JPS5821376B2 - Beam Denryu Program Seigiyosouchi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron beam current control device for an electron beam generator, and more particularly to a beam current program control device for controlling an electron beam current according to a predetermined program.

An electron beam generator, for example, an electron beam generator of an electron beam welding machine, needs to change the current value in a fairly complex manner depending on the welding conditions, and there is a strong need to control it by a program especially when using an automatic welding machine. It has become.

Conventionally, several types of devices have been used to control the electron beam current, such as devices using a pin board and a clock pulse generator, devices using a servo motor to drive a potentiometer or other mechanical modulator, or devices using a digital-to-analog converter. This includes the equipment used.

However, devices using pinboards and clock pulse generators cannot respond to advanced control conditions because the control function signals sent to the electron beam generator are step-like, and are still difficult to combine with numerical control devices. There are some difficulties.

Furthermore, in devices using servo motors, the accuracy of the beam current value depends on the mechanical positioning accuracy, so a high degree of precision is required for the positioning part, which is mainly a movable part, so the device becomes large and expensive. Become.

In addition, a large amount of maintenance is required to prevent a decrease in accuracy due to wear of mechanical parts, and the life of the machine is not sufficient.

Moreover, the circuit using a digital-to-analog converter is complicated.

An object of the present invention is to develop a beam current program that can continuously control beam current with high precision, is easy to connect with a numerical control device, and is practically inexpensive and requires no maintenance. The purpose is to obtain a control device.

The beam current program control device of the present invention includes, for example, a reference voltage stable source, several voltage dividers, and switching means for switching these, and the beam current program control device includes, for example, a reference voltage stable source, several voltage dividers, and switching means for switching these. an integrating means including a setting signal voltage generation means, a comparator for always performing comparison, a second switching means for switching resistance or capacitance, and an integrator, the output of the beam current setting signal voltage generation amount means; The voltage and the output of the integrator are always compared by the comparator, and while the two voltages are different, the resistance or capacitance switching means is used to perform an integration operation at a desired rate of change, and the two voltages are an integrating means configured to stop the integral operation when the The present invention is a beam current program control device that automatically controls a beam current, including a switching device driving device that drives the integrating device to operate the integrating device as a voltage holding element.

In the operation of the apparatus of the present invention, the beam current value is set by switching a reference voltage stable power source and a group of selection switches,
The time rate of change of the beam current is set by a function generator using capacitance and resistance, and by switching a group of selection switches.The combination of these two operations performs program control of the beam current.When combined with a numerical controller, This is connected to the selection switching operation of both the changeover switches.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.

To make the explanation easier, we will first briefly explain the reference numbers or symbols: 1 is a stabilized power supply that provides a reference voltage, 2 is a group of potentiometers for beam current value setting that operate as a voltage divider in response to 10 reference voltages; 3 is a group of selection switches for potentiometer group 2 for beam current value setting, 4 is an operational amplifier that operates as a comparator, 4a is its inverting input terminal, 4b is a non-inverting input terminal, and 3R is for resetting the inverting input terminal 4a to zero volts. It is a point of contact.

5 is a limiting resistor for limiting the output current of the operational amplifier 4; 6a and 6b are negative voltage and positive voltage clip diodes, respectively; 7 is a group of integrating resistors for setting the beam current time change rate; and 8 is a beam current timer group. A group of integral resistance selection switches for setting the rate of change, 9 is an operational amplifier that performs integral operation;
a is its inverting input terminal, 9b is its non-inverting input terminal, and 10 is an integrating capacitor.

. Note that the power supply circuits and off-cent balance circuits of the operational amplifiers 4 and 9 are generally well known, and therefore are omitted.

11 is a potentiometer selection switch group drive circuit for beam current value setting, and 12 is an integral resistance selection switch group for setting beam current time rate of change.

1 drive circuit.

13, before switching the potentiometer selection switch 3 for beam current value setting, all the integral resistance changeover switches 8 for beam current time rate setting are turned off, and the operational amplifier 9 is switched from integral operation to voltage hold operation. 14 is a timing signal B indicating that switching of the beam current value setting potentiometer group 2 is completed and the integral resistance changeover switch 8 for setting a predetermined beam current time rate of change may be turned on. 15 is the output of the operational amplifier 9 and is a function signal consisting of a DC voltage.

16 is a DC conversion amplifier with high voltage resistance on the primary and secondary sides;
17 is an electron beam generating tube, and 18 is a power supply device including a fiber power source and a voltage power source.

Next, the operation will be explained with reference to the above reference numerals and FIG. 1.

The reset state of this device is a state in which the beam current value setting potentiometer selection switch group 3 or 3R is selected and any one of the beam current time change rate setting integral resistance selection switches 8 is turned on.

That is, there is no input voltage at the inverting input terminal 4a of the operational amplifier 4, and only the output of the operational amplifier 9 is applied to the non-inverting input terminal 4b.

The output of the operational amplifier 4 is connected to the inverting input terminal 9 of the operational amplifier 90.
In addition to a, the operational amplifier 4 and the operational amplifier 9 are combined to form one voltage follower circuit.

As a result, the output voltage 15 of the operational amplifier 9 is reset to zero volts.

If any one of the beam current value setting potentiometers is selected from the beam current value setting potentiometer selection switch group 3, a divided voltage corresponding to the selected potentiometer is applied to the inverting input 4a of the operational amplifier.

Here, the operational amplifier 4 has a gain of about 160,000 times, and a maximum output voltage of about ±15 volts.

Note that even if reference voltage 1 is selected to be +5 volts and 0.1% of the reference voltage is selected for beam current value setting potentiometer group 2, assuming that the operational amplifier does not saturate, its output voltage will be 800 volts. This means that unless the set voltage is reduced to almost zero, the operational amplifier 4 will actually reach its saturation value of 115 volts.

This voltage is applied to the current limiting resistor 5 and the clip diode 6a, and most of the voltage is divided to the current limiting resistor 5.
The voltage applied to the next stage beam current time rate setting integrating resistor group 7 is equal to the forward voltage drop of the clip diode 6a -
It will be about 0.7 volts.

This voltage of 0.7 volts is applied to the inverting side input terminal 9a of the operational amplifier 9, which is fed back by the integrating capacitor 10 via the integrating resistor 7 for setting the beam current time rate of change.

The resistance value of the integrating resistor 7 for setting the beam current time rate of change is R, the capacity of the integrating capacitor is C, and the operational amplifier 9
Let Ei and Eo be the input and output of the output voltage 15, which changes over time.

This part is shown in FIG. 2 as a part shown as ■.

When this Eo substantially matches the voltage at the inverting input terminal 4a of the operational amplifier 40, the output of the operational amplifier 4 becomes approximately zero volts, and the integrating operation of the operational amplifier 9 is stopped.

This part is illustrated in the part marked ■ in FIG. 2.

Next, when a command to switch the beam current value setting potentiometer selection switch group 3 to the next level is applied to the beam current value setting potentiometer selection switch group drive circuit 11, the timing signal A13 is set as an integral for beam current time change rate setting. The voltage is supplied to the resistance selection switch group drive circuit 12, and all of the integral resistance selection switch groups 8 for setting the beam current time rate of change are turned off, and the operational amplifier 9 is used as a voltage holding element.

The operation up to this point is to prevent a pulse from being output from the operational amplifier 4 at the moment of switching, thereby preventing the operational amplifier 9 from being reset to zero volts.

During this time, the output of the operational amplifier 9 maintains the portion shown by ■ in FIG.

Then, after a predetermined period of time has elapsed, the beam current value setting potentiometer group selection switch 3 is switched to the next stage.

Here, it is assumed that the current value of the next stage is lower than that of the first stage.

Then, a timing signal B14 is sent from the beam current value setting potentiometer selection switch group drive circuit 11 to the beam current time change rate setting integral resistance selection switch group drive circuit 12, and the beam current time change rate setting integral resistance selection switch group is outputted. 8. Select the desired one.

As a result, the voltage at the inverting input terminal 4a of the operational amplifier 40 becomes more negative than the voltage at the non-inverting input terminal 4b, making the output of the operational amplifier 4 a saturated value of +15 volts.

This voltage peaks at the forward voltage drop of +0.7 volts at the clip diode 6b and is applied to the operational amplifier 9, but the polarity of this voltage is opposite to the polarity of the first stage, so it changes with time. Voltage E.

is given in the same form as in the first stage, but the direction is reversed,
This is the part shown in ■ in Figure 2.

From then on, as with the first stage operation, the integral operation ends when the value set by the beam current value setting potentiometer group 2 matches the output voltage of the operational amplifier 9, and from then on the constant value shown in ■ in Figure 2 is maintained. do.

The part marked ■ in FIG. 2 shows the case where beam irradiation to the target is completed and the potentiometer group selection switch for beam current value setting is selected to 3R and reset.

The operation in this case is the same as that in the case of moving from level 2 to level 2 in FIG. 2, so a description thereof will be omitted.

The function signal 15 as shown in FIG. 2 obtained in the above manner is DC amplified by a DC amplifier 16 whose input and output are designed to withstand high voltage, and is applied to the grid 20 of the electron beam tube 17. .

Although not shown in the figure, this DC amplifier normally modulates the DC into AC once, and converts it into a secondary modulated wave via a transformer that can withstand a voltage higher than the high voltage of the electron beam tube power supply 18. This is converted into a secondary DC voltage by a rectifying and smoothing circuit.

In this way, the grid 20 and filament 220 of the electron beam tube 17 with the target 21 placed close to the ground
In the meantime, a bias voltage proportional to the function signal 15 is applied, and the magnitude of the electron beam current is controlled to a desired value.

In the above explanation, the time rate of change, that is, the time constant, of the integrating circuit was set by switching the integrating resistor for setting the time rate of change. This may be done by switching the capacitor.

However, in case the operational amplifier 9 is operated as a voltage holding element, it is necessary to be able to disconnect it from the limiting resistor 5.

As can be easily seen from the above explanation, the beam current programming device of the present invention has the accuracy of the beam current determined purely electrically by the gain of the operational amplifier 4 for the comparator. In contrast, the increase in accuracy does not have a significant impact on cost.

Furthermore, since it is constructed with a simple electronic circuit, maintenance is unnecessary and the cost is low.

Furthermore, since an integrator is used for function generation, the waveform, that is, the beam current, changes continuously, and the time rate of change of the beam current can be changed simply by changing the setting of the integrating resistor 7. Changes can be made easily.

Furthermore, when combined with a numerical control device, it is not necessary to control the beam current value itself or the beam current time rate of change itself with the numerical control device, and the potentiometer selection switch 3 for setting the beam current value and the integral resistor for setting the beam current time rate of change are not required. The selection switch 8 can be selected by using the auxiliary function of the numerical control device, that is, the auxiliary function used for selecting the cutter or the rotation speed of the spindle axis in a normal machine tool. There is no need to increase

Of course, it goes without saying that the same effect can be achieved by sequentially switching the selection switches using a simple process counter without combining with a numerical control device.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing an embodiment of the apparatus according to the present invention, and FIG. 2 is a diagram showing the beam current waveform thereof. Explanation of symbols: 1 is a stable reference voltage power supply, 2 is a potentiometer group for beam current value setting, 3 is a selection switch, 4 is an operational amplifier for comparator amplification, 6a and 6b are clip diodes, 7 is for setting beam current time rate of change 9 is an integrating resistor group, 9 is an operational amplifier that performs integral operation, 10 is an integrating capacitor, 15 is a function signal, and 17 is an electron beam generating tube.

Claims (1)

[Claims] 1 A signal voltage generating means for beam current value setting which generates a desired voltage by using a first switching means, and a device which performs an integral operation, while the integral output voltage thereof is different from the desired voltage. an integrating means that performs an integral operation at a desired rate of change using a second switching means and stops the integral operation when the voltage matches the desired voltage; a switching means driving device configured to drive the switching means of No. 2 to operate the integrating means as a voltage holding element, and to automatically control the beam current of the electron beam generator using the integrated output voltage as a reference input voltage. beam current program controller.