COOLING WATER MANAGEMENT DEVICE AND THE COOLING WATER MANAGEMENT UNIT INCLUDING THIS

Abstract

A cooling water management device (10) that is connectable to an upstream flow meter (18) provided in an upstream water flow passage (R1) for supplying cooling water to a welding gun (14) with an electrode tip (14a, 14b), to a valve (20) provided between a supply source (16) of the cooling water and the upstream flow meter (18) and configured to switch between supply and non-supply of cooling water, and to a downstream flow meter (22) provided in a downstream water flow passage (R2) for discharging the cooling water from the welding gun (14), wherein the cooling water management device (10) comprises the following elements: signal input means (24a) configured to receive input signals from the upstream flow meter (18) and the downstream flow meter (22). To receive flow meter (22),wherein the signals relate to an upstream flow rate and a downstream flow rate of the cooling water; peak cutting detection means (24c) configured to calculate change values ​​per a specified time unit for the upstream flow rate and the downstream flow rate and to detect the cutting of the electrode tip (14a, 14b) when the change values ​​per specified time unit simultaneously satisfy a detection condition preset for the upstream flow rate and the downstream flow rate; and signal output means (24f) configured to output a control signal to close the valve (20) when the peak cutting detection means (24c) detect the cutting of the electrode tip (14a, 14b), wherein the detection condition determines that a condition exists,in which the change value per unit of time of the upstream flow rate is equal to or greater than a change value setting value, and in which the change value per unit of time of the downstream flow rate is equal to or less than a change value setting value that persists for both the upstream and downstream flow rates for a persistence time setting value or more, wherein the persistence value setting value is preset to be longer than the specified time unit.

Description

Background of the invention; Field of the invention

[0001] The present invention relates to a cooling water management device which manages the cooling water supplied to a welding gun, and to a cooling water management unit which contains the cooling water management device. Description of the state of the art:

[0002] Generally, the section of a welding machine used for spot welding that actually performs the welding process is called a welding gun. This welding gun has electrode tips (for example, an electrode rod) and water passages for the supply and drainage of cooling water. In a welding process, the welding gun is moved to a section to be welded, the electrode tips are brought into contact with the workpiece, an electric current is applied, and the heat generated by the contact resistance melts the base material, thus completing the weld. Once a section is welded, the welding gun is immediately moved to the next section, and the process is repeated.

[0003] When welding is repeated, the welding gun and electrode tips accumulate heat and reach a high temperature. Therefore, it is necessary to cool the welding gun and electrode tips. Cooling is achieved by supplying cooling water from a cooling water tank or similar reservoir to the welding gun via a valve (switching valve) using a power source such as a pump.

[0004] In the case of a welding defect, and especially in the case of an excessive welding defect, the electrode tips are fixed to the welded element. When the welding gun moves to the next process, the electrode tips are cut off. The cutting off of the electrode tips, which also act as covers (plugs) of the water flow passage, causes cooling water to leak from the water flow passage, leading to damage to adjacent devices and contamination of the surrounding area. A design is known, for example, in which covers close mechanically to block a water flow passage when an electrode tip is cut off, as described in Japanese patent publication no.09-057464 (hereinafter referred to as JP 1997-057464 A), and a method for measuring a flow rate of cooling water by means of a flow meter, for comparing this flow rate with a constant flow rate value (threshold) and for detecting the separation of the electrode tips, as in Japanese Patent Publication 06-071459 (hereinafter referred to as JP 1994-071459 A). Summary of the invention

[0005] The use of a design that mechanically closes the covers when the electrode tip is disconnected, as in JP 1997-057464 A, complicates the design of the electrode tips and the water flow passage. While this design prevents cooling water leakage, it does not provide a signal indicating when the electrode tips are disconnected.

[0006] If the electrode tips break off, it is necessary to quickly stop the welding machine before moving to the next welding section and to secure the electrode tips. It is also necessary to install a sensor that detects the broken electrode tip state.

[0007] When multiple welding machines are installed in a factory, the cooling water supply branches from a central source (the tank or similar) to each welding machine, and each welding machine typically performs the welding process independently. Therefore, each branched welding machine is in different states, such as a water flow state and a water stop state, and in a state where the effective cross-sectional areas of the water flow passages change from moment to moment as a whole.

[0008] When electrode tips break off in a welding gun, the resistance at the broken section decreases and cooling water leakage begins. This causes an increase in the upstream flow rate and a decrease in the downstream flow rate. If, in this case, the flow meter is installed only upstream or only downstream, as in JP 1994-071459 A, to detect electrode tip breakage when a flow rate exceeds (or falls below) a certain threshold, then in a situation where the effective cross-sectional area of ​​the entire water flow varies from moment to moment as described above, the problem of false detection or non-detection occurs.

[0009] A cooling water supply source is generally a pump, but the pump's output is not necessarily constant. The pump's discharge flow rate varies depending on changes in viscosity caused by ambient temperature or deterioration of the cooling water. Therefore, a method for detecting electrode tip detachment based on a constant flow rate value (threshold) will result in false detection or non-detection, leading to low detection accuracy.

[0010] It is therefore an object of the present invention to propose a cooling water management device which detects with high accuracy the detachment of an electrode tip of a welding gun and minimizes the leakage of cooling water, and a cooling water management unit which includes the cooling water management device.

[0011] According to the present invention, a cooling water management device is proposed, comprising an upstream flow meter provided in an upstream water flow passage configured to supply cooling water to a welding gun with an electrode tip, a valve provided between a cooling water supply source and the upstream flow meter configured to switch between supply and supply stop of the cooling water, and a downstream flow meter provided in a downstream water flow passage configured to discharge the cooling water from the welding gun, wherein the cooling water management device comprises: signal input means configured to receive input signals from the upstream flow meter and downstream flow meter,wherein the signals relate to an upstream flow rate and a downstream flow rate of the cooling water; peak cutting detection means configured to calculate the magnitude of change per unit time of the upstream flow rate and the downstream flow rate and to detect electrode tip cutting when the magnitude of change per unit time simultaneously satisfies a detection condition preset for the upstream flow rate and the downstream flow rate; and signal output means configured to output a control signal to close the valve when the peak cutting detection means detect electrode tip cutting.

[0012] The present invention utilizes a design for detecting electrode tip shedding when the magnitude of the change per defined unit of time in the upstream and downstream flow rates of the welding gun simultaneously fulfills predetermined detection conditions, instead of comparing an upstream or downstream flow rate of the welding gun with a defined threshold value, as in the prior art. Even if the effective cross-sectional areas of the water flow paths in an entire welding process line with multiple, distributed welding guns change from moment to moment and the overall flow rate increases or decreases, it is possible to detect electrode tip shedding with high accuracy and minimize cooling water leakage.

[0013] The cooling water management device according to the present invention may also include: detection state storage means configured to store the detection state; and detection state setting means configured to set the detection state based on an externally entered setting value, and the peak separation detection means may be configured to refer to the detection state stored in the detection state storage means.

[0014] Accordingly, it is possible to set a value that is optionally entered by a user as a detection condition and to easily change the detection conditions.

[0015] In the cooling water management device according to the present invention, the detection state can be configured to maintain a condition in which the magnitude of the change per unit time of the upstream flow rate and the downstream flow rate is equal to or greater than a change value setting that has been configured for the upstream flow rate and the downstream flow rate, respectively, for a persistence time setting or longer, wherein the persistence time setting is preset to be longer than the specified time. This makes it possible to eliminate sudden increases in the magnitude of the change per unit time of the upstream flow rate or the downstream flow rate as noise and thereby prevent false detection.

[0016] In the cooling water management device according to the present invention, the persistence time setting value can be set separately as an upstream persistence time setting value and a downstream persistence time setting value. This feature makes it possible to detect the electrode tip separation with high accuracy even if there is a time delay between the change in the upstream flow rate and the change in the downstream flow rate.

[0017] In the cooling water management device according to the present invention, the tip break-off detection means can be configured to store data relating to the magnitude of the change in the upstream and downstream flow rates, obtained at the time of detection of electrode tip break-off, as a change-time value in a defined memory area. By storing the magnitude of the change in the upstream and downstream flow rates when electrode tip break-off is actually detected, it is possible to use the stored change values ​​as a guide for determining optimal settings for the detection conditions.

[0018] In the cooling water management device according to the present invention, the detection state can include a standby time setting value that represents the duration from the point in time when another control signal is output to open the valve by the signal output means until the point in time when the detection processing of the electrode tip by the tip-cut detection means starts. Even if the flow rate of the cooling water in the water flow path becomes unstable immediately after the valve opens, this excludes a period of such an unstable state as a target detection period, thus making it possible to improve the detection accuracy for electrode tip cut-off.

[0019] According to the present invention, a cooling water management unit is provided comprising: an upstream flow meter provided in an upstream water flow passage, which is configured to supply cooling water to a welding gun with an electrode tip; a valve provided between a supply source of the cooling water and the upstream flow meter, and configured to switch between supplying and not supplying the cooling water;a downstream flow meter provided in a downstream water flow passage configured to discharge cooling water from the welding gun, and a cooling water management device connected to the upstream flow meter, the valve, and the downstream flow meter, wherein the cooling water management device comprises: signal input means configured to receive signal inputs from the upstream flow meter and the downstream flow meter, wherein the signals relate to an upstream flow rate and a downstream flow rate of the cooling water;Tip-cut detection means configured to calculate the magnitude of change per unit time of the upstream flow rate and the downstream flow rate, and to detect tip cut-off when the magnitude of change per unit time simultaneously satisfies a detection condition preset for both the upstream and downstream flow rates; and signal output means configured to output a control signal to close the valve when the tip-cut detection means detect tip cut-off.

[0020] The present invention employs a design for detecting electrode tip shedding when the magnitudes of the changes per unit time in the upstream and downstream flow rates of the welding gun simultaneously meet the preset detection conditions, instead of comparing an upstream or downstream flow rate of the welding gun with a predetermined threshold, as in the prior art. Even if the effective cross-sectional areas of the water flow paths change from moment to moment throughout the entire welding process line with multiple distributed welding guns, and the overall flow rate increases or decreases, it is possible to detect electrode tip shedding with high accuracy and minimize cooling water leakage.

[0021] The cooling water management unit according to the present invention can further comprise: detection state storage means configured to store the detection state; and detection state setting means configured to set the detection state based on an externally entered setting value; and the peak separation detection means can be configured to refer to the detection state stored in the detection state storage means. Accordingly, it is possible to set a setting value that has been optionally entered by a user as a detection state and to easily change the detection conditions.

[0022] In the cooling water management unit according to the present invention, the detection condition can define a state in which the magnitude of the change per unit time of the upstream flow rate and the downstream flow rate is equal to or greater than a preset change value, which is preset for both the upstream and downstream flow rates, and persists for a duration setting value or longer, wherein the duration setting value is preset to be longer than the predetermined time. This feature makes it possible to eliminate sudden increases in the change per unit time of the upstream or downstream flow rate as noise and thereby prevent false detection.

[0023] In the cooling water management unit according to the present invention, the persistence time setting can be adjusted separately as an upstream persistence time setting and a downstream persistence time setting. Even if there is a time delay between the change in the upstream flow rate and the change in the downstream flow rate, it is thus possible to detect the shedding of electrode tips with high accuracy.

[0024] In the cooling water management unit according to the present invention, the tip break-off detection means can be configured to store data relating to the magnitude of the change in the upstream and downstream flow rates, obtained at the time of detection of electrode tip break-off, as a change value at the time of detection in a defined memory area. By storing the magnitude of the change in the upstream and downstream flow rates when electrode tip break-off is actually detected, it is thus possible to use the stored change values ​​as a guide for determining optimal settings for the detection conditions.

[0025] In the cooling water management unit according to the present invention, the detection condition can include a standby time setting value that represents the duration from the point in time when another control signal is output to open the valve by the signal output means until the point in time when the detection processing of the electrode tip by the tip-cut detection means begins. Even if the flow rate of the cooling water in the water flow path becomes unstable immediately after opening the valve, a period of such an unstable state is thus excluded as a target detection period, making it possible to improve the detection accuracy for electrode tip cut-off.

[0026] According to the present invention, it is possible to propose a cooling water management device which detects the detachment of an electrode tip of the welding gun and minimizes the leakage of cooling water, as well as a cooling water management unit which contains the cooling water management device.

[0027] The above and further tasks, features and advantages of the present invention will become even clearer from the following description in conjunction with the accompanying drawings, in which a preferred embodiment of the present invention is illustrated by way of example. List of characters Fig. Figure 1 is a block diagram showing an overall configuration of a cooling water management unit with a cooling water management device according to a first embodiment; Fig. Figure 2 is a perspective external view of the cooling water management device according to Fig. 1; Fig. 3 is a functional block diagram of a control unit located in Fig. 1 is shown; Fig. 4 is a block diagram showing a welding process line in which several are Fig. 1 welding guns shown are provided; Fig. Figure 5 is a diagram showing a special example in which a conventional device detects the tip breaking off; Fig. Figure 6 is a diagram showing a particular example of a faulty detection of tip detachment in the conventional device; Fig. Figure 7 is a diagram showing a special example of non-detection of the tip breaking off in the conventional device; Fig. Figure 8 is a view to illustrate the processing of the tip separation detection at the control unit according to the first embodiment; Fig. 9A is a diagram showing a special example of a time-series change in the flow rate caused by a Fig. 1 upstream flow meter shown, where the flow rate increases stepwise; Fig. 9B is a diagram showing a special example of a time-series change in the flow rate caused by the in Fig. 1 upstream flow meter shown, where the flow rate varies with a certain slope; Fig. Figure 10 is a flowchart that shows a special example of tip separation detection processing by the control unit according to Fig. 1 shows; Fig. Figure 11 is a diagram illustrating the time series change for a signal and a flow rate from the input of a valve opening / closing command until the valve closes; Fig. Figure 12 is a view illustrating the processing of the tip separation detection by the control unit according to a second embodiment; and Fig. Figure 13 is a flowchart showing a particular example of the processing of the tip separation detection by the control unit according to the second embodiment. Description of preferred embodiments

[0028] Preferred embodiments of a cooling water management device and a cooling water management unit with this cooling water management device according to the present invention are described in detail below with reference to the accompanying drawings. <Erste Ausführungsform>

[0029] Fig. 1 is a block diagram showing the overall configuration of a cooling water management unit 12 with a cooling water management device 10 as shown in the first embodiment.

[0030] The cooling water management unit 12 The cooling water management device includes 10 , a welding gun 14 , an upstream flow meter 18 , a valve 20 , a downstream flow meter 22 and a pump 16 , which form a cooling water circulation path.

[0031] The cooling water management device 10 is a device that controls the supply and stop (non-supply) of cooling water to the welding gun 14 in the cooling water management unit 12 managed.

[0032] The welding gun 14 is a section that contains an element W to be welded in the cooling water management unit 12The welding gun 14 actually welds. It includes electrode tips (e.g., electrode rods) 14a, 14b, which generate heat through the supply of current, and water flow passages for the supply / drainage of cooling water (not shown).

[0033] The pump 16 is a cooling water supply source that connects to a cooling water tank (not shown) or similar. The pump 16 is connected to the water flow passages (not shown) within the welding gun 14 via a water flow passage R1 (referred to as an upstream water flow passage) which is provided upstream of the welding gun 14, and a water flow passage R2 (hereinafter referred to as a downstream water flow passage) which is provided downstream.

[0034] The upstream water flow passage R1 includes the upstream flow meter.18 , which determines the flow rate of the cooling water upstream of the welding gun 14 detected, and the valve 20 , the upstream of the upstream flow meter 18 is arranged and between the supply and non-supply of cooling water to the welding gun 14 switches.

[0035] The downstream water flow passage R2 includes the downstream flow meter. 22 , which determines the flow rate of the cooling water downstream of the welding gun 14 detected.

[0036] The upstream flow meter 18 and the downstream flow meter 22 are sensors that output signals according to the flow rates of the cooling water (in Fig. (1) referred to as "upstream flow rate input" and "downstream flow rate input". The signals are converted into voltage values ​​in a range of 1.0 to 5.0 V, so that they are proportional to, for example, a flow rate value, and output. The signal conversion method is not limited to this. For example, a pulse signal with a frequency proportional to the flow rate value can also be output.

[0037] The cooling water management device 10 includes a control unit 24 , a first connecting piece (connector) 26 , a second connecting piece 28 , a third connecting piece 30 , a fourth connecting piece 32 and a fifth connecting piece 34 .

[0038] The control unit 24 is a small control device, for example a microcomputer, and with the first connecting piece26 , the second connecting piece 28 , the third connecting piece 30 , the fourth connecting piece 32 and the fifth connecting piece 34 tied together.

[0039] The control unit 24 includes various programs that focus on a function for detecting the detachment of the electrode tips 14a , 14b , a function of inputting and outputting signals, a function of controlling the screen display, etc.

[0040] The first connecting piece 26 is a connector through which a valve opening / closing current, for example 24 V DC, is applied between the connector and an earth terminal (GND) from an external device (not shown) (in Fig. 1 referred to as "valve opening / closing current input"), and various parameters (setting values) that can be optionally entered by a user on the external device (in Fig. 1 referred to as "parameter input"). In this respect, the valve opening / closing current input also means the input of a start signal to activate the control unit. 24 .

[0041] The second connecting piece 28 is a connector through which external current ( 24 V direct current) is input, and a status signal which indicates the state of the welding gun. 14 The display is based on the data provided by the control unit. 24 The control carried out is output to the external device (in Fig. 1 referred to as the “state signal output”). In this state signal, “on” indicates that welding is permitted, and “off” indicates that welding is not permitted.

[0042] The third connecting piece 30 is a connecting piece that goes via the control unit 24 with the first connecting piece 26 is connected and a voltage value signal of the valve opening / closing current is used as a valve control signal to switch between opening and closing the valve. 20 based on the control unit 24 outputs the performed control (in Fig. 1 referred to as the "valve opening / closing current output"). For example, if the valve opening / closing current output is on to apply a voltage of 24 V to the valve. 20 to apply the valve 20 open. Conversely, if the valve opening / closing current output is off, the voltage is at 0 V, so the valve is closed. 20 is closed.

[0043] The fourth connecting piece 32is a connector through which a signal is input that represents a cooling water temperature from a temperature sensor (not shown) located near or within the upstream flow meter 18 is arranged, displays (in Fig. 1 (referred to as "temperature input"). A signal indicating an upstream flow rate of the cooling water in the upstream water flow passage R1 is provided by the upstream flow meter. 18 entered (in Fig. 1 referred to as “upstream flow rate input”).

[0044] The fifth connecting piece 34 is a connecting piece through which a signal from the downstream flow meter is transmitted. 22 is entered, which displays the downstream flow rate of the cooling water in the downstream water flow passage R2 (in Fig. 1 referred to as “downstream flow rate input”).

[0045] Fig. 2 is a perspective exterior view of the in Fig. 1 shown cooling water management device 10 The first connecting piece 26 described above, second connecting piece 28 , third connecting piece 30 , fourth connecting piece 32 and fifth connecting piece 34 are on a side surface on a front surface in Fig. 2 arranged.

[0046] A flow rate display monitor 36 , which is measured by the upstream flow meter 18 and the downstream flow meter 22 displays received flow rate values, and an input switch 38 , which is a display setting of the flow rate display monitor 36 The switches are located on a left side of an upper surface of the cooling water management device 10.

[0047] A temperature display monitor 40 , which displays temperature data of the cooling water in the upstream flow passage R1, obtained from the temperature sensor (not shown), and an input switch 42 , which is a display setting of the temperature display monitor 40 The switches are located on the right side of the upper surface.

[0048] Fig. 3 is a functional block diagram of the in Fig. 1. Control unit 24 shown. The control unit 24 includes a signal input unit (signal input means) 24a , a cooling water monitoring unit 24b , a tip separation detection unit (tip separation detection device) 24c , a storage unit (detection condition storage device) 24d , a setting unit (detection condition setting device) 24e , a signal output unit (signal output device) 24f and a display control unit24g .

[0049] The signal input unit 24a receives the input of signals (the upstream input and the downstream input) relating to the upstream flow rate and the downstream flow rate of the cooling water from the upstream flow meter. 18 and the downstream flow meter 22 and sends the signals to the cooling water monitoring unit 24b out. In addition, the signal input unit receives 24a The temperature sensor (not shown) receives an input signal (temperature input) relating to a cooling water temperature in the upstream water flow passage R1, and sends the signal to the cooling water monitoring unit. 24b out of.

[0050] In addition, the signal input unit receives 24aThe input of a valve opening / closing current from the external device and outputs the valve opening / closing current to the signal output unit. 24f out of.

[0051] The cooling water monitoring unit 24b converts the signals (the upstream input and the downstream input) relating to the upstream flow rate and the downstream flow rate, which are supplied by the signal input unit 24a The input data is converted into cooling water flow rate data and the flow rate data is sent to the peak separation detection unit. 24c and the display control unit 24g out of.

[0052] Furthermore, the cooling water monitoring unit converts 24b the signal (temperature input) that relates to the cooling water temperature and is received by the signal input unit 24a The input is converted into temperature data and the temperature data is sent to the display control unit.24g out of.

[0053] The tip separation detection unit 24c calculates the magnitude of the change per defined unit of time in the upstream flow rate and the downstream flow rate and detects the separation of the electrode tips. 14a , 14b , if these change values ​​simultaneously meet detection conditions that were preset for the upstream flow rate and the downstream flow rate.

[0054] In the present embodiment, the tip separation detection unit 24c performs detection processing by referring to the detection conditions that are described in the storage unit described later. 24d are stored. Alternatively, the detection conditions can be defined in a program.

[0055] The tip separation detection unit 24c includes a storage 24h, which stores a history of the upstream flow rate and the downstream flow rate from a specified elapsed time, and a counter 24i , which measures elapsed time.

[0056] In the present embodiment, the upstream flow rate and the downstream flow rate are maintained in a specific cycle, and thus the storage capacity is also maintained. 24h updated in the same cycle. The memory 24h It maintains a history of flow rates over the specified cycle.

[0057] The storage unit 24d stores the detection conditions to which the tip separation detection unit refers. 24c during the processing of the detection of the electrode tip separation 14a , 14bThe detection conditions according to the present embodiment include a sustained time setting, a standby time setting (stabilization wait time setting), and a change value setting for the magnitude of the change over a specific defined time for both the upstream and downstream flow rates. Each setting is optional.

[0058] The setting unit 24e sets (registers / updates) the detection conditions for the storage unit 24d based on an externally entered setting value (parameter input). The setting value can be entered when the flow rate display monitor is open. 36 and the input switch 38 , which in Fig. 2 are shown, to be used.

[0059] There are various methods for entering the settings. For example, the user-defined change value settings for the upstream and downstream flow rates are displayed as values ​​that the user can easily enter and verify on a screen. The values ​​are converted according to a scale of the measured value to set the change value settings.

[0060] It takes a while for the flow rate to stabilize, so a standby time (stabilization wait time) is entered as a user setting. This standby time setting can be configured in milliseconds (ms), and the value is converted into a counter based on the duration of a measurement cycle, after which the processing is carried out.

[0061] If the tip separation detection unit24c separating the electrode tips 14a , 14b The signal output unit detects this. 24f a control signal (state signal output) to close the valve 20 off. The signal output unit 24f It provides a control signal (valve opening / closing current output) to open the valve. 20 based on the valve opening / closing current input.

[0062] The display control unit 24g controls the display content of the flow rate display monitor 36 and the temperature display monitor 40 based on output from the cooling water monitoring unit 24b and the tip separation detection unit 24c For example, if the tip separation detection unit 24c separating the electrode tips 24a , 24b The flow rate display monitor detects this. 36 preferably a warning.

[0063] Fig. 4 is a block diagram showing a welding process line in which several welding guns 14 , which in Fig. 1 are shown, are provided. In addition, it shows Fig. 4, that the branched upstream water flow passage R1 and the branched downstream water flow passage R2 between the common pump 16 and the several welding guns 14 are trained. The valve 20 , the upstream flow meter 18 and the downstream flow meter 22 are for each of the several welding guns 14 planned. Thus, the cooling water management unit will be 12 through the welding gun 14 formed. Thus, the multiple cooling water management units 12 the valves 20 Independently controlled. Therefore, the valves 20in different states, for example a water flow state and a water stop state, and the effective total cross-sectional area of ​​the water flow passages varies from moment to moment.

[0064] Next, the processing of the tip separation detection of the electrode tips will be carried out. 14a , 14b in a conventional device and the processing of the peak separation detection in the cooling water management device 10 compared and described according to the present invention.

[0065] Fig. Figure 5 is a diagram showing a specific example where the conventional device detects tip shedding. In the diagram, the upper part shows a relationship between time and flow rate, and the lower part shows a relationship between time and a control signal for opening and closing the valve. 20in the same chronological order. When the valve 20 When the valve is opened at time t0 (valve opening / closing current output: on), the flow rate remains at a constant level until time t1. After time t1, the flow rate increases and then reaches a defined threshold value Q1 or higher at time t2. At time t2, the valve is then opened. 20 so that it is closed (valve opening / closing power output: off). Thus, it shows Fig. 5, that if at time t1 a tip breaks off, a control is carried out to detect the tip breaking off at time t2 and to interrupt the supply of cooling water.

[0066] Fig. Figure 6 is a diagram showing a specific example of a faulty detection of tip separation in the conventional device. If the valve 20When the valve opens at time t0 (valve opening / closing current output: on), the flow rate remains constant until time t1. After time t1, the flow rate increases. However, the flow rate is lower than the defined threshold Q1. In such a case, the conventional device cannot detect tip separation until the flow rate reaches or exceeds the threshold Q1, even if tip separation actually occurs at time t1.

[0067] Fig. Figure 7 is a diagram showing a specific example of tip breakage failure in the conventional device. While the flow rate is constant between time t0 and time t1, the flow rate at time t0 is at or above the set threshold Q1, and therefore the valve 20The valve is closed at time t0 (valve opening / closing power output: off). Even if the tip cutting actually occurs at time t1, the flow rate already reaches or exceeds the threshold Q1 at time t0 due to an increase in the flow rate caused by a factor other than tip cutting. In such a case, the tip cutting is not detected. For example, if a valve 20 If the flow rate in one unit of the welding process line with the branched water flow passages is closed, it is assumed that the flow rate in the other units increases.

[0068] Fig. Figure 8 is a view to illustrate the processing of the tip separation detection in the tip separation detection unit. 24c the control unit 24 according to the first embodiment. Upstream, a subtractor calculates 24ja difference value dA between an upstream flow rate A, which is currently measured by the upstream flow meter 18 is measured, and a flow rate value that is measured before a predetermined time (a specific time) and stored in the memory 24h is stored. A comparator 24k The COMPARATOR compares this difference value dA with a change value setting THa for the upstream flow rate value A, which was previously set by the user. If the difference value dA is equal to or greater than the change value setting THa (dA ≥ THa), the comparator returns 24k a result “H”.

[0069] Similarly, a subtractor calculates 24I downstream, a difference value dB between a downstream flow rate value B, which is currently measured by the downstream flow meter 22is measured, and a flow rate value that was measured at a past predetermined time and stored in the memory 24h was saved. A comparator 24m The comparator compares this difference value (dB) with a change value setting (THb) for the downstream flow rate value (B), which was previously set by the user. If the difference value (dB) is equal to or less than a change value setting (THb) (dB ≤ THb), the comparator outputs 24m the result of the determination is “H”.

[0070] If the determination results on the upstream and downstream sides are connected to an AND circuit 24p The counter starts when "H" is entered. 24iThe measurement of the persistence time (duration) of the two "H" states. If both "H" states persist for a period equal to or greater than a persistence time setting value Tc, which is set by the user, the electrode tips are disconnected. 14a , 14b recognized (detected).

[0071] If, on the other hand, one or both of the determination results of the upstream side and the downstream side switch to "L" before the counter reading 24i When the persistence time setting value Tc is reached, the electrode tips are cut off. 14a , 14b not recognized.

[0072] The Fig. 9A and Fig. 9B are diagrams which show special examples of the time series changes of the data caused by the data in Fig. 1 upstream flow meter shown 18 show measured flow rate. Fig. 9A is a diagram for a case where the flow rate increases stepwise. Fig. 9B is a diagram for a case where the flow rate changes with a certain slope.

[0073] In a case according to Fig. 9A The flow rate suddenly increases at time t1 and is subsequently held at a constant level. Accordingly, a change value (magnitude of change) between a current flow rate and a flow rate obtained at a predetermined time in the past was calculated between time t1 and time t2. After time t2, the change value is zero.

[0074] Therefore, if the flow rate increases at time t1, it is likely that the tip separation was detected erroneously.

[0075] In the case of Fig. 9B The flow rate changes (increases) with a certain slope from time t1 to time t3 and then remains constant after time t3. If the rate of change is determined over a short period, it is therefore likely that the tipping point was detected erroneously.

[0076] In contrast, the detection conditions in the present embodiment include the persistence time setting value. Accordingly, it is possible to prevent the erroneous detection of tip detachment in both cases. Fig. 9A and Fig. To avoid 9B.

[0077] The operating mode and function of the cooling water management device 10 , which is structured in the manner described above, is referred to in relation to the Fig. 10 and Fig. 11 described.

[0078] Fig. Figure 10 is a flowchart that shows a special example of peak detection processing in the control unit. 24 This processing is carried out in a predetermined cycle after the valve opening / closing current (start signal) is received by the control unit. 24 was entered. In this respect, a variable A, a variable B, a variable mA and a variable mB indicate the upstream flow rate A, the downstream flow rate B, an upstream storage value mA and a downstream storage value mB, respectively.

[0079] If in step S1 the upstream flow meter 18 and the downstream flow meter 22 The control unit receives signals proportional to the measured upstream flow rate value A and the downstream flow rate value B, which are output by the signals. 24 (Signal input unit) 24a) the input of the signals.

[0080] In step S2, the control unit converts 24 (tip separation detection unit) 24c ) the signals of the last upstream flow rate value A and the downstream flow rate value B, which are provided by the upstream flow meter 18 and the downstream flow meter 22 were entered, and then the converted signals are stored as the upstream memory value mA and the downstream memory value mB in the memory. 24h .

[0081] In step S3, the control unit calculates 24 (Peak separation detection unit 24c), the difference values ​​dA, dB between the last flow rate values ​​stored in the memory 24hThe system stores stored data and measured values ​​taken at a specific, elapsed time (for example, an adjustable time n on the order of milliseconds). If the measured values ​​obtained at the elapsed time n are denoted by mA(n) and mB(n), the difference values ​​dA and dB on the upstream and downstream sides are calculated as dA = A - mA(n) and dB = B - mB(n). These difference values ​​dA and dB correspond to the rate of change (slope) of the flow rate per unit time.

[0082] In step S4, the control unit determines 24(Peak separation detection unit 24c), whether the difference value dA calculated in step S3 is equal to or greater than the change value setting THa for the upstream flow rate value A, which was preset to a positive value (> 0), or not, and whether the difference value dB is equal to or less than the change value setting THb for the downstream flow rate value B, which was preset to a negative value (< 0), or not.

[0083] If step S4 determines that the setting condition is met (step S4: YES), the control proceeds to step S5. If it determines that the setting condition is not met (step S4: NO), the control proceeds to step S8.

[0084] In step S5, the control unit determines 24(Peak separation detection unit 24c), whether a persistence time T, for which a state in which the difference value dA is equal to or greater than the change value setting value THa and the difference value dB is equal to or less than the change value setting value THb persists, remains equal to or greater than the preset persistence setting value Tc or not.

[0085] If step S5 determines that the desired state is met (step S5: YES), the control system proceeds to step S6. If it determines that the desired state is not met (step S5: NO), the control system proceeds to step S8.

[0086] In step S6, the control unit determines 24 (Tip separation detection unit 24c), that the change values ​​of the flow rates of the cooling water on the upstream side and the downstream side of the welding gun 14are abnormal, that is, that the electrode tips 14a, 14b on the welding gun are separated. 14 has occurred.

[0087] In step S7, the control unit controls 24 (tip separation detection unit) 24c ) the valve opening / closing current output from the signal output unit 24f based on the determination result in step S6, such that it is in an OFF state in order to thereby close the valve 20 to close. Then the processing will end.

[0088] In the meantime, the control unit determines 24 (tip separation detection unit) 24c ) in step S8, that the change values ​​of the flow rates of the cooling water on the upstream side and the downstream side of the welding gun 14 If they are not abnormal, then the processing will be stopped.

[0089] Fig. Figure 11 is a diagram illustrating the input / output of a signal and the change in flow rate from the time of input of the valve opening / closing current until the time of valve closing. 20 . Fig. Figure 11 shows the relationships of the on / off of the valve opening / closing current input (start signal), the on / off of the valve opening / closing current output to the valve 20, the upstream flow rate, the downstream flow rate and the on / off of the state signal output on a vertical axis relative to time on a horizontal axis.

[0090] From time t0 to time t1, the valve opening / closing current input and output are in an OFF state, and therefore the valve is 20It is controlled so that it is in an OFF state (closed). At this time, both the upstream flow rate and the downstream flow rate remain zero, and the status signal output is also in an OFF state (meaning welding is not possible).

[0091] At time t1, the valve opening / closing current input and output are switched to an ON state, and the valve is accordingly closed. 20 The valve is controlled so that it is in an ON state (open). Then the upstream and downstream flow rates increase, and the flow rates are stable at time t2. However, between time t1 and time t2, the status signal output remains in an OFF state (welding is not allowed). This indicates that immediately after the valve opens... 20the upstream flow rate and the downstream flow rate are not yet stable, and that the processing of the detection of the electrode tip separation 14a , 14b until a standby time setting value (stabilization wait time setting value) Ts has elapsed, the process is not started.

[0092] Between time t2 and time t3, the upstream and downstream flow rates remain at constant levels, and therefore the state signal output is in an ON state (welding is allowed). From time t3 onwards, however, the upstream flow rate increases and the downstream flow rate decreases.

[0093] Between time t3 and time t4, the change values ​​per defined time unit of the upstream flow rate and the downstream flow rate are calculated. Depending on whether a condition persists for the continuation time setting Tc or longer, in which the change value per defined time unit of the upstream flow rate is equal to or greater than the upstream flow rate setting and the change value per defined time unit of the downstream flow rate is equal to or less than the downstream flow rate setting, is determined whether the welding gun 14 separating the electrode tips 14a , 14b has occurred or not.

[0094] At time t4, the electrode tips are being separated. 14a , 14bdetected (recognized) and then the valve opening / closing current output is switched to an OFF state (closed), the status signal output is also switched to an OFF state (welding is not allowed) and the upstream flow rate and the downstream flow rate decrease over time.

[0095] Thus, the cooling water management device utilizes 10 According to the present embodiment, a method for detecting the separation of the electrode tips 14a , 14b , if the change value per fixed time unit of the upstream and downstream flow rates of the welding gun 14 simultaneously meet defined detection conditions, instead of, as in the prior art, the upstream or downstream flow rates of the welding gun. 14to compare with a defined threshold value. Even if the effective cross-sectional areas of the water flow passages vary throughout the entire welding line, in which several welding guns are used. 14 Since the distributed flow rates change from moment to moment and the overall flow rate increases or decreases, it is accordingly possible to detect the separation of the electrode tips 14a, 14b with high accuracy and to minimize the leakage of cooling water.

[0096] By installing in the control unit 24 the program for detecting the detachment of the electrode tips 14a , 14b If implemented in advance, it is possible to output a valve control signal to stop the supply of cooling water when the predetermined detection conditions are met. Accordingly, it is not necessary to provide a sensor that detects the electrode tip shedding. 14a , 14b the welding gun 14detected, and it is possible to simplify the setup. <Zweite Ausführungsform>

[0097] Fig. Figure 12 is a view to illustrate how the control unit processes the detection of the tip separation. 24 according to the second embodiment. In this respect, the same reference numerals as those used in the first embodiment denote the same objects, and therefore their description is omitted here. Deviating sections are described in detail.

[0098] On the upstream side in Fig. The subtractor calculates 12. 24j the difference value dA between the upstream flow rate value A, which is currently measured by the upstream flow meter 18 is measured, and the flow rate value, which is measured at a past, predetermined time and stored in the memory 24hwas stored. The Comparator 24k compares this difference value dA with the change value setting THa for the upstream flow rate value A, which was previously set by the user. If the difference value dA is equal to or greater than the change value setting THa (dA ≥ THa), the Comparator 24k the result of the determination is “H”.

[0099] If the comparator 24k When the result "H" is displayed, the counter begins. 24i The meter measures the duration of the state "H". If the duration becomes equal to or greater than the upstream duration setting value Ta, which was set by the user, the meter determines 24i , indicating that an abnormality exists on the upstream side, and outputs the result “H”.

[0100] Similarly, the subtractor calculates 24Ion the downstream side, the difference value dB between the downstream flow rate value B, which is currently measured by the downstream flow meter 22 is measured, and a flow rate value that was measured at a past, predetermined time and stored in the memory 24h was saved. The comparator 24m The comparator compares this difference value (dB) with the change value setting THb of the downstream flow rate value B, which was previously set by the user. If the difference value (dB) is equal to or less than the change value setting THb (dB ≤ THb), the comparator outputs 24m the result of the determination is “H”.

[0101] If the comparator 24m When the result "H" is displayed, the counter begins. 24iThe meter measures the duration of the state "H". If the duration becomes equal to or greater than the downstream duration setting value set by the user, the meter determines 24i , indicating that an abnormality exists on the downstream side, and outputs the result "H". If both results on the upstream and downstream sides are positive, the AND gate... 24b If the values ​​entered are equal to "H", then the electrode tips will not be separated. 14a , 14b recognized.

[0102] Thus, in the first embodiment, the persistence setting value Tc, which is one of the detection conditions, is defined jointly for both the upstream and downstream sides. The second embodiment, however, differs from the first in that the persistence time settings Ta and Tb are defined individually and separately on the upstream and downstream sides.

[0103] Fig. Figure 13 is a flowchart which is a special example of tip separation detection processing in the control unit. 24 as shown in the second embodiment. This processing is carried out in a defined cycle after the valve opening / closing current (start signal) is received by the control unit. 24was entered. In this respect, the variables A, B, mA and mB denote the upstream flow rate value A, the downstream flow rate value B, an upstream storage value mA and a downstream storage value mB, respectively.

[0104] If the upstream flow meter 18 and the downstream flow meter 22 The control unit receives signals proportional to the measured upstream flow rate value A and downstream flow rate value B. 24 (Signal input unit) 24a ) in step S11 the input of these signals.

[0105] In step S12, the control unit converts 24(Peak detection unit 24c) the signals of the last upstream flow rate value A and downstream flow rate value B, which are from the upstream flow meter 18 and the downstream flow meter 22 The converted signals are entered and are stored as the upstream memory value mA and the downstream memory value mB in the memory. 24h .

[0106] In step S13, the control unit calculates 24 (Peak separation detection unit 24c) the difference values ​​between the last flow rate values ​​that were in the storage 24hThe system stores stored data and measured values ​​taken at a predetermined time (for example, an adjustable time n on the order of milliseconds). If the measured values ​​at the past time n are represented by mA(n) and mB(n), the difference values ​​dA and dB of the upstream and downstream sides are calculated as dA = A - mA(n) and dB = B - mB(n). These difference values ​​dA and dB correspond to the magnitude of the change (change values) per unit of time in the flow rates (slope). When step S13 is complete, processing in step S14 and processing in step S18 are started in parallel.

[0107] In step S14, the control unit determines 24(peak separation detection unit 24c), whether the difference value dA calculated in step S13 is equal to or greater than the change setting value THa for the upstream flow rate value A, which was preset to a positive value (> 0).

[0108] If step S14 determines that the condition is met (step S14: YES), the control proceeds to step S15. If it determines that the condition is not met (step S15: NO), the control proceeds to step S17.

[0109] In step S15, the control unit determines 24 (peak cutoff detection unit 24c), whether a persistence time T1, in which a state in which the difference value dA is equal to or greater than the change setting value THa, remains equal to or greater than the preset persistence time setting value Ta for the upstream side or not.

[0110] If step S15 determines that the condition is met (step S15: YES), the control proceeds to step S16. If it determines that the condition is not met (step S15: NO), the control proceeds to step S17.

[0111] In step S16, the control unit determines 24 (tip separation detection unit 24c), that the change value of the flow rate of the cooling water upstream of the welding gun 14 This is abnormal. Then the control continues to S22.

[0112] In step S17, the control unit determines 24 (tip separation detection unit 24c), that the change value of the flow rate of the cooling water upstream of the welding gun 14 This is not abnormal, and the processing will be terminated.

[0113] In step S18, the control unit determines 24(peak separation detection unit 24c), whether the difference value dB calculated in step S13 is equal to or less than the change value setting value THb for the downstream flow rate value B, which was preset to a negative value (< 0), or not.

[0114] If step S18 determines that the condition is met (step S18: YES), the control proceeds to step S19. If it determines that the condition is not met (step S18: NO), the control proceeds to step S21.

[0115] In step S19, the control unit determines 24 (Peak cutoff detection unit 24c), whether a persistence time T2, in which a state in which the difference value dB is equal to or less than the change value setting value THb remains equal to or greater than the preset persistence setting value Tb for the downstream side, or not.

[0116] If step S19 determines that the condition is met (step S19: YES), the control proceeds to step S20. If it determines that the condition is not met (step S19: NO), the control proceeds to step S21.

[0117] In step S20, the control unit determines 24 (tip separation detection unit 24c), that the change value of the cooling water flow rate downstream of the welding gun 14 This is abnormal. Then the control system proceeds to step S22.

[0118] In step S21, the control unit determines 24 (tip separation detection unit 24c), that the change value of the cooling water flow rate downstream of the welding gun 14 This is not abnormal, and the processing will be terminated.

[0119] In step S22, the control unit determines 24(tip separation detection unit 24c), that the change values ​​of the cooling water flow rates both upstream and downstream of the welding gun 14 are abnormal. If step S22 determines that the condition is met (step S22: YES), the control proceeds to step S23. If it determines that the condition is not met (step S22: NO), processing is terminated.

[0120] In step S23, the control unit controls 24 (tip separation detection unit) 24c ) the valve opening / closing current output from the signal output unit 24f so that it is in an OFF state, based on a determination result in step S22, according to which the change value of the flow rate in the welding gun 14 abnormal means that the electrode tips are detached 14a , 14b occurs, and closes the valve 20and then the processing is terminated.

[0121] Thus, the cooling water management device 10 According to the second embodiment, the persistence time setting value, which is one of the detection conditions, is defined separately as two types: an upstream persistence time setting value Ta and a downstream persistence time setting value Tb. This makes it possible to detect the separation of the electrode tips with high accuracy even if there is a time delay when the flow rate changes on the upstream and downstream sides. [Modification]

[0122] The embodiments described above employ a design in which, if the electrode tips are to be separated, 14a , 14b When detected, a control signal is sent to close the valve. 20 is output, and the flow rate display monitor 36Displays a detection result. However, there can also be a function to store a maximum value of an upstream flow rate change value and a minimum value of the upstream flow rate change value after the flow rates have stabilized.

[0123] For example, the tip separation detection unit 24c Store data relating to the upstream flow rate and the downstream flow rate at the time of detection of electrode tip separation. 14a , 14b are obtained as flow rates at the time of detection in corresponding predetermined storage areas (for example, the storage unit). 24d , the storage 24h etc.).

[0124] By storing the data relating to the flow rates when the electrode tips are cut off. 14a , 14bIf a flow rate is actually detected, it is possible to set an optimal value for the detection conditions. A program for statistically analyzing the stored flow rates during detection and automatically setting an optimal value can be integrated into the control unit. 24 It should be included.

[0125] The cooling water management device 10 and the cooling water management unit 12 with the cooling water management device 10 According to the present invention, the designs are not limited to the embodiments described above and can employ various configurations without departing from the scope of the present invention. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 9057464 A [0004, 0005] JP 06071459

[0004] JP 1994071459 A

[0004] JP 6071459 A

[0008]

Claims

[1] A cooling water management device (10) which is connected to an upstream flow meter (18) provided in an upstream water flow passage (R1) for supplying cooling water to a welding gun (14) with an electrode tip (14a, 14b), to a valve (20) provided between a supply source (16) of the cooling water and the upstream flow meter (18) and configured to switch between supplying and not supplying the cooling water, and to a downstream flow meter (22) provided in a downstream water flow passage (R2) for discharging the cooling water from the welding gun (14), wherein the cooling water management device (10) comprises the following elements: Signal input means (24a) configured to receive input of signals from the upstream flow meter (18) and the downstream flow meter (22), wherein the signals relate to an upstream flow rate and a downstream flow rate of the cooling water; Tip-cut detection means (24c) configured to calculate change values ​​per a specified time unit for the upstream flow rate and the downstream flow rate and to detect the cut-off of the electrode tip (14a, 14b) when the change values ​​per specified time unit simultaneously satisfy a detection condition preset for the upstream flow rate and the downstream flow rate; and Signal output means (24f) configured to output a control signal to close the valve (20) when the tip separation detection means (24c) detect the separation of the electrode tip (14a, 14b). [2] The cooling water management device (10) according to claim 1 further comprising: Detection condition storage means (24d) designed to store the detection conditions; and Detection condition setting means (24e) designed to set the detection condition on the basis of an externally entered setting value, wherein the tip separation detection means (24c) are designed to refer to the detection condition stored in the detection condition storage means (24d). [3] The cooling water management device (10) according to claim 1 or 2, wherein the detection condition determines that a state exists in which the change values ​​per unit of time of the upstream flow rate and the downstream flow rate are equal to or greater than a change value setting value that persists for both the upstream flow rate and the downstream flow rate for a persistence time setting value or more, wherein the persistence value setting value is preset to be longer than the specified time. [4] The cooling water management device (10) according to claim 3, wherein the persistence value setting value is set separately as an upstream persistence time setting value and a downstream persistence time setting value. [5] The cooling water management device (10) according to any one of claims 1 to 4, wherein the tip separation detection means (24c) are designed to store data relating to the change values ​​of the upstream flow rate and the downstream flow rate obtained at a time of detection of electrode tip separation (14a, 14b) as a change value at a detection time in a defined storage area. [6] The cooling water management device (10) according to any one of claims 1 to 5, wherein the detection condition includes a standby time setting value which represents a time period from a time of output of another control signal to open the valve (20) by the signal output means (24f) to a time of commencement of the detection processing of the electrode tip (14a, 14b) by the tip separation detection means (24c). [7] A cooling water management unit (12) with: an upstream flow meter (18) which is provided in an upstream water flow passage (R1) for the supply of cooling water to a welding gun (14) with an electrode tip (14a, 14b); a valve (20) which is provided between a supply source (16) of the cooling water and the upstream flow meter (18) and is designed to switch between the supply and the non-supply of the cooling water; a downstream flow meter (22) which is provided in a downstream water flow passage (R2) for the removal of cooling water from the welding gun (14); and a cooling water management device (10) connected to the upstream flow meter (18), the valve (20) and the downstream flow meter (22), wherein the cooling water management device (10) comprises the following: Signal input means (24a) configured to receive a signal input from the upstream flow meter (18) and the downstream flow meter (22), wherein the signals relate to an upstream flow rate and a downstream flow rate of the cooling water; Tip-cut detection means (24c) configured to calculate change values ​​per a specified time of the upstream flow rate and the downstream flow rate and to detect the cutting of the electrode tips (14a, 14b) when the change values ​​per specified time simultaneously satisfy a detection condition that has been preset for both the upstream flow rate and the downstream flow rate; and Signal output means (24f) configured to output a control signal to close the valve (20) when the tip separation detection means (24c) detect the separation of the electrode tips (14a, 14b). [8] The cooling water management unit (12) according to claim 7, further comprising: Detection condition storage means (24d) designed to store the detection condition; and Detection condition setting means (24e) designed to set the detection condition on the basis of an externally entered setting value, wherein the tip separation detection means (24c) are equipped such that they refer to the detection condition stored in the detection condition storage means (24d). [9] The cooling water management unit (12) according to claim 7 or 8, wherein the detection condition determines that a state in which the change values ​​per unit time of both the upstream flow rate and the downstream flow rate are equal to or greater than a change value setting value preset for the upstream flow rate and the downstream flow rate persists for a persistence time setting value or longer, wherein the persistence time setting value has been preset to be longer than the specified time. [10] The cooling water management unit (12) according to claim 9, wherein the persistence time setting value is set separately as an upstream persistence time setting value and a downstream persistence time setting value. [11] The cooling water management unit (12) according to one of claims 7 to 10, wherein the tip separation detection means (24c) are configured to store data relating to the change values ​​of the upstream flow rate and the downstream flow rate obtained at a time of detection of electrode tip separation (14a, 14b) as a change value at the time of detection in a defined storage area. [12] The cooling water management unit (12) according to one of claims 7 to 11, wherein the detection condition includes a standby time setting value that represents a time period from a time of output of another control signal to open the valve (20) by the signal output means (24f) to a time of commencement of the detection processing of the electrode tip (14a, 14b) by the tip separation detection means (24c).

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