JPS6336286Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for measuring the relative energy consumed in a welding process. More particularly, it relates to a device used as a transducer in conjunction with a Soudronic welding machine adapted to weld longitudinal seams on the sides of thin can bodies. Saudronik welders for this type of application have a secondary transformer rated at 4 to 8 volts and 5000 amps. Welding can be of the high frequency pulse type, in the range of 50 to 900 Hz, with each AC waveform forming a power pulse. A moving electrode of copper wire is placed between the surface to be welded and the output terminal of the secondary winding of the welding transformer. A copper wire is used between each electrode and the metal surface to be welded and is moved after each welding pulse to prevent deterioration of the welding electrode.

The can body usually has a hollow cylindrical structure, which is formed into a cylindrical shape that is closed along its longitudinal edge and open at both ends. The mating ends, formed into a cylindrical shape from a flat blank material, are brought together to be welded. Blank material is pre-printed (lithography)
Preferably, it is made from tin plated or non-tin plated chrome steel, such as MRT3 with 0.25 ETP on the surface. Such materials weigh between 29 and 51 Kg (65 and 112 lbs) per base box.
can have a board weight in the range of . This means a thickness in the range of 0.18 to 0.31 mm (0.007 to 0.0123 inches), which is the thickness used for containers made from tin plate and/or non-tinned chrome steel. It is decided according to the person. Welded side seams are preferred over other types of side seams, such as soldered ring seams or glued seams. More specifically, in aerosol containers that must be able to withstand internal pressures of up to 14 Kg/cm ² (200 lbs/in2),
Welded longitudinal side seams have numerous advantages. Similarly, for containers with special construction that are too large to be produced by pultrusion (for example, two-piece containers), welded sides provide the necessary strength and are too long to be produced by pultrusion. To simplify the manufacture of such containers that are too large or too large. In other applications, it is important to provide lithographic information on the outer surface of the container. Textured side seams are required because quality lithography cannot be added to pultruded containers at high speeds.

Hall effect devices have been used for several transducer applications. Some of them have been applied to welding machines and are disclosed, for example, in US Pat. No. 3,240,961, US Pat. No. 3,194,939, US Pat. Each of these is designed in such a way that a Hall effect device is used in conjunction with a welder to determine the current. Similarly, US Pat. No. 3,365,665 shows the use of Hall transducers in devices for measuring currents in high voltage conductors, such as power lines. Of particular interest in this patent is that corrections are made to Hall gain versus temperature, recognizing the problems posed by temperature changes. The circuit in this patent does not automatically compensate for Hall DC offset when the magnetic field is zero. In the aforementioned prior art patents, Hall effect devices are used to detect changing magnetic fields during welding. In the aforementioned U.S. Pat. No. 3,365,665, the aforementioned Hall effect device also includes:
While recognizing that it is sensitive to current and voltage inputs as well as to ambient temperature,
Such external influences can be adjusted to be relatively small with respect to the signals output by the Hall effect transducers used in the applications disclosed in this prior art.

In high-speed processes, such as welding thin can bodies several hundred times per minute with an AC welder, input current and voltage as well as ambient temperature are important when attempting to measure small changes in welding operating conditions. Impact becomes important. Therefore, the functionality of the circuit described here fully satisfies the aforementioned conditions in an effort to provide a Hall effect transducer useful for monitoring the energy used to weld side seams in thin metal containers. It is to compensate. This converter will be described below.

The improved transducer provided by the present invention is
It uses conventional Hall effect devices known in the prior art. Such a device is
It has a plate responsive to a magnetic field, preferably made of a semiconductor material. This board has two input supply terminals and two output electrodes. When input power is applied to the terminals of the plate and the device is exposed to a magnetic field, an output voltage appears across the output electrodes. This output voltage is proportional to the magnetic field and is thus a measure of the strength of the magnetic field and the energy produced therefrom (ie, the power used between the welding electrodes). The use of Hall effect devices to measure current or voltage between welder electrodes is known in past welder monitors. However, the use of such devices in conjunction with high frequency AC welding machines to measure small relative changes in operating conditions presents considerable difficulties. More specifically, the input power to the Hall effect device must vary with ambient temperature, as well as compensation for DC offset versus temperature at zero magnetic field. Hall effect devices exhibit a linear signal change with increasing temperature when powered by a constant current or voltage source. More specifically, the signal has a tendency to change in the opposite direction as temperature increases at a constant voltage or current, and such a mismatch can be used to
They can be balanced against each other by using appropriate resistors as shown in US Pat. No. 3,365,665. This solution is inadequate for detecting small changes in AC welders and ignores other difficulties of Hall effect devices, such as DC offset versus temperature versus Hall power. More specifically, the Hall device varies linearly in compensated gain.
It has a DC offset signal whose resistance increases with temperature, so even regulated input power is not completely correct for Hall gain and DC offset at the same time. The present invention includes a load responsive circuit in a power supply configured to compensate for changing parameters as a result of temperature differences. The power supply detects the input power terminal resistance and supplements the corrected input current.

The supply circuit includes a light emitting diode (LED);
This is used as a voltage reference source for a constant current source consisting of a transistor and a current sensing resistor.
The voltage-versus-temperature characteristic of a diode has a negative temperature coefficient (base to emitter).
negative temperature coefficient). The diode is connected in series with the resistor so that a current that is the combination of the constant current source and the current flowing through the diode can flow through the Hall effect device. The series resistor can therefore be chosen such that a small portion of the operating current for the Hall effect device passes through the diode with the major portion supplied by the constant current source. Since the Hall effect device resistance increases with increasing operating temperature, the current flowing through the diode decreases. The Hall device signal gain versus temperature can be compensated by proper selection of the resistor placed in series between the power supply and the diode.

The DC offset voltage of a Hall effect device increases or decreases as the temperature increases or decreases. This is corrected by attaching a thermistor to the Hall effect device to detect the Hall element temperature. In addition to the thermistor, an adjustable potentiometer is installed for use in zeroing the initial offset voltage of the Hall device and amplifier. The thermistor is connected in series with the potentiometer in parallel with the resistor, and the offset terminals of the amplifier are used to ensure a linear response within the required temperature compensation range. As the temperature of the Hall effect device increases, the resistance of the thermistor decreases and the offset balance of the amplifier circuit changes inversely with the change in the Hall signal due to the amplifier. As the temperature decreases, the opposite is true.

Accordingly, it is an object of the present invention to provide a circuit that compensates for Hall DC offset signal variations over a wide range of temperatures.

Another object of the present invention is to provide a circuit that compensates for changing Hall device voltage gain over a wide range of temperatures.

Another object of the present invention is to provide a circuit that uses changes in Hall effect device resistance to compensate Hall gain for temperature changes.

Another objective of the present invention is to provide a simple and reliable method with the ability to detect small signal changes in the presence of fluctuating operating temperatures and changing magnetic fields, to monitor the welding of side seams of metal container bodies. The purpose of the present invention is to provide an inexpensive circuit.

The present invention will be explained in more detail below based on the drawings.

FIG. 1 shows a circuit for temperature compensation of a Hall element for detecting a magnetic field. The circuit has a power input section for the Hall element, which is provided to compensate for the change in gain over temperature (Figure 2) as well as the change in Hall element resistance over temperature (Figure 4). It is being This power input circuit is connected at terminal 11 to a Hall element (Hall effect converter, hereinafter the same) 10 and provides a regulated DC voltage source according to the compensation purpose described above. More specifically, there is a voltage source, indicated by +V at the top of the drawing,
It is connected in series with the resistor R ₁ to the base terminal of the transistor Q ₁ and the diode. resistance
R ₁ determines the current I ₁ , _which flows from the DC voltage source to the bottom of the circuit. The part of the circuit through which the current I ₁ flows is connected to the base of the transistor Q ₁ and the light-emitting diode L ₁ , and the forward voltage drop across the light-emitting diode L ₁ is the reference to the transistor Q ₁ and the current sensing resistor R ₂ . Determine the voltage.
The light emitting diode L ₁ has a voltage change with temperature, which compensates for the negative temperature coefficient of the transistor Q ₁ . The other end of the light emitting diode _L1 is grounded via an attenuation capacitor, and is also connected to the current detection resistor and the input terminal 11 of the Hall element.

A resistor R ₂ is connected between the collector of the transistor Q ₁ and the Hall element in parallel with the light emitting diode L ₁ and in series with the input terminal 11 of the Hall element. Therefore, the current I _H flowing through the Hall element
is the sum of the currents I ₂ and I ₃ flowing through the light emitting diode L ₁ and the resistor R ₂ , respectively. The sum of the resistance R ₁ detected at terminal 11 (relative to ground terminal 12) by the load response input circuit and the internal resistance of the Hall element is
Determine the operating current I ₃ . This is because the current I ₂ remains constant (I ₂ is a function of the operational control of the transistor Q ₁ ). The resistance of the Hall element is
When increasing with increasing operating temperature (Fig. 4),
The current I ₃ decreases. Proper selection of R ₁ allows control of the change in current I ₃ needed to compensate for the increase in signal gain of the Hall element with temperature (Figure 2).

The Hall signal outputs at Hall effect output terminals 13 and 14 are connected to the negative and positive inputs of a differential measurement amplifier 15, respectively.

The magnetic field to which the Hall element is exposed is shown in Figure 1, which shows the effect of the pulsed welding current on the Hall element. A thermistor R _T is shown below the Hall element, which in this embodiment is directly bonded to the Hall element chip. This thermistor is connected in parallel with a resistor R ₃ , both of which are connected in series with a potentiometer P ₁ , and the thermistor R _T and the resistor R ₃
The other connection from the combination is connected to one control terminal of the amplifier. These control terminals are shown in FIG. 1 as amplifier offset terminals and are given the symbol T, and they control the amplifier output offset voltage. To be more specific, the initial values output from the Hall elements to terminals 13 and 14
The DC offset signal is applied to a differential measuring amplifier 15 and zeroed by applying it to an initial offset potentiometer _P1 . It should be noted that as the Hall operating temperature increases or decreases, the DC offset output increases or decreases proportionally (see Figure 3). This change in offset is fed to the differential measurement amplifier via terminals 13 and 14, but the amplifier also receives an inverse control signal from the thermistor circuit for temperature compensation. As the DC offset voltage increases at terminals 13 and 14, the corresponding change in Hall element operating temperature is detected by thermistor _RT . R _T is in thermal contact with the Hall element, so the resistance of R _T decreases as shown in FIG. The parallel circuit of thermistor R _T and resistor R ₃ cooperate to provide a linearized signal to the differential measurement amplifier. This signal is proportional to the change in Hall element temperature, so the differential measurement amplifier is adjusted to
The signals received at terminals 13 and 14 are compensated in the output signal from the differential measurement amplifier. If the temperature of the Hall element decreases, the resistance of the thermistor R _T increases and the aforementioned circuit adjusts the amplifier accordingly.

This differential measurement amplifier operates in a manner well known to those familiar with this type of technology. That is, terminals 13 and 14, here with slightly different levels of DC output fluctuation due to the magnetic field.
The difference of the signals from is taken. The differential measurement amplifier adjusts its DC differential in response to temperature determined by a signal from the thermistor compensation circuit.
The output from the differential measurement amplifier is therefore a DC voltage that is proportional to the magnetic field and is completely independent of temperature. This output signal can be connected to a measuring device and/or a recording device and a control device for the Saudronik welding machine, so that the welding power increase can be recorded and/or adjusted on the fly. The fact that the operation and response of this equipment system is automatic allows it to be used in conjunction with high speed (hundreds of can bodies per minute) welding of very thin metals in manufacturing operations to form container bodies. become.

[Brief explanation of drawings]

The accompanying drawings show an embodiment of the present invention, and FIG. 1 is a schematic circuit diagram of a Hall effect device;
the device is connected to a power input source and an output amplifier and a compensating offset circuit;
FIG. 2 is a graph showing changes in the output signal of the Hall effect device with respect to ambient temperature, where the solid line a represents a constant current source and the solid line b represents a constant voltage source. FIG. 3 is a graph showing the change in DC offset gain with respect to temperature changes around the Hall effect device, with the solid line showing the desired flat response and the dotted line showing the compensated gain. Figure 4 is a graph showing the change in resistance of the Hall effect power input terminal with respect to changes in temperature conditions around the Hall effect device, and Figure 5 is a graph showing the response of the thermistor to changes in ambient temperature. The middle curve RT− shows the case with only a thermistor. In the figure, 10 is a Hall element (Hall effect converter),
11 is an input terminal, 12 is a ground terminal, 13, 14
is a Hall effect output terminal, 15 is a differential measurement amplifier,
I ₁ , I ₂ , I ₃ , I _H are currents, R ₁ is a resistor, R ₂ is a current detection resistor, R ₃ is a resistor, R _T is a thermistor, Q ₁ is a transistor, L ₁ is a light emitting diode, P ₁ is a potentiometer,
+V is the power source.

Claims (1)

[Claims for Utility Model Registration] In a temperature/offset voltage compensation circuit for a Hall effect converter, the circuit is connected between a power source +V and an input terminal 11 of a Hall effect converter 10, and is connected to the signal gain and resistance of the converter 10. a supply circuit arrangement that changes the current to the converter 10 accordingly; and
a temperature-responsive control system connected to Hall effect output terminals 13, 14 of the converter 10 to adjust the output according to the ambient temperature at the converter 10 to cancel changes in offset voltage as a function of temperature; an output circuit arrangement; the supply circuit arrangement comprises a load-responsive reference voltage source and a constant current source; the load-responsive reference voltage source connects the power source +V to the input terminal 11 of the converter 10; resistor connected between
a diode L ₁ connected in series with R ₁ , the constant current source comprising a transistor Q _{1 whose base terminal is connected in series with the resistor R 1 and} its emitter terminal and the input terminal of the converter 10; a resistor R ₂ connected in series between the converter 11 and a differential measuring amplifier 15 connected to the output terminals 13, 14 of the converter 10; The converter 1 is installed as
a thermistor R _T in thermal contact with the thermistor RT; a resistor R ₃ connected in parallel to the thermistor _RT to linearize the signal of the thermistor _RT ; and a parallel circuit of the thermistor _RT and the resistor R ₃ . a potentiometer P ₁ connected in series to adjust the initial offset signal of the converter 10, said potentiometer P ₁ being connected to one control terminal T of said differential measuring amplifier 15 and said thermistor R _T
A temperature and offset voltage compensation circuit for a Hall effect converter, characterized in that the connection from the combination of and resistor _R3 is connected to another control terminal T of the amplifier 15.