DE10242924A1 - Internal stress and deformation reduction treatment of a cut end of an extruded plastic product involves heating the cut end face - Google Patents

Abstract

The cut surface (24) of the product (5) is heated (26) so that any deformation of the cut end recovers to the original shape and internal stresses produced during the cutting action are reduced. An Independent claim is made for an extruded product with a cut end which has been relieved of internal stress and deformation employing the process.

Description

The invention relates to a method for the aftertreatment of an end region separated, in particular elongated object in the area of a separating surface and a Object with an end region aftertreated by the method, as shown in the Claims 1 and 6 is described.

DE 195 30 417 A1 discloses a method for rounding sharp edges Injection molded parts made of a thermoplastic material, in which the Edges, which are mostly in the separation area of the injection mold on the component to be manufactured are arranged, made flowable by means of hot air. The hot air flow is concentrated aimed at the edges. Because the edges are relatively small compared to the component Have wall thickness, the heating is relatively easy and quick to carry out, whereby the material retreats due to cohesive forces in the area of the sharp edges and so a safe rounding process without the risk of damaging the Injection molded parts, is feasible.

Another method for deburring molded parts is known from DE 35 43 910 C2 become, in which the burrs on rubber or plastic molded parts by means of a cold Liquid becomes brittle and can thus be detached from the molded part. As a cold liquid liquefied, cryogenic inert gas is used. The treatment takes place in that the treating ridge by two, essentially parallel and spaced apart, flowing full jets is irradiated, the ridge embrittled by the first inert gas jet and this embrittled ridge is cut off by the trailing inert gas jet.

Another device for removing burrs on plastic parts is from DE 42 23 885 A1 become known in which the burrs on the plastic part by irradiation with be separated from a plastic granulate. This is done by means of a blasting device Plastic granules are hurled onto the ridges of the plastic parts and then in one Collecting device for both the plastic granulate and the separated burr parts collected.

The object of the present invention is a method for aftertreatment of an elongated object, which has been severed in its longitudinal extent, in To create an area of the separating surface and an object treated by the method, in which the cross-sectional shape or the dimensions of the end region essentially that Cross-sectional shape or those dimensions of the object in its undivided Condition corresponds or correspond.

The object of the invention is solved by the features of claim 1. The through the features of the characterizing part of claim 1 resulting surprising advantage in that by the subsequent change in temperature of the deformed area by the the inherent property of the material of the automatic return to the undeformed Starting position, an end area is created with all the advantages of the chipless Separation to the desired lengths can be separated into individual parts and stick to it then the original cross-sectional shape or dimension of the object in the area of Partition surface can in turn be made. Likewise, but also in this End area the internal tensions introduced by the separation at least as far as possible minimized or even completely reduced. This can create an object in which the separating surface has a cross-sectional shape, that of the rest Cross-sectional shape of the object in its further longitudinal extent, in another parallel aligned plane.

Furthermore, a procedure according to the features specified in claim 2 is advantageous because this creates a smooth, flat cut surface, in which the separation without Chips are made. This means that a separate suction or Disposal of the resulting cut material is no longer necessary, which additionally can still save a large amount of primary materials.

Another advantageous procedure is described in claim 3, whereby by the selected material, which has a high memory behavior when the temperature rises, a Deformation of the deformations as a result of the separation process was carried out almost completely can be, which means additional, complex machining processes to remove the Burr-shaped swellings along the circumferential edges of the jacket and the webs can be avoided.

A variant of the method according to claim 4 is also advantageous, since it is continuous Warming of the material, the reshaping and the reduction of the internal stresses is almost complete and therefore a representative one for the comparison process Cross-section, which corresponds to the actual profile geometry, for the target-actual comparison is created.

Another method variant is characterized in claim 5, in which ongoing The post-treatment extrusion process takes place and so immediately on a change in the Profile geometry can be influenced and this can be eliminated quickly without a high committee is being produced in the course of ongoing production.

The object of the invention is also independent by the features of the claim 6 solved. Which results from the combination of features of the characterizing part of this claim The resulting advantages are that an object is created with the aftertreatment has been the following a separation process with which the end portion is deformed as well internal tensions have been built back to its original position in a simple way and how has been reshaped and end regions treated in this way have a profile geometry have, which the profile geometry of the object in its undivided state in sections distant therefrom.

The invention is described below with reference to the drawings Exemplary embodiments explained in more detail.

Show it:

FIG. 1 shows an extrusion system for producing an elongated article with a separating device and a treatment device according to the invention, in side view and a greatly simplified schematic representation;

2 shows a partial area of the object during the separation process, in side view and highly simplified, enlarged illustration.

Fig. 3 is a partial cut area of the article after its separation with deformations in the end portion in side view and highly simplified, enlarged representation;

FIG. 4 shows the partial area of the object according to FIG. 3 after the aftertreatment, in a side view and in a greatly simplified, enlarged illustration;

. Fig. 5 shows the cut portion of the article of Figure 4 following a further treatment, in side view and highly simplified, enlarged representation;

Figure 6 shows a part of another article according to its separation in the undeformed state in the region of the interface, cut side view of a highly simplified, enlarged illustration.

Fig. 7 shows the portion of the object of FIG. 6 after an aftertreatment, cut in side view and greatly simplified enlarged view.

As an introduction, it should be noted that in the differently described embodiments Provide the same parts with the same reference numerals or the same component designations are, the disclosures contained in the entire description on transfer the same parts with the same reference numerals or the same component names can be. The location information selected in the description, such as. B. above, below, laterally, etc. related to the figure described and illustrated immediately and are in the event of a change in position, to be transferred accordingly to the new position. Furthermore, also Individual features or combinations of features from those shown and described different embodiments for themselves, inventive or represent solutions according to the invention.

In Fig. 1 an extrusion plant 1 is shown, which consists of an extruder 2, arranged downstream of a molding device 3 and a downstream thereof crawler track 4 for an extruded object 5. The caterpillar take-off 4 is used to pull the object or objects 5 , for example a profile, in particular a hollow profile made of plastic, for window and / or door construction, in the extrusion direction 6 , starting from the extruder 2 , through the entire shaping device 3 . In this exemplary embodiment, the shaping device 3 consists of an extrusion tool 7 assigned to the extruder 2 , a calibration device 8 of at least one, but preferably a plurality of calibration tools 9 to 12 and at least one, but preferably a plurality of vacuum tanks 13 , 14 , in which a plurality of caliber plates 15 are arranged. However, individual caliber plates 15 can also be designed as support panels for the object 5 only for the support function.

In the area of the extruder 2 there is a receptacle 16 in which a material, for example a mixture or a granulate for forming a plastic, is stored, which is fed to the extrusion tool 7 with at least one screw conveyor in the extruder 2 . Furthermore, the extruder 2 also comprises a plasticizing unit, by means of which the material is heated and plasticized during the passage of the material through it by means of the screw conveyor and, if appropriate, additional heating devices, in accordance with the properties inherent therein, under pressure and optionally supply of heat, and conveyed in the direction of the extrusion die 7 becomes. Before entering the extrusion die 7 , the mass flow of the plasticized material is led in transition zones to the desired profile cross section.

The extrusion die 7, the plasticizing unit and the receiving container 16 are supported on a machine bed 17 and supported, wherein the machine bed 17 is placed on a flat support surface 18, such as a flat floor.

In this exemplary embodiment, the entire calibration device 8 is arranged or held on a calibration table 19 , the calibration table 19 being supported on running rails 21 fastened on the contact surface 18 via rollers 20 . This mounting of the calibration table 19 on the rollers 20 serves to be able to move the entire calibration table 19 with the devices or devices arranged thereon in the direction of extrusion 6 from or towards the extrusion tool 7 according to the arrow entered. In order to be able to carry out this adjustment movement more easily and more precisely, the calibration table 19 is assigned, for example, a traversing drive (not shown in more detail) which enables a targeted and controlled longitudinal movement of the calibration table 19 towards the extruder 2 or away from the extruder 2 . Any solutions and units known from the prior art can be used for driving and controlling this traversing drive.

The calibration tools 9 to 12 of the calibration device 8 are supported on a mounting plate and are designed, for example, as a vacuum calibration, the calibration of the object 5 to be extruded taking place within the individual shaping or calibration tools 9 to 12 . In addition, the arrangement of the vacuum slots, the cooling sections and the flow channels or cooling bores as well as their connections and supply can take place in accordance with the known prior art.

This calibration can include, for example, a combination of dry and wet calibration or only a complete dry calibration. Furthermore, access of ambient air, at least between the extrusion tool 7 and the first calibration tool 9 and / or at least between the first calibration tool 9 and further calibration tools 10 to 12 , can be completely prevented. Of course, it is also possible, at least in regions, to allow access of ambient air to the object 5 between the individual calibration tools 9 to 12 or to arrange water baths.

The vacuum tank 13 , 14 has at least one cooling chamber for the object 5 emerging from the calibration tools 9 to 12 , which is formed by a simplified housing and is divided into immediately successive areas by the caliber plates 15 arranged and shown in the interior in a simplified manner. However, it is also possible to lower the interior of the cooling chamber to a lower pressure than the atmospheric air pressure.

After leaving the extrusion tool 7, the object 5 has a cross-sectional shape predetermined by this, which is sufficiently calibrated and / or cooled in the adjoining calibration tools 9 to 12 until the viscous plastic object 5 has cooled to the surface or edge areas thereof to such an extent that its outer shape is stable and its dimensions are designed accordingly. Subsequently to the calibration tools 9 to 12 , the object 5 passes through the vacuum tanks 13 , 14 in order to achieve further cooling and, if necessary, calibration and support, and thus to dissipate the residual heat still contained in the object 5 . After exiting, the object 5 has at least in the area of its outer surface approximately ambient temperature, such as. B. 15 ° C to 25 ° C on.

For the operation of the extrusion system 1 , in particular the devices or devices arranged or held on the calibration table 19 , these can be connected to a supply device (not shown in more detail) with which the most varied units, for example with a liquid cooling medium, with electrical energy, with compressed air and can be applied with a vacuum. A wide variety of energy sources can be freely selected and used as required.

Furthermore, following the caterpillar take-off 4, a separating device 22 is shown in simplified form for the need to separate or cut the object 5 during its continuous and / or discontinuous production, the separation of the object 5 preferably being carried out without cutting. A cutting unit 23 is designed in the form of a guillotine, which is equipped with a drive unit for carrying out the cutting process. Furthermore, it may be necessary to move the entire separating device 22 or the cutting unit 23 for carrying out the cutting or separating process of the object 5 at the same speed with which the object 5 is moved by the caterpillar take-off 4 in order to achieve an approximately normal or to achieve perpendicular to the extrusion direction - arrow 6 - or to the longitudinal extent of the object 5 separating surface 24 by the separation. The separation device 22 can be designed in accordance with the known prior art, although it is also possible, independently of this, to select any other design of the separation device 22 .

Furthermore, it is shown here in a simplified manner that a measuring device 25 can be provided following the separating device 22 , with which the separating surface 24 of the object 5 formed by the cutting unit 23 is recorded in its actual cross-sectional shape, for example optically, and with a desired cross-sectional shape the object 5 to be produced is compared by a comparison operation, for example electronically, by means of a computer unit (not shown here) in order to quickly identify possible deviations from the specified profile geometry and thus corrective measures, for example arn extrusion tool 7 and / or the calibration tools 9 to 12 Calibration device 8 , initiate or perform. This can minimize the production of rejects due to dimensional deviations.

Due to the previously described, non-cutting separation by means of the separating device 22 , it is advantageously achieved that on the one hand no disruptive chips, such as would arise in a cutting separation, arise, but on the other hand the object 5 or the material forming it, at least in sections, starting out from the separating surface 24 in the direction of the object, spatially deformed or internal tensions are built up which lead to a change in the profile geometry, as is shown and described in greater detail in the following figure on an enlarged scale.

Following the separating device 22 or in front of the measuring device 25 , an additional aftertreatment device, in the present case a temperature control device 26 , is shown in simplified form for the separating surface 24 of the object 5 produced in this way, with which it is possible to aftertreat the transversely in its longitudinal extent severed object 5 in the area of the separating surface 24 at least in sections, whereby the material forming the object 5 , starting from the separating surface 24 in the direction of the latter, is heated to such an extent that the deformations or internal stresses introduced by the separation at least for the most part are automatically reset or reduced by the temperature change.

As a result of the preferably steady forward movement of the article 5 in the direction of extrusion - arrow 6 - both the separating device 22 and / or the temperature control device 26 and or the measuring device 25 are designed such that they can be moved to the article 5 at preferably the same speed, whereby the relative movement between the devices described above and the object 5 is almost 0 or there is no relative movement at all. The corresponding devices or units are to be selected in accordance with the known state of the art, but these are not the subject of the invention here.

FIG. 2 shows a partial area of the object 5 within the separating device 22 with a schematically simplified cutting unit 23 , with the same reference numerals being used for the same parts as in the previous FIG. 1.

The cutting unit 23 is designed in the form of a cutting plate 27 which, in the longitudinal extent of the object 5, has a thickness or thickness 28 of, for example, less than 4.0 mm, such as. B. 3.2 mm. However, thicknesses 28 between 0.5 mm and 0.7 mm are also possible, for example, a cutting edge angle 29 being approximately 30 ° in total. The selected thickness 28 of the cutting plate 27 and the cutting angle 29 depend on the material to be cut, the lower the thickness 28 selected, the less the deformation or the build-up of the internal stresses within the object 5 , starting from the separating surface 24 in the direction of item 5 . A lower limit of the thickness 28 is determined by the strength properties of the cutting plate 27 , which must absorb the cutting forces that occur.

The course of the cutting edge of the cutting plate 27 in a plane 30 oriented here perpendicular to the extrusion direction or to the longitudinal extent of the object 5 is, as is known from the guillotine guillotine, chosen to run obliquely, so that in the present case the top of the object 5 is horizontally oriented oblique sequence of cuts, starting from the top shown above, down to the bottom of the object 5 to complete separation is achieved.

This non-cutting separation described here is generally known and is carried out with a wide variety of devices. Furthermore, in the area of the cutting plate 27 facing the object 5 , these limiting cutting surfaces 31 , 32 are shown in a position partially penetrating into the object 5 , these cutting surfaces 31 , 32 defining the cutting angle 29 described above, which is preferably aligned symmetrically with respect to the plane 30 is. Due to the wedge-shaped design of the cutting plate 27 with the cutting surfaces 31 , 32 , a deformed section of the object 5 in the form of a bulge or thickening is shown schematically and exaggerated immediately after it. This bulge or thickening is burr-shaped and projects beyond the outer surface of the object 5 , which, when looking at the later formed separating surface 24 , as previously described for the measuring device 24 , would indicate an apparent increase in wall thickness. This would lead to an incorrect correction in the target / actual comparison of the cross-sectional geometry of the object 5 , since only a small longitudinal section of the object 5 , starting from the separating surface 24 due to the displacement and the deformation associated therewith, is one compared to that produced in the extrusion process and has calibrated cross-sectional geometry.

Since the objects 5 produced are mostly hollow profiles, in particular made of PVC (polyvinyl chloride) for window and door construction, this deformation occurs almost over the entire cross section of the jacket and / or the webs along the separating surface 24 , mostly continuously , preferably on both sides.

An extrudable material, in particular a material made of a polymer material, which is optionally mixed with a fibrous material, and from the group of PVC (polyvinyl chloride), PP, is used as the preferred material for the article 5 , which forms the jacket and optionally the webs (Polypropylene), ABS (acrylonitrile-butadiene-styrene copolymers), ASA (acrylonitrile-styrene-acrylic ester copolymers), etc. is selected. However, it is also possible to at least partially form the object 5 or individual sections thereof from a renewable, biological or vegetable material. Furthermore, all materials known and usable from the prior art can also be used for extrusion and / or injection molding.

Of course, any other materials that have such a thermal Resetting behavior or a reshaping into the previous undeformed position have post-treatment if this appears necessary. Both are Materials made of a plastic material as well as a metallic material are conceivable, which these memory properties with temperature change, especially the strong Temperature increase. In particular, there have been extrudable plastics made out of a memory polymer as particularly suitable. Memory polymers are Polymers with, simply put, "built-in memory" and can below their melting range their shape is reversible depending on the temperature change. Here, the plastics have been formed in the cold and / or warm Condition and subsequent rapid cooling down the tendency to get sufficient Heating in its original state or its original position before the forming zurückzuverformen.

The previously described deformation or the build-up of the internal stresses within the object 5 , starting from the separating surface 24 , depends on the thickness 28 of the cutting plate 27 , the stronger or thicker the cutting plate 27 , the greater the degree of deformation , here surface curvatures extending far into the object 5 , such as, for example, a bulge or an indentation, are visible in the direction of the hollow chambers.

By means of the previously described temperature control device 26 , the material of the object 5 in the area of the separating surface in its deformed section is continuously heated to a temperature between 160 ° C. and 210 ° C., preferably between 180 ° C. and 200 ° C., these specified temperatures being raised refer to the plastic material PVC (polyvinyl chloride). For other materials used, the temperatures or temperature ranges to be used for the reshaping have to be selected according to the respective material. Due to the continuous heating of the material at least in sections, the deformations or internal stresses introduced during the separation are automatically reset by the memory effect inherent in the material, so that after cooling, the actual cross-sectional area of the object 5 for the measuring device 25 arranged thereafter, in particular the profile geometry comparison , can be used so that deviations in the profile geometry can be quickly influenced directly during the extrusion process and these can be corrected immediately.

The separation of the object 5 takes place in the embodiment shown in FIG. 1 in the course of the manufacturing process. This can also be referred to as an inline process, since the separation is carried out simultaneously during the production process as soon as a predetermined length of the article has been produced by the extrusion process. Irrespective of this, however, it is also possible to post-treat objects 5 after their non-cutting separation, as has been described above, so that the deformations or internal stresses introduced during separation are at least largely automatically reset by the temperature change.

In FIGS. 3 to 5, one end portion of the object is respectively shown in a greatly enlarged schematic representation 5, wherein 3, the end in the vicinity of the separation surface 24 has in the Fig. By the separation process, a relatively strong deformation on both sides of the shell, wherein in addition the internal tensions are represented by a large number of simplified points.

In FIG. 4, the same end portion of the object 5 is shown having a release surface 24, said end portion has been already by means of the temperature control device 26 and the after-treatment apparatus a strong temperature change, as mentioned previously in detail acted upon, whereby the deformation at least substantially are reset or the end of the object 5 is at least almost free of internal tensions, as has been shown in simplified form by a few points.

If the object 5 which has already been after-treated once - according to FIG. 4 - is again exposed to the previously described temperature change in the end region - according to FIG. 5 - there is no or a negligibly small further resetting of the deformation or the reduction of the internal stresses, whereby the two end areas are almost.

In Figs. 6 and 7, another end portion of an object 5 is shown, is which is also severed and wherein in the region of the parting surface 24 virtually shown no deformations or are visible, but the end portion of internal stresses which, as by a plurality has been shown in simplified form in FIG. 6.

FIG. 7 shows the same end area as in FIG. 6, but in contrast, however, this has been subjected to one of the temperature changes described above, as a result of which the frozen tensions in the end area are reduced, furthermore a subsequent deformation due to the reduction of the tensions, as this has been schematically represented by a rounding. For example, due to the reduced internal stresses, only a few schematic points that represent these stresses were entered here in FIG. 7.

Thus, each end region of an object 5, which has preferably been cut without cutting, can be checked in a simple manner to determine whether it has been treated with the method according to the invention or whether a separation process has taken place, as described and illustrated in FIG. 6 is. If a corresponding aftertreatment has already been carried out on an object 5 , as can be seen from the overview of FIGS. 3 and 4, this leads to none or one during a further aftertreatment, as has been shown in FIG. 5 insignificant change in shape of the end area.

On the other hand, if an object 5 has been separated without cutting so that after the separation there are no noticeable deformations, as shown in FIG. 6, but internal stresses have been introduced or built up in the material of the object 5 , this follows the aftertreatment to a deformation of the end region, as has been shown in FIG. 7.

For the sake of order, it should finally be pointed out that, for a better understanding of the mode of action of the aftertreatment, the object 5 or its components have been partially shown to scale and / or enlarged and / or reduced.

The task on which the independent inventive solutions are based can Description can be taken.

Above all, the individual in FIGS. 1; 2 to 5; 6, 7 shown form the subject of independent, inventive solutions. The relevant tasks and solutions according to the invention can be found in the detailed descriptions of these figures. Reference number list 1 extrusion system
2 extruders
3 shaping device
4 caterpillar take-off
5 subject
6 extrusion direction
7 extrusion tool
8 calibration device
9 calibration tool
10 calibration tool
11 calibration tool
12 calibration tool
13 vacuum tank
14 vacuum tank
15 caliber plate
16 receptacles
17 machine bed
18 footprint
19 calibration table
20 roller
21 track
22 separating device
23 cutting unit
24 dividing surface
25 measuring device
26 temperature control device
27 insert
28 strength
29 cutting edge angle
30 level
31 cutting surface
32 cutting surface

Claims (6)

1. A process for the aftertreatment of an, in particular elongated and severed in its longitudinal extent, object in the region of a parting surface, characterized in that at least in sections the material forming the object, starting from the parting surface in the direction of the latter relative to its further portion, is heated to the extent that the deformations or internal stresses introduced by the separation are at least largely automatically reset or reduced by the temperature change. 2. The method according to claim 1, characterized in that the separation of the Object is carried out without cutting. 3. The method according to claim 1 or 2, characterized in that the object forming material made of a plastic material, in particular from the group of PVC (Polyvinyl chloride), PP (polypropylene), ABS (acrylonitrile-butadiene-styrene copolymers), ASA (Acrylonitrile-styrene-acrylic ester copolymers) is selected. 4. The method according to one or more of the preceding claims, characterized characterized in that the material of the object, in particular from a PVC (Polyvinyl chloride), in its deformed section continuously to a temperature between 160 ° C and 210 ° C, preferably between 180 ° C and 200 ° C is mentioned. 5. The method according to one or more of the preceding claims, characterized characterized in that the separation of the object in the course of the manufacturing process of the same is carried out. 6. An object with at least one separating surface arranged in its longitudinal extent at one of the end regions, characterized in that the separating surface ( 24 ) has been post-treated with a method according to one or more of the preceding claims and in that the material ( 5 ) forming the article in the section the separating surface ( 24 ) is at least almost undeformed or at least almost free of internal stresses.