METHOD FOR HEATING AN OBJECT, AND HEATING DEVICE

Abstract

In order to provide a method for heating an object (102) that is simple to perform and makes it possible to heat an object (102) efficiently and reliably, it is proposed that the method should include the following: providing an object (102) to be heated; applying at least one energy beam (108, 109) to the object (102) to be heated, wherein at least one energy beam (108) is guided over the object (102) to be heated multiple times, along a predetermined intended heating path (114), and this heats the object (102) along the intended heating path (114); determining a temperature distribution over the intended heating path (114), for identifying one or more deviation points (120) at which an actual local temperature differs from an expected and/or calculated temperature; changing and/or supplementing the application of at least one energy beam (108, 109) in order to compensate for the temperature difference at one or more deviation points (120).

Claims

1. A method for heating an object using a heating device, including the following: providing an object to be heated; applying at least one energy beam to the object to be heated, wherein at least one energy beam is guided over the object to be heated multiple times, along a predetermined intended heating path, and this heats the object along the intended heating path; determining a temperature distribution over the intended heating path, for identifying one or more deviation points at which an actual local temperature differs from an expected and/or calculated temperature; changing and/or supplementing the application of at least one energy beam (108, 109) in order to compensate for the temperature difference at one or more deviation points.

2. A method according to claim 1, wherein the heating device is first put in a basic mode, in which applying at least one energy beam has the effect of inputting energy uniformly along the intended heating path.

3. A method according to claim 1, wherein, in dependence on the determined temperature distribution over the intended heating path, the heating device is put in a compensation mode, in which applying at least one energy beam brings about an energy input to one or more deviation points that is locally reduced or locally increased in comparison with an energy input to the rest of the intended heating path.

4. A method according to claim 1, wherein, in dependence on the determined temperature distribution over the intended heating path, the heating device is put successively in different compensation modes, in which applying at least one energy beam in a manner adapted to respectively determined local temperature differences brings about an energy input to one or more deviation points that is locally reduced or locally increased in comparison with an energy input to the rest of the intended heating path.

5. A method according to claim 3, wherein, in the compensation mode or in a plurality of compensation modes, in dependence on a development of the temperature of the intended heating path over time, a plurality of mutually differing local temperature differences are compensated one after the other or at the same time.

6. A method according to claim 3, wherein the heating device is operated in a compensation mode or successively in different compensation modes until an expected and/or calculated uniformity of the temperature distribution over the intended heating path has been achieved, and/or until an expected and/or calculated absolute temperature distribution over the intended heating path has been achieved.

7. A method according to claim 1, wherein, for the purpose of compensating for one or more local temperature differences, a scanning speed of at least one energy beam at which the at least one energy beam is guided along a beam path is changed locally at one or more deviation points.

8. A method according to claim 1, wherein, for the purpose of compensating for one or more local temperature differences, a power and/or energy density of at least one energy beam with which the at least one energy beam impinges the object is changed locally at one or more deviation points.

9. A method according to claim 1, wherein, for the purpose of compensating for one or more local temperature differences, an adapted actual beam path of at least one energy beam is adjusted, which passes by one or more deviation points temporarily or over the long term and/or partly or entirely.

10. A method according to claim 1, wherein, for the purpose of compensating for one or more local temperature differences, at least one compensation energy beam is used in addition to at least one energy beam that serves as the main energy beam.

11. A method according to claim 10, wherein the at least one compensation energy beam is directed exclusively at one or more deviation points.

12. A method according to claim 1, wherein (i) a measuring device is used to determine a development of the temperature distribution over the intended heating path over time; (ii) a compensation mode is determined, in particular calculated, from this for the purpose of compensating for the temperature difference at one or more deviation points; and wherein (iii) the heating device is put in this compensation mode.

13. A method according to claim 12, wherein a compensation mode includes an application schema for the purpose of specifying a) an actual beam path of at least one energy beam, b) a scanning speed characteristic of at least one energy beam, c) a focusing characteristic of at least one energy beam, and/or d) a power characteristic of at least one energy beam.

14. A method according to claim 1, wherein a spatial course of the intended heating path is determined using the measuring device, and wherein using an object receptacle, one or more objects that are to be heated are oriented in relation to at least one beam source that emits at least one energy beam and/or at least one beam influencing device such that a total of the local spacings of the intended heating path from a focal plane of at least one energy beam is minimal.

15. A heating device for heating an object, which includes the following: a beam source for generating at least one energy beam and for applying it to the object; a beam influencing device for influencing a beam direction, a beam movement, a beam intensity and/or a focus of at least one energy beam; a measuring device for determining a temperature distribution on an intended heating path along which the object is to be heated, and for identifying one or more deviation points at which an actual local temperature measured using the measuring device differs from an expected and/or calculated temperature; a control device for changing and/or supplementing the application of at least one energy beam in order to compensate for the temperature difference at one or more deviation points.

16. A heating device according to claim 15, wherein the measuring device and/or the control device take a form and are set up (i) to determine a development of the temperature distribution over the intended heating path over time; (ii) to determine, in particular to calculate, a compensation mode for compensating for the temperature difference at one or more deviation points; and (iii) to put the heating device in this compensation mode.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0113] FIG. 1 shows a schematic illustration of a heating device for heating an object, wherein the object has been overheated at certain points and, for the purpose of compensating for the overheating, the scanning speed of an energy beam is adapted;

[0114] FIG. 2 shows a schematic illustration of an object to be heated, corresponding to FIG. 1, wherein, for the purpose of compensating for an overheated point, a power of the energy beam is varied;

[0115] FIG. 3 shows a schematic illustration of the object, corresponding to FIG. 1, wherein, for the purpose of compensating for the overheated point, a focus of the energy beam is varied;

[0116] FIG. 4 shows a schematic illustration of the object, corresponding to FIG. 1, wherein, for the purpose of compensating for the local overheating, the energy beam is guided past the overheated point at a certain point;

[0117] FIG. 5 shows a schematic perspective illustration of an object to be heated that has a substantially hexagonal intended heating path forming a closed ring, wherein a heating device for heating the object is operated in a basic mode;

[0118] FIG. 6 shows a schematic illustration of the object to be heated, corresponding to FIG. 5, wherein the heating device is first operated in a basic mode and then in a compensation mode;

[0119] FIG. 7 shows a schematic illustration of an object to be heated, corresponding to FIG. 5, wherein the heating device is operated successively first in a basic mode, then in a compensation mode, and then in the basic mode again;

[0120] FIG. 8 shows a schematic side view of an object receptacle for receiving an object to be heated, together with the object received thereon; and

[0121] FIG. 9 shows a schematic illustration, for illustrative purposes, of a course of the height of an object to be heated and the adaptation of application of the energy beam.

[0122] Like or functionally equivalent elements are provided with the same reference numerals in all Figures.

DETAILED DESCRIPTION OF THE DRAWINGS

[0123] An embodiment, illustrated in FIG. 1, of a heating device that is designated 100 as a whole serves to heat an object 102, for example in order to weld this object 102 to a further object.

[0124] The object 102 is for example made from a plastics material. Consequently, the connection to be made between the two objects is in particular a plastics weld connection.

[0125] Preferably, the heating device 100 includes a beam source 104, for example a laser source.

[0126] The beam source 104 is preferably configured to generate one or more energy beams 108. The beam direction, the beam movement, the beam intensity and/or the focus of the one or more energy beams 108 are preferably influenceable and/or variable using the beam source 104. In particular, preferably a beam power of one or more energy beams 108 may be varied, preferably deliberately controlled and/or regulated, using the beam source 104. Here, the one or more energy beams 108 may for example be temporarily completely switched off, in particular for the purpose of compensating for a temperature difference at one or more deviation points 120.

[0127] Further, the heating device 100 preferably includes a beam influencing device 106, which includes in particular a deflecting device, for example a deflecting mirror, a focusing device, in particular a lens, etc.

[0128] Using the beam influencing device 106, in particular the beam direction, the beam movement, the beam intensity and/or the focus of the one or more energy beams 108 emitted by the at least one beam source 104 may be influenced and/or varied.

[0129] Further, the heating device 100 preferably includes a measuring device 110, for example a pyrometer or an infrared camera.

[0130] The measuring device 110 includes in particular a monitoring device 112, or is a constituent part of such a monitoring device 112.

[0131] Using the measuring device 110, in particular the object 102 is detectable.

[0132] Here, the measuring device 110 serves in particular to determine a temperature distribution over an intended heating path 114 along which the object 102 is to be heated using the heating device 100.

[0133] For the purpose of heating the object 102 along the intended heating path 114, the energy beam 108 is guided over the object 102 in particular along an actual beam path 116.

[0134] The beam path 116 is substantially identical to the intended heating path 114, at least in a basic mode of the heating device 100.

[0135] A control device 118 of the heating device 100 preferably serves to control and/or regulate all the further components of the heating device 100, or at least individual ones or a plurality of these components.

[0136] Using the heating device 100, the energy beam 108 is applicable to the object 102 along the intended heating path 114, preferably a plurality of times, in particular for example 200 times.

[0137] During this, the energy beam 108 is guided along the intended heating path 114, in particular in a cycle or a pass.

[0138] In particular because of material fluctuations along the intended heating path 114, this may result in heating of the object 102 that varies along the intended heating path 114.

[0139] As a result of this, deviation points 120 may in particular arise, at which an actual local temperature differs from an expected and/or calculated temperature.

[0140] Here, the difference is in particular a difference that goes beyond a predetermined limit value.

[0141] The measuring device 110 is preferably configured to detect whether individual or a plurality of deviation points 120 having a differing local temperature are produced during heating of the object 102.

[0142] As soon as the measuring device 110 detects one or more deviation points 120, preferably the control device 118 is used to act on the beam source 104 and/or the beam influencing device 106, in order to change the application of the laser beam 108.

[0143] Here, in particular a heat input by the energy beam 108 along the intended heating path 114 is varied in order ultimately to achieve, at least temporarily, a reduced heat input in overheated regions (deviation points 120), and thus to adapt the initially overheated regions, in thermal terms, to the remaining part of the intended heating path 114.

[0144] In the event of excessively cold deviation points 120, heating to a greater extent may be performed at the deviation points 120 in order ultimately to achieve an adjustment to the temperature of the rest of the intended heating path 114 in this case too.

[0145] As an alternative or in addition to varying an energy beam 108, in particular a single energy beam 108, it may be provided for a compensation energy beam 109 to be used in addition to an energy beam 108 that serves as the main energy beam, in order to compensate for one or more deviation points 120. A compensation beam source 105 is in particular configured to generate the compensation energy beam 109, which is preferably exclusively directable or directed at the one or more deviation points 120.

[0146] FIGS. 1 to 4 illustrate different variants that may respectively be utilised alone or indeed in combination with one another to compensate for the temperature difference at the deviation point 120.

[0147] According to FIG. 1, it is provided for the scanning speed at which the energy beam 108 is guided over the object 102 to be varied locally, in order ultimately to act on the deviation point 120 for a shorter period and thus to reduce the energy input. Here, the scanning speed of the energy beam 108 is preferably reduced in the remaining intended heating path 114 or throughout the rest of the intended heating path 114, such that the total cycle time or total pass time remains constant, independently of the fact of compensating for one or more temperature differences at one or more deviation points 120.

[0148] As an alternative or in addition thereto, in the embodiment illustrated in FIG. 1 one or more compensation energy beams 109 may be provided, for the purpose of compensating for one or more local temperature differences at one or more deviation points 120. In particular, this allows deviation points 120 having an excessively low temperature to be compensated, in that the one or more compensation energy beams 109 are directed at the object 102 in addition to the energy beam 108 that serves as the main energy beam.

[0149] The use of one or more compensation energy beams 109 may, as an alternative or in addition, also be provided in the case of the other described ways of compensating for deviation points 120.

[0150] According to FIG. 2, compensation for the temperature difference at the deviation point 120 is achieved in that the power of the beam source 104 is reduced while the energy beam 108 is heating the deviation point 120.

[0151] The energy input is reduced by the reduction in power, with the result that an overheated point can in particular be adjusted, in thermal terms, to the rest of the intended heating path 114.

[0152] According to FIG. 3, a focus of the energy beam 108 is varied as the energy beam 108 sweeps over the deviation point 120. Here, the focus is for example changed in that a region of the object 102 that is detected by the energy beam 108 occupies for example twice, three times or four times the surface area in the region of the deviation point 120 than in the course of the rest of the intended heating path 114. In this way too, it is possible to compensate for the overheating of a point on the intended heating path 114.

[0153] According to FIG. 4, the energy beam 108 is guided along a beam path 116 that differs locally from the intended heating path 114.

[0154] Here, the energy beam 108 is in particular moved away from the intended heating path 114 at a disengagement point 122, then guided past the deviation point 120, and finally brought back to the intended heating path 114 again at an engagement point 124.

[0155] Preferably, the disengagement point 122 and the engagement point 124 are arranged directly adjacent to the deviation point 120, such that preferably only the deviation point 120 is excluded from further overheating.

[0156] A radius of curvature r over which the energy beam 108 is guided away from the intended heating path 114 or introduced into it again is preferably at most approximately 10 mm, for example at most approximately 5 mm. It is thus preferably possible to avoid or at least reduce undesired partial cooling of the intended heating path 114 upstream and/or downstream of the deviation point 120.

[0157] As mentioned above, the options for compensating for a temperature difference at one or more deviation points 120 according to FIGS. 1 to 4 may be combined with one another in any desired way.

[0158] FIGS. 5 to 7 provide an alternative illustration of functioning of the heating device 100.

[0159] Here, the object 102 is illustrated.

[0160] An upper edge of the object 102 forms the intended heating path 114, which takes a form that is in particular substantially hexagonal and forms a closed ring.

[0161] The rings above this serve to illustrate how the energy beam 108 cycles over the intended heating path 114 successively over time.

[0162] As can be seen from FIG. 5, the cycles of the energy beam 108 are identical in form.

[0163] This provides a uniform application of the energy beam 108 along the intended heating path 114.

[0164] This operation of the heating device 100 is in particular a basic mode or basic operation in which uniform energy input along the intended heating path 114 is achieved.

[0165] FIG. 6, by contrast, shows a mode of operation of the heating device 100 in which initially a basic mode is provided for two cycles of the energy beam 108.

[0166] Using the measuring device 100, a deviation point 120 has for example then been detected, whereupon the control device 118 has put the heating device 100 in a compensation mode.

[0167] This compensation mode is indicated in that the cycles of the energy beam 108 in the region of the deviation point 120 take a course differing from the intended heating path 114.

[0168] In particular according to the option illustrated in FIG. 4 for compensating for a local temperature difference, in the embodiment of the compensation mode illustrated in FIG. 6 it is provided for the energy beam 108 to be guided past the deviation point 120 for a plurality of successive cycles.

[0169] This makes the temperature distribution on the intended heating path 114 uniform.

[0170] According to FIG. 7, likewise, operation is initially carried out in basic mode until the deviation point 120 is detected.

[0171] As a result of bypassing the deviation point 120 for two cycles of the energy beam 108, however, the temperature difference is rapidly brought into alignment.

[0172] The measuring device 110 detects this re-alignment and puts the heating device 100 into the basic mode again, as a result of which ultimately further uniform heating of the object 102 over the intended heating path 114 is achieved.

[0173] In particular if the object 102 to be heated has an intended heating path 114 that takes a three-dimensional shape and is not only in one plane, an initially uniform application of the energy beam 108 to the object 102 can result in a locally greatly varying temperature distribution.

[0174] In particular, local differences in height have the result that parts of the object 102 lie in a focal plane 126 of the beam source 104 and/or the beam influencing device 106 to the optimum extent, while other regions lie outside the focal plane 126 and are consequently subjected to a markedly different heat input.

[0175] Preferably, the heating device 100 includes an object receptacle 128 for receiving the object 102 to be heated.

[0176] In this case, the object receptacle 128 is in particular coupled to the control device 118 and/or the measuring device 110.

[0177] Preferably, using the measuring device 110, the intended heating path 114 over the object 102 is determinable, and using the object receptacle 128 the object 102 is orientable in the optimum manner relative to the beam source 104 and/or the beam influencing device 106.

[0178] In carrying out this orientation, it is preferably provided for a total of local spacings x.sub.1, x.sub.2, etc. between the intended heating path 114 and the focal plane 126 to be minimised.

[0179] In the best case, this enables varying of the focus while the object 102 is being heated to be completely dispensed with.

[0180] As an alternative or in addition to orienting the object receptacle 128 and/or the object 102 using the measuring device 110, it may for example be provided, using CAD data of the object 102, for an optimised arrangement of the object 102 to be determined, in particular calculated. Based on this, the object 102 may preferably be oriented by an optimised pivoted adjustment on the object receptacle 128.

[0181] FIG. 9 illustrates a course of the height of the intended heating path 114 relative to the beam source 104 and/or the beam influencing device 106.

[0182] As is clear from FIG. 9, where there are differences in height along the intended heating path 114, for example three regions that have to be differentiated from one another are produced.

[0183] A region I that lies closer to the beam source 104 and/or the beam influencing device 106, and a region III that lies further away from the beam source 104 and/or the beam influencing device 106.

[0184] The two regions I and III are in particular arranged such that the associated sections of the intended heating path 114 are oriented substantially parallel to one another and substantially perpendicular to a beam direction of the energy beam 108.

[0185] A rising or falling region II that lies between the regions I and III is thus oriented in particular substantially obliquely to the beam direction of the energy beam 108.

[0186] In the event of a uniform and/or continuous scanning speed of the energy beam 108, there will thus be a locally greater speed in the region II and consequently a locally smaller energy input to the object 102.

[0187] Suitably controlling and/or regulating the heating device 100 preferably has the effect of compensating for this three-dimensional contour of the object 102, in particular the course of the height of the intended heating path 114. In particular, it may be provided here for the scanning speed of the energy beam 108 to be reduced in the region II, in particular to such an extent that the local energy input corresponds to that in the regions I and III.

[0188] Otherwise, the embodiment of the heating device 100 that is illustrated in FIGS. 8 and 9 corresponds, as regards its structure and functioning, to the embodiment illustrated in FIG. 1, so in this respect reference is made to the description thereof above.

LIST OF REFERENCE NUMERALS

[0189] 100 Heating device [0190] 102 Object [0191] 104 Beam source [0192] 105 Compensation beam source [0193] 106 Beam influencing device [0194] 108 Energy beam [0195] 109 Compensation energy beam [0196] 110 Measuring device [0197] 112 Monitoring device [0198] 114 Intended heating path [0199] 116 Beam path [0200] 118 Control device [0201] 120 Deviation point [0202] 122 Disengagement point [0203] 124 Engagement point [0204] 126 Focal plane [0205] 128 Object receptacle [0206] r Radius of curvature [0207] x.sub.1, x.sub.2 Local spacing [0208] I, II, III Region