JP2014035236A - Hardness testing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hardness testing device which enables an operator to accurately recognize a result of daily inspection.SOLUTION: A control unit 80 comprises: an automatic measurement unit 84 which controls a camera 17 to take an image of an impression made by pressing an indenter against a reference piece having reference hardness on a mounting table, and also controls a hardness calculation unit 83 to automatically execute hardness measurement operation for calculating hardness of the reference piece on the basis of the image of the impression taken by the camera 17; a measurement value display unit 85 which sequentially displays the measurement value of hardness of the reference piece with the upper limit and the lower limit of hardness of the reference piece; a warning display unit 86 which displays a warning when the measurement value of hardness of the reference piece is greater than the upper limit of hardness of the reference piece or smaller than the lower limit of hardness of the reference piece; and an operation stop unit 87 which stops operation of the device when the measurement value of hardness of the reference piece is greater than the upper limit of hardness of the reference piece or smaller than the lower limit of hardness of the reference piece.

Description

  The present invention relates to a hardness tester that measures the hardness of a test piece.

  Such a hardness tester includes a mounting table for mounting a test piece, an indenter for forming an indentation on the surface of the test piece mounted on the mounting table, and pressing the indenter against the test piece. And a load mechanism for applying a test force to the indenter (see Patent Document 1). Then, the indentation formed on the surface of the test piece is photographed by the photographing mechanism, and the hardness of the test piece is calculated based on the indentation photographed by the photographing mechanism.

JP 2002-188983 A

  Annex C of JIS (Japanese Industrial Standards) Z2244: 2008 requires daily inspection of the hardness tester. In this daily inspection, a hardness test is performed on a reference piece having a reference hardness, and it is determined whether the hardness tester is normal based on the measured value of the hardness at that time. ing.

  However, if this daily inspection is performed manually by an operator, there is a possibility that errors such as wrong recording of hardness may occur. In addition, there is a possibility that the measurement result is falsified. Furthermore, there is a problem that it is difficult to recognize a change in hardness measurement value (measurement error) over time.

  This invention was made in order to solve the said subject, and it aims at providing the hardness tester which can recognize the result of daily inspection correctly.

  The invention according to claim 1 is a mounting table for mounting a test piece, an indenter for forming an indentation on a surface of the test piece mounted on the mounting table, and pressing the indenter against the test piece. A load mechanism for applying a test force to the indenter, a photographing mechanism for photographing an impression formed on the surface of the specimen, and a hardness of the specimen based on the impression photographed by the photographing mechanism. In a hardness tester equipped with a hardness calculation unit, the indentation obtained by pressing the indenter against the reference piece in a state where the reference piece having the reference hardness is placed on the mounting table. An automatic measuring means for automatically performing a hardness measurement operation for performing the hardness measurement operation for calculating the hardness of the reference piece based on an indentation imaged by the imaging mechanism by the hardness calculating unit, and the automatic measurement For hardness measurement by command of means Storage means for storing the measured hardness of the reference piece over time, and measurement value display means for displaying a measurement value of the hardness of the reference piece stored in the storage means over time on a display unit; It is provided with.

  According to a second aspect of the present invention, in the first aspect of the invention, the measured value display means is configured to set the hardness of the reference piece together with a preset upper limit value and lower limit value of the hardness of the reference piece. Display measured values over time.

  The invention according to claim 3 is the invention according to claim 2, wherein the measured value of the hardness of the reference piece is larger than the preset upper limit value of the hardness of the reference piece, or from the lower limit value. A warning display means for displaying a warning when it is small is provided.

  The invention according to claim 4 is the invention according to claim 2 or 3, wherein the measured value of the hardness of the reference piece is greater than a preset upper limit value of the hardness of the reference piece, or And an operation stop means for stopping the operation of the apparatus when it is smaller than the lower limit value.

  According to the first aspect of the present invention, the daily inspection can be automatically executed by the automatic measuring means, and the result of the daily inspection can be accurately recognized by the action of the storage means and the measured value display means. It becomes.

  According to the invention of claim 2, the action of the warning display means can easily recognize the relationship between the measured value of the hardness of the reference piece and the upper limit value or the lower limit value of the hardness of the reference piece, It is possible to easily determine that the test accuracy of the apparatus has decreased.

  According to the invention described in claim 3, the relationship between the measured value of the hardness of the reference piece and the upper limit value or the lower limit value of the hardness of the reference piece can be more reliably recognized by the action of the warning display means. It is possible to more reliably determine that the test accuracy of the apparatus has decreased.

  According to the fourth aspect of the present invention, it is possible to prevent the hardness test from being executed in a state where the test accuracy is lowered due to the action of the operation stop means.

It is a schematic diagram of the hardness testing machine concerning this invention. It is a schematic diagram of the raising / lowering mechanism which raises / lowers the mounting base. It is explanatory drawing which shows arrangement | positioning of the objective lens etc. which were supported by the revolver. 2 is a schematic diagram of a load mechanism for applying a test force to the indenter 19 and the indenter 21 and an optical system for observing an indentation formed on a test piece 100. FIG. It is explanatory drawing which shows typically a mode that an indentation is formed in the test piece 100 with the indenter 21. FIG. 3 is a plan view showing indentations formed on a test piece 100. FIG. It is a block diagram which shows the main control systems of the hardness tester based on this invention. It is a schematic diagram of the graph which shows the measurement result of the hardness displayed on the display part 55 or the liquid crystal display part 59. FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram of a hardness tester according to the present invention. FIG. 2 is a schematic diagram of an elevating mechanism for elevating the mounting table 12.

  The hardness tester includes a table 11 and a mounting table 12 that is placed on the table 11 and on which a test piece 100 is mounted. The mounting table 12 is for moving the test piece 100 in the X direction (left-right direction in FIG. 1) and Y direction (direction perpendicular to the paper surface in FIG. 1). The mounting table 12 is provided with a motor 13 for moving the test piece 100 in the X direction and a motor 14 for moving the test piece 100 in the Y direction. Further, the mounting table 12 is configured to move up and down in the vertical direction (Z direction) by the action of the lifting mechanism shown in FIG. That is, the support portion 51 that supports the mounting table 12 is supported by a lifting member 52 having a rack 53 formed on the side surface thereof. The rack 53 in the elevating member 52 meshes with a pinion 54 that rotates by driving of the motor 15. For this reason, the mounting table 12 moves up and down by driving the motor 15.

  The hardness tester also supports an eyepiece 16 for visually observing the test piece 100, a camera 17 for photographing the test piece 100, an indenter 21 and objective lenses 23 and 24, and the like. Revolver 20. The revolver 20 rotates around an axis that faces the vertical direction by operating the knob 26 or by driving a motor 30 described later. The hardness tester includes a touch panel type liquid crystal display unit 59 that also functions as an input unit and a display unit.

  FIG. 3 is an explanatory diagram showing the arrangement of the objective lens and the like supported by the revolver 20.

  The revolver 20 includes a pair of indenters 19 and 21 pushed into the test piece 100 placed on the placing table 12, a 5 × objective lens 22, a 10 × objective lens 23, and a 40 × objective lens 24 and 100. A double objective lens 25 is provided. The indenters 19 and 21 and the objective lenses 22, 23, 24, and 25 are arranged on a circle around the rotation center of the revolver 20. Note that the magnification and the number of the objective lenses 22, 23, 24, and 25 are not limited thereto.

  Referring to FIG. 1 again, this material testing machine includes a display unit 55 such as a CRT for displaying an image of the surface of the test piece 100, and a keyboard 57 functioning as an input means for inputting various data. The computer 50 includes a mouse 58 and a main body 56.

  FIG. 4 is a schematic diagram of a load mechanism for applying a test force to the indenter 19 and the indenter 21 and an optical system for observing the impression formed on the test piece 100. FIG. 4 shows a cross section at the position indicated by the alternate long and short dash line in FIG.

  The hardness tester includes a load mechanism that applies a test force to the indenters 19 and 21 to push the tips of the indenters 19 and 21 into the test piece 100, and a test piece placed on the mounting table 12. And an optical system for illuminating 100 and observing the indentation.

  As shown in FIG. 4, the revolver 20 has a shaft cylinder 27 connected to a rotary shaft 28 via a bearing 29. The revolver 20 can be adjusted in the vertical direction by operating a knob 26 or by driving a motor 30 described later. It rotates about the rotating shaft 28 that faces it. In FIG. 4, when the test force is applied to the indenter 21 through the load transmission shaft 36 by the rotation of the revolver 20, that is, the case where the indenter 21 is arranged at a position facing the test piece 100 shown in FIG. Show. When a test force is applied to the indenter 19, the indenter 19 is disposed at the position of the indenter 21 shown in FIG.

  The load mechanism includes a lever 32 that can swing around a shaft 31 that faces in the horizontal direction. A hollow pressing portion 35 is disposed at one end of the lever 32. The pressing portion 35 is configured to press a contact portion 37 attached to an end portion of the load transmission shaft 36 connected to the indenter 21 as the lever 32 swings. A permanent magnet 33 is attached to the other end of the lever 32. An electromagnetic coil 34 is disposed outside the permanent magnet 33. The permanent magnet 33 and the electromagnetic coil 34 constitute a voice coil motor. This voice coil motor serves as an electromagnetic load mechanism, and controls the test force applied to the test piece 100 by the indenter 21 disposed at the tip of the load transmission shaft 36 by controlling the current flowing through the electromagnetic coil 34. Is possible.

  In this embodiment, the test force at this time is, for example, 2 kgf, 1 kgf, 0.5 kgf, 0.3 kgf, 0.2 kgf, 0.1 kgf, 0.05 kgf, 0.025 kgf, 0.01 kgf, It can be changed in stages.

  The load transmission shaft 36 is supported by a robust structure in which upper and lower leaf springs 61 are fixed to the shaft cylinder 27 of the revolver 20 via a support member 62, and can be moved up and down according to the test force applied by the load mechanism. ing. A differential transformer type displacement detector 60 for detecting the amount of movement of the load transmission shaft 36 is connected to the load transmission shaft 36. The displacement detector 60 is connected to the shaft cylinder 27 of the revolver 20 via a support member 63 and moves in synchronization with the load transmission shaft 36 by the rotation of the revolver 20. The displacement detector 60 is used for detecting the surface of the test piece 100. That is, the amount of movement when the indenter 21 is lowered with an extremely small force is always detected, and it is determined that the indenter 21 has come into contact with the surface of the test piece 100 when the movement of the indenter 21 is stopped.

  The optical system includes an LED light source 41, a light tube 42 that guides light from the LED light source 41 in the horizontal direction, and light guided by the light tube 42 for illuminating the test piece 100 from above. The half mirror 43 that transmits the reflected light from the surface of the test piece 100 to the camera 17 side, and the reflected light from the surface of the test piece 100 that has passed through the half mirror 43 to the eyepiece 16 and the camera 17. And a half mirror 44 to be divided. When the objective lens 22 is arranged at the position of the load transmission shaft 36 in FIG. 4, that is, at the observation position of the impression formed on the test piece 100, the reflected light from the surface of the test piece 100 is hollow in the pressing portion 35. The light enters the eyepiece lens 16 and the camera 17 via the objective unit 22, the objective lens 22, and the half mirrors 43 and 44. Accordingly, an enlarged image of the test piece 100 can be observed by the eyepiece lens 16 and an enlarged image taken by the camera 17 can be displayed on the display unit 55 in the computer 50. The case where the other objective lenses 23, 24, 25 are arranged at the observation position of the indentation is the same as that by the objective lens 22.

  FIG. 5 is an explanatory view schematically showing how the indentation 21 forms an indentation on the test piece 100, and FIG. 6 is a plan view showing the indentation formed on the test piece 100.

  Of the pair of indenters 19 and 21, the indenter 21 is for executing a Vickers hardness test as a hardness test, and its tip has a quadrangular pyramid shape. As shown in FIG. 5, the indenter 21 is pushed into the surface of the test piece 100 by a depth h by the action of the load mechanism shown in FIG. Next, the test force is released, and the revolver 20 shown in FIG. 1 is rotated to move the objective lens having a desired magnification to a position facing the test piece 100. Then, the diagonal length d [d = (dx + dy) / 2] of the indentation is measured from the image of the indentation (indentation) formed on the surface of the test piece 100 obtained through the objective lens and the camera 17 (FIG. 6). The Vickers hardness is proportional to the value obtained by dividing the test force by the surface area of the indentation assuming that the bottom surface is square and the apex angle is the same pyramid as the indenter 21. Then, the Vickers hardness is calculated from the surface area of the indent and the test force obtained from the diagonal length d (mm: millimeter) of the indentation.

  Here, when the test force is F (N: Newton), the Vickers hardness HV is expressed by the following equation.

HV = 0.1891 (F / d ² )
In addition, as the other indenter 19 of the pair of indenters 19 and 21, for example, a rhombus pyramid indenter used for the Knoop hardness test is used.

  FIG. 7 is a block diagram showing a main control system of the hardness tester according to the present invention.

  This hardness tester includes a control unit 80 that controls the entire apparatus. The control unit 80 is based on an image processing unit 82 for image processing of an image photographed by the camera 17, and the size of the impression in the image processed by the image processing unit 82 and the test force at that time. And a hardness calculator 83 for calculating the hardness of the test piece 100. In addition, the control unit 80 shoots an indentation obtained by pressing the indenter 19 or the indenter 21 against the reference piece with the camera 17 while the reference piece having the reference hardness is placed on the placing table 12. , An automatic measurement unit 84 for automatically executing a hardness measurement operation for calculating the hardness of the reference piece based on the impression taken by the camera 17 by the hardness calculation unit 83, and a measurement value of the hardness of the reference piece, A measured value display section 85 that displays the upper limit value and lower limit value of the hardness of the reference piece over time, and when the measured value of the hardness of the reference piece is greater than the upper limit value of the hardness of the reference piece, or from the lower limit value A warning display unit 86 that displays a warning when it is small, and an operation stop that stops the operation of the device when the measured value of the hardness of the reference piece is greater than the upper limit value of the reference piece hardness or less than the lower limit value. Part 87.

  In addition, the control unit 80 includes the above-described camera 17, liquid crystal display unit 59, LED light source 41, displacement detector 60, electromagnetic coil 34, computer 50, motor 30 for rotating the revolver 20, and mounting table 12 as X, It is connected to motors 13, 14, and 15 for moving in the Y and Z directions. Further, the control unit 80 is also connected to a storage unit 81 that stores the hardness of the reference piece measured by the automatic measurement unit 84 over time.

  Next, the operation in the case of performing daily inspection with the hardness tester having the above-described configuration will be described.

  When performing daily inspection, a reference piece having a reference hardness is placed on the mounting table 12. This reference piece has the same shape as the test piece 100 and is prepared as having a reference hardness. In addition, as this reference | standard piece, the thing of the hardness corresponding to the hardness of the test piece 100 when performing a hardness test with a hardness tester is used. For example, when a Vickers hardness test is performed, a plurality of reference pieces having different Vickers hardness, such as HV700, HV500, HV200, HV100, and HV50, are selectively used as the reference piece.

  In addition, test conditions are set before daily inspection. Examples of the test conditions include the number of tests on the reference piece, test force, test time (time for pressing the indenter), and the like. Further, an upper limit value and a lower limit value of the hardness of the reference piece are also set. The upper limit value and the lower limit value of the hardness of the reference piece represent the range of hardness that will be measured when the hardness of the reference piece used is measured with a hardness tester. If the measured hardness is greater than this upper limit value or less than the lower limit value, it will be determined that the hardness measurement by the hardness tester has not been performed correctly, as will be described later. Display a warning or stop the operation of the device.

  When the test conditions are set and the reference piece is placed on the placement table, the hardness measurement operation is automatically executed. When starting this hardness measurement operation, the operator operates the computer 50 or the start button of the liquid crystal display unit 59. The hardness measurement operation may be automatically started every day at a certain time.

  This hardness measurement operation is executed by a command to the automatic measurement unit 84 in the control unit 80. At this time, the revolver 20 is rotated by driving the motor 30 to move the indenter 19 or the indenter 21 to a test position facing the test piece 100. Here, when the Vickers hardness test is executed, the indenter 21 is arranged at the test position, and when the Knoop hardness test is executed, the indenter 19 is arranged at the test position. Then, the tip of the indenter 19 or the indenter 21 is pressed against the reference piece with a test force and a test time set in advance by the action of the load mechanism to form an indentation on the surface of the reference piece. When the necessary indentation is formed on the test piece 100, the revolver 20 is rotated by driving the motor 30, and one of the objective lenses 22, 23, 24, 25 is placed at a position facing the indentation in the test piece 100. Move. At this time, among the objective lenses 22, 23, 24, and 25, the objective lens corresponding to the size of the indentation is disposed at a position facing the indentation.

  The control unit 80 performs image processing on the image of the impression formed on the surface of the test piece 100 obtained through the camera 17 by the image processing unit 82, and measures the diagonal length d of the impression. The Vickers hardness is proportional to the value obtained by dividing the test force by the surface area of the indentation assuming that the bottom surface is square and the apex angle is the same pyramid as the indenter 21. The hardness calculation unit 83 in the control unit 80 calculates the Vickers hardness from the surface area of the dent and the test force obtained from the diagonal length d of the indentation. Then, the measurement value of the hardness of the reference piece measured by the hardness measurement operation is displayed on the display unit 55 or the liquid crystal display unit 59 of the computer 50 by the measurement value display unit 85 in the control unit 80.

  FIG. 8 is a schematic diagram of a graph showing the measurement result of the hardness displayed on the display unit 55 or the liquid crystal display unit 59 of the computer 50.

  Here, Fig.8 (a) is a graph which shows the measured value of the hardness measured by the daily inspection of the day. Further, FIG. 8B shows a case where the average value of the measured value of the daily hardness test is displayed over time from June 1 to June 5. In these drawings, the broken line indicated by the symbol H indicates the upper limit value of the hardness of the reference piece, and the broken line indicated by the symbol L indicates the lower limit value of the hardness of the reference piece.

  As shown in FIG. 8 (a), the measured value of the hardness measured by the daily daily inspection, together with the upper limit value and the lower limit value of the hardness of the reference piece, due to the action of the measured value display unit 85 in the control unit 80. And displayed on the display unit 55 or the liquid crystal display unit 59 of the computer 50. In this embodiment, the case where hardness is measured 5 times per day is shown. These five measurements are displayed as a graph over time.

  Here, when any of the five measured values is larger than the preset upper limit value of the hardness of the reference piece or smaller than the lower limit value, the color of the display of the point indicating the measured value of the hardness is changed. At the same time, the warning display unit 86 in the control unit 80 displays a warning on the display unit 55 or the liquid crystal display unit 59 of the computer 50. This makes it easy to recognize the relationship between the measured value of the hardness of the reference piece and the upper limit value or lower limit value of the hardness of the reference piece, and easily determines that the test accuracy of the hardness tester has decreased. It becomes possible to do.

  When any of the five measured values is larger than the preset upper limit value of the reference piece hardness or smaller than the lower limit value, the hardness is determined by a command from the operation stop unit 87 in the control unit 80. The hardness test operation in the testing machine is stopped. Thereby, it is possible to prevent the hardness test from being executed in a state where the test accuracy is lowered.

  Further, the measurement value and the average value of the hardness test during the daily daily test are stored in the storage unit 81 over time each time the daily daily inspection is performed. Then, by switching the display from the state shown in FIG. 8 (a) to the state shown in FIG. 8 (b), the average value of the measured values of the hardness test of the day is displayed on the display unit 55 or the liquid crystal display unit of the computer 50. 59 is displayed over time. At this time, when a point indicating the average value is clicked or the like, a range R between the maximum value and the minimum value of the test value of the hardness of the day is displayed. As a result, it is possible to easily recognize the change over time in the measurement value (measurement error) of the hardness.

  As described above, in the hardness tester according to the present invention, daily inspection can be automatically executed by the action of the automatic measuring unit 84. Then, the measurement value of the hardness of the reference piece is stored in the storage unit 81, and the measurement value of the hardness is displayed over time by the action of the measurement value display unit 85, so that the result of daily inspection can be accurately recognized. Is possible. When the measured value of the hardness of the reference piece is greater than the preset upper limit value of the reference piece or smaller than the lower limit value, the warning display unit 86 displays a warning and the operation stop unit 87 is hard. Since the operation of the hardness tester is stopped, it is possible to easily recognize that the accuracy of the hardness tester has decreased, and it is possible to prevent the hardness test from being executed in this state.

DESCRIPTION OF SYMBOLS 11 Table 12 Mounting table 13 Motor 14 Motor 15 Motor 16 Eyepiece 17 Camera 19 Indenter 20 Revolver 21 Indenter 22 Objective lens 23 Objective lens 24 Objective lens 25 Objective lens 26 Knob 27 Shaft cylinder 28 Rotating shaft 29 Bearing 30 Motor 31 Axis 32 Lever 33 Permanent magnet 34 Electromagnetic coil 35 Press part 36 Load transmission shaft
41 LED light source 42 light tube 43 half mirror 44 half mirror 50 computer 53 rack 54 pinion 55 display unit 56 main body 57 keyboard 58 mouse 59 liquid crystal display unit 60 displacement detector 61 leaf spring 62 support member 63 support member 80 control unit 81 storage unit 82 Image processing unit 83 Hardness calculation unit 84 Automatic measurement unit 85 Measurement value display unit 86 Warning display unit 87 Operation stop unit 100 Test piece

Claims (4)

A mounting table for mounting the test piece, an indenter for forming an indentation on the surface of the test piece mounted on the mounting table, and applying a test force to the indenter by pressing the indenter against the test piece A load mechanism; an imaging mechanism for imaging an indentation formed on the surface of the test piece; and a hardness calculation unit that calculates the hardness of the test piece based on the impression taken by the imaging mechanism. In the hardness tester,
While the reference piece having the reference hardness is placed on the mounting table, the indentation obtained by pressing the indenter against the reference piece is photographed by the photographing mechanism, and the photographing mechanism is used by the hardness calculation unit. Automatic measurement means for automatically executing a hardness measurement operation for calculating the hardness of the reference piece based on the impression photographed in
Storage means for storing the hardness of the reference piece measured by the hardness measurement operation according to the command of the automatic measurement means over time;
A measurement value display means for displaying a measurement value of the hardness of the reference piece stored in the storage means over time on a display unit;
A hardness tester characterized by comprising: The hardness tester according to claim 1,
The measurement value display means is a hardness tester for displaying a measurement value of the hardness of the reference piece over time together with a preset upper limit value and lower limit value of the hardness of the reference piece. In the hardness tester according to claim 2,
A hardness tester comprising warning display means for displaying a warning when a measured value of the hardness of the reference piece is larger than a preset upper limit value of the reference piece hardness or smaller than a lower limit value. In the hardness tester according to claim 2 or claim 3,
A hardness test comprising an operation stop means for stopping the operation of the apparatus when the measured value of the hardness of the reference piece is larger than a preset upper limit value of the reference piece hardness or smaller than a lower limit value. Machine.

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