JPH10113776A - Recognizing method of dust generating state - Google Patents

Abstract

PROBLEM TO BE SOLVED: To facilitate the quantitive indication on dust, to recognize the dust generating state and to proceed the examination on a welding condition and working environment based on dust generating quantity quantitively indicated without accepting subjectivety of measuring people by only photographing welding work itself with an infrared camera during actual welding work at site. SOLUTION: The weld zone periphery is photographed with the infrared camera 12, and obtained infrared information is converted into temperature information with a temperature arithmetic part 18. Further, whether temperature information is information that dust becomes a heat source or not is discriminated with the dust discriminating constant executing dust discrimination based on the distribution density of temperature information using a dust arithmetic part 22, the total sum of information discriminated as temperature information due to dust is obtained, the dust generating index corresponding to dust generating quantity is calculated, whereby the dust generating state is recognized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for recognizing dust occurrence, and more particularly to a method for easily recognizing dust generated during welding work.

[0002]

2. Description of the Related Art Generally, in order to stably maintain and control the quality of resistance spot welding and arc welding, it is important to control electrodes in addition to basic welding conditions (welding current, conduction time, pressure). For example, step-up welding current control for increasing the welding current in proportion to the welding point is employed to reduce the electrode management cycle. However, it is difficult to set strictly appropriate welding conditions because disturbances such as the consumption state of the electrodes, the equipment, the state of the workpiece, and the like change with time. Therefore, in order to prevent the occurrence of defects such as welding blemishes, generally, the welding current and the step-up rate tend to be set to a relatively large value by adding a safety factor. As a result, a large amount of dust is generated from the welded portion. In addition, dust generated in resistance spot welding,
In arc welding, it is called spatter, but in the following, both will be referred to as chile.

[0003] The dust is a standard of welding quality assurance at a welding site, and is an effective control amount as a quality monitor. In other words, if there is dust, a sufficient nugget diameter is ensured, and a sense of security is obtained, which can be used for “eye management” of welding quality control.

However, the condition where the welding strength is maximum and the energy efficiency is the best is the welding condition immediately before the occurrence of dust. In addition, dust is generated as a result of melting and scattering of materials and the like at a welded portion, which causes a deterioration in working environment and a reduction in working efficiency. In other words, the scattering of dust causes dirt around it, and if it adheres to the product surface, it needs repair work,
If it adheres to the sensor or sliding part of the equipment, it may cause malfunction or failure. At the actual welding site, the operator visually determines the presence or absence and amount of dust, but the reliability was low because the operator's subjectivity was included.

[0005]

However, in examining a change in welding conditions and a study on improving the working environment, it is necessary to accurately grasp the current situation of dust generation, particularly the amount of dust. Conventional measurement of dust generation is performed by methods such as measuring the weight of the workpiece before and after welding, or arranging a sheet etc. around the welding equipment, actually collecting the scattered dust and measuring the weight. At present, it was difficult to measure the amount of dust at actual production sites. That is, there is a problem that the measurement must be performed by providing a special measurement time or the like and performing the measurement or performing a simulation or the like in a laboratory.

The present invention has been made in view of the above circumstances, and provides a dust generation state recognition method capable of quantitatively grasping the generation state of dust at a welding site without subjectivity of an operator. With the goal.

[0007]

In order to achieve the above object, the present invention comprises a step of obtaining infrared information radiated from the vicinity of a welding portion by an infrared detection sensor; Converting the temperature information to information, obtaining a dust discrimination constant for performing dust discrimination based on the distribution density of the temperature information, and calculating temperature information for each element of the infrared detection sensor based on the discrimination result based on the dust discrimination constant. Performing a summation to calculate a dust generation index, and recognizing the dust generation status based on the dust generation index.

Here, the temperature information is a temperature converted based on an average value of the amount of infrared rays detected by each detecting element of the infrared temperature sensor.
The average amount of infrared rays detected by the detection elements increases, and the value of the temperature information increases. Further, the dust discrimination constant defines the lowest temperature at which the heat source can be recognized as dust, and when temperature information based on the detection result of the detection element is equal to or higher than the lowest temperature,
Judge as Chile. As described above, since the value of the temperature information increases according to the number of heat sources, the temperature information can be the amount of dust. Although the temperature of the welding portion is high, the average value of the infrared ray of the detection element is smaller than the average value of the infrared ray due to dust because the range of the high temperature portion is extremely narrow, and it is discriminated by the discrimination by the dust discrimination constant. Can be.

According to this configuration, the temperature information is identified by the dust discrimination constant, and the sum thereof is calculated to quantify the temperature information. That is, the dust generation state is quantified by utilizing the fact that the distribution density of the temperature increases in the range corresponding to the amount of dust present in the detection range of the detection element and the temperature that can be detected increases. in this way,
By directly detecting the temperature of dust generated during the welding operation, the occurrence of dust can be easily quantified. If necessary, a conversion table between the dust generation index and the actual dust weight or volume can be prepared to display the actual dust weight or volume.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a conceptual diagram of a configuration of a dust recognition device 10 for realizing the dust occurrence situation recognition method. The infrared camera 12 is a commercially available one. For example, indium antimony, mercury cadmium tellurium, or the like is used as an infrared detection element, and the sampling period is 50H.
z, the number of measuring elements is about 120 × 160.

The work 16 to be welded sandwiched between the electrodes 14
When a predetermined voltage is applied under a predetermined clamping pressure,
Start spot welding. The infrared camera 12 is set and arranged so that the vicinity of the welded portion 16a is set as a measurement range, and dust (scattered pieces of molten metal) flying from the welded portion 16a.
Take a photo. Then, the infrared information acquired by the infrared camera 12 is input to the temperature calculation unit 18. The amount of infrared rays received by the infrared detection element of the infrared camera 12 is determined by the material (emissivity) of the object to be measured and the temperature.
The temperature calculation unit 18 converts the infrared information into temperature information based on a conversion table in which the amount of infrared light and the temperature are prepared in advance, and sequentially transfers the information to the data storage unit 20 for storage. Note that an infrared temperature detecting device in which the infrared camera 12 and the temperature calculating unit 18 are integrated may be used.

In the chile operation unit 22, the data storage unit 2
Based on the temperature information of Chile stored in 0, the temperature information is quantified. Although the display unit 24 displays the quantified dust information, the actual dust temperature and the like calculated by the temperature calculating unit 18 may be displayed at the same time.

Next, specific quantification based on infrared information on dust will be described with reference to the flowchart of FIG. 2 in addition to FIG. First, the vicinity of the welded portion 16a is photographed by the infrared camera 12 (S100). And
The infrared radiation emitted from the dust is measured (S101).
Subsequently, in performing the temperature conversion of the measured infrared information, the emissivity and the room temperature (welding site) of the workpiece 16 which are input in advance are acquired (S102). Workpiece 1
6 emits infrared rays even in a normal state. Further, the infrared measurement value also varies depending on the surface condition of the workpiece 16, the lighting condition, the room temperature, and the like. In other words, the emissivity and the room temperature are for accurately correcting the temperature conversion by excluding the infrared rays (background) normally emitted by the workpiece 16. Then, the temperature calculation unit 18 corrects the infrared data obtained by the infrared camera 12 with the separately obtained emissivity and room temperature, and further calculates the original measured temperature of Chile based on the conversion table of the temperature calculation unit 18. (S103).

Generally, the size of the dust is about 1 mm ³ ,
While the flight speed is about 10 m / S, the commercially available infrared camera 12 described above has a sampling cycle of 50 Hz, the number of measurement elements is 120 × 160, and the measurement range (field of view) is 300 mm in length. × When 400 mm wide, the resolution is 300/120 mm long and 400/160 m wide
m, each detecting element of the infrared camera 12 measures an average temperature when a heat source (dust) existing in the measuring range of the detecting element is captured in the entire measuring range.
Under such measurement conditions, the temperature of dust around the welded portion is detected at about several hundred degrees. Note that the actual surface temperature of dust is 1000 ° C. or higher. Therefore, as the number of heat sources (Chile) emitting infrared rays increases, the average amount of infrared rays detected by one detecting element increases, and the value of temperature information based on the average amount increases. Note that, at this time, the imaging range includes a welded part having a very high temperature, but since the range of the high temperature is extremely narrow, when the average temperature in the measurement range is compared, the temperature rise is much smaller than the temperature rise due to dust or the like. The converted temperature data is sequentially stored in the data storage unit 20 (S104).

Subsequently, the dust calculation unit 22 acquires the dust discrimination constant measured and calculated in advance in the laboratory or the like (S10).
5), a dust generation index is calculated (S106). The chile discrimination constant is, for example, a range in which a heat source can be recognized as chile, a minimum temperature Tmin is determined, and an experimental value obtained by analyzing the actual chile temperature in a laboratory or the like in detail. It is. For example, when the temperature T based on the infrared detection result of the detection element is T <Tmin = 122.5 ° C., it is determined that dust as a heat source has not passed through the measurement range of the detection element, and T = 0. . Also, Tmin =
If 122.5 ° C. <T, it is determined that dust is present within the measurement range of the detection element, and the value of T is maintained. With such a temperature correction function relating to temperature as f (T), temperature correction is performed on each detection element of the infrared detection sensor 12, and the sum of the values is defined as a dust generation index E. That is, the dust generation index E can be calculated by the following equation.

[0016]

(Equation 1) Here, T is temperature information based on infrared information of one element of the infrared camera, i is the number of elements in the horizontal direction of the infrared camera, j is the number of elements in the vertical direction of the infrared camera, and n is the sampling number of temperature measurement.

As described above, the temperature to be detected increases according to the number of heat sources recognized as dust due to the temperature correction function f. That is, the temperature information can be a relative amount corresponding to the amount of dust generation.

The graph shown in FIG. 3A shows the relationship between the dust generation index calculated by the above-described method and the total plate thickness of the workpiece, and the graph shown in FIG. It shows the relationship between the amount of dust generated by the method of calculating the amount of dust and that obtained by comparing the weight of the work before and after welding in the laboratory and the total sheet thickness. As is clear from both figures, it is understood that the dust generation index can be used as a substitute for the actual dust generation amount. The dust calculation unit 22 may display the dust generation index as a numerical value on the display unit 24 via the data storage unit 20, or may display it as a graph as shown in FIG.

In the recognition of the situation of occurrence of dust, the absolute amount of dust may be displayed using the dust index. When the absolute amount of Chile is required (S107), FIG.
A dust generation amount conversion table created in advance by (a), (b) or the like is acquired (S108), and the dust generation index is converted into a dust generation amount (S109). The absolute amount of dust is displayed on the display unit 24 together with the dust occurrence index and the graph, and the process is terminated. If the absolute amount of dust is not required in S107, the process is terminated only by displaying the dust occurrence index or the like.

As described above, during the actual work at the welding site, only by photographing the welding work itself with the infrared camera, the display of the quantity of dust is easily performed without the subjectivity of the measurer, and the occurrence of dust is recognized. can do. Based on the quantified and displayed amount of dust, it is possible to proceed with examination of welding conditions and work environment.

Although the present embodiment has been described by taking spot welding as an example, any welding method, such as arc welding, which generates dust, can be generally applied and similar effects can be obtained.

Also, since the dust discrimination constant shown in the present embodiment changes depending on the welding equipment and the state of infrared photographing,
It is necessary to select it appropriately.

[0023]

According to the present invention, during the actual work at the welding site, the welding operation itself is simply photographed with an infrared camera, and the quantitative display of the dust is easily performed without the subjectivity of the measurer. The occurrence situation can be recognized. Then, based on the quantified and displayed amount of dust, it is possible to proceed with the examination of the welding conditions and the work environment.

[Brief description of the drawings]

FIG. 1 is a configuration conceptual diagram of a dust recognition device for realizing a dust occurrence situation recognition method according to an embodiment of the present invention.

FIG. 2 is a flowchart of a dust generation situation recognition method according to the embodiment of the present invention.

FIG. 3A is an explanatory diagram showing a relationship between a dust generation index and a total plate thickness, and FIG. 3B is an explanatory diagram showing a relationship between a dust generation amount and a total plate thickness.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Chile recognition apparatus, 12 Infrared camera, 18 Temperature calculation part, 20 Data storage part, 22 Chile calculation part, 24
Display section.

Claims (1)

[Claims] A step of obtaining infrared information radiated from a periphery of a welding part by an infrared detection sensor; a step of converting the infrared information into temperature information; and a step of performing dust determination based on a distribution density of the temperature information. Obtaining a discrimination constant; and calculating a dust generation index by summing up temperature information for each element of the infrared detection sensor based on the discrimination result by the dust detection constant. A method for recognizing the situation of occurrence of dust based on the recognition of the situation of occurrence of dust on the basis of the situation.