JP4448041B2 - Radiation thermometer optical axis positioning method - Google Patents

Description

The present invention relates to an optical axis positioning method of a radiation thermometer for confirming the optical axis of a radiation thermometer used for measuring the welding temperature of a steel plate welded by a seam welder.

  In a continuous processing line for thin steel sheets, a seam welder is often used to connect the preceding material and the following material. In this welding machine, the operation of the continuous line is stopped, and the tail end portion of the preceding material and the leading end portion of the following material are overlapped in the welding machine mechanism. Next, after fixing a preceding material and a succeeding material with a clamp device and cutting with a shear, the preceding material and the following material are again overlapped by about 2 to 3 mm. Next, after setting the welding current, welding speed, electrode pressing pressure, etc. based on the thickness and material of the preceding and succeeding materials, the strip is pressed from above and below by a disk-shaped conductor (this is called an electrode ring). The strip is run from one end to the other end in the width direction of the strip, and is heated and pressed by electric resistance by passing a predetermined current through the electrode wheel. The quality determination of the welded portion welded by this welder is extremely important for preventing line stoppage due to welded portion fracture in the subsequent process.

  Conventionally, on-line determination of weld quality is based on a method of visually observing the fire color and spatter scattering of the weld during welding, and judging with the operator's feeling and experience, and using a hammer for the weld. Sensual techniques such as hammer testing to confirm weld strength have been used. However, since these methods cannot quantitatively evaluate the quality of the welded part, it has been difficult to completely avoid line troubles due to poor welding.

  As a method for determining the quality of this welding, for example, in Patent Document 1, in the seam welded portion, the relationship between the strip overlap thickness and the weld good strength region is stored in the controller in advance, and the overlap of the strip connection weld portion during welding is stored. A method is disclosed in which the thickness and the temperature of the welded part immediately after welding are introduced into the controller to determine whether or not welding is good.

  The welding state of the strip depends on various factors. For example, changes such as welding current, welding speed (travel speed of the electrode wheel), electrode wheel pressing pressure, and strip overlap allowance all appear as changes in the temperature of the weld. Therefore, measuring the temperature of the welded portion is an extremely effective method for determining the quality of welding. Here, when it is determined that the welding is defective, the welding is performed again. However, when the line is operated at a high speed, there is often no time margin for performing the welding twice. However, the damage caused when the strip breaks in the line due to poor welding is enormous. To prevent breakage, it is more economical to perform re-welding even if the line is stopped. For this reason, the quality determination result with high precision is calculated | required by the welding condition determination apparatus.

  However, there are cases where the welding temperature cannot be measured normally due to abnormalities in the thermometer, dirt on the measuring head of the thermometer, or the like, and the measurement result changes due to a shift in the visual field position of the thermometer. When such a situation occurs, it is easy to determine whether the thermometer is abnormal, whether the thermometer's visual field position has shifted, or whether the welding temperature has actually changed. Can not.

  In general, the quality of the thermometer itself is judged using a black body furnace. However, this method requires that the thermometer be removed and brought to the test site where the black body furnace is installed. It is impossible to determine whether the thermometer was normal during a short period of time.

  Moreover, when it is going to measure the temperature of a welding part, the following problems generate | occur | produce. First, the width of the overlap of the strips is about 2 to 3 mm, and the width of the electrode ring is about 10 to 20 mm. Therefore, the heated width of the welded portion is about 5 to 10 mm at most. However, it is necessary to use a non-contact type thermometer such as a radiation thermometer as a means of measuring the temperature of the welded part. In this case, if the field diameter of the thermometer is increased, the average including the temperature of the non-heated part is included. Temperature becomes impossible to measure accurately. Therefore, it is necessary to make the field diameter small, but if it is made small, it becomes necessary to precisely adjust the field position. Moreover, since it is necessary to measure the temperature immediately after welding, it is desirable that the thermometer be as close as possible to the electrode wheel.

  However, the electrode ring is repeatedly pressed and heated each time it is welded while being strongly pressed against the strip, and the surface of the electrode ring becomes rough because of spatter scattering. Since normal welding cannot be performed when the surface of the electrode ring is rough, the surface of the electrode ring must be periodically ground. Since the diameter of the electrode wheel gradually decreases every time grinding is performed, the electrode wheel must be replaced at a predetermined cycle. During this replacement, the mechanical position of the electrode wheel may be displaced, or the thermometer may be displaced due to touching the thermometer when performing these operations. In this case, the smaller the field of view, the greater the effect of this deviation, and the temperature of the welded part cannot be measured normally.

  Therefore, in order to match the measurement position of the radiation thermometer, it is necessary to adjust the optical axis position of the radiation thermometer. Patent Documents 2 and 3 disclose a technique in which a laser light generator is attached to a radiation thermometer, and optical axis positioning is performed using the laser light.

Furthermore, Patent Document 4 discloses a technique for attaching a heater on the optical axis of a radiation thermometer, performing abnormality determination of the thermometer, and confirming the optical axis.
JP-A-63-203285 JP-A-8-327460 JP-A-10-197466 Japanese Patent Laid-Open No. 10-185848

  However, the methods using laser light disclosed in Patent Document 2 and Patent Document 3 have a problem that even if a laser is projected, it is very difficult to read the optical axis position accurately because the target position is blurred. This is because the condenser lens of the radiation thermometer is shared during laser projection. Usually, the heat input width at the time of welding is several mm to several tens mm, and if the field spot diameter of the radiation thermometer is reduced, the temperature change becomes too large due to the influence of sputtering or the like. The condensing system is adjusted. Since the laser is projected using this condensing system, the laser light diffuses to the spot diameter at the target position, and accurate quantitative reading becomes difficult by visual observation or the like.

  Further, in the method using the heater of Patent Document 4, (1) the apparatus is complicated and large, and installation cost is high. (2) The welding machine carriage moves the heater at the standby position to perform thermometer check and optical axis confirmation. However, since the carriage stop position is generally controlled by the limit SW, it is difficult to position with high accuracy and the optical axis cannot be confirmed with high accuracy. (3) Structure and method for confirming the heater position There is a problem that it is not described.

The present invention has been made in view of the above circumstances. An optical axis positioning method for a radiation thermometer that can easily determine the quality of a thermometer that easily detects the temperature of a welded portion and that can easily confirm the visual field position of the thermometer. It is to provide.

The invention according to claim 1 of the present invention is an optical axis positioning method for a radiation thermometer used when measuring the temperature of a welded portion of a steel plate immediately after being welded by a seam welder having a pair of upper and lower disk electrodes. In the vicinity of the target position of the radiation thermometer, a linear heating element having a diameter smaller than the field diameter of the radiation thermometer is installed, and the heating element is moved in a direction perpendicular to the welding line, And the position can be measured, and the optical axis of the radiation thermometer is quantitatively confirmed and adjusted by measuring the temperature of the heating element by the radiation thermometer and measuring the position of the heating element. This is a method for positioning an optical axis of a radiation thermometer.

Further, the invention according to claim 2 of the present invention is an optical axis positioning method for a radiation thermometer used when measuring the temperature of a welded portion of a steel plate immediately after being welded by a seam welding machine having a pair of upper and lower disk electrodes. A heating element made of nichrome wire having a diameter smaller than the field diameter of the radiation thermometer is installed near the target position of the radiation thermometer, and the heating element is moved in a direction perpendicular to the welding line. And measuring the position of the heating element with the radiation thermometer and measuring the position of the heating element to quantitatively confirm and / or adjust the optical axis of the radiation thermometer. The optical axis positioning method of the radiation thermometer .

The invention according to claim 3 of the present invention is the optical axis positioning method for a radiation thermometer according to claim 1 or 2, wherein the optical axis of the radiation thermometer is quantitatively confirmed and adjusted. An optical axis positioning method for a radiation thermometer, characterized in that it is determined that a position where the indicated value of the radiation thermometer shows a peak is an optical axis position.

  According to the present invention, the optical axis of the radiation thermometer can be checked very easily and with high accuracy, which greatly contributes to the improvement of the welding temperature measurement accuracy.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing an example of a configuration for carrying out the present invention. A state in which the preceding strip 1 and the following strip 2 are welded in a seam welding machine is schematically shown. An electrode wheel 5 and a swaging roll 6 are installed on a carriage 3 movable by a wheel 4 in the vertical direction. ing. A condenser lens 7 is installed between the lower electrode wheel and the swaging roll, and is connected to the temperature detector 9 via the optical fiber 8. The temperature detector 9 outputs the temperature measurement result of the welded portion to the welding state determination device 10. The welding state determination device 10 is set in advance with the plate thickness and steel type of the preceding strip 1 and the succeeding strip 2 from the host computer 11 and the welding conditions from the seam welding machine control device 12, thereby reducing the good range of welding temperature. Determine in advance. Next, measurement is performed in accordance with a measurement start command from the seam welder control device 12, and it is determined that the welding is abnormal when the welding temperature is out of the good range.

  2 and 3 schematically illustrate an example of the optical axis positioning device according to the present invention. FIG. 2 is a view from the top, and FIG. 3 is a view from the side. In FIG. 2, 20 is a heating element for confirming the optical axis of the radiation thermometer, and 21 is a heating element moving mechanism for moving the heating element 20 to a predetermined position. The heating element moving mechanism unit 21 is configured not only to move the heating element 20 to a predetermined position but also to measure the position or the movement amount with high accuracy such as a micrometer. It is necessary to be able to move and measure vertically or horizontally. Reference numeral 22 denotes a base for fixing the heating element 20 and the heating element moving mechanism 21 and installing it at a predetermined position during measurement. Reference numeral 23 denotes a level that is fixed to the base 22 and is used to confirm whether or not the present apparatus can be normally installed. Reference numeral 24 denotes a power supply device for causing a current to flow through the heating element, and is connected to the heating element 20 by an electric wire 25.

  The heating element 20 is a heating element having an area smaller than the field diameter of the radiation thermometer, and since it is easy to obtain and process the nichrome wire, it is preferable to use this heating element. If so, it is not limited to this. Further, when a nichrome wire is used as the heating element 20, if the diameter of the nichrome wire is too thin, it is easy to break during heat generation, so it is preferable to use a wire of about 2 to 3 mm. Moreover, since the nichrome wire will eventually break if it repeatedly generates heat, it is desirable to fix it with screws so that it can be easily replaced. Further, in order to prevent the nichrome wire from being easily bent due to thermal deformation, it is preferable to have a structure in which tension is applied to the nichrome wire by a spring or the like. Furthermore, since the heat capacity of the nichrome wire itself is small, it is easy to be affected by the surrounding environment such as wind, so it is advisable to take environmental measures such as covering the wind directly.

  In FIG. 3, 7 to 9 are the condensing lens, optical fiber, and temperature detector of the radiation thermometer, respectively, as in FIG. 1, and the base 22 to which the heating element 20 is fixed is on the electrode ring 5 and the swaging roll 6. (For this reason, the base 22 has a U-shaped cross section, and a fixing jig is provided on one side surface so as not to be displaced after installation). Then, the base 22 is moved in the direction of the electrode wheel 5 or the swaging roll 6 so that the heating element 20 is positioned in the vicinity of the optical axis of the radiation thermometer.

A specific procedure for confirming and adjusting the optical axis of the radiation thermometer in the present invention will be described below (see FIGS. 2 and 3).
(1) Place the welding machine (not shown) in the standby position and confirm that the levels of the electrode wheel 5 and the swaging roll 6 are in place.
(2) A base 22 to which the heating element 20 and the heating element moving mechanism 21 are fixed is placed on the electrode wheel 5 and the swaging roll 6 so as to cover it. At this time, it is confirmed that there is a relative positional relationship between the heating element 20 and the electrode ring 5. Moreover, it confirms that it is attached horizontally by the level 23. In addition, according to past experiments, since the temperature change is negligible even if the optical axis is displaced by about 10 mm in the welding direction (direction in which the electrode wheel 5 and the swaging roll 6 are connected), it is necessary to strictly match the welding direction. For example, it may be within 10% of the spot diameter of the radiation thermometer described above. After performing the above attachment position confirmation, the base 22 is fixed to the electrode wheel 5 and the swaging roll 6 with a fixing jig.
(3) Next, the electric wire 25 from the power supply device 24 is connected to the terminal of the heating element 20.
(4) A current is passed through the heating element 20 to generate heat. In order to stabilize the heat generation amount, the power source should be a power source with constant current control.

(5) When the heating element 20 becomes red hot and the temperature rises sufficiently, the heating element moving mechanism 21 moves the heating element 20 in the direction perpendicular to the welding line, and confirms the indicated value of the temperature detector 9 at this time. . The position where the indicated value of the radiation thermometer shows a peak is the optical axis position. The heating element moving mechanism has the same structure as the dimension reading mechanism of the micrometer, and the accuracy can be read to at least 0.1 mm or automatically measured. As mentioned above, the soundness of the thermometer must be strictly checked with a blackbody furnace, etc., but the soundness of the degree of whether there is at least a failure is confirmed from the reproducibility of the temperature indication value here. It is possible to. (6) After confirming the optical axis position, the optical axis position is compared with the normal optical axis position confirmed in the past, and if the difference is within an allowable value, the optical axis is not adjusted. However, if it deviates from the allowable value, the heating element moving mechanism 21 moves the heating element 20 to the normal optical axis position.
(7) Next, while measuring the temperature of the heating element moved to the normal optical axis position, the installation position and angle of the radiation thermometer itself are adjusted until the indicated value shows a peak. Thereby, the optical axis adjustment of the radiation thermometer is completed.

  As described above, the present invention measures the temperature of the heating element with a radiation thermometer, determines that the point at which this temperature exhibits a peak value is the optical axis of the radiation thermometer, and the amount of movement of the heating element. It is possible to check the optical axis of the radiation thermometer very easily and with high accuracy by measuring the quantity quantitatively.

It is a figure which shows an example of the structure for implementing this invention. It is a figure (upper surface) which shows typically an example of the optical axis positioning device which concerns on this invention. It is a figure (side) which shows typically an example of the optical axis positioning device concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Leading strip 2 Subsequent strip 3 Carriage 4 Wheel 5 Electrode wheel 6 Swaging roll 7 Condensing lens 8 Optical fiber 9 Temperature detector 10 Welding state determination apparatus 11 Host computer 12 Seam welding machine control apparatus 20 Heating element 21 Heating element moving mechanism Part 22 Base 23 Level 24 Power supply 25 Electric wire

Claims (3)

An optical axis positioning method of a radiation thermometer used when measuring the temperature of a welded portion of a steel plate immediately after being welded by a seam welder having a pair of upper and lower disk electrodes,
In the vicinity of the target position of the radiation thermometer, a linear heating element having a diameter smaller than the field diameter of the radiation thermometer is installed,
The heating element is moved in the direction perpendicular to the welding line , and its position can be measured,
An optical axis positioning method for a radiation thermometer characterized in that the optical axis of the radiation thermometer is quantitatively confirmed and adjusted by measuring the temperature of the heating element with the radiation thermometer and measuring the position of the heating element. . An optical axis positioning method of a radiation thermometer used when measuring the temperature of a welded portion of a steel plate immediately after being welded by a seam welder having a pair of upper and lower disk electrodes,
In the vicinity of the target position of the radiation thermometer, a heating element made of a nichrome wire having a diameter smaller than the field diameter of the radiation thermometer is installed,
The heating element is moved in the direction perpendicular to the welding line, and its position can be measured,
An optical axis positioning method for a radiation thermometer characterized in that the optical axis of the radiation thermometer is quantitatively confirmed and adjusted by measuring the temperature of the heating element with the radiation thermometer and measuring the position of the heating element. . In the optical axis positioning method of the radiation thermometer according to claim 1 or 2 ,
In confirming and / or adjusting the optical axis of the radiation thermometer quantitatively, it is determined that the position where the indicated value of the radiation thermometer shows a peak is the optical axis position. Axis positioning method.

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