is therefore based on the object Generic extrusion system reliable measurement data for the wall thickness as the basis for the extruder setting reach and the dead time between the wall thickness measurement and the necessary correction of the Reduce extruder setting further.

The solution to this problem is inclusive advantageous refinements and developments from Content of the claims which this description are reproduced.

The invention provides in detail that the calibration sleeve protrudes towards the extruder over the vacuum tank and  at its front end one with the vacuum tank Supply of water and vacuum associated intensive cooling Ring has, and that the wall thickness measuring device between the intensive cooling ring and the vacuum tank outside the Vacuum tanks is arranged. In the measurement according to the invention is the earliest possible measuring point for Wall thickness measurements because immediately after exiting the pipe can still be plastically deformed easily, is not suitable for wall thickness measurements. For this Basically, the intensive cooling ring is initially provided to the The pipe must be dimensionally stable before the wall thickness measurement is carried out hold. On the other hand, the material of the invention provided measuring point in an advantageous manner for Ultra sound measurements are still sufficiently temperature-homogeneous, as in usually from the extrusion tool temperature-homogeneous material for further calibration and cooling. Temperature differences on the plastic pipe, which the Ultrasonic measurement, especially in the transverse direction influence only occur in the calibration and cooling area, so that these influences unfavorable for the wall thickness measurement by arranging the wall thickness measurement before entering the calibration cooling section are avoided.

The invention also has the advantage that due to the earliest possible wall thicknesses measurement of the extruded tube before the run the calibration sleeve the error detection extremely done early, so that with extremely little dead time Correction of the setting of the extruder, especially the Centering of the tool sleeve around the tool mandrel possible is.  

Finally, the invention has the advantage that the expenditure on equipment for setting up the Wall thickness measurement is extremely low, especially as far as it is is provided according to embodiments of the invention, the Wall thickness measurement without pressure, that means not under vacuum, perform. Existing extrusion systems only need to a corresponding stem in front of the vacuum tank be, the location of the wall thickness measuring device for Adjustments and repairs during operation are cheap is.

According to one embodiment of the invention Wall thickness measuring device as the calibration sleeve enclosing measuring ring, wherein in the measuring ring in Bores running in the axial direction of the calibration sleeve Connection of the intensive cooling ring to the vacuum tank are. This means that the intensive care is adequately supplied cooling ring despite the interposition of the wall thickness measurement device guaranteed.

In a first embodiment, the wall thickness measurement direction is the measuring ring with openings for receiving its circumference arranged measuring heads, the Provide the calibration sleeve with assigned openings is. In this exemplary embodiment, the measurement is carried out via the stationary measuring heads, being in the area of Measuring ring the same conditions, namely vacuum and Water circulation prevails, like this in the intensive cooling ring given are.

According to another embodiment of the invention front end area of the intensive cooling ring  Calibration sleeve from the rest in the vacuum tank Sleeve body of the calibration sleeve to form a Intermediate space separated, the measuring ring Covering the gap between the vacuum tank and Intensive cooling ring is arranged. Such an arrangement advantageously allows the arrangement of a or more reversing around the extruded tube rotating measuring heads, because in the area of the measuring ring extruded tube with its surface exposed. However, since the width of the measuring ring is comparatively small, can this point on a support of the extruded tube to be dispensed with entirely. Alternative to one reversing arranged measuring head is also the arrangement of stationary Measuring heads possible.

According to an embodiment of the invention Intensive cooling ring against the measuring ring and the vacuum tank sealed with a vacuum and watertight seal, the space enclosed by the measuring ring with Water is filled. This is the special advantage connected that the measurement in the measuring ring under exclusion by vacuum, i.e. without pressure, which means that the apparatus Equipment is essentially agreed. It is understood that the measuring ring itself supply holes for the transfer of Water and vacuum from the vacuum tank to the intensive cooling ring having.

Finally, according to an embodiment of the invention the space enclosed by the measuring ring with a separate vacuum source connected; so it can depending on the Wall thickness of the extruded tube and the  Extrusion speed may be required, even in the area of the measuring ring to work with negative pressure, however this negative pressure is lower than that on the intensive cooling ring and vacuum applied to the vacuum tank; this applies in particular when there is a relatively high negative pressure in the intensive cooling ring must prevail in order to ensure that the extruded tube on the inside of the corresponding Secure the end of the calibration sleeve and an even one Ensure cooling; with an appropriate intake process can then be sucked in with air, such Air fractions not acceptable for an ultrasonic measurement are so that the vacuum in the area of the measuring ring too is reduce.

As far as according to an embodiment of the invention in Connection to the calibration sleeve another wall thickness Measuring device arranged and an evaluation unit for Evaluation of the dimensional data of both wall thickness measuring devices such a combination of two is provided Measuring points an extremely precise control of the extrusion process. So wall thickness measurement allows before entry of the extruded tube in the vacuum tank and a comparison with the wall located behind the calibration sleeve data obtained from the thickness measurement device an improvement Quality monitoring, because of the early determined Measured values and comparison with those after the complete Calibration of the extruded tube can be checked whether the quality values by below different cooling temperatures in the transverse direction of the extru tied pipe over the cooling section.

Exemplary embodiments of the invention are shown in the drawing reproduced, which are described below. It demonstrate:  

Fig. 1 shows the front end portion of a calibration sleeve with intensive cooling ring and the wall thickness measuring device in longitudinal section;

Fig. 2 shows the object of Fig. 1 in partial cross-section,

Fig. 3 shows another embodiment of the Wanddickenmeß device according to Fig. 1,

Fig. 4 shows a further embodiment of the Wanddickenmeß device of FIG. 1.

A partially indicated vacuum tank 10 is closed at its front end facing the pipe tool 33 of the extruder system with a receiving plate 11 . A calibration sleeve 12 is arranged in the vacuum tank 10 and surrounds the extruded tube 14 running in the extrusion direction (arrow 13 ). For this purpose, the calibration sleeve 12 has slots 15 for sucking the pipe 14 against its inner wall, a vacuum acting on the calibration sleeve 12 being held in the vacuum tank 10 . The calibration sleeve 12 is centered and held on the mounting plate 11 via a clamping ring 30 connected to it and it protrudes with its front end 16 over the mounting plate 11 from the vacuum tank 10 ; on the front end is seated an intensive cooling ring 17, which encloses the calibrating sleeve having a first chamber 18, the front end 16 12th Also in this front end, the calibration sleeve 12 slots 15 and annular grooves with connecting bores to the first chamber 18, so that on the fitting on the intensive cooling ring 17 vacuum, the extruded tube 14 after leaving the pipe tool 33 against the inner wall of the front end 16 of the calibration sleeve 12 sucked and thus stabilized in its shape.

Arranged between the receiving plate 11 and the intensive cooling ring 17 is a measuring ring 19 which surrounds the calibration sleeve 12 and which has ultrasonic measuring heads 20 distributed over its circumference in assigned openings. Corresponding to the position of the measuring heads 20 in the measuring ring 19, openings 21 are arranged in the calibration sleeve 12 running through in the exemplary embodiment according to FIG. 1, so that measuring heads 20 capture the extruded tube 14 through the openings 21 . In the axial direction of the calibration sleeve 12 passing through the measuring ring 19 bores 22 for connecting the first chamber 18 of the intensive cooling ring 17 with the vacuum tank 10 in which the bores open 22 into a hole formed in the clamping ring 30 chamber 31 and this chamber 31 of the clamping ring 30 is via a Annular gap 32 between the clamping ring 30 and the calibration sleeve 12 is connected to the interior of the vacuum tank 10 . Via the connection 32, 31, 22 is situated on the first chamber 18 of the intensive cooling ring to the vacuum 17, whereby the supplied via radially arranged on the intensive cooling ring 17 water supply terminals 27 cooling water is drawn off via this conductive path.

The measuring ring 19 surrounds the calibration sleeve 12 with a second chamber 23 which is filled with water as a coupling medium for the ultrasonic measurements via water connections or bores 24 . The chamber 23 is also connected via bores 29 to the chamber 31 formed in the clamping ring 30 , so that due to the connection created in the embodiment shown in FIGS . 1 and 2 there is also a vacuum in the measuring chamber 23 .

In the embodiment shown in FIGS . 3 and 4, the advantage is that the wall thickness measurement in the area of the measuring ring is without pressure, that is, without an applied vacuum. For this purpose, the front end 16 of the calibration sleeve 12, which is enclosed by the intensive cooling ring 17, is separated from the sleeve body of the calibration sleeve 12 arranged in the vacuum tank 10 to form a gap 25 , the gap 25 being bridged by the measuring ring 19 . The measuring ring 19 on the other hand sealed by seals 26 against the opposite in the vacuum tank 10 calibration sleeve 12 on the one hand and against the intensive cooling ring 17, so that the respectively prevailing in the vacuum tank 10 in the intensive cooling ring 17 vacuum the measuring chamber not detected 23 of the Meßringes 19th In the embodiment shown in Fig. 3, a measuring head 20 is arranged in a reversing manner around the intermediate space 25 , care being taken by arranging inlet and outlet bores in the measuring ring 19 to ensure that the measuring chamber 23 is filled with water as a coupling medium for the ultrasonic measurements . In the embodiment shown in FIG. 3, the extruded tube is thus not supported over the width of the measuring ring 19 .

Such a support is now realized in the further embodiment of the invention shown in FIG. 4, which corresponds in principle to the embodiment shown in FIG. 3. Here, in the area of the measuring ring, a gap 25 is arranged between the calibration sleeve 12 arranged in the vacuum tank 10 and its front end 16 held in the intensive cooling ring 17 , which spacer 28 has openings 21 for the passage of the measuring pulses emitted by the measuring head 20 . Otherwise, in accordance with the description of FIG. 3, no vacuum is present in the measuring chamber 23 in the embodiment shown in FIG. 4 either.

As not shown further, it is possible to apply a vacuum to the measuring chamber 23 via a separate feed line in order to ensure that the extruded tube is also supported on the spacer 28 in the area of the measuring ring 19 , but this vacuum can be designed to be substantially less than the vacuum required in particular for intensive cooling in the area of the intensive cooling ring 17 .

The in the above description, the claims, the summary and the drawing disclosed features The subject matter of these documents can be used individually as well in any combination with each other for the Realization of the invention in its various Embodiments may be essential.

Claims (9)

1. extrusion system for plastic pipes, consisting of an extruder, an adjoining, arranged in a vacuum tank and provided with a water cooling calibration sleeve that pulls the extruded pipe against the inside of its wall, and a downstream continuous cooling chamber, a wall thickness measuring device with one or more Radially aligned to the extruded tube, working according to the ultrasound principle measuring heads is provided, characterized in that the calibration sleeve ( 12 ) protrudes towards the extruder over the vacuum tank ( 10 ) and at its front end ( 16 ) one with the vacuum tank ( 10 has) for supplying vacuum and water intensive cooling ring (17) connected, and that the wall thickness measuring device (measuring ring 19 is arranged) between the intensive cooling ring (17) and the vacuum tank (10) outside the vacuum tank (10). 2. Extrusion system according to claim 1, characterized in that the wall thickness measuring device is designed as the calibration sleeve ( 12 ) surrounding measuring ring ( 19 ) and that in the measuring ring ( 19 ) in the axial direction of the calibration sleeve ( 12 ) bores ( 22 ) for connecting the intensive cooling ring ( 17 ) are arranged on the vacuum tank ( 10 ). 3. Extrusion system according to claim 2, characterized in that the measuring ring ( 19 ) has openings on its circumference for receiving the measuring heads ( 20 ) and the calibration sleeve ( 12 ) is provided on its circumference with assigned openings ( 21 ). 4. Extrusion system according to claim 2, characterized in that the front, in the intensive cooling ring ( 17 ) located end ( 16 ) of the calibration sleeve ( 12 ) from the sleeve body of the calibration sleeve ( 12 ) is separated to form a gap ( 25 ), and that the measuring ring ( 19 ) covering the intermediate space ( 25 ) is arranged between the vacuum tank ( 10 ) and the intensive cooling ring ( 17 ). 5. extrusion system according to claim 4, characterized in that the intensive cooling ring ( 17 ) against the measuring ring ( 19 ) by means of a seal ( 26 ) sealed vacuum and watertight and with water connections ( 24 ) for introducing and discharging water into the from the measuring ring ( 19 ) is enclosed space ( 25 ) is provided. 6. Extrusion system according to claim 5, characterized in that in the measuring ring ( 19 ) at least one reversing around the extruded tube ( 14 ) rotating measuring head ( 20 ) is arranged. 7. Extrusion system according to claim 5, characterized in that the measuring ring ( 19 ) has a plurality of stationary measuring heads ( 20 ) distributed over its circumference. 8. Extrusion system according to one of claims 4 to 7, characterized in that the intermediate space ( 25 ) enclosed by the measuring ring ( 19 ) is connected to a separate vacuum source. 9. Extrusion system according to one of claims 1 to 8, characterized in that a further wall thickness measuring device is arranged in the extrusion direction (arrow 13 ) after the calibration sleeve ( 12 ) and that an evaluation unit is provided for evaluating the measurement data of both wall thickness measuring devices.