DD139102B1 - METHOD FOR DETERMINING AND CONTROLLING THE EFFECT OF ENERGY-RELATED CARRYING BEAM RADIATIONS ON MATERIALS AND DEVICE FOR CARRYING OUT THE METHOD - Google Patents

Description

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Applicant: Karl-Otto Mauer

4090 Lialle-Ueustadt Dlock 378/11

Zustellungobevollmächtigter:

Leit-UfN "Welding technology *" in the central institute for welding technology of the DDR 4030 Halle. PSF 16

Field of application of the invention

The invention relates to a method and devices for detecting and controlling the effect of high-energy carrier gangs on material under the jev / hurry conditions of the technological process and for setting and process-dependent control of this effect on the beam focusing, in particular for welding, cutting, melting, evaporation and material processing.

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Characteristic of the known technical solutions

It is already known that, in the event of a brief interruption of the electron beam by one or more sharp-edged probes, it is possible to take advantage of the measurable rate of current increase for the adjustment, control and stabilization of the focusing. For this purpose, a rotating probe periodically interrupting the electron beam is used and the course of the probe current is imaged by an electron beam oscillograph.

Another variant is that the electron beam is interrupted by a pendulum or circular motion of the unchanged in its position probe. If the beam focus is in the plane of the probe surface, the rate of increase of the current has its minimum value. The desired degree of focus (distance between the focal plane and the plane of the workpiece surface) is usually set via the distance between the lens center and the probe surface with the aid of calibration characteristics.

This method has the following disadvantages: The beam power and power density are limited, since the probe edges melt at higher power densities and then the measurement result is falsified. However, if focused at a low beam current intensity, significant variations occur in the welding performance due to the increasing influence of the space charge. If this method is used during the welding to stabilize the degree of focusing, there is a periodic interruption of the electron beam, which can disrupt the continuous process. Information on the influence of the interaction between the electron beam and the matter involved in the welding process on the beam focusing are not obtained,

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because the measured variable used is not connected to the welding process. If calibration curves are used to set the focus, they are only valid for the current working state of the beam gun.

It is also known to scan the electron beam of the welding gun directly on the workpiece surface synchronously with the electron beam of a remote sohmonitor, to use the reflected electrons for brightness control and to apply the image sharpness on dom screen as a measure that the working beam is surface-focused. The size of the rectangular raster image on the workpiece surface is only a few square centimeters. The adjustment of the degree of focus is carried out over the working distance by means of calibration curves.

Although the energy of the electron beam can be distributed over the entire surface of the grid and can thus be focused even at higher powers and power densities, the measured variable used is not directly connected to the welding process.

It is also known to use the intensity of the converted from a photosensitive device in a corresponding electrical size, occurring during dos welding process infrared radiation from the molten bath as a criterion for focusing. The measuring signal is displayed by a measuring instrument or recorded by an oscilloscope. There is a non-linear relationship between the focusing current intensity and the radiation intensity, which is characterized by two maxima and a minimum. At least the characteristic of the electron beam is focused so that the maximum Nahiefeiefe is achieved.

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The main feature of this method is the use of a photosensitive device as a probe. The beam evaporation dependent material evaporation during welding causes an increasing coating of the photosensitive surface of the probe and thus a time dependent change of the measured infrared radiation intensity for equal process conditions. Furthermore, the focusing current range in which this typical characteristic occurs becomes wider as the beam power increases, so that the pitch accuracy decreases. According to another known method, the strength of the backscattering or workpiece flow occurring during electron beam welding is utilized for setting and controlling the beam focusing. For this purpose, the current intensity of the backscatter or workpiece flow during welding is measured and recorded as a function of the focusing current through a recording device. There is a non-linear relationship between the focusing current intensity and the respective measured variable, which is characterized by two maxima and a minimum for the backscattering current and by two minima and a maximum for the workpiece flow. At the minimum of the characteristic for the backscattering current or at the maximum of the characteristic for the workpiece current, the electron beam is in each case focused in such a way that the maximum seam depth is achieved.

This method has the following drawbacks: The focusing current range in which this typical characteristic occurs becomes wider as the beam power becomes larger, so that the setting accuracy decreases. Since the catcher detects only a certain solid angle for the backscattering, lead, for example, dependent on the focusing current strength changes of

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Solid angle for the Ruckstreustrom distortion of the characteristic that make exact adjustment of the beam focusing difficult or impossible. The alternating current component occurring during welding is superimposed on the direct current component of the measuring characteristic and also impedes or prevents inaccurate adjustment of the beam focusing.

It is also known to use the spatial distribution of the backrest rusts during welding to adjust and control the beam focusing. For this purpose, two collectors for the backscattering stream of the same dimensions with respect to the beam axis are arranged symmetrically, usually in the welding direction, at a certain angle, and the differential current intensity is recorded by a recording device. There is a non-linear relationship between the focusing current intensity and the differential current intensity, which is characterized by two maxima and a minimum. At least the characteristic of the electron beam is focused so that the maximum Nahiefeiefe is achieved.

The disadvantage of this method is mainly that the spatial distribution of the backscattering in the welding direction has a significant asymmetry only for higher welding speed, so that the setting accuracy decreases with decreasing welding speed and the course of the characteristic is additionally dependent on this welding parameters.

Object of the invention

It is an object of the invention to provide a method and devices that allow under the particular conditions of the technological process, during the course of the process to determine the effect of high-energy carrier radiation on the material and control

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as well as to adjust the beam focusing and process dependent to reduce the cost of experiments and material in a to be solved technological task.

The essence of the invention

The invention has for its object to examine the backscatter and workpiece flow to the effect whether it can not be obtained from him more information that can be used for the control and control of the Strahlparametor more effective.

The process-dependent control is to ensure process stabilization within predetermined limits, even with time-dependent changes in the geometry of the electron beam optical system of the beam gun.

The object is achieved in that the frequency characteristic of the alternating current component of charge carriers, energy and frequency ranges de3 Rückstrou- and / or Werkstückstromcs is detected and represented such that the distance between the operating point formed by the nominal value of FokussiQ- rungungsstrength and the maximum frequency of the Frequency characteristic indicates the focal position with respect to workpiece level.

The exercise of the method described can gen such successes ^1, that the frequency characteristic during the process path at preselected time intervals displayed for a short time and the set nominal value of the Fokussiorungsstromstärke or accelerating voltage, in which the technological process between the individual pictures of the frequency characteristic runs out, at the same time particularly marked.

For this purpose, the focusing current or voltage during the Proezßverlaufes at certain time intervals, depending on the operating speed of the process, after any, in a certain range

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linearly increasing mathematical function changed once within adjustable limits by the set IJennwert and the necessary time for such a matched to the technological process that the process result is not adversely affected, but the frequency characteristic is clearly measured. A voltage strictly proportional to the momentary change in focus current or voltage is applied to the X input and to a voltage corresponding to the frequency of the backscatter or workpiece current to the X input, preferably an electron beam oscilloscope, which may optionally be a storage oscilloscope. At the same time, at the instant that the instantaneous and nominal values of the focusing current or acceleration voltage coincide, a short pulse is generated which is applied to the z-input of the oscilloscope and causes a corresponding luminous spot on the frequency characteristic shown by the oscilloscope.

Changes in the power density, the power density distribution in the focal spot, the degree of focus and the power density distribution in the longitudinal direction of the charge carrier beam, but also the process conditions are perceived on the screen of the oscilloscope as changes in the course or as a horizontal advance of the frequency characteristic. For given technological conditions, the beam focusing in the frequency maximum is coordinated with the process in such a way that the interaction between the charged particle beam and the matter involved in the process and the process dynamics caused thereby are most intense and, for example, in electron beam welding, the seam depth and the depth-width ratio of the Seam to reach their maximum. The characteristic of the respective technological process distance between the luminous point and the frequency maximum, the a certain relative focus amperage or Beschleunigungsspannungsbebe-

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The frequency characteristics are used to determine and control the effect of the high-energy carrier beam on the material and to set this effect via the beam focusing.

Another expedient feature is that the time between the times in which the Mc-mcntan- and nominal value of the focusing current or acceleration voltage coincide and the Frequenzcharakteri- stik reaches its maximum, measured and controlled and adjusted via the beam focusing and stabilized by process-dependent control becomes.

In order to determine and control the effect of the high-energy charge carrier on the material and to adjust this effect via beam focusing, the time interval between, for example, the front edges of these two pulses is measured and at the same time a positive or negative auxiliary voltage generated in an electronic circuit is evaluated indicates whether the frequency maximum occurs at a focus current strength or acceleration voltage value that is above or below the respective f-value. For the measurement itself, suitable digital measuring devices or an electron-beam oscilloscope, which may optionally be a storage oscilloscope, can be used. Through the use of digital measuring devices, it is still possible to print out, save or process the measurement result.

To stabilize the action of the high-energy carrier beam on the material by a process-dependent control, the measured time between the two pulse edges and the positive or negative auxiliary voltage, which characterizes the position of the frequency maximum with respect to the nominal value of the focusing current or acceleration voltage, fed to a process computer, the given If necessary, it can be a microprocessor.

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It is also possible to supply the two pulses directly or via suitable converters, wherein the time measurement and formation of the auxiliary voltage can be carried out by the process computer itself.

The process computer assumes the function of an electronic digital controller, which compares the respective actual values with the setpoints present in the memory and calculates the associated control values according to the required transmission behavior for the control process and forwards them to the actuator for the focusing current intensity or acceleration voltage. The setpoint values of the control and auxiliary variables, the process equation, the time behavior of the control function of the process computer, and the calculation and control program are stored directly or by a computer system in the process computer via corresponding input units. The synchronization of all involved in the process control devices takes place by appropriate control pulses, which are preferably issued by the process computer itself.

A further expedient variant for carrying out the method is characterized in that for the technological process on the basis of the frequency characteristic a fixed distance between the operating point and maximum frequency is specified, the gehorbige to the operating frequency as setpoint and the beam focusing on the frequency as a controlled variable automatically stabilized ,

For this purpose, the frequency of the backscatter or workpiece flow and the focusing current or acceleration voltage during the process are constantly measured and fed to a working as an electronic controller process computer, which may optionally be a microprocessor. The measurement of these quantities can be done by suitable Digitalmeßgeräte or by the

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Process computer itself. The process computer compares the respective actual values with the setpoint values present in the memory, calculates the associated control values in accordance with the required transmission behavior for the control process and forwards them to the adjusting glide for the focusing current intensity or the ceria acceleration voltage. The desired value of the controlled variable, the process equation, the limit values, the timing of the control function of the Prosoßrechners and the calculation and control program are fed via appropriate input units directly or from a computer system in the process computer. The synchronization of all devices ozeßregelung involved in the P _r is carried out by appropriate control pulses, which are preferably made by the process computer itself. An obvious solution is that the control process is conventionally implemented by suitable control loop members without the intervention of a process computer.

The device for carrying out the method according to the invention initially relates to the design of the per se bekannton catcher. Thus, it is expedient to design the collector for the backscattering stream, since changes in the angular distribution of the backscattering stream do not adversely affect the measuring performance and the plant operator can observe the technological process even without technical aids form a curvature whose focus is in the weld capillary.

In order that charge carriers reflected from the walls of the recipient do not distort the measurement result, the catcher is, as already known, prevented from screening.

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surrounded with slit-shaped opening, which must always be directed to the processing location. In the case of relative movement between the workpiece and the charge carrier beam, the catcher is to be arranged in the direction of movement behind or in front of the beam or offset by an angle to be fixed to one side or the other.

In order to ensure a small time constant for the control variable Gtrahlfokussierung it is forner zweckmüßig to equip the Strahlenkanonc with an additional built-iron-free focusing lens, which allows within predetermined limits fast low-distortion focus shifts around the base focussing generated by the existing magnetic lens.

Ausführungsbeispie1

The invention will be explained in more detail below on several Ausführungsbcispielen. In the accompanying drawings show:

Fig. 1: a schematic representation of the catcher and their spatial arrangement during welding and the principle for measuring the backscatter, workpiece and Durchdringungsstromes;

2 shows a block diagram for periodically repeated, short-time mapping of the frequency characteristic during the welding process;

FIG. 3 shows a diagram with the pulse courses according to FIG. 2; FIG.

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4 shows a schematic representation of the shift of the frequency characteristic when the nominal value is changed, and the change in the depth of the weld depending on the operating point used,

Fig. 5: a Dlockschema for control and process-dependent control of the distance between the operating point and the frequency maximum of the characteristic;

6 shows a Qlock scheme for the continuous control of the actual values for the frequency of the backflow or workpiece flow during the welding process, and for the indication of a limit value violation;

Fig. 7 is a block diagram for prozoßabhängigen control of the frequency of the backscatter or workpiece flow on the Strahlfokussirung during welding;

The EIeUtronenstrahl the jet current intensity I generated by the electron beam welding gun, consisting of cathode I ₁ control electrode Z, anode 3, centering system 4, focusing lens 5 and deflection system б applies to the

Surface of the arranged at working distance a workpiece 7 of thickness s, which moves with the Schweißgeschwindxgkeit ν relative to the electron beam (Fig. 1). By appropriate adjustment of the individual process parameters while a weld is generated. The arranged on insulators 8 workpiece 7 is connected via the resistor R to ground. At the resistance

R is measured a voltage drop, which is directly proportional to the workpiece current I. U _n ter the workpiece 7 is a catcher 9 for the Durchdringungsstrom I "arranged on insulators 0, via the resistor R _p with

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Mass is connected. At the resistor Π_ a voltage drop is measured, which is directly proportional to the penetration current I_. Above the workpiece 7 is in the direction of movement behind the electron beam, an approximately 20 mm wide, depending on the working distance a curved catcher IO arranged for the backscatter rom I, whose focus is in the Schwoißkapillare and whose length is adjusted to the working distance a, that Reductions in the angular distribution of the backflow I do not adversely affect the measurement result. The catcher 10, which is fastened with insulators 8 under the electron beam welding gun, is connected to earth via the switch S and the resistor R .., wherein a voltage source U.sub.E is optionally connected in series with S_.

At the resistor R ₀ , a voltage drop is measured, which is directly proportional to the backscattering I ₀ . In order that charge carriers reflected from the walls of the recipient do not adversely affect the measuring orifice, the receiver 10 was surrounded by a metal shield 11 connected to ground in such a way that the backscattering flux I ₀ only reaches the catcher 10 through an approximately 15 mm wide slit-shaped opening directed towards the place of the hearing can get. In the beam entrance between the welding site and the catcher 10, two grids 12 are fixed in isolation, via the switches S ₁ and S ₂ , the voltage source U. and U ₂ and the resistors R and R ρ are connected to ground. At the resistors R and R 2, voltages are measured which are directly proportional to the grid currents I and I 2. Depending on the switch S, S _? and S, set potential as well as with the potentiometers P; P and P_ potential levels are only certain charge

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carrier and / or certain Enorgiospektren the backscattering I _n measured.

From the generated by the voltage source IG acceleration voltage U ₀ and control electrode voltage U _or the [lomontanvvorte U and adjusted by the potentiometer P. rated values U are measured via corresponding divider resistors R. From that generated by the current source i

Centering current I, and I ^, focusing current ° Zx ^. у

Strength I _c and deflection current I and I, are over F / vx Ay

niederohmigo resistors R located in the respective working circuits measured the instantaneous values I and the nominal values I set with the potentiometer P.

In the device according to FIG. 2, a pulse clock ITG generates nadcl pulses of amplitude U (FIG

to the input for external triggering of the time base X of an electron beam oscilloscope £ 0 or for external single-pulse triggering of a function an- gonator FG. The time interval T between the Nadolimpulsen is set in dependence on the welding speed V and is of the order of 1 to 5 s. The Nadelinipulse trigger each a unique sucker-shaped breakover voltage (Fig. 3 b) in Elektronenstrahloszillograph EC or an example partially sinusoidal pulse voltage (Fig. 3 c) in the function generator FG, which is tapped from the corresponding outputs and oin actuator SG a corresponding change in the focusing current I_ or acceleration voltage U by the set nominal value I- or U_ causes. The duration T and the amplitude of the tilt or generator output voltage are adjusted to the conditions for the welding process, that the process result is not adversely affected, but the frequency characteristic is clearly measured. T _n is of the order of 10 ms and is determined by the frequency at the electron radiation lot.

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lograph EG or set to function generator FG. The short-term change of the focusing current intensity with respect to the nominal value I_ is on the order of + - 0.5 to 2 % and the acceleration voltage U ₁ relative to the nominal value U_, of the order of approximately + - 4 %, when using a function capacitor FG becomes the instantaneous value of the focusing current intensity Ip or acceleration voltage U_. supplied to the gated operating time base amplifier X of the electron beam oscilloscope £ 0. If the breakover voltage of the electron beam oscilloscope EG is used, it must be ensured that the phase shift between the breakover voltage and the focusing current intensity I _p or acceleration voltage U is virtually zero in order to avoid distortions in the imaging of the frequency characteristic. Therefore, it is preferable to use an ironless focusing lens additionally incorporated in the electron beam welding gun. The nominal and instantaneous values of the focusing current I or acceleration voltage U have been fed to a zero pulse generator NIG, which generates a short negative rectangular pulse (FIG. 3 d) at the moment when both values coincide. This Röchckimpuls whose pulse amplitude

tude U and pulse length as a function of T _{0 a} fixed.

are supplied to the dom Z input of the electron-beam oscilloscope EG and causes a light touch, which is perceived on the screen as a luminous spot. The measuring voltage which is proportional to the backscattering and workpiece flow is fed directly above a low-pass filter TPF, bandpass filter BPF or high-pass filter IPF to a frequency voltage converter FSW which generates a voltage corresponding to the respective frequency. This frequency-dependent voltage will be the Y-input of the electron

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Stray oscillographs EO supplied. The frequency characteristic shown on the screen of Elektrononstrahloszillographen EO (Fig. 3 e) is for the existing Prozeßbedingungon the relationship between the frequency of Rückstrou- or W _e rkstückstromes f _o or f and the

KW

Focusing current I or acceleration voltage U again and has, in a first approximation, the shape of the Gaussian normal distribution curve. A change in the nominal value of the focus current I or acceleration voltage U (Figure 4a) is perceived on the oscilloscope's screen as a horizontal shift of the frequency characteristic (Figure 4b) since the frequency maximum for given process conditions occurs at the same focus current or acceleration voltage values the luminous point is fixed relative to the time base of the oscilloscope and marks the respective nominal value I_ or U, it is considered as the operating point. By changing the nominal value, each required operating point can be set to the frequency characteristic. Depending on the position of the operating point on the frequency characteristic different seam depths h and seam widths b are achieved (Fig. 4c). For given conditions of the electron beam welding process, the distance between the frequency maximum and the operating point corresponding, for example, to a particular relative focusing current value Д I_ (Figure 4 b), is characteristic and will be used to detect, adjust and control the effect of the electron beam on the material, especially Nahttiefe, used. The prerequisite for this is the knowledge of the relationship between the seam depth and the position of the operating point on the frequency characteristic. For this purpose, the focusing intensity I or acceleration voltage U for given process conditions is once around the nominal value I.

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or U "changed and the instantaneous value I_ or U" the uo г о

X input of a coordinate writer KS supplied (Fig, 2). The size T ₂ is in this case depending on the welding speed ν and the existing

Length of the workpiece and is on the order of seconds. The measurement voltage corresponding to the frequency of the backscatter or workpiece current is supplied to the Y input of the coordinate writer KS. The relationship between the seam depth and the position of the operating point is determined by comparing a longitudinal section in the middle of the seam with the frequency characteristic taking into account the existing calibration scales. Changes in the shape of the frequency characteristic indicate changes in the geometry of the electron-optical system of the electron beam welding canon with unchanged welding parameters.

In the device of Fig. 5, a digital timing system ZGS generates spikes which are applied to the external single-pulse triggering input of a function generator FG. Each of the needle pulses triggers a one-time, in a certain range linearly increasing pulse voltage in the function generator FG, which via an actuator SG a corresponding change of the Fokusqierungsstromstärke I or acceleration voltage U by the set nominal

value I or IJ causes. The sizes T. and T_ and Fo Bo 12

the amplitude of the pulse voltage are determined according to the explanations to the device of FIG. The nominal and instantaneous values of the focusing current I or acceleration voltage U become

r "B

fed to a zero pulse generator NIG at the moment

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the agreement of both values generates a short square pulse. The measurement voltage which is proportional to the backscatter or workpiece current is supplied directly or via a low-pass filter TPF, bandpass filter BPF or hole-pass filter IIPF to a frequency-voltage converter FSV / which generates a voltage corresponding to the respective frequency. This frequency-dependent voltage is applied to a maximum pulse encoder MIG, which produces a short square pulse at the moment when the frequency reaches its maximum value. The zero and maximum impulse NIG; MIG generated rectangular pulses have the same polarity and reach via an electronic switch EUS with auxiliary voltage generation HSE to the inputs "Start" and "Stop" of a digital timer system ZGS. Depending on the position of the operating point on the frequency characteristic, either the zero or the maximum pulse is generated first. The electronic switch EUS switches the first incoming pulse to the input "Start" and the second to the input "Stop". The measured time ℓ t (Figure 3 d / e), for example, a certain relative focusing current value

A Ip, characterizes the position of the operating point with respect to the frequency maximum and is displayed in numerical form. The zeroing of the ZGS timer system takes place automatically after an adjustable delay by the device. The simultaneously generated positive or negative auxiliary voltage indicates whether the frequency maximum occurs at a focus current or acceleration voltage value that is above or below the respective nominal value. The polarity indicator PA is performed by a digital device. requirement

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For the determination, adjustment and control of the effect of the electron beam on the material, especially the depth of the seam, is the knowledge of the relationship between the seam depth and the measured time Δ t in connection with the polarity of the auxiliary voltage. For documentation or further processing, the digitally coded measurement results are fed to a measured value memory MjVS or via a measured value converter MlVU to a measured value printer WVD or measured value punch HVL. Information about the respective conditions of the electron beam welding process, such as material, sheet thickness, welding speed, working distance, beam current U ₁ a., Are entered using the pointer ZG.

To stabilize the effect of the electron beams on the material by a process-dependent control, the measured or stored time Δt and auxiliary voltage are fed to a process computer PR. If the signals from the zero-pulse generator NIG and maximum pulse generator MIG are input directly into the process computer PR, then the latter carries out the measurement and formation of the auxiliary voltage itself. The measurement signals can also be supplied via a time-pulse-length polarity converter ZLPvV the process computer PR, the time

/ C \ t between the leading edges of both pulses into a rectangular pulse of time-dependent pulse length with positive polarity. Here, the pulse length of the carrier of the time information and the polarity characterizes the position of the operating point with respect to the frequency maximum. The process computer PR operates as an electronic digital controller, which stores the respective actual values with the nominal values present in the data memory DS.

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compares values and, according to the required transmission behavior for the control process, calculates the associated control values according to the computer program present in the program memory PS and forwards them to the actuator SiG for the nominal value of the focusing current intensity I _p or acceleration voltage U via a digital analogue converter DAW. The setpoint values of the controlled variable corresponding to the actual value input used, the process equation, the time behavior of the control function of the process computer PR and the calculation and control program are stored directly in the process computer PR via the input unit EE or by an electronic data processing system EDVA. For synchronization and coordination of the processes with one another, the process computer PR supplies control pulses SI to a control system SS, to which all devices involved in the process control are connected. Information about the course of the process is output by the process computer PR via a corresponding output unit AE. The process control takes place only in the period T ₂ .

In the device according to FIG. 6, the focusing current intensity I or acceleration voltage U and the

B

Frequency of the backscattering current I_ or workpiece current I ... ⁿ RW

constantly measured during the welding process and if necessary stored for documentation. For this purpose, the measurement voltage proportional to the focusing current intensity I or acceleration voltage U is supplied to a digital voltmeter DVM whose digitally coded measurement result is processed by a measured value converter MWU from a measured value MVD or measured value punch MVVL. The backscatter or workpiece flow I; I proportional measurement voltage is fed directly or via a low-pass filter TPF, bandpass filter BPF or high-pass filter HPF a frequency voltage converter FSW or directly via a pulse shaper IF a universal counter UZ. The frequency-voltage converter FSW generates one of

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respective frequency of the backscatter or workpiece flow f _R ; f corresponding measurement voltage, which is measured by a voltmeter SM or a DVM digital voltmeter or recorded by a light beam recorder USS or tape recorder BS. The digitally coded measurement result formed by the digital voltmeter DVM or universal counter UZ is further processed by the measured value converter MWU or supplied to a measured value memory MWS. To synchronize the digital devices are control pulses SI, which are generated by a timer system ZGS or control system SS. Condition for the control of the action of the electron beam on the W _e rkstoff, particularly on the seam depth, is the knowledge of the relationship between the frequency of the backscattered or workpiece current I; I and, for example, the Nahttiefe depending on the focusing current I _p or acceleration voltage U for given process conditions. For this, the frequency characteristics for the respective process conditions once added and the permitted limits for the frequency of the backscatter or W _e rkstückstromes f _E; F _w and the focusing current intensity I _p or acceleration voltage U on the basis of the depth of cut determined Nahttiefe set.

To record the frequency characteristic is a function generator FG whose linearly increasing output voltage via an actuator SG causes a single change in the focusing current I _p or acceleration voltage U in a wide range. The rising

The speed of the focusing current or acceleration voltage change depends on the welding speed ν and the existing

piece length and is on the order of seconds. Information about the respective conditions of the electron beam welding process when recording the

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Frequency characteristics, such as material, sheet thickness, welding speed, working distance, beam current intensity u. a., Are entered with the help of the signal generator ZG in the Meßwertumsetzer MWU.

When exceeding or exceeding the specified limits for the frequency of the backscattering or workpiece flow f "; f is emitted by a limit indicator GWM, which is controlled by the frequency voltage converter FSVV, an acoustic signal AS or light signal LS and / or the technological process via the control electrode voltage U__ interrupted. The interruption can be canceled with the switch S. In digital measurement, a threshold value comparator GWK controlled by the universal payer UZ or digital voltmeter DVM is used, which triggers the signals AS or LS in the event of a limit overshoot or undershoot via an actuator SG and / or interrupts the welding process. The trigger pulses AI of the limit value comparator GWK are simultaneously supplied to the Meßwertumsotzer MWU, for example, to trigger the red pressure.

If a large number of different electron beam welding tasks are to be solved, the measured values are entered into an electronic data processing system EDVA and processed in the data memory DS to form a database. In the case of analog measurement, the input is made via an analog-to-digital converter ADW. The limits, the calculation program and. Additional information about the process conditions are supplied to the computer system via the input unit EE. The control pulses SI for synchronizing all Digitalmeßgeräte be submitted by the computer system itself and forwarded to the control system SS · When controlling the electron beam welding process compares the computer system according to the existing program memory PS computer program the actual values for the frequency of the backscatter or workpiece flow f _R ; f with the

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permissible values and outputs corresponding information about the course of the process and / or control signals at Grenzversüber- or undershooting via an output unit AE.

In the device according to FIG. 7, the actual values of the focusing current intensity I or acceleration voltage U and the frequency of the backscattering flow f _R or workpiece flow f are continuously measured during the welding process and processed by a process computer PR operating as an electronic controller. For this purpose, the measurement current proportional to the focusing current intensity I _p or acceleration voltage U is supplied to a digital voltmeter DVM or analog-digital converter ADW whose digitally coded measurement result reaches the input of the process computer PR. The backscatter or workpiece current I _R ; I proportional measurement voltage is fed directly or via a low-pass filter LPF ₄ bandpass filter BPF or high-pass filter HPF a frequency voltage converter FSW or directly or via a pulse shaper IF a universal counter UZ. The frequency voltage converter generates a FSW of the respective frequency of the backscatter or W _e rkstückstromes f; f corresponding voltage, which is measured by a digital voltmeter DVM. The digitally coded measurement result formed by the digital voltmeter DVM or universal counter UZ reaches the input of the process computer PR. To synchronize the digital devices are control pulses generated by a timer system ZGS or control system SS.

Prerequisite for the stabilization of the effect of the electron beam on the material, especially on the Nahttiefe by process-dependent control over the beam focusing is the K _e nntnis the relationship between the frequency of the backscattering or workpiece flow f _R ; f and the seam depth as a function of the focusing current

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strength I or acceleration voltage U for given process conditions. For this purpose, the frequency characteristic for the respective process conditions are recorded once and the setpoint and the limit values for the frequency of the backscattering or workpiece flow f _R ; f and the focusing current I_ or acceleration voltage U on the basis of the required, established in the longitudinal grinding Nahttiefe set. To record the frequency characteristic, the focusing current I_ or the acceleration voltage U _{Q are} once linearly varied in a wide range and at the same time the digital inputs for the frequency of the backscatter or workpiece current f_; f and the focusing current intensity Ip or acceleration voltage IL · fed to a measured value memory MWL or Meßwertumsetzer MWU, which drives a measured value MlVL or Meßwertdrucker MWD, information about the particular conditions of the electron beam welding process in recording the frequency characteristics, such as material, sheet thickness, welding speed working distance, beam current, etc. , are entered with the help of the signal generator ZG in the measured value converter MlVU. After the setpoint and limit values have been established, all measured values determining the actual frequency characteristic are input from the measured value memory MWS or measured value punch MbVL to the data memory DS of the process computer PR.

In electron beam welding with process control, the process computer PR compares the respective actual values with the set values present in the data memory DS, calculates the associated control values according to the required transmission behavior for the control process according to the computer program PS present in the program memory and forwards them to the actuator SG via a digital analogue converter DAW

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for the focusing current I_ or acceleration voltage U on. The desired value of the controlled variable, the process equation, the limit values, the time behavior of the control function of the process computer PR and the calculation and control program are fed via the input unit EE directly or from the database of an electronic data processing system EDVA in the process computer PR. For synchronization and coordination of the processes with one another, the process computer PR supplies control pulses SI to a control system SS, to which all devices involved in the process control are connected. Information about the course of the process is output by the process computer PR via a corresponding output unit AE.

If the control process in a conventional manner analog without process computer PR, the output of the frequency converter FSW actual value of the controlled variable in the comparator VG is compared with the supplied by a voltage source SQ setpoint and the signal of the control deviation fed to a control amplifier RV, in which executed as feedback Zoitglied the proportional, integral and differential behavior PID of the controller is set. The output signal of the control amplifier RV is fed to the actuator SG for the focusing current I _p or acceleration voltage U.

To ensure a small time constant for the regulator, an ironless focusing lens additionally incorporated in the electron beam welding gun is used.

Claims (1)

208 230 invention claim Method for determining and controlling the effect of high-energy charged-particle beams on materials and for setting and process-dependent control of the technological process via beam focusing during welding, cutting, melting, evaporation and material processing by utilizing the backscatter and / or workpiece flow, characterized the frequency characteristic of the AC component of charge carriers, energy and frequency ranges of the backscatter and / or workpiece current is detected and displayed such that the distance between an operating point mark formed by the nominal value of the focusing current strength and the frequency maximum of the frequency characteristic indicates the focal position with respect to the workpiece plane. Method for determining and controlling the effect of high-energy carrier beams according to point l _y characterized by the measurement of the time interval between the operating point marking and the frequency maximum for automatic stabilization of the beam focusing. Method for determining and controlling the effect of high-energy carrier beams according to items 1 and 2, characterized in that specified for the technological process on the basis of the frequency characteristic a fixed distance between the operating point and frequency maximum, the frequency associated with the operating point as setpoint and the beam focusing on the frequency be automatically stabilized as a controlled variable. Device for carrying out the method according to item Ьіз 3 with a spatial, shielded catcher whose opening is directed to the processing location, characterized 208 230 characterized by the strassenförraige training the catcher with a curvature whose focus is in the weld capillary. Means for carrying out the method according to claim l to 3 with an electromagnetic focusing lens for generating the basic focusing of the charged particle beam, characterized by an additionally incorporated in the beam gun, ironless focusing lens. For this У- sides drawing Documents considered: DE-OS 1941 255
DE-OS 2225 761
DE-AS 2443 563 (B 23 k, 15/00) Dr.-Ing. V.W. Baschenkenko, Dr.-Ing. Karl-Otto Mauer: Investigation of the penetration and reverberation from the vapor channel during electron beam welding; Investigations on the average permeation and backscattering in electron beam welding, ZIS-Mitteilungen 1976, No. 9, pages 923-935 and 11, pp. 1171-1176.