JP2000061649A - Pressure meter for electric resistance welding equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the pressure force of an electrode that is imparted to an object to be welded during the actual production and to give an alarm at the time of abnormality. SOLUTION: The cross section area of a cylinder 3 for pressurizing an electrode is inputted from a cross section input setting unit 8, with the air pressure of the cylinder 3 detected by an air pressure detector 6. A pressure force arithmetic processor 7 calculates a pressure force actuating on electrodes 1, 2 on the basis of the air pressure and the cross section, showing the pressure force on a pressure force display unit 9. If the pressure force so calculated deviates from the area set by an upper/lower limit pressure force setting unit 11, an alarm device 12 sounds an alarm. A pressure force during the actual production can be constantly grasped.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure gauge for an electric resistance welding machine used for measuring a pressure applied to an electrode of the electric resistance welding machine. is there. 2. Description of the Related Art Generally, it is said that welding conditions which determine welding quality by an electric resistance welding machine include three major conditions: a pressing force, a welding current, and a conduction time. Of these, a hydraulic pressure gauge is often used for measuring the pressure. In this pressure gauge, the pressure is measured by sandwiching the pressure receiving portion between the electrodes of an electric resistance welding machine in a state where the welding current is cut off, and slowly operating the electrodes by a cylinder to press the pressure receiving portion. It is a portable device that performs. Oil is sealed in the inside, and the support needle is moved according to the load received by the pressure receiving portion. However, since this conventional pressure gauge must perform measurement while operating the electrode slowly with the welding current turned off, it is difficult to use it for the purpose of adjusting the pressure before the start of welding work. Although suitable, it is not possible to measure the pressure during the actual welding process. For this reason, it has not been possible to grasp fluctuations or shortages in the pressurizing force due to abnormality or failure of the air pressure source occurring during actual production. Further, as described above, in order to avoid damage to the pressure gauge, the electrodes must be moved at a much lower speed than usual, and there is a problem that operation and handling are troublesome. Therefore, conventionally, it takes a long time every time the workpiece is changed, and it is necessary to adjust the pressing force. SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems, and can accurately measure the pressure of an electrode applied to a workpiece during actual production. The purpose of the present invention is to provide a pressure gauge for an electric resistance welding machine capable of immediately issuing an alarm when a pressure abnormality occurs. A pressure gauge for an electric resistance welding machine according to the present invention, which has been made to solve the above-mentioned problems, detects the air pressure of a cylinder for pressurizing an electrode of the electric resistance welding machine. An air pressure detector, a cross-sectional area input setting device for inputting a cross-sectional area on which the air pressure of the cylinder acts, and a pressure calculating device for calculating a pressing force acting on the electrode from the air pressure detected by the air pressure detector and the input cross-sectional area A pressure arithmetic processing unit, a pressing force display for displaying the calculated pressing force, an upper / lower limit pressing force setter for setting upper and lower limits of the pressing force, and a comparison for comparing the upper and lower limit values with the calculated pressing force. It is characterized by comprising an arithmetic processing device and an alarm device for issuing an alarm when the calculated pressing force deviates from the set upper and lower limits. According to the pressure gauge for an electric resistance welding machine of the present invention, the pressure acting on the electrode can be known by multiplying the air pressure by the effective sectional area of the cylinder. Therefore, troublesome operation and handling are not required as compared with the conventional pressure gauge. Further, since the pressure can be easily adjusted even during actual production by adjusting the air pressure, there is no need to interrupt the production for adjusting the pressure. Further, since the upper and lower limits of the pressing force can be set in consideration of the pressing force necessary for the workpiece, an alarm is issued immediately from the alarm device when the actual pressing force is out of the set range. Therefore, it is possible to immediately take measures for controlling the welding quality with respect to the fluctuation or shortage of the pressing force due to the abnormality or failure of the air pressure source. Preferred embodiments of the present invention will be described below. FIG. 1 is a block diagram showing a first embodiment of the present invention, wherein 1 is an upper electrode of an electric resistance welding machine, 2 is a lower electrode, and 3 is an upper electrode 1 facing a lower electrode 2. The cylinder 4 for pressurizing is the piston. The welding current is applied to the workpiece W while being pressurized between the electrode 1 and the electrode 2, and electric resistance welding is performed. [0010] 5 is a line for supplying compressed air to the cylinder 3, this line 5 pressure detector 6 for detecting the air pressure P ₁ always provided. The air pressure P ₁ detected by the air pressure detector 6 is input to the pressure processing unit 7. Reference numeral 8 denotes a cross-sectional area input setting device, which is a cross-sectional area A ₁ above the piston 4 of the cylinder 3
Can be manually entered. The pressure processing unit 7 multiplies the air pressure P ₁ measured by the air pressure detector 6 by the cross-sectional area A ₁ input from the cross-sectional area input setting device 8, and applies the pressure from the electrode 1 to the workpiece W. The applied pressure is constantly calculated. The calculated pressing force is always displayed on the pressing force display 9. A comparison arithmetic processing unit 10 is connected to the pressing force arithmetic processing unit 7. This comparison operation processing device 1
A value of 0 compares the upper and lower limits of the pressing force set using the upper and lower limit pressing force setter 11 with the pressing force calculated by the pressing force calculation processing device 7. When the calculated pressing force deviates from the set upper and lower limits, a warning is issued from the warning device 12. As described above, according to the pressure gauge for an electric resistance welding machine of the present invention, the air pressure P ₁ detected by the air pressure detector 6 and the cross-sectional area A ₁ input from the cross-sectional area input setting device 8 are used.
And the pressure applied to the electrode 1 can always be known. For this reason, the pressing force at the time of actually performing the welding process is always grasped, and if the pressure is out of the set range, the air pressure can be immediately adjusted, so that stable quality welding can be performed. FIG. 2 is a block diagram showing a second embodiment of the present invention. In this second embodiment, the cylinder 3
In addition to the line 5 for supplying compressed air at the top of the cylinder, the line 13 for supplying compressed air is also provided at the bottom of the cylinder 3 so that air pressure can be applied to both the upper and lower surfaces of the piston 4. ing. The line 13 is also provided with an air pressure detector 14. In this case, the pressure calculation processor 7 calculates the air pressure P _{2 at} the lower part of the cylinder 3 from the product of the air pressure P _{1 at} the upper part of the cylinder 3 and the sectional area A _{1 at} the upper part of the piston 4.
The pressure acting on the electrode 1 is calculated by subtracting the product of the pressure and the sectional area A ₂ of the lower part of the piston 4. Other configurations and operations are the same as those of the first embodiment. Such a structure in which air pressure acts on the upper and lower sides of the piston 4 is suitable when the pressure acting on the electrode 1 is changed in two stages. As described above, according to the pressure gauge for an electric resistance welding machine of the present invention, the pressure applied to the electrode can be known from the air pressure and the cross-sectional area. It is possible to measure the pressing force when performing processing. Therefore, it is possible to contribute to quality control, and it is possible to easily adjust the pressing force during the production, so that there is an advantage that productivity can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 2 is a block diagram showing a second embodiment of the present invention. [Description of Signs] W Workpiece 1 Electrode 2 Electrode 3 Cylinder 4 Piston 5 Line for supplying compressed air 6 Air pressure detector 7 Pressure calculation processor 8 Cross-sectional area input setting device 9 Pressure display 10 Comparison processor 11 Upper / lower limit pressure setting device 12 Alarm device 13 Line for supplying compressed air 14 Air pressure detector

Claims (1)

Claims: 1. An air pressure detector for detecting an air pressure of a cylinder for pressurizing an electrode of an electric resistance welding machine, a cross-sectional area input setting device for inputting a cross-sectional area where the air pressure of the cylinder acts, A pressure calculation processor for calculating the pressure acting on the electrode from the air pressure detected by the air pressure detector and the input cross-sectional area; a pressure display for displaying the calculated pressure; An upper and lower limit pressure setting device for setting the lower limit,
An electrical resistance comprising: a comparison operation processing device that compares the upper and lower limit values with the calculated pressing force; and an alarm device that issues an alarm when the calculated pressing force deviates from the set upper and lower limits. Pressure gauge for welding machine.