DE1778884A1 - Process for welding structures made of thermoplastics and device for carrying out the process - Google Patents

Description

Method for welding structures made of thermoplastics and apparatus for carrying out the method. The invention relates to a Method for welding structures made of thermoplastics and device to carry out the procedure.

The invention is based on the object of structures made of thermoplastics in particular have been manufactured in injection molding or extruder processes, at certain Place or in a certain way with each other by welding in simple and more reliable way to connect.

This object is achieved according to the invention in that the connecting parts that previously produced in the thermoplastic or extruder process has cooled down or hardened structures or their parts according to the principle of pixel heating light rays collected by light optics are softened and thus become thermoplastic Welding are brought.

Since not all light beams are suitable for welding, are primarily Used light rays that have a large amount of long-wave light.

In order to achieve the necessary welding temperature, very light-colored Lamps used. The light that does not generate heat affects the controls disturbing. It is useful to retain the short-wave portion by means of a filter. In addition, the light source is usually located in a glass bulb and this in turn in one housing. The distance between the lamp and the welding point required in this way optical measurements to bring a temperature image to the welding point. Such The measures are: spherical mirrors with correction lenses, parabolic mirrors, lenses with great red permeability. As such lenses come into use: spherical with Correction of parabolic dispersion, aspherical, anamorphic and cylindrical. The respective selection must be made depending on the extent of the light source and the shape of the weld. This creates a tlechaelset with axial adjustment, the u 90 should be extensive that every light source shape on every weld joint shape can be aligned.

The light source can be of various power, the choice of Suitable performance depends on the size of the weld or weld area and in relation to this again of whether the weld is at once, in parts or should be irradiated flowing continuously. The latter is in relation to that The process is very beneficial in that it involves mechanical contact with the heat source with the Sxhwei # seam is not done.

To lamps of different power and thus different as required Such lamps can bring strong heat to the welding point be arranged on a turntable so that they can be swiveled to the welding point, that one in the Is able to deal with various welding problems with the device to solve. at which different output powers are required.

For example, with several lamps arranged in a circle of 50, 100, 0 and 1000 watts - depending on which welding process is being carried out - the respective unit should be swiveled into the welding position.

Furthermore, depending on the type of welding required, the Design the light source, i.e. the lamp on the one hand and the optics on the other hand, so that at the welding point a punctured, liiier or surface-shaped collected one should Temperature exhibiting exposure to light takes place in the sense of the geometrical Designs that weld in different ways, depending on the requirements. Here, an image is created in the image point of the optics - be it point-like, line-like or planar - generated. To be more precise, one becomes point-shaped when the weld is made Shall have shape, ensure that the light source, namely the ulühfaden the bulb, also as small as possible, namely point-like shape, while in the case of a line-like weld, the filament of the light bulb has linear dimensions will have, so that the optical image of this filament is also linear appears, and in the case of a flat, for example circular, welding surface either the filament is arranged in a corresponding planar manner within the incandescent lamp is or the optics are adjusted so that the distance between them and the weld is smaller or larger than the pixel distance.

Another way is with the help of suitable optical gowns such as aspherical ones Lenses and mirrors (cylindrical or ana @ or photic Optics) a constant, preferably point-like light source at the welding point a picture shape to give that of the sweat expansion (surface, straight line, round line or not mathematically based curves).

Since both the electric lamps themselves also heat up outside bring the actual welding point with it as well as a warming within the so-called welding tunnel of the device takes place through radiation and reflection according to the invention in order to avoid an inadmissibly high rise in temperature, both the housing of the electric lamp and the welding tunnel with a cooling system equipped, which ensures a constant temperature not only within the lamp housing, but also of the welding tunnel, which means consistent welding quality and an increased service life of the incandescent lamps has a beneficial effect.

Optical means such as mirrors, lenses and diaphragms can also be used use in an arrangement that directs the radiation on the way from the light source Keeps away from housing parts up to the welding point. In this case only the closer The area around the lamp swet hot when exposed to direct omnidirectional radiation is. This position of the lamp can be at a non-intrusive distance from the operator All other light-guiding parts remain up to the welding point cool.

According to the invention, the greatest possible welding performance is obtained when the pixel is adjusted to the optimal position.

This adjustment can either be done by hand using a micro-screw adjustment or also automatically with the help of optical or thermal controls in this way take place that each optimal and constant welding conditions can be achieved.

In the case of certain welding problems, the requirement occurs only to a limited extent Surfaces warm to softening, while neighboring areas do not warm up to Plasticizing may be heated. According to the invention, this can be achieved by a upstream perforated diaphragm or corresponding contour diaphragm achieve that in particular Cases are cooled by a coolant so that they are exposed to radiation as such is not heated. This has made it possible to capture unwanted light rays shield and heat to a precisely delimited area in the welding area to restrict. In addition, the bundle of light rays can be generated by an upstream optics its contour can be influenced, limited, bundled and thus controlled in such a way that that the light scattering is largely eliminated, which also increases the efficiency the facility is significantly improved.

For precise, sharply delimited images, only expensive combined images can be used Optics are used because with simple lenses the refraction over the entire Waveband is different.

In order to achieve a precise image with simple optical means One can achieve those rays which alone show a welding effect through suitable color filters that only allow long-wave light to pass through, the scattering suppress.

Gas discharge lamps do not show a continuous spectrum, they do a band spectrum with interrupted intermediate zones.

It is appropriate to use lamps with predominantly red band and to filter out the unusable, predominantly optically effective rays.

The actual welding process according to the invention can be divided into three individual processes be subdivided, namely into the plasticizing process that is initially effective through the heating by means of the bundled light rays, to which the actual Connection process is followed by the two plasticized zones on the Contact point are pressed together so firmly by pressure that the material is homogenized to a uniform mass at the junction, whereby the actual connection is made in the welding process. Finally froze in a final stage with dbkühlung the thermoplastic material, with which the Hardening and thus uninterrupted solid connection between the parts is achieved will. The two processes described first can be combined in time by softening or plasticizing the plastic material at the same time the pressure for homogenizing is also exerted0 The device according to the invention is designed in such a way that there is a cooling zone in addition to a welding zone. the Pressure tools for compressing the individual structures or

Parts in the area of the welding zone can also be used as cooling tools be formed, the cooling effect by appropriately guiding the coolant only then begins after the pressure for homogenizing or fusing has reached the effect in sufficient wetness. For cooling can be used as a coolant a cold air stream can be used, especially when it comes to welding is about blistering necks. This is particularly important when welding bottle necks sensible, from a certain cycle or a certain welding speed to assume that in dependence on the length of the light beam is set.

Welding conditions can occur in which the AutgaDe is set to suddenly change the welding speed, in particular to increase. In order to solve this problem, two paths are taken according to the invention: One possibility is to use a light bulb higher up at the welding point To use power, for example by swiveling it in ar. the spot the previous one takes over the welding process. Another possibility is to ebn to switch on another lamp unit by subsequently connecting to the ribbon beam of the one unit, a further belt jet of the second unit is added so that the welding speed is correspondingly in the same continuous line can be increased by placing the individual ribbon beams one behind the other along the welding line to a certain extent double in length.

A further increase in welding performance can be achieved by that the plastic material is strongly enriched with corresponding dye particles, which, depending on the dye, have an increased temperature effect during exposure effect the plastic by appropriate absorption of the light rays.

On the other hand, welding conditions can occur in which the plastic cannot be enriched with color particles, especially if it is is a highly transparent plastic material. In these cases the rays of light occur through the plastic material without leaving it within a sufficiently short Time to heat up enough. In order to ensure that there is still enough for plasticization necessary heating of the plastic material is obtained on the back of the materials to be welded or below the weld zone a light-absorbing pad is provided in contact, which ensures that the penetrating rays are effective in the material to be welded and contribute to warming here.

The inventive method is also particularly suitable for clock recording by installing a timer in the electric current for the incandescent lamp so that light pulses are emitted from the incandescent lamp, which the cycle welding enable. By automatically switching the light bulb on and off, the certain rhythms welds in the locomotives below the light bulb Plastic material made.

Instead of pulsing the light bulb on and off, you can thereby upstream of a circumferential screen in front of the incandescent lamp ensure that the rays of light emanating from it only in a certain rhythm to what is to be swept away Meet plastic material so that the desired cycle welding is also achieved thereby will.

Finally, you can also influence the welding process by that the exposure to light is based on certain wavelengths. So can according to the invention when using long-wave light rays it is achieved that these are proportionate penetrate deeply into the plastic material to be welded and thereby a cheap Cause effect.

Since electric lamps are used for the light source, which according to Burning out over a certain period of time can be a detrimental effect on the welding process disruptive interruption time interval enter through which the The quality of the weld seam suffers. To eliminate this disadvantage, at least two lighting units are provided, which are based on automatic electrical switching make sure that at the moment one of the lighting units burns out Pivoting the other unit in their place the exposure to light and thus the Welding is practically not interrupted. You can then use the principle of Replace the burnt-out lamp with a new one in peace and quiet so that through the device, if a lamp burn out again in the foreseeable future should automatically ensure that there is practically no interruption in the Light radiation and thus occurs in the welding process.

The automatic U connection of the unit with the burned out Light source on the one with the intact light source happens that as a result the voltage drop that occurs when it burns out via a relay, the changeover mechanism and at the same time the switch to the new lamp is actuated0 Further advantageous Possible embodiments of the invention emerge from the subclaims.

Exemplary embodiments are explained in more detail with reference to the drawing. B shows: FIG. 1 a schematic representation of the arrangement of two light sources above a part to be welded in elevation, FIG. 2 shows the arrangement of four Light sources of different light intensity on a rotary head in a schematic representation in plan #, 3 shows an elevation of part of a welding device with a cooled beam of light, the 4 the plan of an ochweiMbildes, "5 a Aufri # of a light source with optics connected underneath, FIG. 6 the rowing of three light sources for the purpose of generating a relatively long band of light in the Aufri #, F-, g. 7 the doubling of the lighting effect of two light strips by corresponding Arrangement of two light sources, FIG. 8 the schematic representation of the interleaving three light bands to form a particularly long band, Fig. 9 the compilation of a triangular weld seam by arranging three light sources with tape accordingly Fig. 10 shows the outline of a circular weld seam by putting it together segment-like Licntoänder, which are emitted from four individual lamps, and Pig. 11 the cross arrangement of a weld seam created by combining two angular Bilaer corresponding lamps with associated diaphragms is achieved.

According to the embodiment of FIG. 1, a lamp 1, which located inside a housing 2, a combined light beam through an optics 3 bundle 4 sent to the welding point 5, so that the two in the figure are schematic indicated sheet-like structure made of thermoplastic material 6.7 can be welded together. Can be pivoted about an axis 8, apart from the lamp 1, a second lamp 9 is stored, which is not initially connected to the lighting network connected; only when the bulb 1 should burn out, it will be automatic the incandescent lamp 9 switched on and in the sense of Arrow 10 in the Position of the lamp 1 pivoted by 1800, while the incandescent lamp 1 takes the place of the Bulb 9 arrives and can be replaced here by a new one.

In Figure 2, the storage is schematically in the plan in a circular arrangement Shown by four lamps 11, 12, 13, 14, each 50, 100, 250 and 1000 watts have and in the sense of arrows 15 and 16 each in the welding position Can be pivoted as required, the position of the lamp 11 in FIG 50 watt represents the welding position.

According to the embodiment of FIG. 3 is in the passage of the beam 4, a diaphragm 17 is turned on, which is expanded to form a hollow ring 18 through which A cooling liquid can be passed through the inlet 19 and the outlet 20, which ensures that the heating by the light beam 4 is exclusively remains limited to the welding zone 21.

In Figure 4, a contour diaphragm 22 is shown in a cross position, which allows a weld to be made in a cross shape.

According to FIG. 5, the light bundle 23 emanating from the lamp 1 combined by an upstream optics 24 to form a cone of light 25 and thus a particularly intensive, narrowly delimited weld point 26 is reached.

According to the embodiment of FIG. 6, three incandescent lamps 1 are of this type mounted to each other that their light bundle 4 ribbon-like shape strung together unite at the welding point 27, as shown in the plan to Fig. 8.

In the embodiment of FIG. 7, the light bundles 4, the proceed from the two lamps 1 and have the shape of a ribbon, by Corresponding lamp arrangement guided so that they, overlapping, on the weld meet, whereby the heating of the weld is increased accordingly.

According to Figure 9, the lamps 1 are arranged to each other that the individual bands of light 29 incident on the welding point enclose a triangle, so that the welding figure is correspondingly triangular.

In Figure 10, a total of four light sources are approximately in the sense of 6 provided, the light strips 33 have a quarter circle shape and become a complete a full circle.

Finally, in FIG. 11, two light sources are provided each band of light has the shape of a right angle that turns into one. Cross image add to.

You can see from the various figures that it is possible to use relatively few basic figures - be it band-shaped or segment-like Shape - get by by appropriately arranging the lamps and their number to obtain an extensive possibility of variation in the overall white figure.

If clear plastic parts are to be welded together, then this cannot be done without further ado using the previous methods, because the The collecting surface necessary for the development of the heat is missing. Also the arrangement a reflector cannot remedy this. The same goes for white-colored plastics, although the conditions are better here, while dark-colored plastics are best welded. To now also with crystal clear and white-colored plastics to be welded together, a dark-colored, Support that does not tend to weld in the form of a heat or heat-resistant glass block 32 that lets the red light through (see Fig. 12) used, on which the weld metal 33 and on this a pressure tool 34 is placed which is black and non-reflective matt. The exposure takes place from below through the glass block 32 with concentration of the light rays 35 on the weld metal.

By means of this device, the welding point is heated in fractions of a second, whereby the glass block hardly moves, but the pressure tool if it is made of metal, not insignificantly heated, and in proportion the coefficient of thermal conductivity of steel or non-ferrous metal of approx. 45, of glass of approx. 0.72.

To effectively dissipate heat from the weld point in a useless manner To prevent this, it is useful to cover the printing tool with a black metal-glass block to provide.

Claims (24)

Claims C1. Method for welding existing thermoplastics Formed using a light beam device with which a light optics collected light rays are thrown onto the structures in the area of the welding, characterized in that the connection points of the previously in the thermoplastic or cold or hardened structures produced in the extruder process or the parts of which are collected using the principle of pixel heating by means of light optics Light rays are softened and brought to thermoplastic welding, mainly light rays are used that have a sufficiently large long-wave Have light component. 2. The method according to claim 1, characterized in that to achieve the necessary welding temperature, very bright lamps are used where the short-wave. Share is retained by means of a filter, and that as optical measures spherical mirrors with corrective lenses, parabolic mirrors, lenses with high red permeability, spherical lenses with color dispersion correction, aspherical, anamo @ photic and cylindrical. Lenses are used. 3. The method according to claim 1 or 2, characterized in that for the purpose of adapting the various power requirements on the rotary or turret head of setting up lamps with low stereo power and thus different starter heating effects are provided, which can be swiveled into the welding position as required. 4. Apparatus for carrying out the method according to claim 1 to 3, characterized in that, depending on the type of welding required, the light source, i.e. the lamp on the one hand and the optics on the other, chosen or designed in this way is that at the welding point a point, line or area according to certain Figures collected, a sufficiently high welding temperature developing exposure to light he follows. 5. Apparatus according to claim 4, characterized in that with the help suitable optical means, such as aspherical lenses, and mirrors (cylinder or summer photic Optics) a constant, preferably point-like light source at the welding point results in an image shape that corresponds to the extent of the sweat (area, straight line, round line or curves that are not mathematically founded). 6. Apparatus according to claim 4 or 5, characterized in that both the housing for the electric light bulbs and the welding tunnel (s) are equipped with a jacket and a cooling system that ensure constant Temperature not only inside the lamp housing, but also within the welding tunnel care for. 7. Apparatus according to claim 4 to 6, characterized in that optical means such as mirrors, lenses and diaphragms are also used in an arrangement that the radiation on the way from the light source to the welding point Keeps away from parts of the housing, so that only the immediate vicinity of the lamp is so hot how it is exposed to direct omnidirectional radiation. 8. Apparatus according to claim 4 to 7, characterized in that For the purpose of the greatest possible welding performance, the image point is in the optimal position Adjusted, either by hand using a micro-screw setting or also automatically with the help of optical or thermal controls in such a way that that optimal and constant welding conditions can be achieved in each case. 9. Apparatus according to claim 4 to 8, characterized in that for the purpose of creating limited heating surfaces in front of the light beam optics hole or Contour diaphragms of a corresponding shape are connected upstream, in particular the Perforated or contour panels with cooling spaces or cooling channels for passage through a coolant are provided. 10. Apparatus according to claim 9, characterized in that by a special upstream optic influences the contour of the light beam, limited, bundled and thus controlled in such a way that the light scattering largely is turned off. 11. Apparatus according to claim 4 to 10, characterized in that for the purpose of using simple optical means which nevertheless produce a precise image of those rays which alone show a welding effect, suitable Color filters are used that only allow long-wave light to pass through, the scattering However suppress it. 12. The apparatus of claim 4 bin 11, characterized in that Lamps with predominantly Rotband are used whereas the unusable ones are predominantly optically effective rays are filtered out. 13. Apparatus according to claim 4 to 12, characterized in that for a reliable welding process at the welding points the pressing together of the parts to be welded Formation provided are, which are preferably designed at the same time as Kahlwerkseuge by A coolant comes into play in cavities and channels in the printing tool. 14. Apparatus according to claim 13, characterized in that as Coolant a cooling liquid or a cold air stream is used. 15. A method for welding thermoplastics according to claim 1 to 3, characterized in that r control of the welding speed to the the existing lamp unit is connected to an additional lamp unit, in such a way that that subsequent to the tape beam, which from one unit to the welding point is thrown, another wall beam is thrown in front of the switched-in lamp unit is added so that in the same continuous line the welding speed can be increased accordingly. 16. The method according to claim 1 to 3, characterized in that by increasing the welding performance the plastic material with eat-speaking Dye particles are greatly accumulated, depending on the dye when spotlighting an increased temperature effect on the plastic due to corresponding absorption cause the rays of light. 17. The method according to claim 1 to 3, characterized in that when welding highly transparent plastic material on the back of the to welded structure or below the weld zone a non-reflective one Support is provided, which ensures that the penetration through the plastic Rays are reflected in the material to be welded and so for sufficient distance Contribute to the warming of the plastic material. 18. The method according to claim 1 to 3, characterized in that for the purpose of cycle welding in the electric current of the glow lamp Timer is installed in such a way that light pulses are emitted from the incandescent lamp. 19. The method according to claim 18, characterized in that instead of the pulsed switching on and off of the incandescent lamp in front of this one rotating one Aperture is connected upstream, which ensures that the emanating from the incandescent lamp Beams of light in a certain rhythm onto the plastic material to be welded hit. 20. The method according to claim 1 to 3 and 15 to 19, characterized in that that to influence the welding process when exposed to light from a light certain wavelength, in particular long-wave light is assumed that relatively deep into the plastic material to be welded, as far as this is opaque, can penetrate. 21. The method according to claim 1 to 3 and 15 to 20, characterized in that that at least two lighting units are provided for the purpose of uninterrupted operation of which one device is switched on while the other is in reserve is located, and that due to automatic electrical switching devices for it it is ensured that the moment the switched-on lighting unit burns out the reserve unit is connected to the lighting network and at the same time in the welding position is pivoted, while the burned-out unit automatically according to the principle of the turning bsw. Turret head is pivoted into the rest position, so that the burned out Incandescent lamp can be replaced with a new one. 22. The method according to claim 1 to 3 and 15 to 21, characterized in that that the automatic switchover taking advantage of the occurring when burning through Voltage drop across a relay is torgenosmen. 23. The method according to claim 1 to 3 and 15 to 22, characterized in that that for the purpose of welding clear plastic parts or colored white Plastic parts have a dark-colored surface in Porm that does not tend to weld a heat-resistant or heat-resistant glass block that lets the red light through (32) is used, on which the weld metal (33) and on this a pressure tool (34) is placed, which is black and non-reflective matt execution, wherein exposure is from below. 24. The method according to claim 23, characterized in that the pressure tool is provided with a black metal-glass block (32). L e r s e t e