JP5134460B2 - Inspection method for welded portion of can body - Google Patents

Description

  The present invention relates to a method for inspecting a can body welded portion that inspects the quality of a welded portion of a can body.

  In general, a can body containing a beverage or the like called a three-piece can is manufactured by winding a can lid around both ends of a cylindrical can body. The can body used for the can body is formed by forming a rectangular can body blank into a cylindrical shape, polymerizing both ends thereof, and welding the overlapped portions.

  When welding the can body, the overlapped portion is sandwiched between a pair of electrode rolls, and the can body is fed in the axial direction by rotating both electrode rolls while performing electric resistance welding with both electrode rolls. And the welding part of the width dimension corresponded to the superposition | polymerization width | variety of the said superposition | polymerization part is formed in the can body over the full length. Note that many of the can bodies employed in cans containing beverages or the like have a welding width of 0.5 mm.

  Moreover, welding a plurality of can bodies is continuously performed by continuously putting a plurality of can bodies between both electrode rolls. At this time, an interval is provided between adjacent can bodies so that the can bodies do not contact each other. This interval is set to be appropriately small so as to avoid contact between both electrode rolls and prevent an excessive short-circuit current from flowing between both electrode rolls. And by increasing the rotational speed of both electrode rolls, welding work can be speeded up and many can bodies can be manufactured in a short time.

  By the way, in the welded portion of the can body, the can body blank is bent, dust (paint debris, metal pieces, etc.) is bitten into the overlapped portion, the overlapped portion of the overlapped portion, or the cutout is generated in the overlapped portion. There is a risk of poor welding, leading to poor winding of the can lid and leakage of contents. Therefore, it is necessary to inspect the quality of the welded portion of the can body and to eliminate the can body in which the welded portion is defective.

  Conventionally, as a method for inspecting the quality of the welded portion of the can body, the temperature change of the welded portion is measured by a radiation temperature sensor such as an infrared temperature sensor provided in the vicinity of the delivery side of the can body by the electrode roll. There is known a technique for determining the quality of a welded part based on whether it is within upper and lower limit values (allowable range) based on a reference temperature change (for example, see Patent Document 1).

  When the weld is defective, an extreme temperature change occurs in the temperature of the weld immediately after welding. Therefore, it is possible to determine the quality of the welded portion by predetermining the upper and lower limit values based on normal temperature changes, and setting the measured temperature within the upper and lower limit values as good and setting the others as defective. .

  However, the temperature change of the welded part immediately after welding is relatively stable (the difference in temperature is small) at the longitudinal center of the can body, but the longitudinal end of the welded part (open end of the can body) The temperature of the portion located at the edge changes greatly compared to the central portion of the can body. That is, since heat is not diffused smoothly at the end of the welded portion as compared with the central portion of the can body, a rapid rise in temperature occurs at the end of the welded portion. For this reason, in the center part (part except an edge part) of a welding part, the upper limit and lower limit based on the temperature change made into a reference are continued at substantially constant temperature over the comparatively long distance of the center part of a welding part. The temperature change due to poor welding can be easily detected, but at the end of the welded part, it must be set with reference to the temperature change that suddenly goes up and down. And the change of a lower limit is very large, and it is difficult to determine a welding defect from the upper and lower limits of a big change.

  Therefore, in order to cope with a sudden temperature change at the end of the weld, the peak value of the measured temperature change is regarded as the edge of the weld, and the peak of the waveform indicating the temperature change as a reference (start of inspection) It has been proposed to make correction so as to match (point) (see Patent Document 2). Alternatively, when the waveform indicating the temperature change measured from the end of the welded part deviates from the upper and lower limits of the waveform indicating the reference temperature change, it is proposed that the two waveforms are moved relatively and the determination is performed again. (See Patent Document 3).

However, all of these methods perform correction processing after measurement with respect to the temperature change measured from the welded portion or the reference temperature change, and this processing time is delayed, and high speed cannot be expected. Moreover, the waveform indicating the reference temperature change at the end of the welded portion is composed of a steeply rising and falling slope, and the interval between the rising and falling slopes before and after the peak value is extremely narrow. For this reason, it is difficult to set the upper and lower limit values set at the end of the welded portion to values having the same accuracy as the upper and lower limit values set at the welded portion located in the center portion of the can body, Since the quality of the end of the welded portion has not yet been determined with high accuracy, an erroneous determination of the quality of the end of the welded portion has occurred.
Japanese Patent No. 2568432 Japanese Patent No. 3978990 Japanese Patent Laid-Open No. 2007-118034

  This invention makes it a subject to provide the inspection method of the can body welding part which can test | inspect the quality of the longitudinal direction edge part of a welding part accurately and at high speed in view of said point.

In order to solve the above-described problems, the present invention provides a method for inspecting a can body welded portion in which a weld portion having a predetermined width formed along the axial direction of a cylindrical can body is inspected based on a temperature immediately after welding. A waveform generating step for generating a reference waveform corresponding to a temperature change along the longitudinal direction of the welded portion, and a plurality of determination regions along the longitudinal direction of the welded portion based on the reference waveform generated by the waveform generating step A determination region setting step for setting a tolerance, a tolerance range setting step for setting an allowable range consisting of an upper limit value and a lower limit value in the determination region set by the determination region setting step, and the temperature of the welded portion in the longitudinal direction of the welded portion. A temperature measurement step for measuring along the direction, and a pass / fail determination step for determining that the temperature measured by the temperature measurement step is acceptable when the temperature is within the allowable range in the determination region, and determining that the temperature is defective when the temperature is outside the allowable range; Be equipped The waveform generating step includes, as a reference waveform within a predetermined dimension from a longitudinal edge of the welded portion, an ascending change portion that indicates a temperature change that rises from the longitudinal edge of the welded portion, and the ascending change Generating a waveform including a temperature stabilizing portion that is continuous with the temperature change portion and exhibits a temperature change smaller than the rising change portion, and a falling change portion that is continuous with the temperature stabilization portion and indicates a temperature change that greatly decreases from the temperature stabilization portion, The determination region setting step sets a determination region within the predetermined dimension from the edge in the longitudinal direction of the welded portion at a position corresponding to the temperature stabilizing portion, and the temperature measurement step is longer than the width dimension of the welded portion. A radiation part having a rectangular measurement field whose side is perpendicular to the longitudinal direction of the welded part and measuring a radiation temperature of a part of the welded part, and a welded part to the lens part of the radiation temperature sensor In the longitudinal direction By and measuring the temperature over the entire length of the weld.

  The present inventor determines the temperature of the welded part immediately after welding with respect to a large number of can bodies that are normally welded and a large number of can bodies that are poorly welded along the longitudinal direction (axial direction of the can body) at predetermined intervals. Detailed data on the temperature change along the longitudinal direction of the weld was collected by various tests and various tests. As a result, the temperature immediately after welding at the end portion in the longitudinal direction of the welded portion (the portion within the predetermined dimension from the end edge in the longitudinal direction of the welded portion) In addition to becoming higher, the temperature change is small and stable at the high-temperature part in a substantially constant region before and after the maximum temperature (peak value) (partial region at the longitudinal end of the weld). I found out that there is a part to do. Furthermore, the inventor has found that when a welding failure occurs at the end portion in the longitudinal direction of the welded portion, the region corresponding to the portion that is stable at high temperature is affected. Based on this knowledge, when the temperature immediately after welding is measured along the longitudinal direction of the welded portion, the temperature change immediately after welding at the end of the welded portion that has been normally welded suddenly starts from the opening edge of the can body. It rises and stabilizes at a high temperature, and then descends toward the center of the weld. Furthermore, if a welding failure occurs in the change region of the weld end including the rising portion and the falling portion, stability at a high temperature state cannot be obtained.

  Therefore, in the present invention, when the reference waveform is generated by the waveform generation step, first, the reference waveform within a predetermined dimension is generated from the longitudinal edge of the welded portion based on the temperature change based on the knowledge of the inventor described above. To do. That is, the reference waveform is generated so as to include the rising change portion, the temperature stabilizing portion, and the falling change portion.

  Next, when a plurality of determination regions are set along the longitudinal direction of the welded portion by the determination region setting step, the determination region within the predetermined dimension from the edge in the longitudinal direction of the welded portion is set to the temperature stable portion in the reference waveform. Set to the corresponding position. The temperature stabilization part is the part that stabilizes at the high temperature at the end of the welded part, and by setting one of the judgment areas at this position (partial dimension range at the end of the welded part in the longitudinal direction), the allowable range is set The upper limit value and the lower limit value of the allowable range set by the process can be set as a straight line with no inclination or very little inclination over the entire length of the determination region.

  Then, the temperature of the welded portion of the can body to be inspected in the temperature measurement step is measured along the longitudinal direction of the welded portion, and the quality is determined from the measured temperature in the quality determination step. At this time, in a determination region within a predetermined dimension from the edge in the longitudinal direction of the welded portion, an allowable range based on the temperature stable portion of the reference waveform is set by a substantially constant upper limit value and lower limit value. As a result, if a temperature change due to poor welding occurs at the end of the welded portion of the can body to be inspected (within a predetermined dimension from the edge in the longitudinal direction), the originally stable portion is disturbed. It is out of the allowable range and can be reliably determined as a welding defect.

  Thus, according to the present invention, it is possible not only to accurately inspect the longitudinal end of the welded portion, but also to measure the temperature and reference waveform after measuring the temperature of the welded portion of the can body to be inspected. Therefore, it is possible to inspect the quality of the end of the welded portion in the longitudinal direction at high speed.

  Further, in the waveform generation step, the reference waveform is generated based on a temperature change along the longitudinal direction of the welded portion measured from a number of can bodies that have been normally welded in advance. The accuracy of the lower limit value can be improved.

Further, in the above temperature measuring step of the present invention, in order to measure the temperature of the weld in a non-contact state can body, are use a radiation temperature sensor. By using the radiation temperature sensor, Ru can measure temperature over its entire length in the longitudinal direction of the welded portion with respect to the welded portion of the moving can bodies.

  By the way, the radiation temperature sensor measures the temperature of the welded portion by directing the lens portion that captures infrared radiation or the like toward the welded portion of the can body, but the measurement field of the lens portion is generally circular. And when the measurement visual field of a lens part is circular, it has a measurement visual field of a diameter larger than the width dimension of a welding part, in order to settle the welding part of the can body which moves in the visual field reliably. That is, even when the can body is displaced in the circumferential direction (around the axis of the can body), a measurement visual field larger than the width dimension of the welded portion is required in order to securely fit the welded portion within the visual field.

  However, when the measurement visual field of the lens part is circular, if the diameter is increased, the visual field is widened in the longitudinal direction of the welded part, and it becomes difficult to capture temperature abnormality in a small part. Further, when the can body is displaced in the circumferential direction, the temperature measurement accuracy is lowered because the area of the welded portion that occupies the measurement field of the lens portion varies.

  In particular, when the starting end (edge) in the longitudinal direction of the welded part enters the measurement field of the lens part, the temperature of the end of the welded part can be measured by covering the diameter of the measurement field by moving the can body However, it takes time to cover the diameter of the measurement visual field, and accurate temperature measurement from the end of the weld becomes difficult.

Therefore, in the above temperature measurement step, a portion of the rectangular weld comprises a lens unit having a measuring field of view long long side perpendicular to the longitudinal direction of the welded portion than the width of the welded portion of the present invention The temperature over the entire length of the welded portion is measured by moving the welded portion in the longitudinal direction of the welded portion with respect to the lens portion of the radiation temperature sensor .

  By doing so, the measurement field of view is narrowed only in the longitudinal direction of the welded portion, and it becomes possible to capture temperature abnormalities in small parts. Moreover, since the measurement visual field with respect to the width direction of the welded portion is wide, even if the moving can body is displaced in the circumferential direction, it is difficult for the welded portion to come off the measurement visual field. Furthermore, since the measurement visual field is rectangular, even if the moving can body is displaced in the circumferential direction, fluctuations in the area of the welded portion in the measurement visual field can be suppressed.

  An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of an apparatus used in the inspection method of the present embodiment, FIG. 2 is an explanatory perspective view showing a main part of a radiation temperature sensor employed in the present embodiment, and FIG. 3 is a measurement of the radiation temperature sensor. FIG. 4 is an explanatory diagram for comparing the measurement visual field in the present embodiment with the conventional measurement visual field, FIG. 5 is a block diagram showing the functional configuration of the inspection control device, and FIG. 6 is for the welded portion. FIG. 7 is a diagram illustrating a reference waveform and a determination region at the time of quality determination over the entire length of the welded portion, and FIG. 8 is a diagram illustrating a reference waveform and a determination region at the end of the welded portion.

  In FIG. 1, 1 is a can body, 2 is a radiation temperature sensor such as an infrared temperature sensor, and 3 is an inspection control device. The can body 1 is welded by a welding machine Y including a pair of electrode rolls (an external electrode roll 4 and an internal electrode roll 5). The welding machine Y performs welding while feeding the can body 1 in the axial direction by both electrode rolls 4 and 5. That is, the can body 1 is pre-processed into a cylindrical shape from a rectangular can body blank on the upstream side of the electrode rolls 4 and 5, and ends thereof are polymerized in an unwelded state by a conveyor (not shown). It is conveyed and a superposition | polymerization part is thrown in between both electrode rolls 4 and 5. FIG. The overlapping portion of the can body 1 sandwiched between both electrode rolls 4 and 5 is subjected to electric resistance welding by the both electrode rolls 4 and 5, and the can body 1 is moved downstream by the rotation of the both electrode rolls 4 and 5. Sent out. And the welding part 6 welded by the both electrode rolls 4 and 5 is formed in the can body 1 by predetermined width (about 0.5 mm width) over the axial direction full length of the can body 1. Further, as shown in the figure, a plurality of can bodies 1 are continuously inserted into both electrode rolls 4 and 5, but both electrode rolls 4 and 5 are brought into contact with each other to generate an excessive short circuit current. In order to prevent this, it is inserted between the electrode rolls 4 and 5 at a predetermined interval (0.7 mm to 1.0 mm) in the axial direction.

  The radiation temperature sensor 2 includes a lens unit 7, and the lens unit 7 is positioned near the downstream of the external electrode roll 4. Thereby, the radiation temperature sensor 2 measures the temperature of the welding part 6 formed by both the electrode rolls 4 and 5 immediately after the welding. As shown in FIG. 2, a mask 8 having a rectangular light receiving window 8a is attached to the lens unit 7 on the front surface of a built-in objective lens. Thereby, as shown in FIG. 3, the lens unit 7 has a rectangular measurement visual field 9 that is long in the width direction of the welded part 6, and measures the temperature of the measurement visual field 9. The measurement visual field 9 is set so that its long side is longer than the width dimension of the welded portion 6. Then, when the can body 1 is being sent out downstream by the two electrode rolls 4, 5, the radiation temperature sensor 2 performs temperature measurement in the measurement field of view 9 of the lens unit 7, so that the axial direction of the can body 1 is increased. A temperature measurement is performed along the entire length of the welded portion 6 along the longitudinal direction.

  Here, the point that the measurement visual field 9 of the lens unit 7 of the present embodiment is advantageous will be described in comparison with the measurement visual field 9 'of the conventional lens unit given as a comparative example. As shown in FIG. 4, the measurement visual field 9 ′ mentioned as a comparative example is circular, and the diameter thereof is the same as the long side of the rectangular measurement visual field 9 of the present embodiment. In FIG. 4, at the first stage, the starting ends of the welds 6 reach the respective measurement visual fields 9, 9 ′, and at the second stage, the welds 6 penetrate into the measurement visual fields 9, 9 ′. Then, in the third stage, the starting end of the welded portion 6 reaches the end of each of the measurement visual fields 9, 9 '. When the welding speed 6 (feed speed of the can body 1) is the same, as is apparent from the comparison of the welds 6 that occupy the respective measurement visual fields 9, 9 'in the first to third stages. The time during which the welded portion 6 covers the measurement visual fields 9, 9 'is shorter than the case where the rectangular measurement visual field 9 of the present embodiment is circular like the conventional measurement visual field 9'.

  Thus, by making the measurement visual field 9 of the lens unit 7 rectangular, the measurement visual field 9 is narrowed only in the longitudinal direction of the welded part 6, and it becomes possible to catch a temperature abnormality in a small part. The start end of the welded portion 6 has been described above, but it goes without saying that the same applies to the end of the welded portion 6.

  Furthermore, as shown in FIG. 4, when the measurement visual field 9, 9 ′ is misaligned with respect to the welded portion 6, the area of the welded portion varies in the circular measurement visual field 9 ′. However, by making the measurement visual field 9 rectangular, the measurement visual field in the width direction of the welded portion is wide, and fluctuations in the area of the welded portion can be suppressed, thereby improving measurement accuracy.

  As shown in FIG. 1, the radiation temperature sensor 2 includes the lens unit 7 described above, a fiber 10, and a temperature-voltage converter 11 connected to the lens unit 7 via the fiber 10. The temperature-voltage converter 11 converts the infrared energy incident from the lens unit 7 into a voltage and outputs the voltage to the inspection control device 3.

  A reference pulse generator 12 provided in the welding machine Y main body is connected to the inspection control device 3. The reference pulse generator 12 generates one reference pulse for one can body 1 in accordance with the feed timing of the can body 1 during welding. At the time of welding, the can body 1 is continuously sent at equal intervals, so that reference pulses at equal time intervals can be obtained for each can body 1. Further, the inspection control device 3 displays a reference waveform and the like which will be described later and functions as an operation panel for performing various setting operations, and sorts and discharges the poorly welded can body 1 from the normal can body 1. The discharge means 14 is connected.

  The inspection control device 3 is constituted by a microcomputer and has a function for realizing the inspection method of the present invention. That is, as shown in FIG. 5, the inspection control device 3 includes a reference waveform generation unit 15, a determination region setting unit 16, an allowable range setting unit 17, a pass / fail determination unit 18 as a functional configuration related to the inspection method of the present invention. And a storage unit 19. The storage unit 19 stores a reference waveform and a set value, which will be described later.

  When the can body 1 is inspected using the present embodiment having the above-described configuration, the temperatures of the welded portions 6 of a number of can bodies 1 that have been normally welded are collected in advance and a number of can bodies that are poorly welded are collected. The temperature of 1 welded part 6 is sampled. The temperature sampled from the welded part 6 that has been normally welded is used to form a reference waveform described later, and the temperature sampled from the welded part 6 with poor welding is used as the upper and lower limit values of the allowable range described later. Further, the time from when the reference pulse is generated from the reference pulse generator 12 until the start edge in the longitudinal direction of the welded portion 6 reaches the measurement visual field 9 of the lens portion 7 of the radiation temperature sensor 2 (delay time t described later). Are collected from a number of can bodies 1 that are normally welded.

  And as shown in FIG. 6, the welding part 6 is divided into three areas L, M, and N, and the temperature change of the normal welding part 6 is extract | collected. In the following description, the front end side of the welding body 6 in the feed direction of the can body 1 shown in FIG. 1 is defined as the front end area L of the weld 6 and the opposite side is defined as the rear end area N of the weld 6. Further, a center section M is defined between the front end section L and the rear end section N. The longitudinal edge of the welded portion 6 exists in the front end section L and the rear end section N. Here, according to the temperature change taken from the normal welded portion 6, the tip portion L and the rear end region N are each 5 mm because there are high temperature portions in the range of 5 mm at both ends of the welded portion 6. Set to.

  Further, the starting end in the longitudinal direction of the welded portion 6 is detected as follows. As described above, the reference pulse generator 12 generates one reference pulse for one can body 1 in accordance with the feed timing of the can body 1 during welding. The reference pulse is generated at an earlier time when the starting end of the welded portion 6 sent out between the electrode rolls 4 and 5 of the welding machine Y reaches the temperature measurement position by the lens portion 7 of the radiation temperature sensor 2. Therefore, the time from when the reference pulse is generated until the start of the weld 6 reaches the temperature measurement position is set as a constant delay time t as shown in FIG. As a result, the temperature measured by the lens unit 7 when the delay time t has elapsed since the generation of the reference pulse becomes the temperature of the starting end in the longitudinal direction of the welded part 6.

  Note that by setting the measurement interval at the delay time t to be extremely small, the measurement start point can be set with less variation. Specifically, for example, when the can-making speed is 600 cans per minute and the delay time t is about 10 ms, the measurement interval at the delay time t is 0.1 ms. By doing so, it is not necessary to perform a correction process after the measurement with respect to a temperature change which is a reference of the welded portion 6 as in the related art.

  Then, as shown in FIG. 7, the reference waveform generation unit 15 generates a reference waveform A corresponding to the temperature change based on the temperature change measured over the entire length (three sections L, M, and N) of the welded part 6. Generate (recording step) and record in the storage unit 19. At this time, the temperature is measured about every 0.1 mm in the front end section L and the rear end section N, and the front end section L is based on the delay time t from the generation of the reference pulse in the delay time setting step. The starting end (corresponding to the starting end edge in the longitudinal direction of the welded portion 6) is set. In the central area M, the temperature is measured every about 1.0 mm. As a result, in the front end section L and the rear end section N, the temperature is measured for each of approximately 50 measurement points in the range of 5 mm on both ends of the welded portion 6, and the temperature is measured at a relatively small interval.

  Next, the determination area setting unit 16 determines the determination areas based on the reference waveform A (first determination area B, second determination area C, and third determination area D) for each of the sections L, M, and N. Is set (determination area setting step), and the allowable range setting unit 17 sets an allowable range including an upper limit value and a lower limit value in these determination areas B, C, and D (allowable range setting process). Thereafter, the quality determination unit 18 measures the temperature from the welded portion 6 of the can body 1 to be inspected, and determines that the measured temperature is within the allowable range of each determination region B, C, D, When it is outside the allowable range, it is determined as defective (good / bad determination step). At this time, the can body 1 determined to be defective is discharged by the discharge means 14. Specifically, as shown in FIG. 7, when there is poor welding in the tip section L, the measured temperature of the welded portion 6 of the can body 1 to be inspected is the first determination region B as shown by the broken line e. Therefore, it is possible to easily determine a defect. Further, when there is a welding failure in the central section M, the measured temperature of the welded portion 6 of the can body 1 to be inspected deviates from the allowable range in the second determination region C as shown by the broken line f, so that it is easily defective. Can be determined.

  Here, the procedure for setting each determination area B, C, D and the allowable range will be described. In the front end section L and the rear end section N, heat diffusion during welding is blocked by the edge of the welded portion 6, so that the temperature is higher than that in the central section M. Accordingly, the first determination region B and the third determination region D and their allowable ranges are set by a method different from the second determination region C of the central section M and its allowable range, as will be described in detail later. . As shown in FIG. 7, the second determination region C can obtain a relatively stable reference waveform A with a small temperature difference, so that the temperature of about 1.0 mm is obtained over the entire length of the central section M. Is set to an allowable range in which + 30 ° C. to + 50 ° C. is set as the upper limit value h and −30 ° C. to −50 ° C. is set as the lower limit value i.

  On the other hand, in the front end section L, the first determination region B and its allowable range are set as follows. That is, the inspection control device 3 measures the temperature by the radiation temperature sensor 2 at about 0.1 mm in the tip end section L. At this time, in the tip end section L, since the diffusion of heat at the time of welding is blocked at the edge of the welded portion 6, the temperature becomes high. As shown in FIG. 8, the reference waveform A) within a predetermined dimension from the edge of the direction is a rising change portion A-1 showing a rising temperature change, and a temperature stabilizing portion A showing a temperature change smaller than the rising change portion. -2 and a descending change portion A-3 indicating a temperature change greatly descending from the temperature stabilizing portion. The reference waveform generation unit 15 records this waveform in the storage unit 19 as the reference waveform A in the tip end section L and displays it on the display device 13.

  Next, the determination region setting unit 16 sets the first determination region B only in the temperature stabilizing portion A-2 in the reference waveform A in the tip end section L. The determination area setting unit 16 sets the time from the edge of the can body 1 to the start point of the first determination area B, and based on the time, the first determination area is within the interval of the temperature stabilizing section A-2. Set the start and end points of B. The edge of the can body 1 is set based on the delay time t described above.

  Subsequently, the allowable range setting unit 17 sets an allowable range including an upper limit value h and a lower limit value i in the first determination region B. The upper limit value h and the lower limit value i are set based on the temperature collected from the welded part 6 with poor welding, and set so as to have a difference of 30 ° C. to 50 ° C. with respect to the maximum temperature in the temperature stabilizing part A-2. Is done. That is, in the temperature stabilization part A-2 of the first determination region B, + 30 ° C. to + 50 ° C. is set as the upper limit value h, and −30 ° C. to −50 ° C. is set as the lower limit value i with reference to the temperature of about 0.1 mm. The allowable range is set. Moreover, in the temperature stabilization part A-2, since it is a substantially flat waveform, the upper limit value h and the lower limit value i of the allowable range can be set linearly.

  And if the quality determination of the front-end | tip part area L of the can body 1 is performed using the tolerance | permissible_range of the 1st determination area | region B set to the front-end | tip part area L as mentioned above, it will respond | correspond to temperature stabilization part A-2. Of course, even if a defect occurs at a position corresponding to the rising change part A-1 or the descending change part A-3, the temperature as shown by a broken line e in FIG. The measurement temperature at the position corresponding to the stable portion A-2 is affected, so that it is out of the allowable range of the first determination region B, and the quality determination can be performed reliably. In the rear end section N, as shown in FIG. 7, the allowable range of the third determination region D corresponding to the temperature stabilizing section A-2 can be set in the same manner as the front end section L. The description is omitted.

  As described above, in the present embodiment, the welded portion 6 is divided into three sections L, M, and N, and in the front end section L and the rear end section N, the temperature stabilizing section A− of the reference waveform A. The determination areas B and D and their allowable ranges are set only at the position corresponding to 2. Thereby, compared with the case where the upper limit value and the lower limit value over the entire length of the welded portion 6 are set as allowable ranges along the reference waveform A as in the prior art, in particular, the end portions of the welded portion 6 (the leading end region L and the trailing end). The pass / fail judgment accuracy of the section N) is high. In addition, since it is not necessary to correct the measurement temperature and the reference waveform of the welded portion 6, the inspection can be performed at high speed.

  Note that the dimensions and measurement intervals of the welded portion 6 used in the description in the present embodiment, the upper and lower limit temperatures of the allowable ranges in the determination regions B, C, and D are not limited to this, and the size of the can body 1 Needless to say, it is appropriately set according to the can-making speed and the like.

Explanatory drawing which shows schematic structure of the apparatus of one Embodiment used for the test | inspection method of this invention. An explanatory perspective view showing a lens part of a radiation temperature sensor. Explanatory drawing which shows the measurement visual field of a radiation temperature sensor. Explanatory drawing for contrasting the measurement visual field in this invention with the conventional measurement visual field. The block diagram which shows the functional structure of a test | inspection control apparatus. Explanatory drawing which shows the area | region of the test object with respect to a welding part. The figure which shows the reference | standard waveform at the time of quality determination over the full length of a welding part, and a determination area | region. The figure which shows the reference | standard waveform and determination area | region of the edge part of a welding part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Can body, 2 ... Radiation temperature sensor, 6 ... Welding part, 7 ... Lens part, 9 ... Measurement visual field, A ... Reference waveform, A-1 ... Ascending change part, A-2 ... Temperature stabilization part, A-3 ... descending change part, B, C, D ... determination area.

Claims (2)

In the inspection method of the can body welded portion, which inspects the weld portion of a predetermined width formed along the axial direction of the cylindrical can body, based on the temperature immediately after welding,
A waveform generating step for generating a reference waveform corresponding to a temperature change along the longitudinal direction of the weld;
A determination region setting step for setting a plurality of determination regions along the longitudinal direction of the weld, based on the reference waveform generated by the waveform generation step;
An allowable range setting step for setting an allowable range consisting of an upper limit value and a lower limit value in the determination region set by the determination region setting step;
A temperature measurement step of measuring the temperature of the weld along the longitudinal direction of the weld; and
A pass / fail judgment step in which the temperature measured by the temperature measurement step is determined to be good when the temperature is within the allowable range in the determination region and is determined to be defective when the temperature is outside the allowable range;
The waveform generating step includes, as a reference waveform within a predetermined dimension from the longitudinal edge of the welded portion, an ascending change portion that indicates a temperature change that rises from the longitudinal edge of the welded portion, and the ascending change portion Generating a waveform including a temperature stabilizing portion that is continuous to the temperature changing portion and showing a temperature change smaller than the rising changing portion, and a falling changing portion that is continuous to the temperature stabilizing portion and shows a temperature change greatly decreasing from the temperature stabilizing portion,
In the determination region setting step, a determination region within the predetermined dimension is set at a position corresponding to the temperature stabilizing portion from an edge in a longitudinal direction of the welded portion ,
The temperature measuring step includes a lens unit having a rectangular measurement field whose long side longer than the width of the welded part is perpendicular to the longitudinal direction of the welded part, and measures the radiation temperature of a part of the welded part. A method for inspecting a can body welded portion, comprising using a temperature sensor, and measuring the temperature over the entire length of the welded portion by moving the welded portion in the longitudinal direction with respect to the lens portion of the radiation temperature sensor .   The said waveform production | generation process produces | generates the said reference | standard waveform based on the temperature change along the longitudinal direction of the welding part measured from the several can barrel provided with a favorable welding part previously. Inspection method for can body welds.