MX2008001579A - Device and method for detecting flaw on tube - Google Patents

Abstract

A detection device and a detection method for automatically detecting flaws occurring on a raw tube manufactured by rolling a hollow shell by using a mandrel mill. The flaw detection device (100) comprises a wall thickness gauge (1) disposed on the extension side of the mandrel (M) and measuring the wall thicknesses of the hollow shell (P) in a press-down direction on the stands (#1 to#5) of the mandrel, rolling load measuring devices (2) measuring rolling loads on the stands (#1 to#5), and an judgement device (3) for judging whether flaws are present or absent on the raw tube based on the measured wall thickness values of the hollow shell (P) in the press-down direction and the measured rolling load values on the stands. The judgement device (3) judges that flows occur on the raw tube when the measured wall thickness value of the hollow shell in the press-down direction on any of the stands (#1 to#5) partially varies a predetermined amount or more and the measured rolling load value of the hollow shell in the press-down direction on any of the stands (#1 to#5) partially varies a predetermined amount or more.

Description

DEVICE AND METHOD OF DETECTION OF DEFECTS FOR PIPES TECHNICAL FIELD This invention relates to an apparatus for defect detection and a defect detection method for tubes. Specifically, the present invention deals with an apparatus for defect detection and a defect detection method for automatic detection failures that occur in matrices when carrying out lamination of hollow tubes using a laminator. BACKGROUND FIGS. 5 (a) - 5 (b) are explanatory views showing various types of defects that occur in a matrix tube manufactured by laminating a hollow tube using a laminator. Figure 5 (a) shows indentation defects on the interior surface that are indentations 4 on the interior surface of a matrix tube P. Figure 5 (b) shows perforation defects that are holes 5 that occur when indentation defects of inner surface advance and reach the outer surface of a matrix tube P. Figure 5 (c) and Figure 5 (d), which is a cross section in the circumferential direction of the matrix tube P of Figure 5 (c), they show a wrinkle defect which is a portion 6 where the outer surface of a matrix tube P is bent inwardly. Each of these defects is a leading cause of occurrence of defective matrices. In a laminator, the presence of the various defects described above has conventionally been detected by direct visual observation of a laminated matrix tube by an operator working in a control room located in the vicinity of the laminator. However, in recent years, as the automation of pipe forming facilities progresses, a control room is located in a remote location of a rolling mill. Therefore, situations occur where an operator can not visually and directly observe the various types of defects in a matrix tube after lamination. Accordingly, even if several types of defects occur in die tubes that have undergone lamination using a mandrel laminator, they can not be detected quickly and there is a possibility that more defective products will occur more than in the past. For example, the patent documents 1-6 disclose inventions in which in order to suppress variations in the wall thickness of the end portions of a matrix tube that was laminated using a laminator and in thickness deviations in the circumferential direction of the matrix tube, the wall thickness of a laminated matrix tube in the laminator is measured by a wall thickness gauge placed on the exit side of the laminator, and based on the results of the measurement, the laminate conditions of the laminator are change Patent Document 1: JP H7-246414 To Patent Document 2: JP H8-71616 To Patent Document 3: JP 2001-293503 To Patent Document 4: JP 2002-35817 To Patent Document 5: JP 2003-220403 Al Patent Document 6: JP 2004-337941 To the Disclosure of the Invention However, a wall thickness gauge placed on the exit side of a laminator according to what is disclosed in the patent documents 1-6 is used to measure the thickness of the wall of a matrix tube in order to detect variations in wall thickness at the ends of a matrix tube or thickness deviations in the circumferential direction of the matrix tube and this can not detect various defects that are defects in shape that appear locally in a laminated matrix tube with a laminator. Therefore, as matters of the course, the inventions disclosed in these patent documents do not make it possible to automatically detect defects found in a laminated matrix tube using a laminator. The present inventors placed a wall thickness gauge on the exit side of a laminator in order to measure the wall thickness of a matrix tube in the reduction directions (laminar reduction directions) on each stand of the laminator and verified the variations in the measured value of the wall thickness in the longitudinal direction of the matrix tube. As a result, found the following: (a) when a defect by indentation of inner surface or a perforation defect occurs in a matrix tube, the measured value of the wall thickness in a portion corresponding to the portion where a surface indentation defect inner or a perforation defect is present is locally reduced, and when a wrinkle defect occurs in a matrix tube, the measured value of the wall thickness in a portion corresponding to the portion where the wrinkle defect is present locally increases; (b) when an inner surface indentation defect, a perforation defect or a wrinkle defect occurs in a matrix tube, the measured value of the lamination load in a support varies locally. Consequently, by monitoring local variations in the measured value of the wall thickness in the longitudinal direction of a matrix tube during lamination with a wall thickness meter and by monitoring local variations in the measured value of the rolling load, when these two measured values exceed their respective predetermined threshold values, it is decided that a defect of indentation of inner surface, a defect of perforation or a wrinkle defect occurred, for this reason it is possible that the occurrence of a defect is automatically detected with great precision of a matrix tube that is laminated using a laminator. The present invention is an apparatus for detecting a defect in a matrix tube that is characterized by comprising a wall thickness meter placed on the exit side of a laminator for measuring the wall thickness of the tube in each of the reduction directions of a hollow tube that is laminated into a plurality of supports constituting the laminator, rolling load measuring devices for measuring the rolling load in each of the plurality of supports and a decision unit that determines, based on the measured value of the tube wall thickness in each of the reduction directions of a hollow tube in the plurality of frames that is measured through the wall thickness meter and the measured value of the rolling load in each of the pluralities of frames that is measured through the rolling load measuring devices, that a defect has occurred in the die tube when the measured value of the wall thickness of the tube and n any of the reduction directions locally varies at least a predetermined amount and when the measured value of the rolling load in any of the frames locally varies by at least a predetermined amount. The present invention is also a method for detecting a defect in a matrix tube that is characterized by measuring the thickness of the wall of the tube in each of the reduction directions of a hollow tube that is being laminated in a plurality of frames that constitute A mandrel, according to the present invention, can automatically detect with high accuracy the indentation defects of the inner surface, the perforation defects and the wrinkle defects that occur in a matrix tube that is manufactured by laminating a hollow tube using a Mandrel laminator. Therefore, by generating an alarm or equivalent when a defect that occurs in a matrix tube is automatically detected by the present invention, even if a control room is placed in a remote location of a laminator, an operator can immediately stop the operation of the laminator identify the cause of the occurrence of the defect and quickly perform a countermeasure. Therefore, the occurrence of a large number of defects can be avoided in advance.

Furthermore, in accordance with the present invention, in a laminator consisting of two-cylinder frames, when the measured value of the wall thickness locally varies only in one of the reduction directions, it is possible to identify the occurrence of defects such as that caused by lamination already in odd-numbered racks or even-numbered racks that have the same reduction directions and when only the measured value of the rolling load in any of the racks locally varies, it is possible to identify the occurrence of defects as that caused by rolling in this frames. Therefore, a countermeasure to eliminate the defect can be executed quickly. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a schematic explanatory view showing the structure of a laminator for which an embodiment of a defect detection apparatus according to the present invention, if applicable. Figure 2 is a schematic explanatory view showing the structure of the wall thickness meter of Figure 1. Figure 3 shows graphs describing an example of the measured values of the wall thickness measured by the wall thickness meter of the Figure 1 and the measured value of the rolling load or measured by the rolling load measuring device of Figure 1 for a die tube in which a perforation defect has occurred. Figure 4 shows graphs describing an example of the measured values of the wall thickness measured by the wall thickness meter of Figure 1 and the measured value of the rolling load measured by the rolling load measuring device of the Figure 1 for a matrix tube in which a wrinkle defect has occurred. Figure 5 provides explanatory views illustrating various defects that occur in a matrix tube manufactured by laminating a hollow tube using a laminator. Figure 5 (a) shows inner surface indentation defects, Figure 5 (b) shows perforation defects and Figure 5 (c) and Figure 5 (d) show a wrinkle defect. List of symbols 1: Wall thickness gauge 2: Laminating load measuring device 3: Decision unit 4: Indenting defect 5: Hole 6: Wrinkle portion, 12a: Lightning projection? 11b, 12b: Lightning receiver? 100: Defect detection device M: Laminator B: Mandrel bar P: Hollow tube or matrix tube R: Ribbed cylinder Best Way to Carry Out the Invention The best way to make an apparatus for defect detection and method for a matrix tube in accordance with the present invention will be explained in detail while referring to the accompanying drawings. In the following explanation an example of the case will be given where an apparatus for detecting defects for a matrix tube according to the present invention is applied to a rolling mill of the cylinder type. Figure 1 is an explanatory view showing the structure of a laminate M employing an apparatus for defect detection of this embodiment. As shown in this figure, this laminator M is made up of a total of 5 racks, that is, racks # 1 - # 5. This laminator M is a two-roll laminator in which pairs of opposed ribbed cylinders R having reducing directions that differ by 90 ° between the adjacent frames are alternately provided in each of the frames # 1 - # 5. A hollow tube P passes through elongation lamination using a mandrel bar B which is inserted inside the hollow tube P and the grooved cylinders R which are installed in each of the frames # l- # 5, by means of which The matrix tube is manufactured. An apparatus for detecting defects 100 in accordance with this embodiment includes a wall thickness meter 1 which is installed on the exit side of rolling mill M constituted as described above and which measures the thickness of the rolled tube (die tube) in each of the reducing directions of the hollow tube P in the frames # 1- # 5 of rolling mill M, a plurality of measured laminate loading devices 2 that measure the rolling loads in the frames # l- # 5, and a decision unit 3 that determines whether a defect in the matrix tube P based on the measured value of the thickness of the tube wall in each reducing direction of the hollow tube P measured by the wall thickness meter 1 and the measured values of the rolling loads in the frames # l- # 5 measured by the rolling load measuring devices 2. A ray wall thickness gauge? What measures the wall thickness based on the attenuation of the rays? which pass through the matrix tube P is used as the wall thickness meter 1 in this embodiment. This wall thickness meter 1 is equipped with a plurality of ray projectors? lia and 12a which is placed so that the direction of the irradiation of the rays? correspond to the reductive directions of the roach tube P in the frames # l- # 5 and a plurality of lightning receptors? 11b and 12b which are placed opposite each other to the projectors of the rays and lia, 12a, along the matrix tube P. The wall thickness meter 1 is constituted so as to be able to continuously measure the wall thickness by means of the matrix tube P in each direction of irradiation of the rays? along the longitudinal direction of the tube P. Figure 2 is an explanatory view schematically showing the structure of the wall thickness meter 1 of Figure 1. As shown in this figure, the wall thickness meter 1, of according to this embodiment includes a ray projector? What is the direction and irradiation corresponding to a reducing direction (lch) of the hollow tube in frames # 1, # 3 and # 5 which are the frames of the odd number and a lightning receiver? 11b placed opposite to this, and a ray projector? 12a having a radiation direction corresponding to a reducing direction (2ch) of the hollow tube P in frames # 2 and # 4 which are even-numbered frames and a lightning receiver? 12b placed in front of this one. The wall thickness meter is constructed so that it can continuously measure the average wall thickness of the matrix tube P in each of the reducing directions lch and 2ch along the longitudinal direction of the matrix tube P. In this way of embodiment, the piezoelectric batteries are used as the meters of the mobile load 2. These are constituted so that they can continuously measure the mobile load applied to the hollow tube P in each of the frames # l- # 5 in the longitudinal direction of the hollow tube P. A mobile load measuring device according to the present invention is not limited to a piezoelectric battery, and can determine the moving load, for example, by calculation in the pressure applied by a hydraulic press device that adjusts the position of rolling of the ribbed cylinders R in each frame. The decision unit 3 receives as input the measured value of the wall thickness (the average wall thickness) of the rolled tube in each of the reducing directions (lch and 2ch) of the hollow tube P measured with the wall thickness meter 1 and the measured value of the mobile load for each of the frames # l- # 5 as measured by the mobile load measuring devices 2. Based on these capture data, the decision unit 3 determines whether a defect in the matrix tube has occurred. The decision unit 3 determines that a defect has occurred in the matrix tube P when the measured value of the wall thickness in any of the reducing directions varies locally by at least a predetermined amount and when the measured value of the mobile load in any of the frames varies locally by a least predetermined amount. Figure 3 are graphs showing an example of the measured values of the wall thickness 1 of Figure 1 and the measured value of the mobile load measured by a mobile load measuring device 2 of Figure 1 for a matrix tube in which a perforation defect has occurred. Figure 3 (a) shows the measured value of the wall thickness in the reductive direction lch of Figure 2 and Figure 3 (b) shows the measured value of the wall thickness in the reductive direction 2ch of Figure 2. Figure 3 (c) shows the measured value of the moving load for frame # 2. The distance M from the forward end of the tube which is the horizontal axis in the graphs of Figures 3 (a) -3 (c) shows the distance from the leading end of the matrix tube P after rolling, and in the graph of Figure 3 (c), this is calculated by converting the time from when the hollow tube P is held by the cylinders in the frame # 2 until it passes the frame in the length of the matrix tube P. In In the case shown in the graphs of Figure 3, the decision unit 3 first compares the measured value of the wall thickness in each of the reducing directions lch and the reducing direction 2ch with a predetermined threshold value.

At this time, in order to eliminate slight variations in the wall thickness produced even when defects are not occurring, the measured value of the wall thickness in each of the reduction directions Ich and 2ch can be differentiated in the longitudinal direction of the matrix tube. P, and the data after differentiation can be compared to a predetermined threshold value. Alternatively, the measured value of the wall thickness in each of the reduction directions lch and 2ch for a normal matrix tube P without defect can be saved previously, and the difference between this value and the measured value of the wall thickness in each of the lch and 2ch reduction directions that was measured can be compared to a predetermined threshold value. When the threshold value is exceeded in the locations At the measured value of the wall thickness in the direction of reduction 2ch shown in the graph of Figure 3 (b), it is decided that the measured value of the wall thickness in the Al locations has varied locally by at least a predetermined amount . The threshold value can be an absolute value or can be a ratio with respect to the wall thickness of the matrix tube, for example, when a matrix tube with a wall thickness of 20 mm is manufactured, it can be decided that a perforation defect has been produced if there is a portion where the wall thickness has decreased by at least 2 mm, and it can be decided that a wrinkle defect has occurred if there is a portion where the wall thickness has increased by at least 2 mm. If 20% of the wall thickness of a matrix tube is made from a threshold value, it can be decided that a perforation defect has occurred if there is a portion where the wall thickness has decreased by at least 4 mm, and it can be Decide that a wrinkle defect has occurred if there is a portion where the wall thickness has increased by at least 4 mm. Next, the decision unit 3 determines whether the measured value of the mobile load in each of the frames has locally varied by at least a predetermined amount. Mainly in the same way as in the case described above in relation to the measured value of the wall thickness, the measured value of the moving load in each frame is compared with a predetermined threshold value. At this time, the measured values of the moving load in the frames can be differentiated with respect to the longitudinal direction of the hollow tube P in order to eliminate slight variations in the moving load that occur even when no defects have occurred, and the data after the differentiation treatment they can be compared with a predetermined threshold value. Alternatively, the measured value of the moving load in each frame for a normal matrix tube P in which defects have not occurred can be saved previously, and the difference between this and the measured value of the mobile load measured in each frame is You can compare with a predetermined threshold value. When the threshold value is exceeded in the location A2 that appears in the graph of Figure 3 (c) which is the place of the measured value of the mobile load corresponding to the frame # 2, it is decided that the measured value of the mobile load at location A2 it has varied locally at least by a predetermined amount. The threshold value of the load to be used in the preference decision is a percentage. An average predicted value of the moving load can be previously determined either by numerical calculation or empirically from the previous record of the mobile loads, and a variation in the load by at least 20%, for example of the predicted value of the load can be the threshold value for use in the decision. When the measured value of the wall thickness only in a certain direction of 2ch reduction varies locally as in the example of Figure 3, it is not always necessary to decide whether the measured values of the moving load in all the frames are locally varying at least in a predetermined amount, and this may be sufficient to decide whether the measured values of the mobile load are varying locally by at least a predetermined amount in the values with even numbers, ie frames # 2 and # 4 that have this 2ch reduction direction. When the measured value of the wall thickness in any of the reduction directions varies locally by at least a predetermined amount (in the example shown in the graphs of Figures 3, the measured value of the wall thickness in the direction of 2ch reduction varies in said amount), and the measured value of the moving load in any of the frames varies locally by at least a predetermined amount (in the example shown in the graphs of Figures 3, the measured value of the load mobile in the frame # 2 varies in that amount), the decision unit 3 decides that a defect has occurred in the matrix tube P and this generates an alarm in an appropriate way as generating an alarm sound from a speaker installed in the room of control or producing flicker of a lamp installed on a control panel in the control room. At this time, in the example shown in the graphs in Figure 3, the cause of the occurrence of the defects is immediately identified as the laminate in the # 2 frame. Therefore, in order to quickly resolve this situation, a warning is preferably issued not only with respect to the occurrence of a defect but with respect to the rack number that was the cause of the occurrence of the defect. In the example shown in the graphs in Figure 3, the measured value of the wall thickness has decreased locally, so it is still preferable that an alarm be issued that produces the notification that it is very possible that the defect that was decided which occurred, is a perforation defect or an inner surface indentation defect in order to make it possible to take countermeasures more quickly and accurately after the alarm. In the example shown in Figure 3, if an alarm is generated indicating the appearance of a perforation defect or an internal surface indentation defect caused by frame # 2, the operator may, for example, operate the control unit for the mandrel laminator M shown in Figure 1 and control the cylinder space of the ribbed cylinders R installed in the frame # 2 so that it opens more. As a result, the occurrence of the perforation defects of the P-tubes that are going to be laminated afterwards can be eliminated. The causes of the occurrence of a perforation defect include the tensile forces acting on the tube between the frames of a mandrel laminator that is too large and the reduction of lamination in a frame that is too large. In the above case, the rotational speed of the ribbed cylinders R can be adjusted such that the tension between the frames is reduced. In the second case, it is effective to increase the space between the ribbed cylinders R of this frame. It can be determined if the cause is the first or the second establishing the variation of the load. Figure 4 are graphs showing an example of the measured values of the wall thickness measured by wall thickness meter 1 in Figure 1 and the measured value of the mobile load measured by a mobile load measuring device 2 in Figure 1 Figure 4 (a) shows the measured value of the wall thickness in the direction of reduction lch, Figure 4 (b) shows the measured value of the wall thickness in the direction of reduction 2ch and Figure 4 (c) shows the measured value of the moving load for frame # 5. The horizontal axes and vertical axes of the graphs of Figures 4 (a) -4 (c) are the same as the horizontal axes and vertical axes of the graphs in Figures 3 (a) -3 (c). Also in the example that appears in the graphs of figure 4, the decision unit 3 first compares the measured value of the wall thickness in each of the reduction directions lch and 2ch with a corresponding predetermined threshold value. Then, when the measured value of the wall thickness in the direction of reduction lch appearing in the graph of Figure 4 (a) exceeds the threshold value of location Bl, it is decided that the measured value of the wall thickness is locally varying in at least a predetermined amount in location Bl. Next, the decision unit 3 determines whether the measured value of the mobile load in each frame is locally varying by at least a predetermined amount. Mainly, in the same way as for the measured value described above of the wall thickness, the measured value of the moving load in each frame is compared to a corresponding predetermined threshold value. When the threshold is displayed at location B2 shown in Figure 4 (c) which is the location of the measured value of the mobile load for frame # 5, it is decided that the measured value of the mobile load at location B2 it is varying locally in at least a predetermined amount. In the example shown in the graphs in Figure 4, when the measured value of the wall thickness only in a certain direction of reduction lch is varying locally, it is not always necessary to decide whether the measured values of the moving load in all the frames are varying locally by at least a predetermined amount, and it may be sufficient to decide whether the measured values of the moving load in odd-numbered frames, ie frames # 2, # 3 and # 5 that have the predetermined reduction direction lch they are varying locally in at least a predetermined amount. When the measured value of the wall thickness in any direction of reduction varies by at least a predetermined amount (the measured value of the wall thickness for lch varies by such amount in the example shown in graphs 4) and the measured value of the mobile load in any frame locally varies by at least a predetermined amount (the measured value of the moving load for the frame # 5 varies by an amount such as in the example shown in Figure 4), the unit of decision 3 decides that a defect has occurred in the matrix tube P and generates an alarm. In this case, in the example that appear in the graphs of figure 4, it can be determined that the cause of the occurrence of the defect is the frame # 5, so it is preferable to generate an alarm that indicates not only the occurrence of a defect but also the number of the frame that is the cause of the occurrence of the defect in order to make it possible to take appropriate countermeasures quickly. In the example shown in the graphs of Figure 4, the measured value of the wall thickness was locally reduced, so that it is still preferred to generate an alarm which also indicates that there is a great possibility that the defect is a wrinkle defect. In the example shown in the graphs of Figure 4, when an alarm is generated indicating that a wrinkle defect caused by frame # 5 has occurred, the operator can put into operation the control unit for the mandrel laminator M of Figure 1 so as to reduce the rotational speed of the ribbed cylinders R installed in the frame # 4, thereby taking control so that the tension between the frame # 4 and the frame # 5 decreases. As a result, the occurrence of wrinkle defects in the matrix P tubes that are to be subsequently laminated can be avoided. The cause of the occurrence of wrinkle defects is a required compressive force acting on the tube between the frames of the mandrel laminator. Therefore, the rotational speed of the ribbed cylinders R can be adjusted so that the tension between the frames is increased. Of this menara, according to this embodiment, defects such as indentation on the inner surface, perforation defects and wrinkling defects that occur in the fabricated matrix tube by laminating a hollow tube by using a mandrel laminator M can be automatically detected with great precision. Therefore, when generating an alarm or equivalent when a defect occurs in the matrix tube, it is automatically detected even in an installation distribution that has a control room in a remote location of the mandrel laminator M, and the operator immediately It can interrupt operations and identify the cause of defects and take quick countermeasures so that a large number of defective products can be avoided in advance. When only the measured value of the wall thickness in any of the reduction directions varies locally, in the case of a two-cylinder frame, it can be decided that a defect is occurring due to lamination, either in the even-numbered frame or in the odd-numbered frame that has this reduction direction. When only the measured value of the moving load in any of the frames is varying locally it can be decided that a defect is occurring during the rolling in this frame. Therefore, a countermeasure can be carried out against the occurrence of defects in a rapid manner. In the foregoing explanation of the embodiment, an example was given of the case where a defect detection apparatus according to the present invention is applied to a twin-cylinder mandrel mill. However, the present invention is not limited to the same, and can be applied in the same way to a four-roll mandrel mill having four ribbed cylinders with reduction directions at a 90 ° angle to each other, or a mill of three-cylinder mandrel having three grooved cylinders installed in the reduction directions with an angle of 120 ° to each other and with the direction of reduction of the rollers in a difference of 60 ° between the adjacent frames. In the explanation of the embodiment described above, an example was given of the case where the control unit for the mandrel laminator and the decision unit 3 of FIG. 1 is located separately. However, the present invention is not limited to the above, and the control unit can also perform the function of the decision unit 3. A control unit for a typical mandrel mill, the measurement results are entered with a meter wall thickness 1 installed on the output side and the measurement results of the mobile load measuring devices 2.1 Therefore, when programming a control unit that can perform the same operation as the decision unit 3, it can be reduced the cost of the complete apparatus since the control unit is also used as the decision unit 3. Example 1 The present invention will be explained more specifically while reference is made to the examples.

A defect decision unit 100 according to the embodiment shown in Figure 1 was applied to a two-roll mandrel laminate M, and through the decision unit 3 it was decided whether there was a defect occurrence in the matrix tube. When the unit decided the occurrence of a defect, the spaces between cylinders and the rotational speed of the ribbed cylinders R that are used for the rolling of a hollow tube P were adjusted according to the result of the decision. In this example, the threshold value of the wall thickness was fixed at 20% of the target wall thickness of the matrix tube, if the threshold value of the moving load was set at 20% of the average moving load for the pre-laminated matrices that They have the same size and are of the same material. As a result, the percentage of occurrence of defects in a matrix tube (the number of matrix tubes P in which a defect / number of matrix tubes P rolled out by 100) was markedly decreased to 0.03% compared to the value of 0.2% prior to the application of the present invention for automatic defect detection.

Figure 1 1. Control unit 2. Alarm Figure 2 1. Odd number frame 2. Even number frame Figure 3 1. Wall thickness measured (mm) 2. Distance from the front end of the pipe (m) 3. Wall thickness measured (mm) 4. Distance from the front end of the pipe (m) . Measured moving load 6. Distance from the front end of the tube (m) Figure 4 1. Wall thickness measured (mm) 2. Distance from the front end of the pipe (m) 3. Wall thickness measured (mm) 4. Distance from the front end of the pipe . Measured mobile load 6. Distance from the front end of the tube

Claims (2)

1. CLAIMS 1. An apparatus for detecting defects for a matrix tube that is manufactured by laminating a hollow tube in a mandrel laminator having a plurality of frames, characterized by comprising: a wall thickness gauge installed on the exit side of the mandrel laminator for measuring the wall thickness of the matrix tube in the rolling directions of a hollow tube which is laminated in the plurality of frames of the mandrel laminator; a mobile load measuring device installed in each of the plurality of frames to measure the moving load in each frame, and a decision unit that determines, based on the measured value of the wall thickness of the die tube in the rolling directions of a hollow tube in the plurality of frames that is measured along the longitudinal direction of the matrix tube through the wall thickness meter and the measured value of the moving load in each of the plurality of frames that is measured with the mobile load measuring device, that a defect has occurred in the die tube when the measured value of the wall thickness in any of the rolling directions locally varies by at least a predetermined amount and when the measured value of the moving load in any of the racks varies at least a predetermined amount.
2. 2. A method for detecting defects for a matrix tube that is manufactured by rolling a hollow tube in a mandrel laminator having a plurality of frames, which is characterized by measuring the wall thickness of the matrix tube in the directions of rolling a hollow tube that is laminated in the plurality of frames using a wall thickness gauge installing on the exit side of the mandrel laminator, which measures the moving load in each of the plurality of frames, and which determines that a defect has occurred in the matrix tube when the measured value of the tube wall thickness in any of the rolling directions of the hollow tube in the plurality of frames varies locally in the longitudinal direction of the matrix tube in at least a predetermined amount and when the measured value of the moving load in any of the plurality of the frames varies by at least a predetermined amount. RESUME OF THE INVENTION An apparatus for detecting defects and a method for detecting defects that automatically detects the occurrence of a defect of a matrix tube made by laminating a hollow tube using a mandrel lamellae. A defect detection apparatus 100 according to the present invention includes a wall thickness gauge 1 which is installed on the outlet side of a mandrel laminator M and measures the wall thickness of tube in each of the directions of reduction of a hollow tube P in the frames # l- # 5 of the mandrel laminator, mobile load measuring devices 2 that measure the moving load in the frames # l- # 5 and a decision unit 3 that determines if there are defects in the die tube based on the measured value of the tube wall thickness in each of the hollow tube reduction directions P and the measured value of the moving load in each frame. The decision unit 3 determines that a defect of the matrix tube has occurred when the measured value of the tube wall thickness in any direction of reduction in the frames # l- # 5 varies locally by at least a predetermined amount and the measured value of the moving load in any of the frames # l- # 5 varies locally in at least a predetermined amount.