JP2501170Y2 - Welding condition monitor device - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resistance welding machine that executes a welding operation by sequence control, and more particularly to a device for monitoring welding conditions.

[0002]

2. Description of the Related Art In resistance welding, the welding force, welding current, and energization time are the three major factors of welding conditions. The more precisely these factors are controlled, the more stable the nugget size and joint strength, and the higher the welding quality. Is obtained. Therefore, in a sequence control type resistance welding machine that automatically controls the operation sequence and timing of each welding condition, it is essential to set each of the above welding conditions to an optimum value.

By the way, recently, a resistance welding machine in which a pressure gauge is incorporated in a pressurizing mechanism has become widespread, and such a resistance welding machine can monitor a change in pressure force during energization. However, most resistance welding machines do not yet incorporate a pressure gauge, and measure the characteristics of the pressure using a pressure gauge. When measuring the applied pressure, a pressure sensor such as a load cell is inserted between the pair of electrode tips instead of the material to be welded, and only the applied pressure is applied to the sensor without energizing.

[0004]

As described above, in a resistance welding machine that does not incorporate a force gauge, the force measurement must be carried out without power supply, that is, with the power supply operation stopped. From this, conventionally, the welding pressure (welding current, voltage, etc.) related to the pressure and the energization can be monitored independently and
Each setting and adjustment was done.

However, when the sequence control is performed, a predetermined timing relationship is required between the applied pressure and the welding condition related to energization. For example, an appropriate squeeze time (initial pressurization time for stabilizing the pressure and improving the familiarity of the workpiece) is required between the pressurization start time and the energization start time, and An appropriate hold time (holding time for improving the properties of the nugget by solidifying the metal under the applied pressure) is required between the pressurizing end time and the pressurizing end time.

[0006] However, conventionally, since the welding pressure and welding conditions related to energization are separately and independently monitored as described above, it is difficult to set the squeeze time, hold time, etc. to optimum values, and setting / adjusting work is performed. I spent a lot of effort and time on it.

The present invention has been made in view of the above problems, and provides a resistance welding machine in which a pressure sensor is not incorporated.
The welding pressure waveform and the welding condition
It is an object of the present invention to provide a welding condition monitoring device that can be displayed on a screen and monitored at any time so that the timing relationship between the two can be easily set and adjusted.

[0008]

In order to achieve the above object, the welding condition monitoring device of the present invention is equipped with a pressure sensor.
Applying a predetermined pressure to the work piece with a resistance welding machine that does not penetrate
In the welding sequence in which a predetermined welding current is applied while
A welding condition monitoring device for monitoring welding conditions,
A means for applying only the pressing force at the same timing as in the welding sequence without applying the welding current to the pressing force sensor temporarily attached to the resistance welding machine from the outside, and applying the pressing force. A pressure force waveform storage means for storing a waveform of the pressure force obtained from the pressure force sensor, an energization-related welding condition waveform detection means for detecting a waveform of an energization-related welding condition during execution of the welding sequence, and Waveform display output means for synchronizing and displaying the welding condition waveform detected by the energization-related welding condition waveform detection means and the welding force waveform stored in the welding force waveform storage means at the same time. It was configured.

In the present invention, the welding condition relating to energization is current, voltage or power supplied to the object to be welded.

[0010]

In the present invention, prior to executing the welding sequence, the time characteristic (waveform) of the pressing force is detected at the same timing as in the welding sequence, and the detected pressing force waveform is stored in the memory. Then, the waveform of welding conditions (welding current, voltage, power, etc.) related to energization is detected when the welding sequence is executed, and the waveform of the detected welding conditions related to energization and the pressure waveform stored in the memory are synchronized. And output at the same time. As a result, it is possible to obtain a pseudo simultaneous measurement monitor screen in which not only welding conditions related to energization but also pressing force are measured at the same time during the welding sequence and they are displayed together.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram of a main configuration of a resistance welding machine system to which an embodiment is applied, and FIG. 2 is a waveform diagram of a welding condition waveform displayed and output in the embodiment.

In FIG. 1, the AC power supply voltage E input to the input terminals 10 and 12 is a pair of thyristors 14 and 16.
Is supplied to the primary coil of the welding transformer 18 via a contactor composed of. The secondary coil of the welding transformer 18 is connected to the pair of electrode tips 20 and 22. As a result, the secondary side voltage obtained in the secondary side coil is applied to the electrode tips 20 and 22, and when the workpiece 24 is inserted between the electrode tips 20 and 22, the secondary side circuit is applied. The welding current Iw flows. The welding current Iw is controlled by CP
It is performed by the firing circuit 26 under the control signal C1 from U40.

When the welding current Iw flows through the secondary side circuit, an output signal qi representing a differential waveform of the welding current Iw is obtained from the toroidal coil 28. This signal qi is supplied to the waveform restoration circuit 30 composed of an integration circuit, and the waveform restoration circuit 3
A signal (welding current detection signal) Qi representing the waveform of the welding current Iw is obtained at the 0 output terminal. This welding current detection signal Q
i is converted into a digital signal by the A / D converter 32 and then given to the CPU 40.

Further, when the primary voltage is supplied to the primary coil of the welding transformer 18, the electrode tips 20, 22 are
A voltage V is obtained between the two chips as long as they are not short-circuited. The inter-chip voltage V is amplified by the amplifier circuit 34, converted into a digital signal by the A / D converter 36, and then given to the CPU 40.

A pressing force P is applied to the both electrode chips 20, 22 from a pressurizing device 42 via a chip supporting member (not shown). The pressurizing device 42 has a pressurizing force generating means such as an air cylinder and outputs a predetermined pressurizing force P for a predetermined time in response to a control signal C2 from the CPU 40. The pressurizing device 42 has no built-in pressure gauge. Therefore, in order to measure the pressing force P,
A single commercially available force gauge 44 is used. This pressure gauge 44 has a load cell 44a attached to the tip of a handle 44b, and the output terminal of the load cell 44a is C through a cable 45, a connector 46 and an A / D converter 48.
It is connected to the PU 40.

Before the welding operation is performed, the worker inserts the load cell 44a of the pressure gauge 44 between the electrode chips 20 and 22 and presses a predetermined button on the keyboard 50. Then, in response to the button operation, the CPU 40 gives the pressurizing device 42 the same control signal C2 as in the welding sequence.

The pressurizing device 42 receives the control signal C2.
Applies a predetermined pressing force to the load cell 44a for a predetermined time at the same timing as when welding is performed. As a result, an output signal (pressing force detection signal) G representing the time characteristic (waveform) of the pressing force is obtained from the load cell 44a, and this signal G is A / D.
After being converted into a digital signal by the converter 36, C
It is supplied to the PU 40.

When the CPU 40 takes in the pressing force detection signal G from the pressing force gauge 44, it stores this in the nonvolatile memory 56 as pressing force waveform data. Note that the CPU 40 stops the operation of the ignition circuit 26 or the contactors (14, 16) during the measurement of the applied pressure. As a result, since the power supply voltage E is not supplied to the welding transformer 18, the welding current Iw does not flow in the secondary side circuit and the inter-chip voltage V is not applied to the load cell 44a.

The keyboard 50 is provided with various data input buttons and control buttons in addition to the above-mentioned pressurization force measurement start button. Through these buttons, an operator can perform various welding conditions and sequence necessary for sequence control. Set and input the timing. The data set and input is stored in the CPU 4
The arithmetic processing of 0 is received and stored in the memory 56.

After the measurement of the pressing force and the setting input of the welding conditions and the like as described above are performed, at a predetermined time t in FIG.
At 0, it is assumed that a predetermined welding start button on the keyboard 50 is operated or a predetermined welding start signal is input from the outside. Then, the CPU 40 gives the pressure device 42 a control signal C2. As a result, the pressurizing device 42 operates, and pressurization of the workpiece 24 is started at time t1.
Then, at time t2, the control signal C1 is sent from the CPU 40 to the ignition circuit 26, so that the thyristors 14 and 16 are
Starts the switching operation, a voltage is applied between the electrode tips 20 and 22 (FIG. 2 (B)), and a welding current Iw flows (FIG. 2 (C)). Then, when the predetermined time TC has passed, at time t3, the control signal C1 from the CPU 40 to the ignition circuit 26 is sent.
As a result, the switching operation of the thyristors 14 and 16 is stopped, and the supply of the inter-chip voltage V and the welding current Iw is stopped. Thereafter, the application of the pressing force P to the material 24 to be welded is released at time t4, and one welding sequence ends at time t5. Then, after the elapse of the predetermined time TF, the next welding sequence is started at time t6.

In such welding sequence, time TA
Is the upper electrode drop time, TB is the squeeze time (initial pressurization time), TC is the energization time, TD is the hold time,
TE is the electrode opening time and TF is the off time.

According to the welding machine system of this embodiment, when the welding sequence is started at time t0, the CPU 40
At the same time as sending the control signal C2 for starting the pressurization to the pressurizing device 42, the reading of the pressurizing force waveform data from the memory 56 is started, and the pressurizing force detected by the above-mentioned pressurizing force measurement based on the sequentially read pressurizing force waveform data. The waveform of P (time characteristic) is displayed on the screen of the display 52. Then, when the energization is started at time t2, the welding current detection signal Qi and the inter-chip voltage detection signal V are CP from the A / D converters 32 and 36, respectively.
U40 is input to the CPU 40, and these signals Qi, V
The waveforms of the welding current Iw and the tip-to-tip voltage V are displayed on the screen of the display 52 based on the above.

As a result, on the screen of the display 52, as shown in FIG. 2, the welding condition waveforms of the pressing force P, the inter-chip voltage V, and the welding current Iw are simultaneously displayed. Among the waveforms of these three phenomena, the voltage V between chips and the welding current Iw
Is the waveform detected in the actual welding sequence, while the waveform of the pressing force P is the waveform detected in the pressing force measurement performed prior to the welding sequence. However, the waveform of the pressing force P is similar in pattern and timing to the waveform obtained in the welding sequence, and is in synchronization with the waveforms of the tip-to-tip voltage V and the welding current Iw. It is as if a monitor screen for quasi-simultaneous waveform observation was obtained, as if these three phenomena P, V and Iw were observed simultaneously and the respective waveforms were displayed together.

From this monitor screen, the worker presses the pressure P
It is possible to know at a glance the timing relationship between the welding conditions V and Iw, which are related to the energization, and the squeeze time TB, hold time TD, etc. Therefore, it is possible to accurately grasp and analyze the current welding sequence, and it is easy to optimize or reset welding conditions.

The waveform display as shown in FIG. 2 may be hard-copied by the printer 54. It is also possible to display only the pressing force P and the welding current Iw, or only the pressing force P and the tip-to-chip voltage V. Also,
In the above-described embodiment, the current Iw flowing through the secondary side circuit of the welding transformer 18 is detected as the welding current and the waveform thereof is displayed, but the current of the primary side circuit may be detected and the waveform may be displayed. The same applies to the voltage. Instead of the inter-chip voltage, the primary side voltage may be detected and the waveform thereof may be displayed. Furthermore, it is also possible to detect the welding power or the resistance value between chips from the welding current and voltage and display the power waveform or the resistance value waveform between chips. Also,
The resistance welding machine of the above-mentioned embodiment was a single-phase AC type,
The present invention can be applied to other types of resistance welding machines such as a three-phase AC type, an inverter type, and a condenser type.

[0026]

The present invention has the following effects by having the above-mentioned configuration. Pressure sensor
In a resistance welding machine that does not incorporate the, the welding force is measured in advance at the same timing as the welding sequence, the welding force waveform is detected, and the welding force waveform is stored in memory. Of the welding conditions (welding current, voltage or power, etc.) of the welding condition are detected, and the detected welding condition waveform of the welding condition and the pressing force waveform stored in the memory are synchronized and simultaneously output. Therefore, the welding force is not measured during actual welding.
Moreover , it is possible to obtain a monitor screen as if the welding conditions related to energization as well as the applied pressure were measured during the welding sequence and they were displayed together. Therefore, the worker can accurately and at a glance the timing relationship (for example, squeeze time, hold time, etc.) between the welding pressure and the welding condition related to the energization in the welding sequence. The welding sequence can be set and adjusted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a resistance welding machine system to which an embodiment of the present invention is applied.

FIG. 2 is a waveform diagram showing a welding condition waveform displayed and output by the resistance welding machine system of the embodiment.

[Explanation of symbols]

 28 Toroidal Coil 30 Waveform Restoring Circuit 34 Amplifying Circuit 40 CPU 42 Pressurizing Device 44 Pressure Meter 50 Keyboard 52 Display 54 Printer 56 Memory

Claims (4)

(57) [Scope of utility model registration request] 1. A resistance welding machine without a pressure sensor incorporated therein.
While applying a predetermined pressure to the work piece,
Monitor welding conditions in a flowing welding sequence
A welding condition monitoring device, wherein only the welding pressure is applied at the same timing as in the welding sequence without passing the welding current to a welding pressure sensor temporarily attached to the resistance welding machine from the outside. Means, a pressurizing force waveform storage means for storing a waveform of the pressurizing force obtained from the pressurizing force sensor to which the pressurizing force is applied, and an energizing relationship for detecting a waveform of welding conditions related to energizing when the welding sequence is executed. Welding condition waveform detection means and the waveform of the welding conditions detected by the energization-related welding condition waveform detection means and the waveform of the pressing force stored in the pressing force waveform storage means are synchronized and simultaneously output for display. A welding condition monitoring device comprising: a waveform display output means. 2. The welding condition monitoring device according to claim 1, wherein the welding condition relating to the energization is a current supplied to a workpiece. 3. The welding condition monitoring device according to claim 1, wherein the welding condition relating to the energization is a voltage supplied to the object to be welded. 4. The welding condition monitoring device according to claim 1, wherein the welding condition relating to the energization is electric power supplied to the object to be welded.