JP2018008278A - Testing device and testing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To evaluate sliding characteristics more accurately.SOLUTION: A testing device 10 includes a heating furnace 2 for heating a testing metal plate 1, a pull-out device 8 for pulling the testing metal plate 1 in a direction in which it is pulled out from the heating furnace 2, a mold 5 being disposed between the heating furnace 2 and the pull-out device 8 and pressing each of both faces 1a and 1b of the testing metal plate 1 pulled out from the heating furnace 2, a pressing device 6 for pressing the mold 5 against both faces of the testing metal plate 1, a thermocouple 3 attached to the testing metal plate 1, and a detection part 9 for acquiring a temperature of the testing metal plate 1 detected from the thermocouple 3, pull-out force by which the pull-out device 8 pulls out the testing metal plate 1, and a load by which the mold 5 is pressed against the testing metal plate 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a test apparatus and a test method for evaluating sliding characteristics between a metal plate and a mold in a press method.

  In recent years, a technique of pressing and molding a metal in a heated state has been used. For example, in hot pressing (hot stamping), molding and heat treatment are performed simultaneously. In this way, when the heated metal is pressed against the mold and molded, the heated metal moves while sliding in contact with the mold. That is, the metal slides with respect to the mold. Understanding the sliding characteristics of the heated metal is important in determining whether or not press forming is possible.

  Japanese Patent No. 5609172 (Patent Document 1) discloses a high-temperature sliding test apparatus for evaluating sliding characteristics between a steel plate and a press die in a hot press method. In this high-temperature sliding test apparatus, when the sliding characteristic evaluation part of the test steel plate heated by the heating device reaches a predetermined temperature, the drawing cylinder grips and pulls the test steel plate. By operating the drawing cylinder, the test steel plate and the sliding mold are sequentially slid by the length of the sliding characteristic evaluation section. When the sliding characteristic evaluation unit and the sliding mold slide, the vertical load and the pulling force are measured. The sliding characteristics are evaluated by the measured vertical load and pulling force.

Patent No. 5609172

  The present application discloses a test apparatus and a test method that can more accurately evaluate sliding characteristics.

  A test apparatus according to an embodiment of the present invention is disposed between a heating furnace that heats a test metal plate, a pulling apparatus that pulls the test metal plate in a direction of pulling out the test metal plate, and the heating furnace and the pulling apparatus. A mold that presses each of the upper and lower surfaces of the test metal plate drawn out from the heating furnace, a pressure device that presses the mold against the upper and lower surfaces of the test metal plate, and the test metal plate A thermocouple for measuring the temperature of the test metal plate, a conducting wire connected to the thermocouple, a temperature of the test metal plate detected from the thermocouple and the conducting wire, and the drawing device is the test A pulling force for pulling out the metal plate, and a detection unit for acquiring a load for pressing the mold against the test metal plate.

  According to the present disclosure, the sliding characteristics can be more accurately evaluated.

FIG. 1 is a diagram illustrating a configuration example of a test apparatus according to the present embodiment. FIG. 2 is a diagram illustrating a state of the test apparatus during sliding. FIG. 3 is a graph showing an operation example of the drawing device and the pressing device. FIG. 4 is a graph showing the measurement result of the test metal plate temperature in the test using the test apparatus. FIG. 5 is a graph showing the measurement results of the friction coefficient of the test metal plate in the same test as FIG.

  The inventors investigated the influence of the sliding characteristics between the heated metal plate and the mold on the formability. In that process, we tried to predict the formability during pressing by calculation (simulation) based on the sliding characteristics. In order to increase the accuracy of this prediction, the sliding characteristics are required to be accurate. The inventors have examined the accuracy of the sliding characteristics for use in predicting formability, and found that the temperature change of the sliding characteristics is important. Therefore, in a test for evaluating the sliding characteristics, a configuration for accurately measuring the temperature of the sliding portion was examined.

  At first, the inventors examined using a radiation thermometer to measure the temperature of the portion where the metal plate slides with respect to the mold, as in the prior art. As an example, as described in the above-mentioned Japanese Patent No. 5609172, a test metal plate (on the entrance side of the mold) before sliding with the mold and the mold metal (after mold opening) after sliding with the mold. The configuration of measuring the test metal plate on the side with a radiation thermometer was examined. In this method, since the location where the test metal piece is sliding is hidden by the shadow of the mold, the temperature of the test metal piece during sliding cannot be measured. For this reason, the temperature of the metal piece during sliding is estimated from the temperature of the test metal piece before and after sliding. However, it has proven difficult to accurately estimate temperature. As a result of the study, in the above conventional configuration, the surface state of the test metal plate changes before and after sliding with the mold, so the emissivity of the test metal plate is different, and the measured temperature has an error. Was found to occur. Therefore, we examined increasing the accuracy by correcting the emissivity in the radiation thermometer. However, it was found that the roughness of the surface of the test metal plate after being rubbed with the mold differs depending on the test conditions such as pressing of the mold, so that it is difficult to improve the accuracy by emissivity correction.

  As a result of further studies, the inventors have conceived that the accuracy of temperature measurement can be improved by taking a thermocouple in contact with the test metal plate without taking a non-contact temperature measurement method. Specifically, the inventors have come up with a test apparatus and a test method for accurately measuring the temperature of the sliding portion using a thermocouple. Embodiments of this test apparatus and test method will be described below.

  A test apparatus according to an embodiment of the present invention is disposed between a heating furnace that heats a test metal plate, a pulling apparatus that pulls the test metal plate in a direction of pulling out the test metal plate, and the heating furnace and the pulling apparatus. , A mold for pressing each of the opposing surfaces of the test metal plate drawn out from the heating furnace, a pressing device for pressing the mold against the opposing surfaces of the test metal plate, and the test metal Obtain a thermocouple attached to the plate, the temperature of the test metal plate detected from the thermocouple, the pulling force with which the drawing device pulls the test metal plate, and the load that presses the mold against the test metal plate And a detecting unit (first configuration).

  In the first configuration, the test metal plate is heated in a heating furnace with a thermocouple attached thereto. Therefore, the temperature of the test metal plate during heating can be accurately measured by the thermocouple. A mold is pressed by a pressing device onto both surfaces of the test metal plate that are drawn from the heating furnace by the drawing device. As a result, the heated test metal plate and the mold slide. As the test metal plate exits the furnace, it is cooled by the outside air. Further, the portion of the test metal plate that contacts the mold is cooled by the mold. A thermocouple is attached to the test metal plate. Thereby, a thermocouple moves with a test metal plate. Therefore, a temperature change until this test metal plate comes out of a heating furnace and slides with a metal mold | die can be tracked with a thermocouple. As a result, the temperature of the part where the test metal plate slides with the mold can be accurately measured. In addition to the temperature measured by the thermocouple, the drawing force with which the drawing device pulls the test metal plate and the load that presses the mold against the test metal plate are detected. Thereby, in addition to the sliding characteristics obtained from the pulling force and the load, an accurate temperature during sliding can be obtained. Therefore, the relationship between the sliding characteristics of the mold and the material (test metal plate) and the temperature can be more accurately evaluated.

  A test apparatus according to an embodiment of the present invention includes a heating furnace that houses a heat source and has an opening, a drawing device, a pressing device, and a thermocouple. The drawing device is arranged on a straight line passing through the opening of the heating furnace, and is connected to the coupler that can attach and detach a test metal plate, and the movable part that is movable in the direction of the straight line together with the coupler. A supporting portion that movably supports the movable portion in the direction of the straight line, a power source that generates a force in the linear direction with respect to the movable portion, and a force in the linear direction that is applied to the movable portion. A pulling force meter to measure. The pressing device is attached to the pair of molds and a pair of molds arranged to face each other via the straight line in a direction intersecting the straight line between the opening and the drawing device, A pressure device that generates a force for pressing the pair of molds in a direction crossing the straight line; and a pressing device that includes a load meter that measures the force applied to the mold. The thermocouple is attached to the test metal plate on the straight line (second configuration).

  In the second configuration, the test metal plate arranged on a straight line passing through the opening of the heating furnace can be attached to the coupler of the drawing device. Thereby, the test metal plate inserted into the heating furnace through the opening can be pulled out by the pulling device. A metal mold is pressed against both surfaces of the test metal plate drawn out of the heating furnace by the drawing device and facing each other in the direction crossing the straight line. A thermocouple is attached to the test metal plate. Thereby, a thermocouple moves with a test metal plate. Therefore, a temperature change until this test metal plate comes out of a heating furnace and slides with a metal mold | die can be tracked with a thermocouple. As a result, the temperature of the part where the test metal plate slides with the mold can be accurately measured. Moreover, the drawing force with which the drawing device pulls out the test metal plate can be obtained by the drawing meter of the drawing device. A load for pressing the mold against the test metal plate can be obtained by a load meter of the pressing device. Thereby, in addition to the sliding characteristics obtained from the pulling force and the load, an accurate temperature during sliding can be obtained. Therefore, the relationship between the sliding characteristics of the mold and the material (test metal plate) and the temperature can be more accurately evaluated.

  In the second configuration, as an example, the pressurizing device is connected to at least one of the pair of molds and movable in a direction intersecting the direction of the straight line, and the pair of molds. Each can be configured to have a pair of support portions that are supported directly or via the movable portion, and a connection portion that fixes the pair of support portions to each other.

  In the first or second configuration, an end portion of the thermocouple and an intermediate fixing portion of the thermocouple may be spaced apart from each other and attached to the test metal plate (third configuration). Thereby, interference of the thermocouple with respect to the operation | movement with which a test metal plate is pulled out while sliding with respect to a metal mold | die can be suppressed.

  The said 3rd structure WHEREIN: The space | interval of the said edge part of the said thermocouple and the said fixing | fixed part can be made longer than the space | interval of the said opening part and the said metal mold | die (4th structure). Thereby, the interference of the thermocouple with respect to the sliding operation of the test metal plate can be further suppressed. Here, the interval between the “opening and the mold” refers to the position of the end of the opening on the mold side and the direction of the straight line (the drawing direction of the test metal plate) of the end of the mold on the opening side. It can be the distance in the parallel direction.

  In the third or fourth configuration, at least one of the end portion or the fixed portion of the thermocouple may be attached to a side surface of the test metal plate (fifth configuration). The side surface is a surface located between both surfaces in contact with the mold among the surfaces of the test metal plate, and is a surface extending in the direction of the straight line passing through the opening. When sliding, the mold touches both sides of the test metal plate facing each other and does not touch the side. By connecting the thermocouple to the surface of the test metal plate that is not in contact with the mold during sliding, the thermocouple can be prevented from being sandwiched between the test metal plate and the mold. As a result, the sliding characteristics can be evaluated more accurately.

  The test method in the embodiment of the present invention includes an attachment step of attaching an end portion of a thermocouple to a test metal plate, and a heating step of heating at least a portion of the test metal plate to which the end portion of the thermocouple is attached in a heating furnace. And a drawing step of pulling out the test metal plates heated to a predetermined temperature in the heating furnace while pressing the opposite surfaces of the test metal plate with a pair of molds arranged outside the heating furnace. In the drawing step, when the portion of the test metal plate to which the end of the thermocouple is attached passes through the pair of molds, the pulling force for pulling out the test metal plate, and the pair of molds is the test The load for pressing the metal plate and the output voltage of the thermocouple are measured (first method).

  In the first method, a thermocouple is attached to a portion of a test metal plate that is heated in a heating furnace and pulled out from the heating furnace by a drawing apparatus. The surface near the test metal plate to which the thermocouple is attached is pulled out of the heating furnace, and then the mold is pressed against it. Therefore, the temperature until the test metal plate is pulled out of the heating furnace and slid with the mold can be tracked by the thermocouple. As a result, it is possible to accurately measure the temperature of the portion of the test metal plate that slides with the mold. In the drawing process, in addition to the pulling force for pulling out the test metal plate and the sliding characteristics obtained from the load (pressing force) that presses the die against the test metal plate, the exact temperature of the test metal plate sliding with the die is can get. Therefore, the sliding characteristics can be evaluated more accurately.

  In the first method, the attaching step may include a step of attaching an end portion of the thermocouple and an intermediate fixing portion of the thermocouple apart from the test metal plate (second method). . Thereby, a thermocouple can be arrange | positioned along a test metal plate. Therefore, in the process in which the test metal plate is pulled out of the heating furnace and slides with the mold, the thermocouple is less likely to be caught between the mold and the test metal plate. That is, the interference of the thermocouple with the sliding operation of the test metal plate can be further suppressed.

  In the second method, an interval between the end portion and the fixing portion can be longer than an interval between the opening and the mold (third method). This makes it difficult for the thermocouple to be caught between the mold and the test metal plate in the process of sliding the test metal plate with the mold.

  In the attachment step of the second or third method, at least one of the end portion or the fixing portion of the thermocouple may be attached to a side surface of the test metal plate (fourth method). Thereby, a thermocouple can be arrange | positioned along a test metal plate. Therefore, the interference of the thermocouple with respect to the sliding operation of the test metal plate can be further suppressed.

  Hereinafter, embodiments will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, and the same description is not repeated. For convenience of explanation, in each drawing, the configuration may be simplified or schematically illustrated, or a part of the configuration may be omitted.

[Embodiment]
(Example of device configuration)
FIG. 1 is a diagram illustrating a configuration example of a test apparatus 10 according to the present embodiment. The test apparatus 10 is a test apparatus that evaluates the sliding characteristics of the test metal plate 1 by sliding a heated test metal plate 1 (hereinafter simply referred to as the metal plate 1) and a mold 5. The test apparatus 10 includes a heating furnace 2, a thermocouple 3, a mold 5, a pressing device 6, a drawing device 8, a detection unit 9, and a control unit 11.

  For example, the metal plate 1 is formed in a plate shape extending in the longitudinal direction. The metal plate 1 has an upper surface 1a and a lower surface 1b facing each other. The upper surface 1 a and the lower surface 1 b are wider than any other surface (that is, the side surface) of the metal plate 1. The shape of the metal plate 1 seen from the upper surface 1a can be a rectangle. The direction of the long side of the rectangle is the longitudinal direction. In the example shown in FIG. 1, the metal plate 1 is arranged so that the longitudinal direction coincides with the x direction (drawing direction). In this embodiment, as an example, the x direction and the y direction are orthogonal to each other on the horizontal plane, and the z direction is the vertical direction.

  The heating furnace 2 heats the metal plate 1. The heating furnace 2 includes a heating chamber 2a and a heat source 2b that adjusts the temperature of the heating chamber 2a. An opening 2c is provided in the heating chamber 2a. In the example shown in FIG. 1, the metal plate 1 is heated while being inserted from the opening 2c. Thereby, the part including the one end of the metal plate 1 is heated. The atmosphere in the heating chamber 2a can be, for example, nitrogen or air.

  The drawing device 8 pulls the metal plate 1 in the direction in which the metal plate 1 is drawn from the heating furnace 2. The drawing device 8 includes a gripping portion 81 that grips the other end of the metal plate 1 and a pulling cylinder 83 that pulls the gripping portion 81 in one direction. In the example shown in FIG. 1, the drawing device is arranged so that the drawing direction of the drawing cylinder 83 is the horizontal direction (x direction). The gripping part 81 grips the metal plate 1 so that the longitudinal direction of the metal plate 1 is the pulling direction of the pulling cylinder 83. The drawing device 8 includes a drawing force meter 82 that measures the drawing force with which the drawing device 8 pulls the test metal plate. The pulling force measured by the pulling force meter 82 is sent to the detection unit 9. Thereby, the detection part 9 can acquire extraction force.

  The gripping part 81 is an example of a coupler that can attach and detach the test metal plate. The gripping portion 81 is disposed on a straight line passing through the opening 2c of the heating furnace 2 (a line parallel to the x axis in FIG. 1, that is, a line in the drawing direction). The drawing cylinder 83 includes a movable part, a support part, and a power source. The movable part is connected to a gripping part 81 that is a coupler. The support portion supports the movable portion so as to be movable in the drawing direction. The power source generates a force in the pulling direction with respect to the movable part. The pulling force meter 82 measures the pulling force applied to the movable part. For example, when the extraction cylinder 83 is a hydraulic cylinder, the movable portion may be a cylinder rod, the support portion may be a cylinder that supports the rod, and the power source may be a hydraulic pressure generator that generates hydraulic pressure in the cylinder.

  The mold 5 is disposed between the heating furnace 2 and the drawing device 8. The mold 5 presses each of the upper surface 1 a and the lower surface 1 b of the metal plate 1 drawn out from the heating furnace 2. Therefore, a pair of molds 5 are arranged above and below the metal plate 1. The pair of molds 5 is supported by the pressing device 6. The pressing device 6 presses each of the pair of molds 5 against the upper surface 1 a and the lower surface 1 b of the metal plate 1. The mold 5 is pressed in a direction perpendicular to the drawing direction. That is, the mold 5 is moved in a direction (z direction in this example) perpendicular to the direction in which the metal plate 1 is moved by the drawing device 8. The mold 5 applies a load to the metal plate 1.

  The pressing device 6 includes a mold 5, a pressing device, and a load meter 61. The pressurizing device is attached to a pair of molds 5 and generates a force for pressing the pair of molds 5 in a direction (vertical direction, that is, z direction in the example of FIG. 1) intersecting the drawing direction (x direction). The pressure device includes, for example, a movable part 62, a support part 63, and a connection part 64. The movable part 62 is connected to one of the pair of molds 5 and is movably supported in the vertical direction. The support part 63 supports each of the pair of molds 5 via the movable part 62 or directly. The connection part 64 fixes the pair of support parts 63 that respectively support the pair of molds 5 to each other. The pressurizing device can be constituted by, for example, a pressing cylinder that generates a force for pressing the mold 5 against the metal plate 1. In this example, the pressing device 6 generates a force for sandwiching the metal plate 1 between the pair of molds 5. The vertical load meter 61 measures a load that presses the mold 5 against the metal plate 1 (hereinafter, referred to as a vertical load as an example). The pulling force measured by the vertical load meter 61 is sent to the detection unit 9. Thereby, the detection part 9 can acquire a vertical load.

  The thermocouple 3 is attached to the metal plate 1. The end 3 a of the thermocouple 3 can be connected to the side surface of the metal plate 1. For example, the end 3 a of the thermocouple 3 is attached to the side surface 1 c extending in the drawing direction of the metal plate 1. That is, the end 3 a of the thermocouple 3 can be attached to a surface that extends in the drawing direction of the metal plate 1 and does not slide with the mold 5. The portion of the metal plate 1 to which the end 3 a of the thermocouple 3 is attached is heated in the heating furnace 2 and then moved by drawing to pass between the pair of molds 5. That is, in the metal plate 1, the end 3 a of the thermocouple 3 is attached at a position corresponding to a portion that is heated and slid with the mold 5. The attachment of the end 3a of the thermocouple 3 means that the temperature measuring contact of the thermocouple 3 is connected.

  The thermocouple 3 includes a conductive wire 4. The conducting wire 4 may be a compensating conducting wire having a thermoelectromotive force equivalent to that of the thermocouple 3 or may be formed of the same material as the thermocouple 3.

  The test apparatus 10 is provided with a fixing means 7 for fixing a part (fixing part) of the conducting wire 4 to the metal plate 1. By the fixing means 7, the thermocouple 3 is configured to have a fixing portion that is fixed to the metal plate 1 at an intermediate portion that is not the end portion 3 a. The fixing means 7 can be formed, for example, by attaching a metal member such as a wire to the metal plate 1. The shape of the fixing means 7 can be a shape having a hole or a recess through which the conducting wire 4 passes, such as a hook or a ring. The fixing means 7 is not limited to the above example, and the fixing portion can be fixed to the metal plate 1 by, for example, welding, brazing, or an adhesive or other fixing means.

  An interval L1 in the drawing direction (x direction) between the end 3a and the fixed portion of the thermocouple 3 is longer than an interval L2 in the drawing direction of the opening 2c of the heating furnace 2 and the mold 5. Thereby, at least the portion between the end of the thermocouple 3 and the fixed portion can be along the metal plate 1 between the opening 2 c and the mold 5. Therefore, when the metal plate 1 is pulled out while being pressed by the mold 5, the thermocouple 3 is less likely to interfere with the opening 2 c or the mold 5.

  The conducting wire 4 is fixed to the metal plate 1 at a position closer to the drawing device 8 than the end 3 a of the thermocouple 3. That is, the fixed part of the thermocouple 3 is closer to the extraction device 8 than the end 3a. The conducting wire 4 can be fixed to the side surface 1 c of the metal plate 1. For example, as shown in FIG. 1, when the metal plate 1 is heated, the lead wire 4 extending from the end 3a of the thermocouple 3 located in the heating furnace 2 is opposite to the end 3a with the mold 5 interposed therebetween. The metal plate 1 can be fixed to a part of the side surface 1c.

  In the example shown in FIG. 1, the end portion 3 a and the fixing portion of the thermocouple 3 are respectively fixed at positions separated in the drawing direction on the side surface 1 c of the metal plate 1. Thereby, the thermocouple 3 can be arranged along the side surface 1 c of the metal plate 1. When the metal plate 1 is pulled out, the thermocouple 3 moves along with the metal plate 1 along the side surface 1 c of the metal plate 1. Therefore, it is avoided that the thermocouple 3 is caught in the mold 5 or the pressing device 6.

  The thermocouple 3 is connected to the detection unit 9. The detection unit 9 can include a measuring device (not shown) that outputs a temperature based on the electromotive force generated in the thermocouple 3. The detection unit 9 can acquire the temperature of the metal plate 1 based on the thermoelectromotive force of the thermocouple 3.

  In the example shown in FIG. 1, the heating furnace 2, the pressing device 6, and the drawing device 8 are connected to the control unit 11. The control unit 11 controls the heating furnace 2, the pressing device 6, and the drawing device 8. For example, the control unit 11 controls the temperature of the heating chamber 2 a by controlling the heat source 2 b of the heating furnace 2. Thereby, the metal plate 1 can be heated on arbitrary heat treatment conditions.

  The control unit 11 can control the vertical load by the mold 5, the speed of the mold 5, and the displacement of the mold 5 by controlling the pressing device 6. The control unit 11 can control the drawing speed, displacement, and drawing force of the metal plate 1 by controlling the drawing device 8. Further, the control unit 11 can adjust the timing of heating the metal plate 1 by the heating furnace 2, pressing the mold 5 against the metal plate 1 by the pressing device 6, and drawing of the metal plate 1 by the drawing device 8. . This makes it possible to evaluate the sliding characteristics under various conditions.

  For example, when the end 3a of the thermocouple 3 passes through the mold 5, the pulling force, load, and temperature are measured. That is, during the period when the end 3 a of the thermocouple 3 passes through the mold 5, the extraction force, load, and temperature values are acquired by the detection unit 9. For example, in the period from before the end 3a of the thermocouple 3 passes through the mold 5 to after it passes, the detection unit 9 can acquire the pulling force, the load, and the temperature in a predetermined cycle.

  In addition to the aspect in which the pulling force, load, and temperature at the moment when the end of the thermocouple passes through the mold are acquired, in a period in which the tip of the thermocouple can be regarded as passing through the mold, The mode in which the pulling force, load, and temperature are measured is also included in the mode in which the pulling force, load, and temperature are measured when the end of the thermocouple passes through the mold.

  In the above example, in the pressing device 6, the movable part 62 is provided in the upper mold 5 of the pair of molds 5. On the other hand, the movable part 62 may be provided in the lower mold 5 or both of the pair of molds 5.

  The detection unit 9 and the control unit 11 can be configured using, for example, one or a plurality of computers.

(Example of device operation)
Here, an operation example of the test apparatus 10 shown in FIG. 1 will be described.
<Preparation process>
As shown in FIG. 1, the metal plate 1 is disposed in a state where one end is inserted into the heating furnace 2 and the other end is gripped by the gripping portion 81 of the drawing device 8. The pair of molds 5 is disposed between the heating furnace 2 and the drawing device 8 at a position sandwiching the metal plate 1 in the vertical direction (z direction).

  An end 3 a of the thermocouple 3 is attached to a portion of the metal plate 1 inserted into the heating furnace 2. The thermocouple 3 extends along the side surface 1 c of the metal plate 1 and exits from the heating furnace 2. The thermocouple 3 coming out of the heating furnace 2 further extends in the drawing direction (x direction) and is fixed to the metal plate 1 by a fixing means 7 provided on the metal plate 1 between the mold 5 and the drawing device 8. The

<Heating process>
The heating furnace 2 can heat the metal plate 1 at a temperature of 100 to 1000 ° C. As an example, when the metal plate 1 is a steel plate, the steel plate can be heated at a temperature of 700 ° C. or higher.

<Sliding process>
The temperature of the metal plate 1 in the heating furnace 2 can be acquired by, for example, the thermocouple 3. When the temperature of the metal plate 1 in the heating furnace 2 reaches a desired temperature, the drawing device 8 pulls the metal plate 1 in the direction of pulling out the metal plate 1 from the heating furnace 2 (x direction). In response to the drawing of the metal plate 1 by the drawing device 8, the pressing device 6 presses the mold 5 against the metal plate 1. Thereby, the metal mold 1 slides in the mold 5 while moving in the drawing direction. When the metal plate 1 moves a predetermined distance in the drawing direction, the drawing device 8 stops drawing. The pressing device 6 stops the pressing of the mold 5 according to the stop of the drawing.

  FIG. 2 is a diagram illustrating a state of the test apparatus 10 during sliding. As shown in FIG. 2, the thermocouple 3 connected to the side surface 1 c of the metal plate 1 moves so as to pass between the pair of molds 5. At this time, the upper surface 1 a and the lower surface 1 b of the metal plate 1 corresponding to the portion to which the end 3 a of the thermocouple 3 is connected slides in contact with the mold 5. Since the end 3a of the thermocouple 3 is located near the sliding upper surface 1a and lower surface 1b, the temperature of the sliding surface can be measured. Accurate temperature during sliding is obtained.

  By using the thermocouple 3, an accurate temperature can be obtained as compared with the case where the temperature of the metal plate 1 is measured using a radiation thermometer. The radiation thermometer detects light from the surface of the metal plate 1 at a position away from the sliding surface of the metal plate 1. In this case, the temperature of the portion other than the sliding surface of the metal plate 1 is reflected in the measured value. Further, the inventors have found that an error occurs in the temperature measured by the radiation thermometer when the surface of the metal plate 1 is oxidized. On the other hand, when the thermocouple 3 is used as in this embodiment, the temperature of the sliding surface of the metal plate 1 can be accurately measured.

  FIG. 3 is a graph showing an operation example of the drawing device 8 and the pressing device 6. In FIG. 3, the vertical axis represents the vertical load or the drawing stroke, and the horizontal axis represents time. A dotted line St indicates a change in the length (drawing stroke) of the metal plate 1 drawn by the drawing device 8, and a solid line Sw indicates a change in the vertical load of the mold 5 by the pressing device 6. In the example shown in FIG. 3, the drawing is started at time t1. At time t2 after a predetermined time has elapsed, application of a vertical load by the mold 5 is started. In this way, by adjusting the start of drawing and the start of application of vertical load, sliding can be started at the timing when the portion of the metal plate 1 heated in the heating furnace 2 reaches the position of the mold 5. it can.

  Further, the pulling speed is higher than the pulling speed after time t2 from time t1 to time t2. That is, the drawing speed until the portion of the metal plate 1 heated in the heating furnace 2 moves to the position of the mold 5 is faster than the drawing speed after the heated metal plate 1 starts to slide on the mold 5. . Thereby, time until the part of the heated metal plate 1 is slid can be shortened. Further, during the period in which the heated metal plate 1 is slid, any drawing speed can be set according to the purpose of the test.

  Thus, the drawing device 8 can change the drawing speed step by step in one drawing. The pressing device 6 can change the vertical load on the metal plate 1 by the mold 5 and the displacement of the mold 5 in a stepwise manner. These operations can be controlled by the control unit 11.

<Measurement process>
The detection unit 9 acquires the drawing force from the drawing force meter 82 until the drawing device 8 starts drawing and ends. For example, the detection unit 9 can acquire time-series data indicating a temporal change in the extraction force. The detection unit 9 acquires, from the vertical load meter 61, the vertical load from when the pressing device 6 starts pressing the mold 5 to when it ends. The detection unit 9 can acquire time-series data indicating the time change of the vertical load force. The detection unit 9 acquires the temperature of the metal plate 1 from the thermocouple 3 from the start of heating by the heating furnace 2 to the stop of drawing by the drawing device 8. The detection unit 9 can acquire time-series data indicating the time change of the temperature of the metal plate 1. The detection unit 9 can synchronize the extraction timing, the vertical load, and the temperature acquisition timing of the metal plate 1 with each other. For example, the pulling force of the pulling force meter 82, the vertical load of the vertical load meter 61, and the temperature of the thermocouple 3 can be acquired at a timing based on a predetermined synchronization signal.

  For example, the detection unit 9 can calculate a value indicating the sliding characteristics by using the pulling force T and the vertical load W when the metal plate 1 slides with the mold 5. For example, the value indicating the sliding characteristic is, for example, a friction coefficient μ. The friction coefficient μ can be calculated by, for example, μ = T / 2W. The detection unit 9 can record a value (for example, a friction coefficient μ) indicating a sliding characteristic at each of a plurality of time points within a sliding period and a temperature in association with each other. Thereby, the information which shows the temperature change of a sliding characteristic can be obtained.

<Measurement example>
FIG. 4 is a graph showing the measurement result of the test metal plate temperature in the test using the test apparatus 10. In FIG. 4, the vertical axis indicates temperature and the drawing stroke, and the horizontal axis indicates time. Line TS shows the temperature of the metal plate 1 measured through the thermocouple 3. A line St indicates a drawing stroke of the metal plate 1 by the drawing device 8. FIG. 5 is a graph showing the measurement results of the friction coefficient of the metal plate 1 in the same test as FIG. In FIG. 5, the vertical axis represents the friction coefficient, and the horizontal axis represents the drawing stroke.

The tests shown in FIGS. 4 and 5 were performed under the following conditions. As the thermocouple, a K thermocouple was used.
(A) Heating furnace Furnace type: Near infrared heating furnace Heating temperature: Maximum 1000 ° C
Heating furnace dimensions: Width 100mm x Length 150mm
Soaking length: 130 mm
(B) Load load, etc. Vertical load: Max. 75kN
Extraction force: Up to 30kN
Sliding speed: ~ 1000mm / s
(C) Test steel plate (test piece)
Material: Galvanized steel sheet for HS Dimensions: Thickness 1.6mm x width 30mm x length 500mm
(D) Sliding mold Material: (1) SKD61, (2) SKD61 + nitriding treatment
Shape: Sliding part is flat, length 10mm x 90mm
Surface condition: # 600 polishing (e) Test conditions Furnace temperature setting: 900 ° C
Furnace time: 4 min
Sliding mold initial temperature: Room temperature Sliding distance: 80 mm (Sliding characteristics are evaluated for the first 40 mm)
Sliding speed: 10mm / s after moving to the rating part at 100mm / s
Vertical load: 2.97kN

  In the measurement result shown in FIG. 4, a dotted line t4 indicates the time when the pressing of the mold 5 against the metal plate 1 is started, that is, the sliding start time. A dotted line t <b> 5 is a time when a portion of the metal plate 1 corresponding to the end 3 a of the thermocouple 3 starts to contact the mold 5. From this result, it was found that the temperature of the metal plate 1 changed from the start of drawing until it contacted the mold 5. Moreover, it turned out that the temperature of the metal plate 1 of the part which contacts the metal mold | die 5 and slides is also changing with time. When the metal plate 1 comes into contact with the mold 5, the temperature suddenly decreases. As described above, by using the thermocouple 3, the accurate temperature of the sliding portion can be obtained.

  In the measurement result shown in FIG. 5, the position of the drawing stroke when the portion of the metal plate 1 where the end 3a of the thermocouple 3 is connected starts to slide is indicated by a dotted line S1. In the region of the drawing stroke smaller than S1, the change in the friction coefficient is large. This is considered to be due to a change in the temperature of the sliding portion of the metal plate 1. As described above, the friction coefficient indicating the sliding characteristics may change depending on the temperature. For this reason, the temperature of the sliding portion is an important factor in predicting moldability.

(Application example of equipment)
As an example, the test apparatus 10 of the present embodiment is suitably used for testing a hot press metal material. For example, the sliding characteristics of a steel plate that is a material for hot pressing can be evaluated by the test apparatus 10. In this case, the test apparatus 10 can be operated under conditions corresponding to the conditions of the hot press temperature and the forming speed to be implemented. Thereby, the information regarding the sliding characteristics suitable for predicting the formability under the conditions of hot pressing can be obtained. For example, the coefficient of friction of the material at a temperature close to the temperature at the time of pressing in the hot press can be obtained. As a result, it is possible to improve the accuracy of formability prediction in hot pressing.

(Modification)
The configuration of the test apparatus 10 is not limited to the above example. For example, a thermometer that measures the temperature of the heating chamber 2 a of the heating furnace 2 and a thermometer that measures the temperature of the mold 5 may be further provided. Further, the position where the thermocouple 3 is connected is not limited to the side surface 1c of the metal plate 1, but may be the upper surface 1a or the lower surface 1b. Further, the fixing means 7 may also be provided on the upper surface 1 a or the lower surface 1 b of the metal plate 1.

  The drawing cylinder of the drawing device 8 is not limited to a hydraulic cylinder, and may be, for example, an air cylinder. In addition, the drawing device 8 may be configured to include, for example, a gear, a rod having unevenness aligned in the drawing direction and engaging with the gear, and a motor for rotating the gear instead of the drawing cylinder. . In this case, the extraction device is a mechanism that converts the rotation of the power source (motor) into the linear motion of the rod.

  In the above example, the drawing direction of the metal plate 1 by the drawing device 8 and the direction of the load applied to the metal plate 1 by the die 5 by the pressing device 6 are orthogonal to each other. The direction in which the mold 5 moves is not necessarily perpendicular to the drawing direction, and may be any direction that intersects the drawing direction. In the above example, the load direction of the mold 5 is the vertical direction (vertical direction), and the drawing direction of the metal plate 1 is the horizontal direction. The load direction and the drawing direction are not limited to this. The load direction may have an angle with respect to the vertical direction. The drawing direction may have an angle with respect to the horizontal direction.

  As mentioned above, although one Embodiment of this invention was described, embodiment mentioned above is only the illustration for implementing this invention. Therefore, the present invention is not limited to the above-described embodiment, and can be implemented by appropriately modifying the above-described embodiment without departing from the spirit thereof.

1: Metal plate, 2: Heating furnace, 3: Thermocouple, 4: Conductor, 5: Mold, 6: Pressing device 7: Fixing means 8: Pulling device 9: Detection unit

Claims (9)

A heating furnace for heating the test metal plate;
A drawing device for pulling the test metal plate in a direction of drawing from the heating furnace;
A mold that is disposed between the heating furnace and the drawing device and presses each of both opposing surfaces of the test metal plate drawn from the heating furnace;
A pressing device that presses the mold against the opposing surfaces of the test metal plate;
A thermocouple attached to the test metal plate;
A test unit comprising: a temperature of the test metal plate detected from the thermocouple; a pulling force with which the drawing device pulls the test metal plate; and a detection unit that obtains a load pressing the mold against the test metal plate. apparatus. A heating furnace containing a heat source and having an opening;
A coupler that is arranged on a straight line passing through the opening of the heating furnace and that can attach and detach a test metal plate, a movable part that is connected to the coupler and is movable in the direction of the straight line together with the coupler, and the movable part A movably supporting member in the direction of the straight line, a power source for generating a force in the direction of the straight line on the movable part, and a pulling force meter for measuring the force in the direction of the straight line applied to the movable part A drawing device comprising:
Between the opening and the drawing device, a pair of molds arranged to face each other through the straight line in a direction intersecting the straight line, and the pair of molds attached to the pair of molds A pressure device that generates a force that pushes in a direction intersecting the straight line, and a pressure device that has a load meter that measures the force applied to the mold,
A test apparatus comprising: a thermocouple attached to the test metal plate on the straight line.   The test apparatus according to claim 1, wherein an end portion of the thermocouple and an intermediate fixing portion of the thermocouple are attached to the test metal plate apart from each other.   The test apparatus according to claim 3, wherein an interval between the end portion of the thermocouple and the fixing portion is longer than an interval between the opening and the mold.   The test apparatus according to claim 3 or 4, wherein at least one of the end portion or the fixing portion of the thermocouple is attached to a side surface of the test metal plate. An attachment process for attaching the end of the thermocouple to the test metal plate;
A heating step of heating at least a portion of the test metal plate to which the end of the thermocouple is attached in a heating furnace;
A drawing step of pulling out the test metal plates heated to a predetermined temperature in the heating furnace while pressing the opposing metal plates with a pair of molds arranged outside the heating furnace;
In the drawing step, when the portion of the test metal plate to which the end of the thermocouple is attached passes through the pair of molds, the pulling force for pulling out the test metal plate, and the pair of molds is the test A test method for measuring a load pressing a metal plate and an output voltage of the thermocouple.   The test apparatus according to claim 6, wherein the attaching step includes a step of attaching an end portion of the thermocouple and an intermediate fixing portion of the thermocouple separately to the test metal plate.   The test method according to claim 7, wherein an interval between the end portion and the fixed portion is longer than an interval between the opening and the mold.   The test apparatus according to claim 7 or 8, wherein in the attachment step, at least one of the end portion or the fixed portion of the thermocouple is attached to a side surface of the test metal plate.

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