Quality Evaluation Method

Abstract

To provide a quality evaluation method of making it easy to determine whether or not the quality of a member continuously manufactured is satisfactory and also making it easy to manufacture a member that satisfies the predetermined quality.SOLUTION: There are included: an information acquisition step S101 of acquiring member measurement information obtained by continuously measuring an eddy current along the length of a member continuously manufactured; signal acquisition steps S102 and S112 of dividing the continuous member into a plurality of lots and acquiring a switching signal corresponding to a border with the adjacent lot included in the plurality of lots; information division steps S104 and S114 of creating lot measurement information obtained by dividing the member measurement information for each lot based on the switching signal; and determination steps S105 and S115 of calculating an index value based on the magnitude of a value of the separated member measurement information included in the lot measurement information and determining the quality of the lot based on the calculated index value.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a method for evaluating the quality of continuously manufactured parts. [Background technology]

[0002] Known continuously manufactured components include those manufactured by rolling, etc., and those manufactured by casting, etc. For example, drawn wire rods are manufactured by reducing the diameter of thick wire rods in a wire drawing process using dies or a rolling process using rolls.

[0003] In addition, drawn wire material is made by continuously processing large-diameter wire material that has been joined together through processes such as wire drawing and rolling to reduce the diameter, and then cutting it into a specified length. In this way, drawn wire material can be produced stably and at low cost.

[0004] On the other hand, it is required to carry out quality control of the produced drawn wire material so that the quality in the continuous longitudinal direction is stable. Here, the quality of the drawn wire material includes the presence or absence of scratches on the surface of the drawn wire material.

[0005] A known method for managing the quality of drawn wire material is to use an eddy current flaw detector that uses eddy currents (see, for example, Patent Document 1). The eddy current flaw detector detects the presence or absence of flaws in the drawn wire material to be managed. For example, the value of a signal (hereinafter also referred to as "output signal") output from the eddy current flaw detector changes depending on the size of the flaw in the drawn wire material. The quality of the drawn wire material is managed based on the change in the value of this output signal.

[0006] To date, quality control methods using eddy current flaw detectors have included, for example, evaluation based on the number of times the output signal value exceeds a predetermined threshold, and evaluation by continuously recording the change in the output signal value over time on chart paper and graphing it. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 8-166372 Summary of the Invention [Problem to be solved by the invention]

[0008] The output signal described above is analog data whose values ​​change continuously. When a computer is used to manage the quality of drawn wire material, the analog output signal is converted into digital data whose values ​​change discretely (converted into a digital output signal) that can be processed by the computer.

[0009] If the sampling rate is not set appropriately during the process of converting the signal into digital data, the following problems may occur: If the sampling rate is too long, data related to flaws contained in the analog output signal may be lost from the digital output signal, making it difficult to properly control quality; if the sampling rate is too short, the amount of data in the digital output signal may be too large, making it difficult to organize the data used for quality control.

[0010] Furthermore, when quality control is performed by counting the number of times the value of the output signal exceeds a predetermined threshold, there is a problem in that it is difficult to determine whether the quality is good or bad because the length of the drawn wire material is not constant.

[0011] In other words, the length of the drawn wire material, which is the product, is determined according to customer requests, and can be long or short. If the drawn wire material is long, the number of times the threshold is exceeded is likely to be large, and if the drawn wire material is short, the number of times the threshold is exceeded is likely to be small. As such, simply counting the number of signals that exceed the threshold makes it difficult to quantitatively evaluate the drawn wire material, which makes it difficult to determine whether the quality is good or bad.

[0012] The present invention has been made to solve the above-mentioned problems, and aims to provide a quality evaluation method that makes it easier to determine the quality of continuously manufactured parts and makes it easier to manufacture parts that meet specified quality. [Means for solving the problem]

[0013] In order to achieve the above object, the present invention provides the following means: A quality evaluation method according to a first aspect of the present invention includes an information acquisition step of acquiring component measurement information obtained by continuously measuring eddy currents along the longitudinal direction of components manufactured in series, a signal acquisition step of acquiring, from the components divided into a plurality of lots by lot, a switching signal corresponding to a boundary between adjacent lots among the plurality of lots, an information division step of creating lot measurement information by dividing the component measurement information corresponding to each lot based on the switching signal, and a determination step of calculating an index value based on the magnitudes of the values ​​of the plurality of component measurement information included in the lot measurement information, and determining the quality of the lot based on the calculated index value.

[0014] A manufacturing method according to a second aspect of the present invention is a method for manufacturing continuously manufactured components, and includes a processing step for continuously manufacturing the components, an inspection step for continuously measuring eddy currents along the longitudinal direction of the manufactured components using an eddy current flaw detector, an information acquisition step for acquiring component measurement information output from the eddy current flaw detector, a signal acquisition step for dividing the continuous components into a plurality of lots and acquiring switching signals corresponding to boundaries between adjacent lots among the plurality of lots, an information division step for creating lot measurement information by dividing the component measurement information corresponding to each lot based on the switching signals, and a judgment step for calculating an index value based on the magnitude of the values ​​of the plurality of component measurement information included in the lot measurement information, and judging the quality of the lot based on the calculated index value.

[0015] According to the quality evaluation method of the first aspect and the manufacturing method of the second aspect of the present invention, lot measurement information divided according to the lot is created, and quality is judged using an index value based on the magnitude of the values ​​of the multiple discretized component measurement information included in the lot measurement information. For example, compared to when quality is judged using component measurement information with a larger amount of data, the lot measurement information used has a smaller amount of data due to division, making it easier to set the sampling rate when digitizing the data.

[0016] Quality is judged using an index value based on the magnitude of the values ​​of multiple discretized component measurement information, which makes it easier to make quantitative judgments by eliminating the influence of lot length compared to when evaluating by counting the number of times a threshold is exceeded. [Effects of the Invention]

[0017] According to the quality evaluation method of the present invention, lot measurement information is created that is divided according to the lot, and quality is judged using an index value based on the magnitude of the values ​​of the discretized multiple component measurement information contained in the lot measurement information. This makes it easier to judge the quality of continuously manufactured components, and has the effect of making it easier to manufacture components that meet the specified quality. [Brief explanation of the drawings]

[0018] [Figure 1] 1A to 1C are schematic diagrams illustrating steps in a method for producing a drawn wire rod according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram illustrating an outline of the configuration of the eddy current flaw detector of FIG. 1. [Figure 3] FIG. 2 is a block diagram illustrating the configuration of the quality evaluation device of FIG. [Figure 4] 1 is a flowchart illustrating a method for manufacturing a drawn wire material. [Figure 5] FIG. 10 is a schematic diagram illustrating a case where a drawn wire material has a flaw. [Figure 6] 1 is a flowchart illustrating a method for evaluating the quality of a product lot of a drawn wire material. [Figure 7] 1 is a flowchart illustrating a method for evaluating the quality of a material lot of a drawn wire material. [Figure 8] 10 is a graph illustrating the details of the calculation process of a digital measurement signal. [Figure 9] FIG. 10 is a diagram showing an example of quality data created for each material lot. [Figure 10] FIG. 10 is a diagram showing an example of quality data created for each product lot. DETAILED DESCRIPTION OF THE INVENTION

[0019] A method for manufacturing and evaluating the quality of a drawn wire material according to one embodiment of the present invention will be described with reference to Figures 1 to 10. In this embodiment, the object to be manufactured and evaluated for quality is a drawn wire material DM (corresponding to a component), but the object may also be any continuously manufactured component, and is not limited to a drawn wire material. Continuously manufactured components include components manufactured using at least one of a wire drawing process using a die, a rolling process using rolls, a casting process, etc.

[0020] First, the configurations of the production line 1 and quality evaluation device 50 used in producing the drawn wire material DM will be described, followed by a description of the production method and quality evaluation method. Note that the quality evaluation device 50 may or may not be included in the production line 1. Figure 1 is a schematic diagram illustrating the production process of the drawn wire material according to this embodiment.

[0021] The production line 1 continuously produces drawn wire material DM, which is a relatively thin wire material having a desired diameter (for example, an outer diameter of 0.5 mm or more and 3.0 mm or less), from a wire rod WR (corresponding to a wire stock) which is a relatively thick wire material (for example, an outer diameter of 6 mm or more and 15 mm or less). In this embodiment, the wire rod WR and drawn wire material DM are described as being copper wire material, but are not limited to copper as long as they are made of any conductive material such as iron or aluminum. The wire rod WR is produced in an upstream process different from the production line 1 and is supplied to the production line 1.

[0022] 1, the production line 1 is mainly provided with a delivery section 10, a wire drawing section 20, an eddy current flaw detector 30, a winding section 40, and a quality evaluation device 50. In this embodiment, an example will be described in which the production line 1 includes the quality evaluation device 50.

[0023] The delivery section 10 has a wire rod WR manufactured in an upstream process placed therein and supplies the wire rod WR to the wire drawing section 20. Known configurations can be used for the configuration of the section where the wire rod WR is placed and the configuration of the section that supplies the wire rod WR to the wire drawing section 20, and the specific configurations are not limited thereto.

[0024] For example, a wire rod WR may be arranged for each material lot, which is a unit of continuous wire rod, or a wire rod WR connecting multiple material lots may be arranged in the delivery section 10. The wire rods WR may be connected between material lots produced in the same upstream process, or between material lots produced in different upstream processes.

[0025] The delivery section 10 may be provided with a configuration that enables connection of material lots, and the connection of material lots may be performed in the delivery section 10, or the connection of material lots may be performed at a location different from the delivery section 10. The connection of material lots can be performed using a known connection method such as welding, and the specific connection method is not limited.

[0026] The wire drawing unit 20 converts the wire rod WR supplied from the delivery unit 10 into a drawn wire material DM. Specifically, it processes the wire rod WR by reducing the diameter thereof to produce a drawn wire material DM. The wire drawing unit 20 may perform at least one of a wire drawing process using a die and a rolling process using a roll. Furthermore, the wire drawing unit 20 may also include other processes.

[0027] The eddy current flaw detector 30 inspects the quality of the drawn wire material DM that has been processed to a desired diameter in the wire drawing section 20. Specifically, it measures whether or not there are scratches on the drawn wire material DM processed in the wire drawing section 20.

[0028] Fig. 2 is a schematic diagram illustrating an outline of the configuration of the eddy current flaw detector of Fig. 1. As shown in Fig. 2, eddy current flaw detector 30 is mainly provided with coil 31 and flaw detection section 32. In this embodiment, the eddy current flaw detector 30 is described as being of a single type using a single coil 31, and is of a self-induction type in which excitation and detection are performed by the same single coil 31.

[0029] The eddy current flaw detector 30 may be used in a single mode, a self-comparison mode, or a standard comparison mode. The induction mode of the eddy current flaw detector 30 may be a self-induction mode or a mutual induction mode.

[0030] The coil 31 is a conductor wire arranged in a spiral shape. An alternating current is supplied to the coil 31, and a flaw detector 32 that detects flaws in the drawn wire material DM is electrically connected to the coil 31. In this embodiment, an example will be described in which the coil 31 is arranged so that the drawn wire material DM passes through the inside of the coil 31.

[0031] In other words, the description will be given by applying it to an example in which the eddy current flaw detector 30 is of a penetration type. Note that the coil 31 may be of a penetration type, or may be of a rotary type in which a plurality of (for example, two or four) coils 31 rotate around the drawn wire material DM.

[0032] The flaw detection unit 32 has a function as a power source that supplies AC current to the coil 31, and a function of outputting a measurement signal (corresponding to component measurement information) of the drawn wire material DM to the quality evaluation device 50. In this embodiment, the description will be given by applying it to an example in which the measurement signal is a voltage whose value changes depending on the presence or absence of flaws, the size of the flaws, etc.

[0033] The measurement signal may be a voltage value, a current value, or an impedance value, and is not particularly limited. The flaw detection unit 32 may have any known configuration, and its type, etc., is not limited thereto.

[0034] The winding unit 40 winds up the drawn wire material DM after it has been inspected by the eddy current flaw detector 30. The winding unit 40 may have any known configuration, and the specific configuration is not limited thereto.

[0035] The quality evaluation device 50 evaluates the quality of the drawn wire material DM based on the measurement signal output from the eddy current flaw detector 30. Specifically, it evaluates the quality of the drawn wire material DM with respect to the presence or absence and size of flaws.

[0036] The quality evaluation device 50 is connected to the eddy current flaw detector 30 so that information can be communicated with the device. In this embodiment, the description will be given of an example in which measurement signals are sequentially transmitted and received using wired or wireless information communication devices. Note that the measurement signals may be transferred from the eddy current flaw detector 30 to the quality evaluation device 50 using a portable information storage medium.

[0037] Fig. 3 is a block diagram illustrating the configuration of a quality evaluation device. As shown in Fig. 3, the quality evaluation device 50 is an information processing device such as a computer or server having a CPU (central processing unit), ROM, RAM, an input / output interface, etc. A program stored in the storage device such as the ROM causes the CPU, ROM, RAM, and input / output interface to cooperate with each other to function as at least an information acquisition unit 51, a signal acquisition unit 52, an information division unit 53, a judgment unit 54, a data creation unit 55, and a condition comparison unit 56.

[0038] The information acquiring unit 51 acquires the measurement signal output from the eddy current flaw detector 30 that has continuously measured eddy currents along the longitudinal direction of the drawn wire material DM. In this embodiment, an example will be described in which an analog measurement signal is output from the eddy current flaw detector 30 and converted into a digital measurement signal by the information acquiring unit 51. The position where the analog measurement signal is converted into a digital measurement signal may be the information acquiring unit 51 as described above, or may be the eddy current flaw detector 30, and the position is not limited. In other words, the information acquiring unit 51 may acquire the digital measurement signal output from the eddy current flaw detector 30.

[0039] The signal acquisition unit 52 acquires a switching signal corresponding to a boundary located between adjacent lots among a plurality of lots. A lot is a unit into which a drawn wire material DM (or wire rod WR), which is a long material, is divided into a plurality of parts in the longitudinal direction. A boundary is a boundary between adjacent lots, for example, a portion where the nth lot switches to the n+1th lot (hereinafter, n is an integer equal to or greater than 1).

[0040] The switching signals acquired by the signal acquiring unit 52 include a product switching signal and a material switching signal. The switching signal is a signal obtained by detecting the boundary between adjacent lots. In this embodiment, the present invention will be described as being applied to a method of detecting the boundary between adjacent lots based on the weight of each lot calculated from the diameter, weight per unit volume, and length of the drawn wire material DM.

[0041] The method for detecting the boundary between adjacent lots may also be a method of detecting traces of joined wire rods present on the drawn wire rod DM as the boundary between adjacent lots, a method of detecting the boundary between adjacent lots based on the length of the drawn wire rod DM being fed and the length of the lot, or a method of detecting a physical mark such as a marking on the drawn wire rod DM as the boundary between adjacent lots.

[0042] The product switching signal is a signal output from the product switching signal output unit 45, and corresponds to the boundary between adjacent product lots among multiple product lots. A product lot is a unit obtained by dividing a continuous drawn wire material DM into multiple parts in the longitudinal direction. A product lot is also a unit sold as a product. The product switching signal is a signal obtained by detecting the boundary between adjacent product lots among multiple product lots. For example, it is a signal obtained by detecting the part where the nth product lot switches to the n+1th product lot.

[0043] The material switching signal is a signal output from the material switching signal output unit 15, and corresponds to the boundary between adjacent material lots among multiple material lots. A material lot is a unit obtained by dividing the drawn wire material DM into multiple parts in the longitudinal direction, and corresponds to the multiple wire rods WR used to form the drawn wire material DM. The material switching signal is a signal obtained by detecting the boundary between adjacent material lots among multiple material lots. For example, it is a signal obtained by detecting the part where the nth material lot switches to the n+1th material lot.

[0044] The product switching signal output unit 45 is disposed near the winding unit 40 and is connected to the quality evaluation device 50 so as to be able to communicate signals with the quality evaluation device 50. The product switching signal output unit 45 outputs a product switching signal which is a signal corresponding to the boundary between adjacent product lots.

[0045] The product switching signal output unit 45 may be located near the winding unit 40 as described above, or may be located away from the winding unit 40 as long as it is capable of outputting a product switching signal.

[0046] In this embodiment, an example will be described in which the product switching signal output unit 45 outputs a product switching signal based on the weight of the drawn wire material DM wound on the winding unit 40. Specifically, a product switching signal is output based on the weight of each product lot calculated from the diameter, weight per unit volume, and length of the drawn wire material DM. For example, a product switching signal is output indicative of a switch from the nth product lot to the n+1th product lot.

[0047] The method by which the product switching signal output unit 45 outputs the product switching signal is not limited to the above-mentioned method, and various other methods capable of outputting the product switching signal may be used.

[0048] The material switching signal output unit 15 is disposed near the delivery unit 10 and is connected to the quality evaluation device 50 so as to be able to communicate signals with it. The material switching signal output unit 15 outputs a material switching signal, which is a signal corresponding to the boundary between material lots.

[0049] In this embodiment, the material switching signal output unit 15 detects a joint that is a boundary between adjacent material lots in the wire rod WR and outputs a material switching signal indicating that the material lot has been switched. Note that the method by which the material switching signal output unit 15 outputs the material switching signal is not limited to the above-described method, and various other methods capable of outputting a material switching signal may be used.

[0050] The information dividing unit 53 divides the multiple measurement signals (corresponding to component measurement information) acquired by the information acquiring unit 51 according to the product lots, based on the product switching signal, to create product lot measurement information (corresponding to lot measurement information). In other words, it determines the boundaries between product lots in the multiple measurement signals based on the product switching signal, and divides the multiple measurement signals at the boundaries between product lots to create product lot measurement information. Specific calculation processing will be described later.

[0051] For example, product lot measurement information corresponding to the nth product lot includes multiple measurement signals measured from the boundary between the n-1th product lot and the nth product lot to the boundary between the nth product lot and the n+1th product lot.

[0052] Furthermore, the information dividing unit 53 creates material lot measurement information (corresponding to lot measurement information) by dividing the multiple measurement signals (corresponding to component measurement information) acquired by the information acquiring unit 51 according to each material lot based on the material switching signal. In other words, it determines the boundary between material lots in the multiple measurement signals based on the material switching signal, and divides the multiple measurement signals at the boundary between material lots to create material lot measurement information. Specific calculation processing will be described later.

[0053] For example, material lot measurement information corresponding to the nth material lot includes multiple measurement signals measured from the boundary between the n-1th material lot and the nth material lot to the boundary between the nth material lot and the n+1th material lot.

[0054] The judgment unit 54 performs arithmetic processing to calculate index values ​​based on the magnitudes of the values ​​(hereinafter also referred to as "output values") of the multiple discretized measurement signals included in the product lot measurement information and material lot measurement information. It also performs arithmetic processing to judge the quality of the product lot and material lot based on the calculated index values. The details of the arithmetic processing in the judgment unit 54 will be described later.

[0055] In this embodiment, the explanation will be given by applying the present invention to an example in which the index value is a value indicating the variation in the magnitude of a plurality of output values. More specifically, the explanation will be given by applying the present invention to an example in which the index value is a standard deviation. Note that the index value may be the standard deviation or may be a value indicating other variations such as variance.

[0056] Furthermore, the index value may be a value that indicates the variation in the magnitude of multiple output values, such as a standard deviation, or a value that represents the magnitude of the values ​​in multiple output values, such as the average or median of the magnitude of the output values.

[0057] The data creation unit 55 creates quality data for each product lot of the drawn wire material DM based on the judgment result of the judgment unit 54. The data creation unit 55 also creates quality data for each material lot of the drawn wire material DM based on the judgment result of the judgment unit 54.

[0058] The condition comparison unit 56 compares manufacturing conditions in the upstream process of manufacturing the wire rod WR based on the quality data for each material lot created by the data creation unit 55. The processing contents of the data creation unit 55 and the condition comparison unit 56 will be described later.

[0059] Next, a method for manufacturing the drawn wire material DM and a method for evaluating its quality in this embodiment will be described. The drawn wire material DM is manufactured from a wire rod WR in a manufacturing line 1 shown in Fig. 1. Fig. 4 is a flowchart illustrating the method for manufacturing the drawn wire material DM.

[0060] First, as shown in FIGS. 1 and 4, a wire rod WR manufactured in an upstream process is supplied to the manufacturing line 1 (supply step S10). Specifically, the wire rod WR manufactured in the upstream process is placed in the delivery section 10. The wire rod WR, to which a plurality of material lots have been connected in advance, may be placed in the delivery section 10, or the wire rod WR may be delivered for each material lot. 10 and may be connected to other material lots already located in the delivery section 10.

[0061] Next, the wire rod WR delivered from the delivery unit 10 is processed into a drawn wire material DM (processing step S20). Specifically, the wire rod WR is processed to reduce its diameter in the wire drawing unit 20, thereby producing the drawn wire material DM. The diameter reduction process employs at least one of a wire drawing process using a die and a rolling process using rolls.

[0062] Next, the drawn wire material DM produced in the wire drawing section 20 is inspected (corresponding to measuring eddy currents) using an eddy current flaw detector 30 (inspection step S30). Specifically, as shown in Fig. 2, the drawn wire material DM is passed through a coil 31 of the eddy current flaw detector 30.

[0063] An AC current is applied to the coil 31 from the flaw detection unit 32. Eddy currents EC are generated on the surface of the drawn wire material DM passed through the coil 31 due to the magnetic field generated from the coil 31 to which the AC current is applied. Furthermore, the magnetic field generated by the eddy currents EC is detected by the coil 31 and the flaw detection unit 32, and the flaw detection unit 32 outputs a measurement signal of a voltage corresponding to the eddy current EC.

[0064] As shown in Fig. 5, when a flaw SH is present on the surface of the drawn wire material DM, the eddy current EC flows around the flaw SH, and the magnitude of the eddy current EC changes. The change in the magnitude of the eddy current EC is detected by the coil 31 and the flaw detection unit 32, and the voltage of the measurement signal output from the flaw detection unit 32 also changes. In this embodiment, an example will be described in which the voltage of the measurement signal increases when a flaw SH is present on the surface of the drawn wire material DM.

[0065] After inspection using the eddy current flaw detector 30, the drawn wire material DM is wound around the winding section 40 (winding step S40). This completes the production of the drawn wire material DM in the production line 1. The drawn wire material DM wound around the winding section 40 is then cut into individual product lots.

[0066] Furthermore, a process for evaluating the quality of the drawn wire material DM is performed based on the measurement signal output from the eddy current flaw detector 30 in the inspection step S30 (quality evaluation step S100). The process for evaluating the quality is performed in a quality evaluation device 50.

[0067] Fig. 6 is a flowchart explaining a quality evaluation method for a product lot of drawn wire material DM. Fig. 7 is a flowchart explaining a quality evaluation method for a material lot of drawn wire material DM. First, the calculation process for evaluating the quality of the product lot will be described with reference to Fig. 6. Then, the calculation process for evaluating the quality of the material lot will be described with reference to Fig. 7.

[0068] In this embodiment, the calculation process for evaluating the quality of a product lot and the calculation process for evaluating the quality of a material lot are performed in parallel. For ease of explanation, the two processes are described separately using Figures 6 and 7, but the calculation process may also be performed based on a flowchart that combines both processes.

[0069] 6, the quality evaluation device 50 performs a process of acquiring a measurement signal, which is continuous data output from the eddy current flaw detector 30 (information acquisition step S101). Specifically, the information acquisition unit 51 of the quality evaluation device 50 acquires an analog measurement signal output from the flaw detection unit 32 of the eddy current flaw detector 30. The information acquisition unit 51 performs a process of converting the acquired analog measurement signal into a digital measurement signal.

[0070] Furthermore, the quality evaluation device 50 performs a process of acquiring a product switching signal (signal acquisition step S102). Specifically, the signal acquisition unit 52 of the quality evaluation device 50 acquires the product switching signal output from the product switching signal output unit 45.

[0071] Thereafter, the quality evaluation device 50 performs a calculation process to compare the digital measurement signal with the product switching signal (S103). Specifically, the information dividing unit 53 of the quality evaluation device 50 performs a calculation process to compare the digital measurement signal with the product switching signal based on time information included in the digital measurement signal and the product switching signal.

[0072] Furthermore, the information dividing unit 53 performs a calculation process to determine a joint, which is a boundary between product lots in the digital measurement signal. In the process of determining the joint, it is preferable to take into consideration the time difference between when the drawn wire material DM is inspected by the eddy current flaw detector 30 and when the boundary between product lots is detected by the product switching signal output unit 45.

[0073] After the collation process, the quality evaluation device 50 performs an arithmetic process to create product lot measurement information by dividing the digital measurement signal according to the product lot (information division step S104). Specifically, the information division unit 53 performs an arithmetic process to divide the digital measurement signal at the connection portion that is the boundary between the product lots in the digital measurement signal determined in S103.

[0074] When the product lot measurement information is created, the quality evaluation device 50 performs a calculation process to determine the quality of each product lot (in other words, each piece of product lot measurement information) (determination step S105). In this embodiment, an example will be described in which the determination unit 54 of the quality evaluation device 50 performs a quality determination process based on a threshold value for each piece of product lot measurement information, and a quality determination process using a standard deviation as an index value.

[0075] In the threshold-based quality determination process, the determination unit 54 determines whether the voltage value in the product lot measurement information exceeds a predetermined threshold. The number of times the voltage value in the product lot measurement information exceeds the predetermined threshold is linked to the product lot measurement information and stored. Here, the voltage value in the product lot measurement information is a value that increases according to the size of the flaw SH in the drawn wire material DM.

[0076] The threshold value used for the determination may be one or more. In this embodiment, an example will be described in which two threshold values ​​are used: a threshold value (small) corresponding to small scratches SH and a threshold value (large) corresponding to large scratches SH.

[0077] In the quality judgment process using the standard deviation as an index value, the judgment unit 54 performs a calculation process to determine the standard deviation using the voltage values ​​in the product lot measurement information as a population. The standard deviation value determined by the calculation process is associated with the product lot measurement information that was the subject of the calculation process and stored. Note that a known calculation method can be used to determine the standard deviation, and the calculation method is not limited to a specific one.

[0078] After the calculation process for determining the quality for each product lot has been performed, the quality evaluation device 50 performs calculation process for creating quality data for each product lot of the drawn wire material DM (S106). Specifically, the data creation unit 55 of the quality evaluation device 50 creates quality data that summarizes the number of times the voltage value exceeded a predetermined threshold and the value of the standard deviation for each product lot (in other words, for each piece of product lot measurement information).

[0079] The created quality data may be displayed on a display device such as a display provided in the quality evaluation device 50, may be output to a storage device, or may be output to another information processing device connected so that information can be communicated.

[0080] Next, the calculation process for evaluating the quality of a material lot will be described. As shown in Fig. 7, the quality evaluation device 50 performs a process for acquiring a measurement signal, which is continuous data output from the eddy current flaw detector 30 (S101). The specific content of this process is similar to the calculation process for evaluating the quality of a product lot, so a detailed description will be omitted.

[0081] Furthermore, the quality evaluation device 50 performs a process of acquiring a material switching signal (signal acquisition step S112). Specifically, the signal acquisition unit 52 of the quality evaluation device 50 acquires the material switching signal output from the material switching signal output unit 15.

[0082] Thereafter, the quality evaluation device 50 performs a calculation process to compare the digital measurement signal with the material switching signal (S113). Specifically, the information dividing unit 53 of the quality evaluation device 50 compares the digital measurement signal with the material switching signal based on the time information included in the digital measurement signal and the material switching signal, and performs a calculation process to determine the connection portion, which is the boundary between material lots, in the digital measurement signal.

[0083] In the process of determining the joint, it is preferable to take into consideration the time lag between when the material switching signal output unit 15 detects the boundary between the material lots and when the drawn wire material DM is inspected by the eddy current flaw detector 30.

[0084] After the collation process, the quality evaluation device 50 performs an arithmetic process to create material lot measurement information by dividing the digital measurement signal according to the material lot (information division step S114). Specifically, the information division unit 53 performs an arithmetic process to divide the digital measurement signal at the connection portion that is the boundary between the material lots in the digital measurement signal determined in S113.

[0085] After creating the material lot measurement information, the quality evaluation device 50 performs a calculation process to determine the quality of each material lot (in other words, each piece of material lot measurement information) (determination step S115).

[0086] In this embodiment, the description will be given by applying it to an example in which the judgment unit 54 of the quality evaluation device 50 performs a quality judgment process based on a threshold value and a quality judgment process using a standard deviation as an index value for each piece of material lot measurement information. Note that the processing contents of the quality judgment process based on a threshold value and the quality judgment process using a standard deviation as an index value are the same as the processing contents in S105, and therefore the description thereof will be omitted.

[0087] After the calculation process for determining the quality for each material lot has been performed, the quality evaluation device 50 performs calculation process for creating quality data for each material lot of the drawn wire material DM (S116). Specifically, the data creation unit 55 of the quality evaluation device 50 creates quality data that summarizes the number of times the voltage value exceeded a predetermined threshold and the value of the standard deviation for each material lot (in other words, for each piece of material lot measurement information).

[0088] After the calculation process for creating the quality data is performed, the quality evaluation device 50 performs a calculation process for comparing the manufacturing conditions of the upstream process (S117). Specifically, the condition comparison unit 56 of the quality evaluation device 50 compares the manufacturing conditions of the upstream process for manufacturing the wire rod WR based on the quality data for each material lot.

[0089] The comparison results of the manufacturing conditions may be displayed on a display device such as a display provided in the quality evaluation device 50, may be output to a storage device, or may be output to another information processing device connected so that information can be communicated.

[0090] Next, an example of the arithmetic processing of the digital measurement signal in the quality evaluation device 50 will be described. Fig. 8 is a graph illustrating the details of the arithmetic processing of the digital measurement signal. In the graph shown in Fig. 8, the horizontal axis represents the length of the drawn wire material DM, and the vertical axis represents the level indicating the size of the flaw SH. The level of the flaw SH also represents the magnitude of the voltage in the measurement signal. In Fig. 8, the description will be applied to an example in which the wire rod WR is a copper wire material with an outer diameter of 8 mm, and the drawn wire material DM is a copper wire material with an outer diameter of 2.6 mm.

[0091] The graph shown in Figure 8 shows product switching signals indicated by vertical dotted lines. Product lots are shown as the portions sandwiched between the product switching signals. Figure 8 shows product lots (1) to (13).

[0092] Furthermore, multiple material lots are shown at the top of the graph in Figure 8. In Figure 8, material lots A-1 to A-4, B-1 and B-2 are shown. The boundaries between material lots correspond to material switching signals.

[0093] Material lots A-1 to A-4 have the same alphabet, which indicates that they are lots manufactured in the same upstream process. The numbers also indicate that they are manufactured in different lots. Material lots B-1 and B-2 have different alphabets from A-1 to A-4, which indicates that they are lots manufactured in different upstream processes.

[0094] Additionally, the graph shown in Fig. 8 illustrates the threshold (small) and threshold (large) used to determine quality. The values ​​of the threshold (small) and threshold (large) can be set appropriately and are not limited to any particular value. Furthermore, the number of thresholds is not limited to two, and may be one, or three or more.

[0095] Next, a description will be given of the quality data created by the quality evaluation device 50. Fig. 9 shows an example of quality data created for each material lot, and Fig. 10 shows an example of quality data created for each product lot.

[0096] As shown in Figure 9 Looking at the number of large and small scratches in the quality data created for each material lot, materials A-1 to A-4 have one or more large and small scratches, while materials B-1 and B-2 have zero large and zero small scratches. Also, looking at the standard deviation, materials A-1 to A-4 have a standard deviation of 0.096 or more, while materials B-1 and B-2 have a standard deviation of 0.018 or less.

[0097] In other words, it can be seen that the occurrence of scratches SH on the surface of the drawn wire material DM differs between materials A-1 to A-4 and materials B-1 and B-2, as clearly reflected in the number of scratches (large) and scratches (small) and the standard deviation.

[0098] As shown in Figure 10, by focusing on the number of scratches (large) and scratches (small) in the quality data created for each product lot, it is possible to determine whether or not there are sudden scratches SH, but it is difficult to grasp the overall trend, such as the frequency of occurrence of scratches SH. On the other hand, by focusing on the standard deviation, it is relatively easy to grasp the overall trend, such as the frequency of occurrence of scratches SH.

[0099] According to the above manufacturing method and quality evaluation method, product lot measurement information divided according to the product lot is created, and the quality of the product lot is judged using the standard deviation, which is an index value based on the magnitude of the output value included in the product lot measurement information. Also, material lot measurement information divided according to the material lot is created, and the quality of the material lot is judged using the standard deviation, which is an index value based on the magnitude of the output value included in the material lot measurement information.

[0100] As a result, compared to when quality is determined using the measurement signal of the wire drawn material DM, which has a larger data volume, the measurement signal of the wire drawn material DM is divided and product lot measurement information and material lot measurement information, which have a smaller data volume, are used, making it easier to set the sampling rate when converting analog data to digital data.For example, it becomes easier to set an appropriate sampling rate based on the movement speed of the wire drawn material DM and the length of the product lot and material lot.In addition, it becomes possible to appropriately compress this information to the extent that information indicating the presence or absence of scratches in the product lot measurement information and material lot measurement information is not lost.

[0101] Because the quality of the drawn wire material DM is judged using the standard deviation, it is easier to make a quantitative judgment by eliminating the influence of lot length compared to when the evaluation is simply performed by counting the number of times a threshold is exceeded. Furthermore, by combining this method with the evaluation method of counting the number of times a threshold is exceeded, quantitative judgment becomes even easier. Therefore, it becomes easier to manufacture drawn wire material DM that meets the specified quality.

[0102] By using a product switching signal that corresponds to the boundary between wire drawn material DM product lots, the quality of each product lot can be quantified and visualized, making it easier to judge the quality. In addition, the judged quality can be fed back to the wire drawn material DM manufacturing process, making it easier to manufacture wire drawn material DM that meets the specified quality.

[0103] By using a material switching signal corresponding to the boundary between material lots of the drawn wire material DM, the quality of the wire rod WR before it becomes the drawn wire material DM can be quantified and visualized, making it easier to judge the quality. In addition, the judged quality can be fed back to the wire rod WR manufacturing process, making it easier to manufacture drawn wire material DM that meets the specified quality.

[0104] By using the standard deviation, which indicates the variation in quality, it becomes easier to quantitatively determine the quality of a product lot or material lot compared to using the number of times a threshold value is exceeded. In other words, it becomes easier to eliminate the influence of the length of the product lot or material lot when making a determination.

[0105] Furthermore, when the average or median of the output values ​​is used to judge quality, the amount of calculation required for judgment tends to be smaller than when standard deviation or variance, which indicates variation, is used, making it easier to perform quality evaluation of product lots and material lots more quickly.

[0106] The technical scope of the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. For example, although the above-described embodiments have been described as being applied to an example in which quality evaluation is performed on both product lots and material lots, quality evaluation may be performed on either the product lots or material lots alone. [Explanation of symbols]

[0107] 30...Eddy current flaw detector, DM...Drawn wire material (component), WR...Wire rod (wire material), S20...Processing step, S30...Inspection step, S40...Winding step, S100...Quality evaluation step, S101...Information acquisition step, S102, S112...Signal acquisition step, S104, S114...Information division step, S105, S115...Judgment step

Claims

1. A quality evaluation method comprising: an information acquisition step of acquiring component measurement information obtained by continuously measuring eddy currents along the longitudinal direction of components manufactured in succession; a signal acquisition step of acquiring, from the components divided into a plurality of parts by lot, a switching signal corresponding to the boundary between adjacent lots among the plurality of lots; an information division step of creating lot measurement information by dividing the component measurement information corresponding to each lot based on the switching signal; and a determination step of calculating an index value based on the magnitude of the values ​​of the plurality of component measurement information included in the lot measurement information, and determining the quality of the lot based on the calculated index value, wherein the components are drawn wire material.

2. 2. The quality evaluation method according to claim 1, wherein the switching signal corresponds to a boundary between adjacent product lots among a plurality of product lots obtained by dividing the continuous member.

3. 2. The quality evaluation method according to claim 1, wherein the wires in the component, which are a connection of a plurality of wires, correspond to a plurality of material lots, respectively, and the switching signal is a signal corresponding to a boundary between adjacent material lots in the plurality of material lots.

4. 4. The quality evaluation method according to claim 1, wherein the index value is a value that indicates a variation in magnitude of the values ​​of the plurality of discretized component measurement information in the lot measurement information.

5. The quality evaluation method according to claim 1 , wherein the index value is an average value or a median value of the magnitudes of the plurality of discretized values ​​of the component measurement information in the lot measurement information.

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