JPH06347389A - Error correcting method for rockwell tester - Google Patents

Abstract

PURPOSE:To obtain an accurately measured value by measuring several types of hardnesses of known hardness and a hardness of a reference piece, obtaining errors of hardness reference values of testers from the value, forming an error polygonal line graph, and obtaining an error at a measured hardness to correct it. CONSTITUTION:A hardness is measured by using reference pieces having several types of hardnesses in which the hardnesses are previously known such as 30HRC, 40HRC, 50HRC, 60HRC. An error polygonal line graph is formed with hardness reference values at an abscissa axis and with an error at an ordinate axis. The errors at various hardnesses can be calculated by using the polygonal line, the calculated error is used as a correction value, added to a primarily measured value thereby to measure an accurate Rockwell hardness of a sample. Incidentally, calculations of forming the graph, a correction value are conducted by a calculator contained in a microcomputer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an error correction method for a Rockwell hardness tester, and more particularly to an error correction method suitable for a digital display type Rockwell hardness tester.

[0002]

2. Description of the Related Art In general, Rockwell hardness testers have different characteristics depending on the individual testers. Therefore, before the hardness test, the characteristics of the hardness tester, that is, the error is measured, and the actual measurement is performed. The true value is calculated by adding the above error as a correction value to the value (primary measurement value). This point will be described in further detail using an example. Before performing the hardness tester using the Rockwell hardness tester, as a preliminary step, several hardness reference values whose hardness is known in advance (for example, 30HRC) are used. , 40HRC, 50HRC and 60HR
The hardness is measured by the tester for the four hardness reference pieces having C). And it is assumed that the result of the hardness measurement is as shown in [Table 1].

[0003]

[Table 1]

FIG. 2 is a graph of the measurement results shown in [Table 1] with the hardness reference value on the horizontal axis and the measured value on the vertical axis. The solid line b in FIG. A broken line showing the relationship between the reference value and the measured value, which is created by sequentially connecting the values (calibration points) with a straight line, and a dotted line c shows an ideal line with zero error. As shown by the broken line b in FIG. 2, in the Rockwell hardness tester, the relationship between the indicated value (actual measurement value) and the hardness of the sample is not a simple curve, and the pattern of the characteristic curve is different in each tester. . Furthermore, when the indenter, which is an important part, is replaced, the characteristic curve also changes. By the way, in the conventional digital Rockwell hardness tester, the average value of the errors is calculated from [Table 1] or FIG. 2 and used as the correction value, and this correction value is added to the actual measurement value (primary measurement value), This is displayed as hardness.

[0005]

As can be seen from the above example, in the Rockwell tester, the measurement error differs depending on the hardness of the sample. Therefore, the conventional error correction method that adds a constant value (average error value) to the primary measurement value irrespective of the hardness of the sample has a problem that the error in hardness measurement cannot be reduced. The present invention is intended to solve such a problem, and performs a hardness test of a plurality of types of hardness reference pieces whose hardness is known in advance by a Rockwell tester, and the data of the hardness test. From the above, a measurement error at each hardness reference point is connected by a straight line to create an error line graph, and the error at each measurement hardness of the Rockwell tester is calculated from this error line graph, and this is used as the correction value, Rockwell test An object of the present invention is to provide an error correction method in a machine.

[0006]

In order to achieve the above object, an error correction method in a Rockwell tester according to the present invention corrects a measurement error by adding a correction value to a primary measurement value obtained by the Rockwell tester. In doing so, the hardness of the hardness reference piece of several kinds of hardness reference value whose hardness is known in advance is measured by the Rockwell tester, and from the measured value to the hardness reference value of the tester. Calculate the corresponding error, connect the errors corresponding to the respective hardness reference values with a straight line, and create an error line graph showing the relationship between the above error and the hardness reference value. Is calculated and used as the correction value.

[0007]

In the error correction method for the Rockwell tester of the present invention described above, several types of hardness reference pieces whose hardness is known in advance are measured to show the relationship between the error of the tester and the hardness reference value. An accurate measured value can be obtained by creating an error line graph, calculating an error in each measurement hardness from the error line graph, and using this as a correction value for each measurement value.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An error correction method in a Rockwell tester as an embodiment of the present invention will be described below with reference to FIG. 1, and FIG. 1 is its error line graph. Also in this embodiment, four hardness reference pieces (30HRC, 40HRC, 50HRC and 60HRC, whose hardness is known in advance, are used).
It is assumed that the hardness measurement results are as shown in [Table 1] and FIG. 2.

FIG. 1 is a graph in which the error (correction value) in each hardness reference value calculated from [Table 1] or FIG. 2 is plotted with the hardness reference value on the horizontal axis and the error on the vertical axis. Things
A solid line a in FIG. 1 represents an error polygonal line showing the relationship between the error and the hardness reference value, which is created by connecting the respective errors on the drawing with a straight line. In addition, outside the both ends of the error polygonal line a, a straight line (two-dot chain line) to which the error value of each end is directly applied
Let a ₁ and a ₂ be error polygonal lines. Then, the error in every hardness can be calculated from the error polygonal line shown in FIG. 1, and the error thus calculated is added as a correction value to the primary measurement value to obtain the accurate Rockwell hardness of the sample. Can be measured. The calculation of the error line graph and the calculation of the correction value from the error line graph are performed by a calculator having a microcomputer.

That is, the arithmetic unit is equipped with a changeover switch for switching between a mode in which the correction value is added to the primary measurement value and a mode in which the correction value is not added. A hardness test is performed using a standard piece, the measurement data is input to a storage device, an error is calculated based on the measurement data stored in the storage device, and an error polygonal line (correction characteristic) graph is created. Next, the hardness of the sample is measured by switching to the mode in which the correction value is added by operating the changeover switch, and the hardness is displayed by adding the correction value obtained from the error line graph to the primary measurement value. . In this way, the exact Rockwell hardness can be digitally displayed.

[0011]

As described above in detail, according to the error correction method in the Rockwell tester of the present invention, the error of the tester corresponding to each measurement hardness is calculated and used as the correction value. , There is an advantage that the accurate Rockwell hardness can be measured.

[Brief description of drawings]

FIG. 1 is an example of an error line graph in an error correction method in a Rockwell tester of the present invention.

FIG. 2 is a graph showing an example of measured values for several hardness reference values in a Rockwell tester.

[Explanation of symbols]

 a Error broken line b Break point connecting measured values for each hardness reference value with a straight line c Ideal line with zero error

Claims (1)

[Claims] 1. In a hardness test using a Rockwell tester, a correction value is added to a primary measurement value obtained by the Rockwell tester to correct a measurement error, and several types of hardness whose hardness is known in advance are corrected. The hardness of the hardness reference value is measured by the Rockwell tester, and the error corresponding to each hardness reference value of the tester is calculated from the measured value. Create an error line graph that represents the relationship between the above error and the hardness reference value by connecting the corresponding errors with a straight line, calculate the error at each measured hardness from the error line graph, and use this as the above correction value. An error correction method in a Rockwell tester, which is characterized in that