GB2026209A - Improvements in or relating to methods of and apparatuses for controlling movable energy sources when operated to heat the surfaces of objects - Google Patents

Abstract

A method of controlling a movable energy source eg a laser or plasma beam or electric arcs when it is being operated to heat a surface 1 (Figure 9) of an object eg an ingot and to maintain the predetermined temperature of the surface, comprises controlling the velocity (Vi) and power of the energy source (4) as it is moved along a predetermined path (3), in accordance with error signals derived from the difference between predetermined and measured temperatures at different elemental areas (21,...,2i...,2n) of the said surface (1). From the temperature error signals correction values are produced. The power of the energy source (4) is varied in proportion to the average deviation between the measured and desired temperature for each of the elemental areas. The correction values for velocity (Vi) are converted into rectangular coordinate signals (Uy, Ux) representative of the components determined by the law of movement of the source and related to rectangular axes (Y,X), these signals being used to control the velocity. The temperature is measured by a scanner unit 17 coupled optically to a temperature sensor 9. <IMAGE>

Description

SPECIFICATION Improvements in or relating to methods of and apparatuses for controlling movable energy sources when operated to heat the surfaces of objects The invention relates to systems that automatically control the temperature of an object being heated, and more particularly to a method of and apparatus for controlling a movable energy source when it is being operated to heat the surface of an object.

The invention may be used to control a spatial movement of localized energy sources such as electron, ion, laser or plasma beams and electric arcs. The invention may thus be used in metallurgy for melting, ingot pulling and zone type cleaning; in mechanical and instrument engineering; in welding, mechanical treatment and heat treatment, in microelectronics; in vacuum film deposition, and in microtreatment.

Known in the art is a method of controlling electron beam heating, wherein an electron beam is caused to be rotated along the circumference of a circle of a given radius, which is adjusted by varying the amplitude of size sweep voltages, and the velocity of movement of the electron beam is adjusted by varying the oscillation frequency of a sine voltage. An apparatus for performing this method comprises two phase shifters, an adder, three amplifiers, and a double amplitude limiter. The sine voltages that are 90" out of phase with respect to each other are applied, via matching amplifiers, to the deflection system of an electron gun.

Known in the art is another method for controlling electron beam heating, wherein an electron beam is caused to pass over the predetermined locations on an object and is held immovable for a certain time interval at each such location. An apparatus for carrying out this method comprises two locked-on generators providing step voltages and coupled to the deflected systems of an electron gun.

Known in the art is a method and apparatus for automatic control of the heating mode of an electronic thermal installation. In accordance with this method, the power of the electron beam is adjusted by varying the power delivered to the cathode of the electron gun with the help of a Hall sensor, that reads the beam power. The apparatus comprises a Hall sensor, a comparison unit and a regulator that controls the power fed to the cathode of the electron gun.

The above-mentioned methods and apparatus are disadvantageous in that they do not provide for a correction of the movement and power of the energy source, which is necessary to compensate for any deviation in the distribution of the temperature measured on the surface of an object from a preset distribution.

There is a method of controlling electron beam heating, which method is performed by an apparatus providing for controlling the electron beam heating mode of a furnace (cf. the USSR Inventor's Certificate No.418,836 dated August 2, 1972).

The known method comprises the steps as follows: measuring the temperature of the surface of an object by means of a scanning pyrometer that receives pertinent data in passing along a predetermined path on the object surface; obtaining a signal representative of a difference between the measured and the preset temperature of the object surface and remembering that signal; varying the power and movement of the energy source along the predetermined path in accordance with the signal representative of the temperature difference.

An apparatus for performing the above-described method comprising a temperature pickup to sense the temperature on the surface of an object and a scanning unit which constitute together a scanning pyrometer with a deflection system, a temperature setter arranged to set a temperature to which the object is heated, a comparison unit arranged to compare the predetermined and the measured temperature, control units arranged to control the movement of the energy source relative to rectangular axes, and memory units to store the signals representative of the predetermined and measured temperature.

In the described method and apparatus, the same path is used along which the energy source (electron beam) is moved and along which the temperature on the surface of the object is measured. Note that the same signal provides for the displacement of the energy source and for the scanning movement of the pyrometer, that signal being formed on the basis of the signal representative of the difference between the predetermined and measured temperature. As a result, the temperature pickup for sensing the temperature on the object surface can be implemented only as a camera tube with electronic scanning. This in turn imposes limitations on the described method and apparatus since the present-day temperature sensors with optical/mechanical scanning feature higher accuracy.

In addition, the most useful applications of the described method and apparatus are concerned with the case where the movement of the energy source, and, therefore, the path along which the temperature is measured are one-dimensional; on the other hand, sufficient difficulties arise when the energy source is caused to move along an arbitrary path on the object surface. Finally, it is not possible to utilize the described method and apparatus in the case where the path along which the energy source is moved and that along which the temperature is measured do not coincide with each other or in the case where the temperature is to be measured concurrently at several points on the object.

According to one aspect of the invention, there is provided a method of controlling a movable energy source when it is being operated to heat a heating surface of an object to maintain a predetermined temperature thereof and when it is being moved along a predetermined path in accordance with the difference between the predetermined and measured temperatures of the heating surface of the object, the method comprising: dividing the heating surface of the object into elementary areas; forming and remembering error signals representative of the difference between the predetermined and the measured temperature at each of the elementary areas of the heating surface of the object; utilizing the error signals for producing signals representative of the corrosion values of the velocity and power of the energy source at the elementary areas including segments of the predetermined path; converting the signals representative of the correction values of the velocity of the energy source to signals representative of the components determined by the law of movement of the energy source and related to rectangular axes; and varying the velocity of the energy source along the predetermined path in accordance with the signals representation of the components determined by the said law of movement.

It is thus possible to move an energy source along an arbitrary path on the surface of an object and for the correction of the velocity and power of the energy source in the course of its movement along this path to be effected in response to the signals from a temperature sensor that checks on the distribution of temperature at arbitrary points on the surface of the object.

The velocity of the energy source can be varied along the predetermined path so that the difference between the predetermined and the measured temperature, related to each of the elementary areas, is decreased.

Preferably the signals representative of the correction values forthe velocity of the energy source are converted to the signals representative of the components determined by the law of movement of the energy source and related to the rectangular axes by: approximating the predetermined path using straight line segments and determining the projections of each of the segments on the rectangular axes; providing the signals representative of the components of the velocity of the energy source, related to the rectangular axes, and proportional to the values of the projections of the straight line segments of thee predetermined path; dividing the signals representative of the correction value for the velocity of the energy source for each of the segments of the path into two signals representative respectively of the correction values of the components of the velocity of the energy source, related to corresponding rectangular axes, and each proportional to the value of the projection of a given straight line segment of the path on a respective rectangular axis; adding each of the signals representative of the correction values of the components of the velocity of the energy source related to corresponding rectangular axes to a respective signal representative of one of the components of the velocity, related to a respective rectangular axis; and integrating the summation signals so produced to obtain the signal representative of the components determined by the law of movement of the energy source and related to the rectangular axes.

Preferably, the signals representative of the correction values of the velocity of the energy source are converted to the signals representative of the components determined by the law of movement of the energy source and related to the rectangular axes by: approximating the predetermined path of the energy source using circular arcs and determining the value of the curvature of each of the circular arcs; providing control signals by summing the signals representative of the predetermined velocity of the energy source and the signals representative of the correction values of the velocity; switching the control signals to provide the signal representative of the velocity of the energy source; integrating the signal representative of the velocity of the energy source to provide a signal representative of the distance passed by the energy source along the predetermined path; forming a signal which is representative of the form of the path of the energy source and which is proportional to the obtained values of the curvature of the circular arcs of the path, multiplying the latter signal by the signal representative of the velocity of the energy source and integrating the signal so obtained to provide a resulting signal; simultaneously integrating the sine and cosine values of the resulting signal and providing the signals representative of the components determined by the law of movement of the energy source and related to the rectangular axes.

Preferably the energy source performs a periodical or an approximately periodical movement and the method further comprises generating, from the error signals, an average signal representative of an average value of the error signals and varying the power of the energy source in accordance with that average signal; and generating, from the signals representative of the differences between each of the error signals and the average signal, the signals representative of the correction value for the velocity of the energy source.

According to another object of the invention there is provided an apparatus for controlling a movable energy source when it is being operated to heat a heating surface of an object, comprising: two control units arranged to control the movement of the energy source along two rectangular axes; a control unit arranged to control the power of the energy source; a temperature setter arranged to set a predetermined temperature of the heating surface of the object and having an output coupled to a first input of a comparison unit arranged to compare the predetermined and measured temperature of the heating surface of the object and arranged to produce error signals corresponding to the difference therebetween, the comparison unit having a second input coupled to an output of a temperature sensor arranged to measure the temperature of the heating surface of the object; a switching unit arranged to switch the error signal; a scanning unit coupled to the temperature sensor; a memory unit arranged to store the error signal, having inputs coupled to the outputs of the switching unit, data input coupled to the output of the comparison unit, and a control unit coupled to the scanning unit; a signal forming unit arranged to form signals representative of the correction values of the velocity and power of the energy source, the signal forming unit being coupled to the output of the error signal memory unit and to the power control unit; a further memory unit arranged to store the signals representative of the correction value of the velocity of the energy source, the further memory unit being coupled to the signal forming unit arranged to form the signals representative of the correction value of the velocity and power of the energy source; and a functional signal converter arranged to convert the signals representative of the velocity of the energy source to signals representative of the energy source to signals representative of the components determined by the law of movement of the energy source and related to respective rectangular axes, the functional signal converter having inputs coupled to the outputs of the further memory unit arranged to store the signals representative of-the correction value of the velocity of the energy source, and outputs coupled respectively to the control units arranged to control the movement of the energy source along the two rectangular axes.

Preferably apparatus for carrying out the method of the invention comprises two units adapted to control the movement of the energy source along the rectangular axes, a unit adapted to control the power of the energy source, a temperature setter adapted to set the temperature of the heating surface of the object, a comparison unit adapted to compare the predetermined and the measured temperature of the heating surface of the object, the comparison unit having a first input coupled to the output of a temperature sensor adapted to sense the temperature of the heating surface of the object, having a second input coupled to the temperature setter, and having its output coupled to a data input of a switching unit adapted to switch over the error signals representative of the difference between the predetermined and the measured temperature and having its control input coupled to a scanning unit, the output of the switching unit being coupled to a memory unit adapted to store the error signals and having its output coupled to a signal forming unit adapted to form the signals representative of the correction values of the velocity and the power of the energy source the correction value signal forming unit having a first output coupled to a memory unit adapted to store the signals representative of the correction values of the velocity of the energy source, and having a second output coupled to the power control unit, the velocity correction value memory unit having its outputs coupled to the inputs of a functional signal converter adapted to convert the signals representative of the correction values of the velocity to the signals representative of the components determined by the law of movement of the energy source and related to the rectangular axes.

Preferably, the functional signal converter comprises a signal generator arranged to generate the signals representative of the two components of the velocity of the energy source; a signal dividing unit arranged to divide the signal representative of the correction value of the velocity of the energy source into two signals which are representative respectively of the correction values of corresponding components of the velocity, related to respective rectangular axes, the input of the signal dividing unit being used as a respective rectangular axes, the input of the signal dividing unit being used as a respective input of the functional signal converter and coupled to a respective output of the velocity correction value memory unit; a multichannel switch arranged to switch the signal representative of one component of the velocity of the energy source related to one rectangular axis and a multichannel switch arranged to switch the other component of the velocity of the energy source related the other rectangular axis, the two multichannel switches having their data inputs coupled to those outputs of the signal generator which correspond to the components of the velocity of the energy source related to the rectangular axes; a multichannel switch arranged to switch the signal representative of the correction value of one component of the velocity related to one rectangular axis and a multichannel switch arranged to switch the signal representative of the correction value of the other component of the velocity related to the other rectangular axis, the inputs of the two multichannel switches being coupled to respective inputs of the signal dividing unit; a first adder having a first input coupled to the output of the one component signal multichannel switch, and having a second input coupled to the one component correction value signal multichannel switch; a second adder having a first input coupled to the other component signal multichannel switch, and having a second input coupled to the other component correction value signal multichannel switch first and second integrators having their inputs coupled respectively to the first and second adders and having outputs coupled to respective movement control units; first and second threshold networks having their inputs coupled respectively to the outputs of the first and second integrators; a signal synchronization unit arranged to synchronize the signals representative of the components of the velocity and the signals representative of the correction values of the components of the velocity related to respective rectangular axes, the signal synchronization unit having its inputs coupled to the outputs of the first and second threshold networks and having its output coupled to the control inputs of all the multichannel switches.

Preferably, the functional signal converter comprises a velocity setter arranged to set the velocity of the energy source, an adder unit having a first input group coupled to the velocity setter, and having a second input group used as a respective input of the functional signal converter and coupled to the velocity correction value memory unit, a switch unit arranged to switch the control signals and having its data inputs coupled to the outputs of the adder unit, a first integrator having a data input coupled to the output of the control signal switch unit, having a control input coupled to the output of a threshold network, and having its output coupled to the input of the threshold network and to the input of a conversion unit arranged to convert the signal representative of the distance passed by the energy source along the predetermined path to the signal representative of the form of the path, a first multiplication unit having a first input coupled to the output of the distance conversion unit, having a second input coupled to the control signal switch unit, and having its output coupled to the input of a second integrator, two channel networks arranged to form respectively the signals representative of the two components of the velocity of the energy source related respective rectangular axes, the two channel networks having respectively a cosine converter and a sine converter whose inputs are joined together and coupled to the second integrator, having respectively second and third multiplication units whose corresponding inputs are coupled to the cosine and sine converters and whose other inputs are coupled to the output of the control signal switch unit, and having respectively third and fourth integrators arranged to form in their respective channel networks the signals representative of the two components of the velocity of the energy source related to respective rectangular axes, the third and fourth integrators being coupled respectively to the second and third multiplication units and having their outputs coupled to the control inputs of the control signal switch unit.

Preferably there is provided a signal forming unit arranged to form an average signal and coupled to the error signal memory unit, and another signal forming unit arranged to form a signal representative of the difference between each of the error signals and the average signal, the second signal forming unit having an input coupled to the output of the first signal forming unit and to the input of the power control unit, having another input coupled to the error signal memory unit, and having its output coupled to the velocity correction value signal forming unit.

The invention will be further described, by way of examples, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic representation of a heating surface of an object, bearing the path of a movable energy source; Figure 2 is a graph showing how signals U2 are functionally converted in the case where the path of the energy source is approximated using straight line segments; Figure 3 is a graph showing how signals U2 are functionally converted in the case where the path of the energy source is approximated by circular arcs; Figure 4 is a graph showing electrical signals used to vary the velocity and power of the energy source; Figure 5 is a block diagram of an apparatus for controlling the movable energy source;; Figure 6 is a block diagram of a functional signal converted used in the case where the path of the energy source is approximated using straight line segments; Figure 7 is a block diagram of a functional signal converter used in the case where the path of the energy source is approximated using circular arcs; Figure 8 is a block diagram of apparatus for controlling the movable energy source whose power is controlled in accordance with the average value of the signal representative of the difference between the predetermined and the measured temperature of the heating surface of an object; Figure 9 is a circuit diagram of apparatus for controlling the movable energy source; and Figure 70 is a circuit diagram of a functional signal converter used in the case where the path of the energy source is approximated by straight line segments.

A heating surface 1 (Figure 1) of an object is divided into elementary areas 2a,..., 2;,..., 2n. An energy source 4 is moved along a predetermined path 3 at a velocity V1 Vj,..., Vn corresponding to the elementary areas 2a,..., 2i,..., 2,. The tem temperature of the heating surface 1 is measured along a scanning path 5.

To provide for control of the velocity V1,..., Vj,..., Vn during the heating of the heating surface 1 of the object, the path 3 (Figure 2) is approximated by a broken line represented by a piecewise linear function. To this end, the path 3 represented by points Ao, Awl,..., Am is divided into straight line segments 6. Curves 8,7 are employed to represent the components determined by the law of movement of the energy source 4 (Figure 1) and related to rectangular axes X, Y as functions of time t.The vector Vj corresponds to the velocity of the energy source 4 (Figure 1 ) at a segment 6 of the path 3 and Vix and Vjy (Figure 2) are the components of the velocity Vi at the segment 6i (Figure 1), related to rectangular axes X,Y while AVj corresponds to the correction value for the velocity Vj and AVix and AVjy are the correction values for the components Vix and Viv for the velocity Vj at the segment 6j, related to the axes X,Y.

According to another embodiment of the invention it is possible to dividide the path 3 (Figure 3) into segments separated by points Bo, B1 Bm, where m is the number of the segments approximated by the circle arcs having corresponding radii Ro, ..., Raj,..., Rum 1, X0 andY0 are the coordinates of the initial point Bo of the path 3, V0 is the vector of the tangent related to the path 3 at its initial point Bo, and Bm is the final point of the path 3. The value of the curvature Xi of the path 3 is inversely proportional to the radius R1 of the arc of the approximating circle.

Figure 4 shows the electrical signals used to vary the power and the velocity Vj (Figure 1 ) of the energy source 4; U0 is the signal representative of the predetermined temperature of the heating temperature 1 (Figure 1) of the object; U1 is the signal representative of the measured temperature of the heating surface 1 (Figure 1) of the object; AU is a continuous signal representative of a difference between the predetermined and the measured temperature of the heating surface 1 (Figure 1) of the object; Qi is the error signal representative of a difference between the predetermined and the measured temperature for each of then elementary areas; Q is the average signal representative of the average value of the error signals Qj; ; AQ is the signal representative of a difference between the average signal Q and a given error signal Qj; U2 is the signal representative of the correction value Vi (Figure 2) of the velocity V for each of the elementary areas 2r,...,2j,...,2n; U3 is the signal representative of the velocity Vi (Figure 1) of the energy source 4; U4 iS the control signal representative of the sum of the signals U2 and U3; / is the length of the scanning path 5 (Figure 1); S is the distance passed by the energy source 4 (Figure 1) of the heating surface 1 of the object, i.e. the length of the path 3; U8 is the signal representative of the distance S; U6 is the signal representative of the form of the path 3 (Figure 1);; U7 is the signal representative of the angle (p by which the vector of the velocity Vi (Figure 3) is rotated with respect to the vector of the tangent to the path 3 at its initial point Bo; Ux, Uy are the signals representative of the components 8, 7 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1); U8 is the signal representative of sin ; Ug is the signal representative of cos (p;; An apparatus for controlling the movable energy source 2 (Figure 5) comprises a temperature sensor 9 that senses the temperature of the heating surface 1 of the object and is coupled to an input 10 of a comparison unit 11 arranged to compare the predetermined and the measured temperature of the heating surface 1, the comparison unit 11 having an input 12 coupled to a temperature setter 13 arranged to set the temperature of the heating surface 1 of the object. The output of the comparison unit 11 is coupled to a data input 14 of a switching unit 15 arranged to switch the error signals Qi (Figure 4). A control input 16 (Figure 5) ofthe switching unit 15 is coupled to a scanning unit 17which is coupled optically with the temperature sensor 9.The outputs of the switching units 15 are coupled to the inputs of a memory unit 18 adapted to store the error signals Qi (Figure 4) and having its outputs coupled to the inputs of a signal forming unit 19 (Figure 4) arranged to form the signals U2 representative of the correction values AVj (Figure 2) for the velocity Vi of the energy source 4 and signals representative of the correction values for the power of the energy source 4. An output 20 of the signal forming unit 19 is coupled to the input of a unit 21 arranged to control the power of the energy source 4 while outputs 22 of the unit 21 are coupled to a memory unit 23 arranged to store the signals U2 (Figure 4).Outputs 24 (Figure 5) of the memory unit 23 are coupled to the inputs of a functional signal converter 25 arranged to convert the signals U2to the signals Uy, Ux (Figure 4) representative of the components 7, 8 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axes Y, X. Outputs 26, 27 (Figure 5) of the functional signal converter 25 are coupled respectively to units 28, 29 adapted to control the movement of the energy source 4 relative to the rectangular axes X, Y (Figure 2).

In the case where the straight line segments 6 are used to approximate the predetermined path 3 (Figure 2), the functional signal converter 25 (Figure 6) employs the following circuitry. A signal generator 30 arranged to generate the signals representative of the components Vix, Viy (Figure 2) of the velocity Vj of the energy source 4 (Figure 1) related to the rectangular axes X,Y has its output 31 (Figure 6) coupled to a multichannel switch 32 arranged to switch the signal representative of the components Vix (Figure 2) of the velocity Vj of the energy source 4 (Figure 1) related to the rectangular axis X.An output 33 (Figure 6) of the signal generator 30 is coupled to a multichannel switch 34 arranged to switch the signal representative of the component Viv (Figure 2) of the velocity Vi of the energy source 4 related to the rectangular axis Y. There is a signal dividing unit 35 (Figure 6) arranged to divide the signal U2 (Figure 4) representative of the correction value AVi (Figure 2) of the velocity Vi of the energy source 4 (Figure 1) into two signals which are representative respectively of the correction values AVix, AVjy (Figure 2) of the components Vix, Viy of the velocity Vi related to corresponding axes X,Y.The signal dividing unit 35 has its input used as a respective input of the functional signal converter 25 (Figure 6) and coupled to an output 24 of the memory unit 23, and has an output 36 coupled to a multichannel switch 37 arranged to switch the signal representative of the correction value AVix (Figure 2) of the component Vix of the velocity Vi of the energy source 4 (Figure 1) related to the rectangular axis X. An output 38 (Figure 6) of the signal dividing unit 35 is coupled to a multichannel switch 39 arranged to switch the signal representative of the correction value AVy (Figure 2) of the component ViV of the velocity Vi of the energy source 4 (Figure 1) related to the rectangular axis Y.The outputs of the mu Itichannel switches 32, 37 (Figure 6) are coupled respectively to inputs 40, 41 of an adder 42, while outputs of the multichannel switches 34,39 are coupled respectively to inputs 43,44 of an adder 45.

The outputs of the adders 42, 45 are coupled respectively to the inputs of integrators 46,47 whose outputs are used as the outputs of the functional signal converter 25 and are coupled to the control units 28, 29 and to threshold networks 48,49. The outputs of the threshold networks 48, 49 are coupled to inputs 50, 51 of a signal synchronization unit 52 arranged to synchronize the signals representative of the components Vix, Viy (Figure 2) of the velocity Vj and the signals representative of the correction values AVix and AViy of the components Vix, Viy of the velocity Vj related to the rectangular axes X,Y. The output of the signal synchronization unit 52 (Figure 6) is coupled to the control inputs of the multichannel switches 32,34,37,39.

In the case where the circle arcs are used to approximate the predetermined path 3 (Figure 3), the functional signal converter 25 (Figure 7) employs the following circuitry. A velocity setter 53 arranged to set the velocity1 (Figure 2) of the energy source 4 (Figure 1) is coupled to an input group 54 (Figure 7) of an adder unit 55 which has its input group 56 used as respective inputs of the functional signal converter 25. The outputs of the adder unit 55 are coupled to data inputs 57 of a switch unit 58 arranged to switch the control signals U4 (Figure 4). The output of the switch unit 58 (Figure 7) is coupled to a data input 59 of an integrator 60 having its control input 61 coupled to a threshold network 62 which has its input coupled to an output 63 of the integrator 60.A conversion unit 64, arranged to convert the signal U5 (Figure 4) representative of the distance S passed by the energy source 4 (Figure 1) along the path 3 to the signal U8 (Figure 4) representative of the form of the path 3 (Figure 1), is coupled to an output 63 (Figure 7) of the integrator 60. The output of the conversion unit 64 is coupled to an input 65 of a multiplication unit 66 whose input 67 is coupled to the output of the switch unit 58 (Figure 4) and whose output is coupled to the input of an integrator 68 (Figure 7).

The functional signal converter 25 comprises a channel network 69 arranged to form the signal Ux (Figure 4) representative of the component 8 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axis X. The channel network 69 (Figure 7) comprises a serial arrangement including a cosine converter 70, a multiplication unit 71 and an integrator 72. The cosine converter 70 is coupled to an input 73 of the multiplication unit 71 whose input 74 is coupled to a respective output of the switch unit 58. The output of the integrator 72 serves as the output 26 of the functional signal converter 25 and is coupled to the control unit 28 which controls the movement of the energy source 4 (Figure 1) relative to the axis X.

A channel network 75 (Figure 7) arranged to form the signal Uy (Figure 4) representative of the component 7 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the axis Y comprises a serial arrangement including a sine converter 76, a multiplication unit 77 and an integrator 78.

The sine converter 76 is coupled to an input 79 of the multiplication unit 77 whose input 80 is coupled to the switch unit 58. The inputs of the sine and cosine converters 76,70 (Figure 7) are connected together and are coupled to the output of the integrator 68. The output of the channel network 75 serves as the output 27 of the functional signal converter 25 and is coupled to the control unit 29 that controls the movement of the energy source 4 (Figure 1) relative to the axis Y. In addition, the outputs of the integrators 72,78 are coupled to control inputs 81,82 of the switch unit 58.

In the case where the energy source 4 (Figure 8) moves over the heating surface 1 of the object according to a periodic law, the apparatus comprises a signal forming unit 83 arranged to form the average signal Q (Figure 4). The input of the signal forming unit 83 is coupled to the memory unit 18 (Figure 8) arranged to store the error signal Qi (Figure 4). The output of the signal forming unit 83 (Figure 8) is coupled to the power control unit 21 and to an input 84 of a signal forming unit 85 arranged to form the signal AQ (Figure 4) representative of the difference between a given error signal Qi and the average signal Q. The signal forming unit 85 (Figure 8) has an input 86 coupled to the memory unit 18 and has its output coupled to the signal forming unit 19.

Figure 9 shows a circuit diagram of an apparatus constituting a preferred embodiment of the invention.

The temperature sensor 9 is an optoelectronic pyrometer, using either luminance or colour. Optically coupled to the temperature sensor 9 is an optomechanical attachment 87 of the scanning unit 17, which is a Weyler rotating drum. Mounted on the periphery of the mirrors of the drum are magnetic projections 88 that pass through the slit of the magnetic circuit of a closk pulse transmitter 89. An electromagnetic winding 90 of the closk pulse transmitter 89 has its one end connected to one of the plates of a capacitor 91 having its other plate coupled first lead of a resistor 92 and to a diode 93. The other end of the winding 90 and a second lead of the transistor 92 are coupled to a grounding bus.The cathode of the diode 93 is coupled to the R input of a flip-flop 94 having its output coupled to one of the inputs of an AND gate 95 that has its other input coupled to the output of a clock pulse generator 96. The output of the AND gate 95 is coupled to the input of a pulse counter 97 having its outputs coupled to the inputs of a decoder 98 and of an OR gate 99 that has its output coupled to the S input of the flip-flop 94. Outputs 100,...,100j,..., 100n of the decoder 98 are coupled to the control input 16 of the switching unit 15.

The temperature setter 13 comprises a potentiometer 101 that has one end coupled to a voltage source and its other end coupled to the grounding bus. A slider 102 ofthe potentiometer 101 is coupled to the input 12 of the comparison unit 11, said input 12 being provided by the non-inverting input of an operational amplifier 103. The feedback related to the inverting input of the operational amplifier 103, which inverting input is the input 10 of the comparison unit 11, includes a resistor 104. The inverting input of the operational amplifier 103 is coupled to the output of the temperature sensor 9, while the output of the operational amplifier 103 is coupled to the data input 14 of the switching unit 15.That data input 14 is coupled to contacts 105r,...,105j,...,105n of double-throw switches that have their control elements 106a,...106j,...,106n coupled to respective outputs 100a,...,100j,...,100nofthedecoder98. Contacts 1071,..., 1071,..., 107, constitute a multichannel data output of the switching unit 15 and are coupled respectively to corresponding inputs of accumulation capacitors 1081,.., 1081,... 108, used as the store locations of the memory unit 18.The outputs of the accumulation capacitors 108r,...,108j,...,108narecoupledtoimmovablecontacts 109,...,109j,...,109n of the switches that have their movable contacts 110"...,110j,...,110n operated as a multichannel data output of the memory unit 18 and coupled to the input of the signal forming unit 83. The latter is an operational amplifier 111 having a transfer ratio of 1/h where n is the number of the elementary areas 2l (Figure 1). The operational amplifier 111 (Figure 9) has its non-inverting input coupled to the grounding bus and has its inverting input coupled, via resistors 1121 112 1 12n and the contacts 1091 lO9i 109n and 1101 and 110l,..., 110n, to corresponding store locations of the memory unit 18, namely, to the capacitors 1081,....

108l,...,108n. The inverting input of the operational amplifier 111 is coupled to its output via a resistor 113 and a capacitor 114 connected in parallel.

The output of the signal forming unit 83 is coupled, via a resistor 115, to the input of the power control unit 21 that is operated to control, for example, the power of an electron beam impinging on the heating surface 1 of the object. The power control unit 21 includes an operational amplifier 116 provided with a feedback related to the non-inverting input thereof via a resistor 117. The inverting input of the operational amplifier 116 is coupled to a slider 118 of a potentiometer 119 that has one end coupled to the grounding bus and its other end coupled to the minus side of the voltage source. The output of the operational amplifier 116 is coupled, via a power amplifier 120, to a filament circuit 121 of a cathode 122 of an electron gun.

The store locations of the memory unit 18, which are the accumulation capacitors 1081,..., 1081,..., are coupled to the inverting input of an operational amplifier 125 via the contacts 1091,..., 109i,..., 109, and 110@,..., 110l,..., 110n of the switches and via resistors l23 123 1 23 of a delay unit 125. A feedback path to the inverting input of the operational amplifier 125 is provided by means of a resistor 126, while the non-inverting input of the operational amplifier 125, which is the input 84 of the signal forming unit 85, is coupled to the resistor 115.

The signal forming unit 19 is a ratio-type converter comprised of resistors 127, 128 and an operational amplifier 129 that has its inverting input coupled to the resistors 127, 128 and has its non-inverting input coupled to the grounding bus. The other end of the resistor 127 is coupled to the output of the signal forming unit 85 whereas the other end of the resistor 128 is coupled to the output of the operational amplifier 129, which latter output is used as the output of the signal forming unit 19 and is coupled to the input of the memory unit 23.

The memory unit 23 is built around accumulation capacitors 130"...,130w,...,130mwhich have their first ends coupled, via the contacts of switches 131@,..., 131@,...,131n to the output of the operational amplifier 129.

The second ends of the capacitors 1301,..., 130@,..., 130m are coupled, via the contacts of switches l321321,....

132j,...,132m and via resistors 1331,..., 1331,..., 133,, to the inverting input of an operational amplifier 134, a feedback path to that inverting input being provided by virtue of a resistor 135. Coupled to the non-inverting input of the operational amplifier 134 via resistors 1361,..., 136i,..., 136, and via the contacts of switches 1371,..., 1371,..., 137, are the sliders of potentiometers 138"...,138;,...,138m the latter having their ends connected respectively to the grounding bus and the supply source.The control elements of the switches 137a,...,137i,...,137m are coupled to outputs 1391,..., decoder140.Theinputsofthedecoder 140 are coupled to the outputs of analog-to-digital converters 141, 142 which are connected respectively to the control units 28, 29 operated to control the movement of the energy source. The analog-digital converters 141, 142 employ the circuits described in the book entitled "Multichannel Analog-to-Digital Converters" by E.M. Shushkov and M.B. Tsodikov, the "Energya" publishers, 1975.

The inputs of the digital-to-analog converters 141,142 provide respectively the control inputs 82,81 of the switch unit 58 (Figure 7). The output of the operational amplifier 134 (Figure 9) is the output of the switch unit 58 (Figure 7) and is coupled, via a resistor 143, to the input 59 of the integrator 60 built around an operational amplifier 144, a feedback path being provided to the inverting input thereof by means of a capacitor 145 and a switch 146. The inverting input of the operational amplifier 144 is the input 59 of the integrator 60, while the non-inverting input of the cperational amplifier 144 is coupled to the grounding bus. The output 63 of the integrator 60 is coupled to the threshold network 62.

The threshold network 62 is built around an operational amplifier 47 having its inverting input coupled to the output 63 of the integrator 60 and having its non-inverting input coupled to a potentiometer 148. The latter has its ends coupled to a potentiometer 148. The latter has its ends coupled to the grounding bus and supply source. Afeed back path to the non-inverting input of the operational amplifier 147 is provided by virtue of a resistor 149. The output of the operational amplifier 147, which is the output of the network 62, is coupled to the control element of the switch 146, which is the input 61 of the integrator 60.

The output 63 of the integrator 60 is coupled to the input of the conversion unit 64 which may utilize a circuit described in the article entitled "Automatic Adjustment of a Multipurpose Converter Providing Piecewise Linear Approximation" in the Journal of Automatics and Telemechanics, No. 10 vol. XXIII, 1962, pp. 1343-1351. The output of the conversion unit 64 is coupled to the input 65 of the multiplication unit 66 having its input 67 coupled to the output of the switch unit 58 (Figure 7). An integrated circuit multiplier can be used as the multiplication unit 66 (Figure 9).

The output of the multiplication unit 66 is coupled via a resistor 150 to the input of an integrator 67 built around an operational amplifier 151 that has its non-inverting input coupled to the grounding bus and has its inverting input coupled via a capacitor 152 to its own output. The inverting input of the operational amplifier 151 is the input of the integrator 68.

The output of the integrator 68 is coupled to the channel networks 69, 75 which comprise respectively the integrators 72,78 and the multiplication units 71,77.

The channel network 69 also comprises the cosine converter 70, while the channel network 75 also includes the sine converter 76. The inputs of the converters 70,76 are joined together and are coupled to the operational amplifier 151, whereas the outputs of the converters are coupled to the inputs 73,79 of the multiplication units 71, 77 respectively. The outputs of the multiplication units 71,77 are coupled, via resistors 153, 154, via the integrators 72,78, and via power amplifiers 155, 156 intended for the deflection signals, respectively, to the units 28, 29 that control the movement of the energy source 4.

The cosine and sine converters 70, 76 may utilize either cosine and sine potentiometers or diode arrays (cf.

B. Ya. Kogan "Electronic Simulating Devices and Their Usage for Investigation of Automatic Control Systems", the "Fizmat" Publishers, Moscow, 1963).

The multiplication units 71,77 are similar to the multiplication unit 66.

The integrators 72, 78 are built around operational amplifiers 157,158 which are connected to capacitors 159, 160 provided for feedback to their corresponding inverting inputs. The operational amplifiers 157, 158 have their non-inverting inputs coupled to the grounding bus and have their inverting inputs coupled to the resistors 153, 154, respectively.

Figure 10 illustrates a circuit diagram of the functional signal converter 25 whose block diagram is shown in Figure 6. The functional signal converter 25 comprises the signal generator 30 (Figure 10) arranged to generate the signals representative of the components Vix, Viy (Figure 2) of the velocity Vi, said signal generator comprising resistance-type voltage dividers 1611,..., 161@,..., 161m (Figure 10) and 1621,..., 1621,..., 162m that are connected in parallel with the voltage sources.

The signal dividing unit 35 comprises resistance-type voltage dividers 1631,..., 163@,..., 163m and 164,..., 164i 164m which constitute corresponding pairs connected in parallel and have common points l6S165@,..., 165j,...,165m which are connected to the outputs 24 of the memory unit 23, and have a point 166 connected to the grounding bus.

The multichannel switches 32,37 are built around field-effect transistors 167@,..., 167@,..., 167m and l68@,..., and 168@,..., 168m, respectively, the substrate of the transistors being joined together and coupled to the voltage source. The sources of the transistors 1671,..., l67@,..., l67@,..., 167m and 168@,..., 168@,..., 168m are coupled to resistors 169, 170, respectively. The drains of the transistors l671, ..., 167i, ..., 167m and 1681, ..., 168i, ..., 168m 168,, which are the data inputs of the switches 32,37, are coupled respectively to the sliders of the dividers 161 1,..., 161i,.., 161m of the signal generator 30 and to the sliders of the dividers 1631, 163i,..., 163m, of the signal dividing unit 35.The multichannel switches 34,39 utilize similar circuits, the data inputs of the switch 34 being coupled to the sliders of the dividers 1621,..., 162i,..., 162m of the signal generator 30, and the data inputs of the switch 39 being coupled to the sliders of the dividers 1641,..., 164i,..., 164m of the signal dividing unit 35.

The resistors 169, 170 have a common point 171 coupled to the inverting input of an operational amplifier 172 provided with a feedback path into which a capacitor 173 is inserted. The output of the operational amplifier 72 is coupled to the input of the control unit 28 and to the non-inverting inputs of operational amplifiers 1741,..., 174i,..., 174, of which the threshold network 48 is comprised. The inverting inputs of the operational amplifiers 1741,..., 1741,..., 174, are coupled to the sliders of resistance-type voltage divider 175a,...,175j,...,175m which are coupled in parallel to the voltage source.

The signal synchronization unit 52 comprises a shift register built around Dflip-flops 1761,..., 176i,..., 176m and pulse forming networks arranged to form pulses using the leading edge of the output signals provided bythethreshold network 48, these pulse forming networks having inverters 1771,..., 177i,..., resistors 178,...,178i,...,178m, capacitors 1791,..., 179i,..., 179m and AND gates 1801 l8Oi 18Om having their outputs coupled to an AND gate 181.

In addition, the signal synchronization unit 52 includes a network to set the initial state of the shift register, which network utilizes an inverter 182, a resistor 183, a capacitor 184, an AND gate 185 and a switch 186. The complement outputs of D-flip-flops 1761,..., 176i,..., 176m are coupled to the gates of corresponding transistors 1 67i 167- 1 67m and 1681 and 1 68m, of the multichannel switches 32,37 and to the transistors of the switches 34, 39. One terminal of each of the resistors 1781,..., 1781,..., 178, is coupled to the output of a respective one of the inverters 1771,..., 177i,..., 177m, while the other terminal of each of the resistors 1781,..., 178i,..., 178m is coupled to one input of a respective one of the AND gates 180q,...,180i,....

1 80m and to one end of a respective one of the capacitors 1791,..., 179i,..., 179m whose other ends are coupled to the grounding bus. The other input of each of the AND gates 1801,..., 1801,..., 180, is connected to the input of a respective one of the inverters 1771,..., 177i,..., 177m and to the output of a respective one of the operational amplifiers 1741 174i,..., 174m of the threshold network 48. The output of the AND gate 181 is coupled to the C (clock) inputs of the D-flip-flops 1761,..., 176i,..., 176,. The R (reset) inputs of the D-flip-flops 1762,...,176j,...,176m are connected together and coupled to the output of the AND gate 185 and to the S (set) inputs of the D-flip-flop 1761.The true output of each of the D-flip-flops 1761,..., 176i,..., 176m is coupled to the control or data input of the respective following D-flip-flops 1762,..., 176m-1, while the true output of the D-flip-flop 176m is coupled to the control input of the D-flip-flop 1761.

The resistor 183 has one end coupled to the output of the inverter 182 and its other end coupled to one input of the AND gate 185 and to one end of the capacitor 184 whose other end is coupled to the grounding bus. The other input of the AND gate 185 is connected to the input of the inverter 182 and to the immovable contact of the switch 186 whose first movable contact is coupled to the voltage source and whose second movable contact is coupled to the grounding bus.

A method constituting a preferred embodiment of the invention is as follows. The energy source 4 (Figure 1) is moved along the predetermined path 3 on the heating surface 1 (Figure 1) of the object with the velocity V1,..., Vi,..., Vn corresponding to the elementary areas 21,...,2i,..., 2n into which the heating surface 1 is divided. For each elementary area 2j, the error signal Qi (Figure 4) is formed and remembered which is representative of a difference between the predetermined and the measured temperature of that area 2i. The temperature of the areas 21,..., 2i,..., 2n (Figure 1)can be measured either concurrently or in a sequential manner when the data is picked up along the scanning path 5. Using the error signals Q (Figure 4) one can provide the signal representative of the power of the energy source 4 (Figure 1) and the signals U2 (Figure 4) representative of the correction value #Vi (Figure 2) for the velocity Vi of the energy source 4 at the areas 2 (Figure 1). The signals so obtained are converted functionally into the signals Uy, Ux (Figure 4) representative respectively of the components 8, 7 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1), related to the respective rectangular axes Y, X and providing for the movement of the energy source 4 relative to these axes.The signals Uy, Ux tend to vary with time in a manner such that the energy source 4 is caused to move along the predetermined path 3 and the velocity Vi of the energy source 4 at a given area 2 tends to vary according to the signal U2 (Figure 4) representative of the correction value AVi (Figure 2) with the result that the difference between the predetermined and the measured temperature at that area 2 is decreased.

In the case where the energy source 4 is moved along the path 3 in a discrete manner and is caused to stay for a certain time interval at one or more points of a given area 2j, or is moved over a given areas 2 with a variable velocity, the velocity Vi at the given area 2i is an average velocity which is AS Vi = At (1) where AS is the length of an arc portion of the path 3, and At is the total time during which the energy source is within the area 2j.

There are two methods according to which the signals U2 (Figure 4) representative of the correction values AVi (Figure 2) for the velocity Vi of the energy source 4 at the area 2i are converted to the signals Uy, Ux (Figure 4) representative respectively of the components 7,8 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axes Y,X respectively.

According to the first method, the path 3 is approximated using the straight line segments 6. The projection of the segments 6 of the approximating broken line on the rectangular axes X,Y are then determined. For a segment 6i the components Vix, Viy of the velocity Vi of the energy source 4 (Figure 1), related to the rectangular axes X,Y are determined in proportion to the value of the projection of the segment 6 Vix2 +V21, = V? (2) where Vi is the velocity of the energy source 4(Figure 1) at the segment 6i.

During the control of the energy source 4, its velocity Vi is varied in accordance with the difference of the predetermined and the measured temperature, provided by the signals U2 (Figure 4) representative of the correction value AVi (Figure 4) for the velocity Vi. To this end, the signal U2 is divided into two signals, which are representative respectively of the correction values Avid, #Viv (Figure 2) of corresponding components Vx, Viy, so that the sum of the squares of the correction values Avid, AViv is equal to the square of the correction value AVi, according to the equation as follows AV ix2 + AV j2 = AV?, In addition, the relationship of the correction values Avid, AViy must be equal to the relationship of the components Vix, Viy, thereby providing for a condition in which the proper form of the path 3 is maintained during the control of the velocity Vi. The resultant signals representative of the components Vix, Vy of the velocity Vi are determined by summing the signals representative of the components and the signals representative of the correction values Avid, and AViv. After that, the resultant signals are integrated with the result that the control signals are provided which are used to control the movement of the energy source 4 (Figure 1) relative to the rectangular axes X,Y.

The above-mentioned method provides for an appreciably good accuracy with which the path 3 can be represented in the cases where it has a small curvature or is approximated using the piecewise linear function. If the path 3 has a large curvature, a more accurate approximation can be attained as follows. The path 3 (Figure 3) is divided into segments using points Bo, Boa,..., B"..., Bm and the segments are approximated by virtue of circle arcs having radii Ro, R1,..., Raj,..., Ri,..., Rm-1, respectively. The curvature Xi, where i=O =O,...., m - 1, of a given segment of the path 3 is the value that is the reciptocal of the radius Ri of the arc of the approximating circle.As a result, a piecewise continuous function X(s), O ss < S of the curvature of the path 3 is obtained, where s is the length of the arc of the path 3, measured from the initial point Bo, and S is the length of the whole path 3 from the initial point Bo to the final point Bm, namely, the distance passed by the energy source 4 along the path 3. The control signals U4 (Figure 4) are obtained by summing the signals U3 representative of the velocity V1 (Figure 2) and the signals U2 (Figure 4) representative of the correction value #Vi (Figure 2) forthe area 2 (Figure 1).

The control signals U4 (Figure 4) are switched over in a given time sequence and the signals US SO obtained are representative of the desired velocity Vi (Figure 1) of the energy source 4 at the elementary areas 2i. After that, the signal U3 is integrated and the signal U4 = kS (Figure 4) is obtained which is representative of the distance S passed by the energy source 4 (Figure 1) along the path 3, where k is a constant factor. The signal U8 (Figure 4) corresponds to the law of movement of the energy source 4 (Figure 1) along the path 3.

When it is necessary for the energy source 4 to pass along the path 3 several times, two cases are possible after it reaches the final point Bm (Figure 3): the energy source 4 (Figure 1) continues to move in reverse direction from the point Bm to the point Bo or it is returned to the initial point Bo and begins to move from the point Bo to the point Bm. In the first case, the control signals U5 (Figure 4) are switched over in a sequence which is a reverse one with respect to the original sequence and the signal U3 is inverted before integration.

In the second case, the signal U3 is inverted before integration, In the second case, the signal U5 is set to zero and the control signals U4 are then switched over in accordance with the original sequence.

The signals U5 is then converted in accordance with the relationships determined by the formulaes of differential geometry. The signal U6 (Figure 4) representative of the form of the path 3 (Figure 1) is given by

The signal U7 (Figure 4) is provided by integrating the signal U6 which is multiplied previously by the signal U3. Then, the sine and cosine values of the signal U7, after multiplication by the signal U3, are integrated simultaneously, thereby providing the signals Uy, Ux representative of the components 7,8 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axes Y, X.

TAKE IN HERE If the energy source 4 (Figure 1) performs periodical or approximately periodical movement along the path 3, its power is then varied in proportion to the average signal Q (Figure 4) corresponding to an average value of the error signal Q. In this case, the signal U2 representative of the correction value AVj of the velocity Vi of the energy source 4 (Figure 1) at the elementary area 2j is formed using the signals AQ representative of the difference AQj of the average signal Q the error signals Qj.

The apparatus constituting a preferred embodiment of the invention (Figure 5) operates in the following manner.

At the beginning of the operation, the signals obtainable from the output of the memory unit 23 arranged to store the signals U2 (Figure 4) representative of the correction value AVi (Figure 2) of the velocity Vj are equal to zero. The functional signal converter 25 (Figure 5) produces the signals Uy, Ux (Figure 4) representative of the components 7, 8 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axes Y, X. The signal representative of the power of the energy source 4 (Figure 5) is delivered, at the beginning of the operation, from the output of the signal forming unit 19 to the input of the power control unit 21. The signals Ux, Uy (Figure 4) are supplied to the inputs of the units 28,29 (Figure 5) arranged to control the movement of the energy source 4.As a result, the energy source 4 having a preset power moves along the predetermined path 3 on the heating surface 1 of the object in accordance with the given law of movement. The temperature sensor 9 measures the temperature of the heating surface 1 of the object at the elementary areas 2j in a manner such that the temperature is measured simultaneously at all areas 2j or is measured sequentially along the scanning path 5. The output signal from the temperature sensor 9 is applied to the input 10 of the comparison unit 11 and the input 12 thereof receives the signal from the output of the temperature setter 13. The output signal of the comparison unit 11 and the input 12 thereof receives the signal from the output of the temperature setter 13.The output signal of the comparison unit 13 (Figure 5), which is the error signal Q (Figure 4) representative of the difference between the predetermined and the measured temperature, is applied to the input 14 of the switching unit 15. The input 16 of the latter receives the signal from the output of the scanning unit 17 that provides for the scanning movement of the temperature sensor 9 and for the control of the switching unit 15. Each store location of the memory unit 18 corresponds to a certain elementary area 2j of the heating surface 1 of the object.The switching unit 15 operates in a manner such that the memory unit 18 stores the signals representative of the difference between the predetermined and the measured temperature in the store locations corresponding to the areas 21. The signals from the memory unit 18 are applied to the signal forming unit 19. The output 20 of the latter provides a signal representative of the correction value of the power of the energy source 4, which is applied to the input of the power control unit 21. The signal forming unit 19 also produces the signals U2 (Figure 4) representative of the correction values AVi (Figure 2) of the velocity of the energy source 4 (Figure 5). The signals U2 are delivered from the output 22 to the memory unit 23 and then to the functional signal converter 25 (Figure 5) whose output produces the signals Ux, Uy (Figure 4) representative of the components 8,7 (Figure 20 determined by the law of the movement of the energy source 4 (Figure 1), related to the rectangular axes X,Y and providing for the correction of the law of movement of the energy source 4 along the path 3.

In the case where the path 3 (Figure 2) is approximated using the straight line segments 6, the functional signal converter 25 (Figure 6) operates as follows. The signal U2 (Figure 4) representative of the correction value AVi (Figure 2) of the velocity Vi is delivered from the output 24 (Figure 6) of the memory unit 23 to the input of the comparison unit 35 in which it is divided into two signals. One signal is representative of the correction AVix (Figure 2) of the component Vix of the velocity Vi related to the rectangular axis X and is passed from the output 36 (Figure 6) of the signal dividing unit 35 to the data inputs of the multichannel switch 37.The other signal is representative of the correction value AViv (Figure 2) of the component Viy of the velocity Vi related to the rectangular axis Y and is passed from the output 38 (Figure 6) of the signal dividing unit 35 to the data inputs of the multichannel switch 34. At the same time, the signals representative of the components Vix, Vy (Figure 2) of the velocity Vi are applied from the outputs 31,33 (Figure 6) of the temperature setter 30 to the data inputs of corresponding mu Itichannel switches 32, 34.To synchronize the operation of the multichannel switches 32,34,37,39 in accordance with a sequential movement of the energy source 4 (Figure 4) along the segments 6 (Figure 2) of the path 3, their control inputs receive simultaneously a signal from the output of the synchronization unit 52 (Figure 6). The signals being switched, obtainable from the outputs of the switches 32,37 and the switches 34,39 respectively, are delivered in pairs to the inputs 40,41,43,44 of the adders 42, 45 and the summation signals are applied to the inputs of the integrators 46,47. The outputs of the integrators 46, 47 provide the signals that tend to increase linearly at a rate proportional to the signals at their inputs.The output signals of the integrators 46, 47 are applied to the inputs of the control units 28,29 and to the inputs of the threshold networks 48,49 which operate to quantize the signals according to the segments 6 of the path 3 (Figure 2). The output signals of the threshold networks 48, 49 (Figure 6) are applied to the input of the synchronization unit 52 which controls the operation of the multichannel switches 32,34,37,39.

In the case where the path 3 (Figure 3) of the energy source 4 (Figure 1) is approximated by the arcs of a circle, the functional signal converter 25 (Figure 7) operates as follows. The signal U2 (Figure 4) representative of the correction value AVi (Figure 2) of the velocity Vi at the elementary area 2 (Figure 1) is applied to the input group 56 (Figure 7) of the adder unit 55 and the input group 54 of the latter receives the output signal U3 (Figure 4) of the velocity setter 53 (Figure 7), representative of the velocity Vi (Figure 2).The control signals from the output of the adder unit 55 (Figure 7) are applied to the data inputs 57 of the switch unit 58 and the control inputs 81,82 of the latter receive the signals Ux, Uy (Figure 4) representative of the components 8,7 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axes X,Y, the signals Ux, Uy being delivered from the outputs of the integrators 72,78 (Figure 7). These signals are employed to control the operation of the switch unit 58 in a manner such that its output provides successive signals U4 (Figure 4) representative of the desired velocity (Vj + AVi) (Figure 2) of the energy source 4 (Figure 1) at the segments of the path 3.

The output signal U4 (Figure 4) of the switch unit 58 (Figure 7) is integrated in the integrator 60 which therefore provides the signal U6 (Figure 4) representative of the distance S passed by the energy source 4 (Figure 1) along the path 3. At the end of the distance S, in the case where the energy source 4 performs non-returnable multicycle movement, the signal at the output of the integrator 60 (Figure 7) is zero, which is attained by means of the threshold network 62. This provides for a condition in which the energy source 4 (Figure 1) is transferred to the initial point Ao of the path 3.

In the distance conversion unit 64 (Figure 7), the signal U5 (Figure 4) representative of the distance S passed by the energy source 4 (Figure 1) along the path 3 from the initial point Ao is converted to the signal U6 (Figure 4) representative of the curvature Xi of the path 3 (Figure 1) at that point thereof which is occupied by the energy source 4 at the given point in time. The signal U6 (Figure 4) is multiplied by the signal U2 with the result that a transfer from the distance variable S to the time variable t is effected. The produce x.S.ds/dt is integrated in the integrator 68 (Figure 7) and the signal U7 (Figure 4) is therefore produced which is representative of the angle (p of rotation of the vector of the velocity of the energy source 4 moved along the path 3 (Figure 1).The angle (p is measured with respect to the initial position of the vector VO (Figure 3) of the velocity, which is in coincidence with the axis X.

The signal U7 (Figure 4) is converted in the channel networks 69, 75 (Figure 7) into the signals Ux, Uy (Figure 4) representative of the components 8,7 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axes X,Y. The conversion is effected by means of the cosine converter 70 (Figure 7) for the axis X (Figure 1) and the sine converter 76 (Figure 7) for the axis Y (Figure 1), as well as the multiplication units 71,77 (Figure 7) and the integrators 72,78.

In the case where the energy source 4 (Figure 1) performs a periodical or approximately periodical movement during the heating of the object, the velocity Vj of the source at the elementary area 2j is controlled so that its period of movement is held constant. To this end, the error signals Q1 (Figure 4) are delivered from the memory unit 18 (Figure 8) to the input of the signal forming unit 83 in which the average signal Q is formed. According to this signal, the power of the energy source 4 (Figure 1) is controlled by means of the power control unit 21 (Figure 8). When the signal at the output of the power control unit 21 is equal to zero, the power of the energy source 4 is maintained at the nominal level. A positive signal at the output of the signal forming unit 83 provides for an increase in the total power of the energy source 4 relative to the nominal level, while a negative signal at the output of the signal forming unit 83 tends to decrease the total power of the energy source 4 relative to the nominal level. As a result, the total amount of the energy received by the object depends on the average temperature of the latter. The received energy is distributed on the elementary areas 2 in accordance with a distribution of the associated velocities relative to the average velocity of the energy source 4.For this, the signals AQ (Figure 4) representative of the difference AQi between the average signal Q and the error signals Qi and produced in the signal forming unit 85 (Figure 8) are applied to the input of the signal forming unit 19 which provides the signals U2 (Figure 4) representative of the correction value AVi (Figure 2) of the velocity V1.

The apparatus whose circuit diagram is shown in Figure 9 operates as follows. The heating surface 1 of an object, for example, an ingot, is heated using the energy source 4 (Figure 1) is controlled by means of a power control unit 21 (Figure 8). When the signal at the output of the power control unit 21 is equal to zero, the power of the energy source 4 is maintained at the nominal level. A positive signal at the output of the signal forming unit 83 provides for an increase in the total power of the energy source 4 relative to the nominal level, while a negative signal at the output of the signal forming unit 83 tends to decrease the total power of the energy source 4 relative to the nominal level. As a result, the total amount of the energy received by the object depends on the average temperature of the latter.The received energy is distributed on the elementary areas 2j in accordance with a distribution of the associated velocities relative to the average velocity of the energy source 4. For this, the signals SQ (Figure 4) representative of the difference AQi between the average signal Q and the error signals Qf and produced in the signal forming unit 85 (Figure 8) are applied to the input of the signal forming unit 19 which provides the signals U2 (Figure 4) representative of the correction value AVi (Figure 2) of the velocity Vi.

The apparatus whose circuit diagram is shown in Figure 9 operates as follows. The heating surface 1 of an object, for example, an ingot, is heated using the movable energy source 4, for example, an electron beam that is generated by the cathode 122 of an electron gun of a thermal electron-beam installation. The control units 28, 29, which are electromagnetic deflection coils in the embodiment, are arranged to control the movement of the energy source 4 along the heating surface 1 of the object.

The unit 28 provides for the movement of the energy source 4 along the axis X, while the unit 29 provides for the movement of the energy source along the axis Y, the axes X, Y being rectilinear ones. This is attained with the help of the signals Ux, Uy (Figure 4) applied to the inputs of the units 28, 29 and produced in the channel networks 69,75 in accordance with the signals representative of the path of movement and the velocity related to that path. The form of the path is selected by the operator who operates a setter adapted to set the path 3 (curvature X), which setter is the conversion unit 64 arranged to convert the signal U5 (Figure 4) representative of the distance S passed by the energy source 4 (Figure 9) to the signal U6 (Figure 4) representative of the curvature X of the path 3 (Figure 9).

The absolute values of the velocity Vi of the energy source at different segments of the path 3 are selected by the operator who operates the sliders of the potentiometers 1381,...,138j,...,138m of the velocity setter 53 (Figure 7) and are corrected automatically according to the signals provided by the temperature sensor 9 (Figure 9), the latter signals being used to correct the power of the energy source 4 too.

The temperature at all required points of the heating surface 1 of the object is measured in succession by means of the temperature sensor 9 including the scanning optomechanical attachment 87 which is a mirror-type Weyler drum. The measurement result is compared in the operational amplifier 103 to the signal representative of the predetermined temperature and produced by the potentiometer 101. The signal AU (Figure 4) so obtained is divided into n elementary error signals Q1 (i = 1,2,..., n) in the switching unit 15 (Figure 9). The elementary error signals Q1 (Figure 4) are remembered in the locations utilizing the accumulation capacitors 1081t...,108"...,108n (Figure 9) and a train of clock pulses from the scanning unit 17 is delivered in this case.

The data from the store locations of the memory unit 18 is delivered sequentially to the inputs of the signal forming units 83,85. The data is fetched by making sequentially the contacts 1091,..., 109i,..., 109, and 1 and 1101,..., 110j,...,110n of the switches of the store locations. The stored data is used to form the signals U2 (Figure 4) representative of the correction values AVi (Figure 2) of the velocity Vi and the signals representative of the correction value of the power of the energy source 4 (Figure 9).

In the case where the energy source 4 performs a periodical movement on the heating surface 1 of the object, the signal representative of the correction value of its power is produced by the operational amplifier 111 11 (Figure 9) having a transfer ratio or gain of 1/n.

The error signals Qi (Figure 4) from the memory unit 18 are applied one at a time to the input of the operational amplifier 111 with the result that its output, after arrival of the latter, nth, error signal Qi from the nth store location, provides the average

In the operational amplifier 16 (Figure 9) the average signal Q is added to the signal representative of the power of the energy source 4 and delivered from the output of the potentiometer 119 and the power amplifier 120 operates to control the current through the filament circuit 121 of the cathode 122 of the electron gun.

The clock pulses to control the switches are produced in the scanning unit 17. To this end, the mirror-type drum of the scanning attachment 87 is provided with magnetic projections 88 arranged to form in the electromagnetic winding 90 of the clock pulse transmitter 89 the clock pulses corresponding to the beginninc of scanning a new line. These signals are differentiated in an R-C circuit comprised of the resistor 92 and the capacitor 91 and are used to control the operation of the flip-flop 94. When a pulse appears at the input of the flip-flop 94, the pulses from the clock pulse generator 96 pass through the AND gate 95 to the counter 97 which is operated in conjunction with the AND gate 99 to control the operation of the decoder 98.As a result, the scanning of each line requires that a pulse train of nip pulses,wherep is the number of the mirror of the drum, be provided by the decoder 98 which produces a pulse train of n pulses during the overall scanning period for the whole heating surface 1 of the object, equal to the period of rotation of the drum.

The signals U2 (Figure 4) representative of the correction value AVi (Figure 2) of the velocity Vi and delivered from the memory unit 18 to the signal forming unit 85 are delayed in the delay unit 124 by the time interval equal to the time during which n error signals Qi (Figure 4) are integrated in the unit 85 (Figure 9).

This delay causes production at the output of the operational amplifier 125 of a sequence of signals AQ (Figure 4). The signals AQ are then converted proportionally to the signals U2 by means of the operational amplifier 129 (Figure 9) and resistors 127, 129. In the given embodiment, the signals AQ (Figure 4) are converted to the signals U4 in accordance with a simplest law which is a proportional one. In a general case, the conversion can be effected according to a more complex law. The signals U4 are then remembered in a given succession in the memory unit 23 (Figure 9) by means of the accumulation capacitors 1301,..., 130c..., 130n and the switches 1311,...,131 131i,..., 131..

To form the signals U3 (Figure 4) representative of the velocity Vi (Figure 2) of the energy source 4 for each of them segments 6 into which the path 3 is divided, use is made of the velocity setter 53 (Figure 9), the adder unit 55 and the switch unit SB. In this case, the memory unit 23 (Figure 9) provides the signals U2 (Figure 4) in a time sequence determined by those points in time at which the energy source 4 is transferred from one segment 6 (Figure 2) of the path to another. The signals U2 (Figure 4) are added to the signals U3 produced in the velocity setter 53 (Figure 9) with the help of the potentiometers 138 of the adder unit 55 (Figure 7) that includes the operational amplifier 134 (Figure 9) and resistors 1331,...,133m and 1361,...,136m.

These signals are added according to a sequence in which the outputs 1391,...,139i,..., 139m of the decoder 140 provide clock pulses.

The clock pulses are formed in accordance with the signals Ux, Uy (Figure 4) representative of the components 8,7 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axes X,Y. The signals Ux, Uy (Figure 4) are converted by means of the analog-to-digital converters 141, 142 (Figure 9) and the decoder 140 into a train of code pulses which appear at corresponding outputs 1391,..., ., 139"..., 139m of the decoder 140 each time the energy source 4 is transferred from one segment 6 (Figure 2) of the path 3 to another. The clock pulses are applied concurrently to the control elements of the switches 132, 137 (Figure 9). As a result, the output of the operational amplifier 134 provides sequentially the signals U4 (Figure 4).The potentiometers 1381,..., 138i,..., 138, (Figure 9) and the capacitors 13Oi 13Oi 13Om are connected to the input of the operational amplifier 134 in a given succession with the result that the signals U4 (Figure 4) representative of the desired velocity Vi + AVj (Figure 2) along the path 3 are produced.

The signals U4 (Figure 4) are applied in a given succession to the input of the operational amplifier 144 (Figure 9) which is operated in conjunction with the capacitor 145 in the integrator mode. When the output signal provided by the operational amplifier 144 reaches a maximal preset level, the switch 146 makes and the integrator 60 assumes the 0 state. This change is attained by applying a pulse from the output of the threshold network 62 to the control element of the switch 146. The maximum preset level mentioned above is selected by the slider of the potentiometer 148 coupled to the non-inverting input of the operational amplifier 147.

The output signal U5 (Figure 4) of the integrator 60 (Figure 9) is representative of the distance S (Figure 4) passed by the energy source 4 (Figure 1) along the path 3 by the given point in time t. The distance conversion unit 64 (Figure 9) operates to convert the signal U5 (Figure 4) to the signal U6 representative of the curvature X of the segments of the path 3 (Figure 1) of the energy source 4. The signal U6 (Figure 4) provided by the output of the distance conversion unit 64 (Figure 9) is multiplied by the signal U4 representative of the velocity Vi = AVi (Figure 2) and the signal so obtained is applied to the input of the integrator 68 (Figure 9) which converts it to the signal U7 (Figure 4) representative of the angle (p of rotation of the vector of the velocity Vi (Figure 1) of the energy source 4.

The channel networks 69, 75 (Figure 9) are then operated to convert the signal U7 (Figure 4) to the signals Ux, Uy (Figure 4) representative of the components 8,7 (Figure 2) determined by the law of movement of the energy source 4 (Figure 1) along the path 3. To this end, the outputs of the cosine and sine converters 70,76 (Figure 9) of the channel networks 69,75 respectively provide the signals Ug, U8 (Figure 4) representative of the cosine and sine values of the signals applied to their corresponding inputs. After that, the signals Ug, U8 (Figure 4) are multiplied by the signal U3 representative of the velocity Vi (Figure 2) of the energy source 4 (Figure 1) and the products so obtained are integrated. The integrators 72,78 (Figure 9) are supplied with the values of the coordinates XO, YO (Figure 2) of the position of the energy source 4 at the initial point in time.

The circuit diagram of the apparatus for an energy source moved at a low velocity may alternatively be implemented using a microprocessor provided with high-speed analog-to-digital and digital-to-analog converters.

The functional signal converter 25 of Figure 10 operates in the following manner. The resistance-type voltage dividers 1611,..., 161i, 161 m are operated to set the voltages corresponding to the components Vix (Figure 2) of the velocity Vi of the energy source 4 (Figure 1) related to the rectangular axis X for the segments 6 (Figure 2) of the path 3, while the resistance-type voltage dividers 1621,..., 1621,..., 162, (Figure 10) are operated to set the voltages corresponding to the components Viy (Figure 2) of the velocity Vi of the energy source 4 (Figure 1) related to the rectangular axis Yforthe segments 6 (Figure 2) of the path 3.The signals U2 (Figure 4) representative of the correction value AVi (Figure 22) of the velocity Vi are delivered from the memory unit 23 (Figure 10) to the inputs of the dividers 163i 163 163rn and l64i 164 1641,...,164j,....

164m of the signal dividing unit 35. The division factors of the dividers 1611-m, 1631-m, 1 631-m, and 1641-m are set in proportion to the signals representative of the components Vix, Viy (Figure 2) of the velocity Vi, related to respective axes X, Y. The signals provided by the dividers 1611 161 161 m (Figure 10) are switched over by the transistor switches 1671, l67 1 67m and are applied to the input of the integrator via the resistor 169. The signals provided by the dividers 1621,...,163i,...,163m are switched over bythetransistor switches 168a,...,168i,...,168m and pass to the resistor 170.The signals from the outputs of the dividers 1621,..., 1621,..., 162, and 1641,..., 164i,..., 164m 164i,..., 164 are applied to corresponding data inputs of the multichannel switches 39, 34. The signal synchronization unit 52 is operated to control the multichannel switches 32,34, 37,39. With the switch 186 in the operating position, the outpu of the AND gate 185 provides a reset signal for the D-flip-flops 1761,..., 176i,..., 176m 1761,..., 176i,..., 176m of the shift register. In this case, the D-flip-flop 1761 assumes the 1 state, while the D-flip-flops 1762,...,176j,...,176m assumes the 0 state.The signal from the complement output of the D-flip-flop 1761 causes the transistor switches 1671, 1681 to close; with the result that the signal representative of the component Vix (Figure 1) of the velocity Vi and the signal U2 (Figure 4) representative of the components AVj (Figure 3) of the component ix for the first segment 6 (Figure 2) of the path 3 are passed to the input circuits of the operational amplifier 172 (Figure 10). The rate with which the voltage across the output ofthe operational amplifier 172 is changed, is proportional to the sum ofthe signals delivered to the circuits of the resistors 169, 170 and corresponds to the desired velocity at that segment.The output signal of the operational amplifier 172 is applied to the input of the control unit 28 adapted to control the movement of the energy source 4 (Figure 1) relative to the axis X, and is also applied to the non-inverting input of the operational amplifiers 1741,..., 174i,..., 174m 174,..., 174, (Figure 10) of the threshold network 48. When the output signal of the operational amplifier 172 reaches one of the voltage levels provided by the dividers 1751,..., 1751,..., 175m in accordance with a condition where the path 3 (Figure 2) is divided into the straight line segments 6, the polarity of the signal at the output of a respective threshold network, 48 or 49, (Figure 6) is reversed. In this case, the output of a respective AND gate 180 (Figure 10) provides a pulse of negative polarity.The AND gate 181 intended for logic O's performs the OR function, which means that its output provides a pulse signal. The latter is applied to the C inputs of D-flip-flops 1761,..., 1761,..., 176, and causes the shift register to change states with the result that the logic 1 is shifted one position to the right. The control signals of the multichannel switches 32, 34,37, 39 are switched over to supply the signal representative of the component V2ix (Figure 2) of the velocity V2j at the next segment 6 of the path 3 and the signal U2 (Figure 4) representative of the correction value AV2i (Figure 2) of the component V2ix.The piecewise linear function signal representative of the components 7, 8 determined by the law of movement of the energy source 4 (Figure 1) and related to the rectangular axes Y,X is therefore formed.

The method and apparatus provide for the control of the velocity and power of a localized energy source 4 moved along an arbitrary path 3 on the heating surface 1 of the object. A conversion temperature sensor 9 (Figure 5) provides the signals according to which the velocity Vi and power of the energy source 4 are controlled, while the velocity Vi (Figure 2) of the energy source 4 (Figure 1) is controlled with the help of conventional rectangularly oriented units 28, 29 (Figure 5).

The heating surface 1 (Figure 1) of the object is divided into elementary areas 21,..., 2i,..., 21 2- 2, (Figure 4).

Conventional means are used to produce, for the elementary areas, the error signals Q1 (Figure 4) representative of the difference between the predetermined and the measured temperature and the control signals for controlling the velocity and power of the energy source, the velocity control signals being converted to the signals Uy, Ux representative of the components Y, X (Figure 2) determined by the law of movement of the energy source 4 (Figure 1), related to the rectangular axes X, Y and providing for a variation of the velocity Vi of the energy source 4 (Figure 1) moved along the predetermined path 3.

The method and apparatus possess universality and invariance, which means that an arbitrary velocity of the energy source 4 along an arbitrary path 3 can be attained so that they do not interfere with each other.

Claims (10)

1. A method of controlling a movable energy source when it is being operated to heat a heating surface of an object to maintain a predetermined temperature thereof and when it is being moved along a predetermined path in accordance with the difference between the predetermined and measured temperatures of the heating surface of the object, the method comprising: dividing the heating surface of the object into elementary areas; forming and remembering error signals representative of the difference between the predetermined and the measured temperature at each of the elementary areas of the heating surface of the object; utilizing the error signals for producing signals representative of the correction values of the velocity and power of the energy source at the elementary areas including segments of the predetermined path; converting the signals representative of the correction values of the velocity of the energy source to signals representative of the components determined by the law of movement of the energy source and related to rectangular axes; and varying the velocity of the energy source along the predetermined path in accordance with the signals representative of the components determined by the said law of movement.

2. A method as claimed in claim 1, in which the conversion of the signals representative of the correction value of the velocity of the energy source to the signals representative of the components determined by the law of movement of the energy source and related to rectangular axes comprises: approximating the predetermined path by means of straight line segments: determining the projections of the straight line segments of the rectangular axes; forming the signals representative of the velocity components determined by the law of movement of the energy source and related to the rectangular axes, the said signals being proportional to the values of the projections of the straight line segments of the predetermined path; dividing the signals representative of the correction values of the velocity of the energy source into two signals representative respectively of the correction values of the corresponding components of the velocity related to the respective rectangular axes, each of the said two signals being proportional to the value of the projection of a given straight line segment on a respective rectangular axis; adding each of the signals representative of the correction values of the components of the velocity of the energy source related to corresponding rectangular axes to the respective signal representative of the component of the velocity related to the respective rectangular axis; and integrating the signals obtained during addition.

3. A method as claimed in claim 1, in which the conversion of the signals representative of the correction value of the velocity of the energy source to the signals representative of the components determined by the law of movement of the energy source and related to rectangular axes comprises: approximating the predetermined path by means of circular arcs; determining the value of the curvature for each of the circular arcs; forming control signals by summing the signals representative of the velocity of the energy source and the signals representative of the correction value of the velocity for the elementary areas; switching over the control signals to form a signal corresponding to the velocity of the energy source; integrating the signal representative of the velocity of the energy source in order to obtain a signal representative of the distance passed by the energy source along the predetermined path; forming, in proportion to the values of the curvature of the circular arcs of the path, a signal representative of the form of the path of the energy source; multiplying the signal representative of the form of the path by the signal representative of the velocity of the energy source: integrating the signal resulting from the said multiplication in order to obtain a resultant signal; and simultaneously integrating the sine and cosine values of the resultant signal to form the signals representative of the components determined by the law of movement of the energy source and related to corresponding rectangular axes.

4. A method as claimed in claim 1, in which the energy source performs a periodical movement: further comprising forming an average signal from the error signals representative of an average value of the error signals; varying the power of the energy source in proportion to the average signal; and forming the signals representative of the correction value of the velocity of the energy source at the elementary areas of the path from the difference between the error signals and the average signal.

5. An apparatus for controlling a movable energy source when it is being operated to heat a heating surface of an object, comprising: two control units arranged to control the movement of the energy source along two rectangular axes; a control unit arranged to control the power of the energy source; a temperature setter arranged to set a predetermined temperature of the heating surface of the object and having an output coupled to a first input of a comparison unit and arranged to compare the predetermined and measured temperature of the heating surface of the object and arranged to produce error signals corresponding to the difference therebetween, the comparison unit having a second inut coupled to an output of a temperature sensor arranged to measure the temperature of the heating surface of the object; a switching unit arranged to switch the error signals;a scanning unit coupled to the temperature sensor; a memory unit arranged to store the error signals, having inputs coupled to the outputs of the switching unit, a data input coupled to the output of the comparison unit, and a control unit coupled to the scanning unit; a signal forming unit arranged to form signals representative of the correction values of the velocity and power of the energy source, the signal forming unit being coupled to the output of the error signal memory unit and to the power control unit; a further memory unit arranged to store the signals representative of the correction value of the velocity of the energy source the further memory unit being coupled to the signal forming unit arranged to form the signals representative of the correction value of the velocity and power of the energy source; and a functional signal converter arranged to convert the signals representative of the velocity of the energy source to signals representative of the components determined by the law of movement of the energy source and related to respective rectangular axes, the functional signal converter having inputs coupled to the outputs of the further memory input arranged to store the signals representative of the correction value of the velocity of the energy source, and outputs coupled respectively to the control units arranged to control the movement of the energy source along the two rectangular axes.

6. An apparatus as claimed in claim 5, in which the functional signal converter comprises: a signal generator arranged to generate the signals representative of the two components of the velocity of the energy source, related to the rectangular axes; a signal dividing unit arranged to divide the signal representative of the correction value of the velocity of the energy source into two signals representative of the correction values of the velocity of the energy source, related to the respective rectangular axes, an input ofthe signal dividing unit being used as the input of the functional signal converter and being coupled to the output of the further memory unit arranged to store the signals representative of the correction value of the velocity of the energy source; two multichannel switches one of which is arranged to switch the signal representative of one component of the velocity of the energy source related to one rectangular axis and the other of which is arranged to switch the signal representative of the other component of the velocity of the energy source related to the other rectangular axis, the multichannel switches having data inputs connected to the outputs of the signal generator; two further multichannel switches, one of which is arranged to switch the signal representative of the correction value of one component of the velocity of the energy source related to one rectangular axis and the other of which is arranged to switch the signal representative of the correction value of the other component of the velocity of the energy source related to the other rectangular axis, the inputs of the further multichannel switches being coupled to the outputs of the signal dividing unit; two adders, a first of which has a first input coupled to the output of one of the component signal multichannel switches, and a second input coupled to one of the component correction value signal multichannel switches, and a second of which has a first input coupled to the output of the other component signal multichannel switch and a second input coupled to the other component correction value signal multichannel switch; two integrators having inputs coupled respectively to the outputs of the corresponding adders, and having their outputs coupled to the respective control units arranged to control the movement of the energy source along the rectangular axes; two threshold networks having their inputs coupled respectively to the outputs of the integrators; and a signal synchronization unit arranged to synchronize the signals representative of the components of the velocity of the energy source and the signals representative of the correction values of the components of the velocity related to the rectangular axes, the signal synchronization unit having inputs coupled to the outputs of the threshold networks and an output coupled to the control inputs of all the multichannel switches.

7. An apparatus as claimed in claim 5, in which the functional converter comprises a velocity setter arranged to set the velocity of the energy source; an adder unit having input groups, one of the input groups being coupled to the output of the velocity setter and a second of the input groups being used as the input of the functional converter and being connected to the further memory unit arranged to store the signals representative of the correction value of the velocity of the energy source; a switch unit arranged to switch the control signals and having data input coupled to the adder unit; a first integrator having a data input coupled to the output of the control signal switch unit; a threshold network having an input coupled to the first integrator, and having an output coupled to a control input of the first integrator; a conversion unit arranged to convert the signal representative of the distance passed by the energy source along the path to a signal representative of the form of the path, the distance conversion unit being coupled to the output of the first integrator; a multiplication-unit having an input coupled to the output of the control signal switch unit and having another input coupled to the distance conversion unit; a second integrator coupled to the multiplication unit; channel networks arranged to form the signals representative of the components of the velocity of the energy source related to the rectangular axes, the channel networks comprising respectively cosine and sine converters whose inputs are connected together and to the second integrator, each of the channel network being provided with a multiplication unit having an input coupled to a respective converter and having another input coupled to the output of the control signal switch unit; the channel networks each having an integrator arranged to form the signal representative of the component of the velocity of the energy source related to the respective rectangular axes, the integrators being coupled to the respective multiplication units which have outputs coupled to the control inputs of the control signal switch unit.

8. An apparatus as claimed in claim 5, further comprising a signal forming unit arranged to form an average signal and coupled to the signal error memory unit; a further signal forming unit arranged to form a signal representative of the difference between each of the error signals and the average signal and having an input coupled to the output of the average signal forming unit and to the input of the power control unit, another input coupled to the output of the error signal memory unit, and an output coupled to the signal forming unit arranged to form the signals representative of the correction value of the velocity of the energy source.

9. A method of controlling a movable energy source when it is being operated to heat a heating surface of an object substantially, as hereinbefore described with reference to the accompanying drawings.

10. An apparatus for controlling a movable energy source when it is being operated to heat a heating surface of an object substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.