JP2021063776A - Linear expansion coefficient measurement method and linear expansion coefficient measurement device - Google Patents

Abstract

To provide a linear expansion coefficient measurement method which suppresses malfunction of a probe and which can measure a linear expansion coefficient with high accuracy.SOLUTION: A linear expansion coefficient measurement method includes: a setting step of sequentially setting a preset temperature of a thermostatic chamber 30; a detection step of inserting a stylus 211 of a three-dimensional measurement device 20 into the thermostatic chamber 30 while the temperature in the thermostatic chamber 30 is stable at the preset temperature so as to detect a measured object; and a running-in step of inserting the stylus 211 into the thermostatic chamber 30 while the temperature in the thermostatic chamber 30 changes.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for measuring a coefficient of linear expansion and a device for measuring a coefficient of linear expansion.

Conventionally, a method for measuring the coefficient of linear expansion of a substance is known (see, for example, Patent Document 1).
The linear expansion coefficient α changes the length dimension of the object to be measured at the standard temperature by L, the amount of temperature change from the standard temperature (temperature at the time of measurement-standard temperature) by ΔT, and the temperature of the object to be measured by ΔT from the standard temperature. It is obtained by the following equation (1), where ΔL is the amount of change in the length dimension (the amount of linear expansion) when the temperature is increased.

In the equation (1), ΔL / L is on the ^{order of 10-5} , so the accuracy of ΔL is important in order to improve the accuracy of the value of ΔL / L.
Therefore, Patent Document 1 discloses a method of measuring the linear expansion amount ΔL using a constant temperature bath and a three-dimensional measuring machine. In the method of Patent Document 1, the object to be measured is placed in a constant temperature bath, the temperature of the object to be measured is stabilized at an arbitrary set temperature, and the stylus of the probe of the coordinate measuring machine is inserted into the constant temperature bath. Measure the length dimension of the object to be measured. Then, the linear expansion amount ΔL is calculated based on the difference in the length dimension of the object to be measured between the plurality of set temperatures.

Japanese Unexamined Patent Publication No. 2017-62192

By the way, in Patent Document 1, while the internal temperature of the constant temperature bath is changing toward an arbitrary set temperature, the stylus stands by outside the constant temperature bath and is accustomed to the environmental temperature outside the constant temperature bath. There is. Therefore, when the stylus is inserted into a constant temperature bath, it may be suddenly exposed to a temperature environment that is significantly different from its own temperature. In such a case, the stylus may thermally expand while the length dimension of the object to be measured is being measured, or the characteristics of the probe containing the stylus may change due to heat. It cannot be measured, and the accuracy of the coefficient of linear expansion may decrease.

An object of the present invention is to provide a linear expansion coefficient measuring method and a linear expansion coefficient measuring device capable of measuring a linear expansion coefficient with high accuracy.

The linear expansion coefficient measuring method of the present invention is a linear expansion coefficient measuring method for measuring the linear expansion coefficient of an object to be measured, and includes a setting step of sequentially setting a set temperature with respect to a constant temperature bath and a inside of the constant temperature bath. While the temperature is stable at the set temperature, the detection step of inserting the stylus of the coordinate measuring device into the constant temperature bath to detect the object to be measured, and while the temperature inside the constant temperature bath is changing. It is characterized by carrying out a break-in step of inserting the stylus into the constant temperature bath.

In such a method, the temperature of the stylus follows the change in the temperature inside the stylus by performing a break-in step of inserting the stylus into the constant temperature bath while the temperature inside the stylus is changing toward the set temperature. Change. This allows the temperature of the stylus to reach a temperature close to the set temperature before the detection step begins.
Therefore, at the start of the detection step, the stylus is not exposed to a temperature environment significantly different from its own temperature, and it is possible to avoid a sudden change in the temperature of the stylus. As a result, it is possible to prevent the stylus from thermally expanding and the characteristics of the probe including the stylus from being significantly changed during the detection step, so that the measurement accuracy by the detection step is improved and the coefficient of linear expansion is increased. Can be measured with high accuracy.
In addition, even when the difference between the temperature inside the constant temperature bath and the ambient temperature outside is large, the stylus can be gradually acclimatized to the temperature inside the tank, so that the probe is subjected to thermal impact. It can be avoided. As a result, it is possible to prevent the probe from failing due to the difference in the coefficient of thermal expansion.
Further, according to the linear expansion coefficient measuring method of the present invention, the overall measurement time is shortened as compared with the example in which the stylus is inserted into the constant temperature bath to acclimatize to the tank temperature after the tank temperature stabilizes at the set temperature. can do.

The method for measuring the coefficient of linear expansion of the present invention includes the break-in step of inserting the stylus into the constant temperature bath and the evacuation step of retracting the stylus from the constant temperature bath while the temperature inside the constant temperature bath is changing. It is preferable to carry out alternately.
According to such a method, since the temperature of the stylus changes stepwise according to the change in the temperature in the tank, it is possible to more preferably avoid a sudden temperature change of the stylus. Further, by closing the opening of the constant temperature bath while the stylus is retracted from the constant temperature bath, the time required for the temperature inside the constant temperature bath to stabilize at the set temperature can be shortened.

In the method for measuring the coefficient of linear expansion of the present invention, it is preferable to further carry out a temporary detection step of detecting the object to be measured using the stylus while the stylus is inserted into the constant temperature bath by the break-in step.
According to such a method, it is possible to detect the object to be measured while the temperature inside the constant temperature bath is changing, and to confirm the temporal transition of the detection result. The information obtained by the tentative detection step can be used as reference information for measurement or to determine when to start the detection step.

In the method for measuring the coefficient of linear expansion of the present invention, it is preferable that the detection step is started after the temporal transition of the detection result by the provisional detection step is stable.
According to such a method, since the detection step can be performed after the length dimension of the object to be measured is stabilized, the coefficient of linear expansion can be measured with higher accuracy. Further, the start timing of the detection step can be appropriately determined according to the difference in the shape, length, volume or heat capacity of the object to be measured, and unnecessary waiting time can be omitted.
Regarding whether or not the temporal transition of the detection result by the provisional detection step is stable, for example, the difference between the detection result by the previous provisional detection step and the detection result by the current provisional detection step is set in advance. It can be judged based on whether or not it is below the threshold value.

The present invention is a linear expansion coefficient measuring device for measuring the linear expansion coefficient of an object to be measured, in which a constant temperature bath for adjusting the temperature inside the tank to a set temperature and accommodating the object to be measured and the constant temperature bath. A probe that is inserted to detect the object to be measured, a moving mechanism that moves the probe, and a control unit that controls the moving mechanism are provided, and the control unit changes the temperature inside the constant temperature bath. While, the moving mechanism is controlled so that the stylus of the probe is inserted into the constant temperature bath.
According to such a linear expansion coefficient measuring device, the same effect as the above-mentioned effect can be obtained with respect to the linear expansion coefficient measuring method of the present invention.

The perspective view which shows the linear expansion coefficient measuring apparatus which concerns on one Embodiment of this invention. The block diagram which shows the functional structure of the linear expansion coefficient measuring apparatus which concerns on the said embodiment. The perspective view which shows the step gauge which is the object to be measured of the said embodiment. The flowchart which shows the linear expansion coefficient measurement method of the said embodiment. The figure for demonstrating the measurement operation of the said embodiment. The figure which shows the example of the time transition of the temperature command, the temperature in a tank, and the measurement operation of the said embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In this embodiment, an example in which the linear expansion coefficient α of the step gauge is measured using the step gauge, which is a dimensional reference device, as an object to be measured will be described.

As shown in FIG. 1, the linear expansion coefficient measuring device 1 of the present embodiment includes a three-dimensional measuring machine 20 for measuring the dimensions of a step gauge 10 as an object to be measured, a constant temperature bath 30 for accommodating the step gauge 10. It is provided with a control device 60.

The coordinate measuring machine 20 includes a probe 21 and a probe moving mechanism 22 for moving the probe 21. The probe moving mechanism 22 includes a column 24 provided on the upper surface of the surface plate 23, a crossbar 25 provided on the column 24, a head 26 supported by the crossbar 25, and a ram 27 installed on the head 26. Is configured to include. A probe 21 is supported at the tip of the ram 27.

The column 24, the head 26, and the ram 27 can be moved in each axial direction by being driven by a motor or the like. Specifically, the column 24 is movable in the Y-axis direction with respect to the surface plate 23, the head 26 is movable in the X-axis direction with respect to the crossbar 25, and the ram 27 is Z with respect to the head 26. It is movable in the axial direction. The probe 21 can move three-dimensionally with respect to the surface plate 23 by such three-axis movement.
The probe 21 has a stylus 211 for contacting the object to be measured. The coordinate measuring machine 20 outputs the three-dimensional coordinates of the probe 21 when the stylus 211 comes into contact with the object to be measured to the control device 60.

The constant temperature bath 30 has a container-shaped accommodating portion 31 and a top plate portion 32 that closes the upper opening of the accommodating portion 31. The accommodating portion 31 and the top plate portion 32 partition an internal space that is thermally shielded from the external space. The top plate portion 32 is provided with a plurality of openings 33 and a plurality of lids 34 capable of opening and closing each opening 33.

Further, as shown in FIG. 2, the constant temperature bath 30 includes a temperature sensor 35 that detects the temperature of the internal space (temperature inside the tank) and a temperature adjusting mechanism 36 for keeping the temperature inside the tank constant at an arbitrary set temperature. It also has a lid opening / closing mechanism 37 for opening / closing the lid 34. The temperature sensor 35 outputs the detected information on the temperature inside the tank to the temperature adjusting mechanism 36 and the control device 60, respectively. The temperature adjusting mechanism 36 is configured to include, for example, a cooler or a heater, and has a function of adjusting and stabilizing the temperature inside the tank based on the set temperature. The lid opening / closing mechanism 37 includes, for example, a motor and the like, and is controlled by the control device 60 to open / close the lid 34.

Further, as shown in FIG. 3, in the internal space of the constant temperature bath 30, a step gauge 10 which is an object to be measured and a reference block gauge 40 which is a reference for comparative measurement of the step gauge 10 and these are supported. The support unit 50 and the support unit 50 are housed.

The step gauge 10 has a prismatic main body portion 13 having a length in the Lt direction, and a plurality of convex portions 14 provided on the upper surface of the main body portion 13 along the Lt direction. The convex portion 14 arranged at one end in the Lt direction has a first surface 11, and the convex portion 14 arranged at the other end in the Lt direction has a second surface 12. The length dimension Dr of the step gauge 10 is defined as the distance between the first surface 11 and the second surface 12.

The reference block gauge 40 is a block gauge having a length in the Lr direction, and has a first reference surface 41 and a second reference surface 42 at both end portions in the Lr direction. The length dimension Drx of the reference block gauge 40 is defined as the distance between the first reference surface 41 and the second reference surface 42. Further, as the reference block gauge 40, a gauge whose length dimension Drx is known and shorter than the nominal dimension of the step gauge 10 is used.
Further, the material of the reference block gauge 40 has an extremely low expansion coefficient or a zero expansion coefficient that can be accurately ignored in a predetermined temperature range set in the constant temperature bath 30. Alternatively, the material of the reference block gauge 40 may be one in which an accurate coefficient of linear expansion is known and high-precision temperature correction is possible.

The support unit 50 includes a highly rigid bottom plate portion 51, an object support base 52 and a reference gauge support base 53, which are installed on the bottom plate portion 51, respectively. The object support 52 to be measured supports the step gauge 10 so as to allow expansion and contraction of the step gauge 10 in the Lt direction, and the reference gauge support 53 supports the reference block gauge 40 above the step gauge 10.

As shown in FIG. 2, the control device 60 is composed of a computer such as a personal computer, and includes a calculation unit 61 and a storage unit 62. The calculation unit 61 executes various processes by reading and executing various programs stored in the storage unit 62. Specifically, the calculation unit 61 sets the temperature for the probe control unit 63 that controls the probe movement mechanism 22, the linear expansion coefficient calculation unit 64 that calculates the linear expansion coefficient α of the object to be measured, and the constant temperature bath 30. It has a temperature command unit 65 that commands the temperature command unit 65, and a lid body control unit 66 that controls the lid body opening / closing mechanism 37 of the constant temperature bath 30. The specific functions of each configuration will be described later.

[Measurement operation of coefficient of linear expansion]
FIG. 4 shows a procedure for measuring the linear expansion coefficient α of the step gauge 10 using the linear expansion coefficient measuring device 1.
First, the measurer installs the step gauge 10 and the reference block gauge 40, which are the objects to be measured, in the constant temperature bath 30 (step S1). Specifically, the bottom plate portion 51 and the object to be measured support 52 are installed inside the constant temperature bath 30, and the step gauge 10 is supported by the object support 52 to be measured. After that, a reference gauge support base 53 is installed inside the constant temperature bath 30, and the reference gauge support base 53 supports the reference block gauge 40.

Next, the measurer inputs the measurement conditions including the measurement length by the coordinate measuring machine 20 and a plurality of set temperatures for the constant temperature bath 30 to the control device 60 (step S2). As a result, the coefficient of linear expansion measuring device 1 starts the measuring operation.

After the start of the measurement operation, the temperature command unit 65 outputs a temperature command regarding the set temperature of any of the input measurement conditions that have not been measured to the constant temperature bath 30 (step S3; setting step of the present invention). .. As a result, the temperature adjusting mechanism 36 of the constant temperature bath 30 starts adjusting the temperature inside the tank based on the set temperature. It is assumed that all the lids 34 of the constant temperature bath 30 are closed at the start of the measurement operation of the linear expansion coefficient measuring device 1.

After step S3, the probe control unit 63 determines whether or not the predetermined waiting time tw has elapsed (step S4), and if Yes, the process proceeds to step S5, and if No, the process returns to step S4. That is, the probe control unit 63 repeats step S4 until the waiting time tw elapses.
The standby time tw is, for example, an arbitrary time set in advance, and is counted from the output time of the temperature command or the end time of the provisional measurement described later.

In step S5, the probe control unit 63 outputs a measurement operation command to the probe moving mechanism 22 to control the probe 21. As a result, the probe 21 performs an operation of measuring (provisionally measuring) each length dimension of the step gauge 10 and the reference block gauge 40. Further, the lid body control unit 66 controls the lid body opening / closing mechanism 37 according to the operation of the probe 21 to open / close the lid body 34.

Each operation of the probe 21 and the lid 34 in the provisional measurement in step S5 is the same as the main measurement performed in a later step. Here, each operation of the probe 21 and the lid 34 in the provisional measurement will be specifically described with reference to FIG.
First, the lid 34 arranged on one side of the constant temperature bath 30 is opened, the stylus 211 is inserted into the constant temperature bath 30 through the opening 33, and the probe 21 is inserted into the first surface 11 and the convex portion 14 of the step gauge 10. Contact detection of top and side surfaces. Following this, the probe 21 contacts and detects the first reference surface 41 of the reference block gauge 40 and the adjacent top and side surfaces. After that, the stylus 211 is retracted from the constant temperature bath 30, and the lid 34, which has been in the open state, closes.
Next, the lid 34 arranged on the other side of the constant temperature bath 30 is opened, the stylus 211 is inserted into the constant temperature bath 30 through the opening 33, and the probe 21 is the second surface 12 of the step gauge 10 and the reference block gauge 40. The second reference surface 42 of the above is contact-detected. After that, the stylus 211 is retracted from the constant temperature bath 30, and the lid 34, which has been in the open state, closes.

Further, in step S5, the linear expansion coefficient calculation unit 64 determines the three-dimensional coordinates of the center positions of the first surface 11 and the second surface 12 of the step gauge 10 and the step gauge 10 based on the detection result by the probe 21 described above. The three-dimensional coordinates of the center positions of the first reference surface 41 and the second reference surface 42 of the reference block gauge 40, and the orientation of the reference block gauge 40 are calculated. Then, the linear expansion coefficient calculation unit 64 determines the distance between the center position of the first surface 11 and the center position of the first reference surface 41, and the distance between the center position of the second surface 12 and the center position of the second reference surface 42. Based on this, the distance between the first surface 11 and the second surface 12 is calculated.
By the above provisional measurement in step S5, the length dimension of the step gauge 10 while the temperature inside the tank is changing is measured.

In the provisional measurement of step S5, the operation of inserting the stylus 211 into the constant temperature bath 30 corresponds to the break-in step of the present invention, and the operation of the stylus 211 retracting from the constant temperature bath 30 corresponds to the withdrawal step of the present invention. The operation of the probe 21 for contact detecting the step gauge 10 corresponds to the provisional detection step of the present invention, and the process of calculating the length dimension of the step gauge 10 by the linear expansion coefficient calculation unit 64 is the provisional calculation step of the present invention. Corresponds to.

After the tentative measurement is completed, the probe control unit 63 determines whether or not the temperature inside the constant temperature bath 30 is stable at the set temperature based on the output of the temperature sensor 35 (step S6). Then, in the case of Yes in step S6, it is determined whether or not the temporal transition of the measurement result (length dimension of the step gauge 10) by the provisional measurement is stable (step S7). If Yes in step S7, the process proceeds to step S8.

On the other hand, if No in step S6 or step S7, the process returns to step S4. As a result, the tentative measurement is repeated until the temperature inside the constant temperature tub 30 is stable at the set temperature and the temporal transition of the measurement result by the tentative measurement is stable.

In step S6, whether or not the temperature inside the tank is stable can be determined based on, for example, whether or not the range of change in the temperature inside the tank at predetermined time intervals is within a preset range.
Further, in step S7, regarding whether or not the temporal transition of the measurement result of the provisional measurement is stable, for example, the difference between the measurement result of the previous provisional measurement and the measurement result of the current provisional measurement is set in advance. It can be judged based on whether or not it is below the threshold value.

In step S8, the present measurement (detection step of the present invention) is carried out by the same operation and processing as the above-mentioned provisional measurement. By this main measurement, the length dimension of the step gauge 10 at the current set temperature is measured. The length dimension of the step gauge 10 measured by this measurement is stored in the storage unit 62 in association with the current set temperature.

Next, the temperature command unit 65 determines whether or not there is a set temperature that has not been measured, that is, whether or not it is necessary to change the current set temperature among the input setting conditions (step S9). .. Then, in the case of Yes in step S9, the process returns to step S3, and a temperature command regarding the next set temperature is output to the constant temperature bath 30. As a result, the above steps S4 to S8 based on the next set temperature are repeated. On the other hand, if No in step S9, the process proceeds to step S10.

In step S10, the linear expansion coefficient calculation unit 64 calculates the linear expansion coefficient α of the step gauge 10 based on the length dimension of the step gauge 10 associated with each set temperature. As for the method of calculating the coefficient of linear expansion α, the same method as in the prior art can be used.

〔effect〕
The effect of this embodiment will be described with reference to the example shown in FIG. FIG. 6 is a diagram showing temperature commands, tank temperature, and measurement operation commands for the passage of time when set temperatures T1 to T3 (T1 <T2 <T3) are set, for example.

As shown in FIG. 6, in the linear expansion coefficient measuring device 1, the temperature inside the constant temperature bath 30 is set to a plurality of set temperatures T1 to T3 by sequentially outputting temperature commands corresponding to the set temperatures T1 to T3. It is set sequentially.
In such a linear expansion coefficient measuring device 1, this measurement is carried out by outputting a measurement operation command while the temperature inside the constant temperature bath 30 is stable at each set temperature T1 to T3. As a result, data for calculating the coefficient of linear expansion α is acquired.

Further, in the linear expansion coefficient measuring device 1, provisional measurement is performed by outputting a measurement operation command while the temperature inside the constant temperature bath 30 is changing toward the set temperatures T1 to T3. That is, the linear expansion coefficient measuring device 1 carries out a break-in step of inserting the stylus 211 into the constant temperature bath 30 while the temperature inside the tank is changing. As a result, the temperature of the stylus 211 can be changed according to the change in the temperature inside the tank to reach a temperature close to the set temperatures T1 to T3 before the main measurement is started.

Therefore, at the start of this measurement, the stylus 211 is not exposed to a temperature environment significantly different from its own temperature, and it is possible to avoid a sudden change in the temperature of the stylus 211. Therefore, it is possible to prevent the stylus 211 from thermally expanding and the characteristics of the probe 21 from being significantly changed during the main measurement. Therefore, the measurement accuracy by this measurement is improved, and the coefficient of linear expansion α can be measured with high accuracy.
Further, even when the difference between the temperature inside the constant temperature bath 30 and the outside environmental temperature is large, the stylus 211 can be gradually acclimatized to the temperature inside the tank, so that the probe 21 receives a thermal impact. You can avoid receiving it. As a result, it is possible to prevent the probe 21 from failing due to the difference in the coefficient of thermal expansion.
Further, in the present embodiment, the overall measurement time can be shortened as compared with the example in which the stylus is inserted into the constant temperature bath 30 to acclimatize to the temperature inside the tank after the temperature inside the tank has stabilized at the set temperature.

In the linear expansion coefficient measuring device 1, provisional measurement is repeatedly performed at arbitrary time intervals while the temperature inside the constant temperature bath 30 is changing. The provisional measurement of the present embodiment includes a break-in step of inserting the stylus 211 into the constant temperature bath 30 and a retracting step of retracting the stylus 211 from the constant temperature bath 30, and the provisional measurement is repeatedly performed. This means that the break-in step and the evacuation step are alternately performed.
According to such a method, since the temperature of the stylus 211 changes stepwise according to the change of the temperature in the tank, a sudden temperature change of the stylus 211 can be more preferably avoided.

In the provisional measurement of the present embodiment, a provisional detection step of detecting the step gauge 10 using the stylus 211 is carried out while the stylus 211 is inserted into the constant temperature bath 30 by the break-in step. Thereby, it is possible to confirm the temporal transition of the length dimension of the step gauge 10 while the temperature in the tank is changing. The information obtained by this provisional detection step can be used as reference information for measurement or for determining the transition time to this measurement.

For example, in step S9 of the present embodiment, it is determined whether or not the temporal transition of the length dimension of the step gauge 10, which is the measurement result of the provisional measurement, is stable, and when it is determined that the transition is stable, the main measurement is performed. Is being carried out. As a result, the linear expansion coefficient α can be measured with higher accuracy because the main measurement is performed after the length dimension of the step gauge 10 is surely stabilized. Further, the start timing of the main measurement can be appropriately determined according to the difference in the shape, length, volume or heat capacity of the object to be measured, and unnecessary waiting time can be omitted.

In the linear expansion coefficient measuring device 1 of the present embodiment, the stylus 211 is inserted into the constant temperature bath 30 while the measurement operation command is output (during the provisional measurement or the main measurement), and the opening 33 of the constant temperature bath 30 is inserted. Is open for inserting the stylus 211. On the other hand, while the measurement operation command is not output, the stylus 211 is retracted from the constant temperature bath 30, and the opening 33 of the constant temperature bath 30 is closed by the lid 34.
According to such a method, the exchange of air inside and outside the constant temperature bath 30 can be minimized, the fluctuation of the temperature inside the tank can be kept small, and the time required for the temperature inside the tank to stabilize at the set temperature can be shortened.
Further, in the present embodiment, since the provisional measurement is repeatedly performed at regular time intervals, the lid 34 is also opened and closed at regular time intervals. As a result, the influence of the exchange of air inside and outside the constant temperature bath 30 can be averaged, and the fluctuation of the temperature inside the tank can be moderated.

[Modification example]
The present invention is not limited to the configuration of each of the above-described embodiments, and modifications within the range in which the object of the present invention can be achieved are included in the present invention.

In the above embodiment, while the temperature inside the constant temperature bath 30 is changing, the break-in step of inserting the stylus 211 into the constant temperature bath 30 and the evacuation step of retracting the stylus 211 from the constant temperature bath 30 are alternately performed. However, the present invention is not limited to this. That is, the present invention may be such that the break-in step is performed at least once while the temperature inside the constant temperature bath 30 is changing.

In the above embodiment, a temporary detection step of detecting the step gauge 10 using the stylus 211 is performed while the stylus 211 is inserted into the constant temperature bath 30 by the break-in step, but the present invention is not limited to this. .. For example, while the temperature inside the constant temperature bath 30 is changing, only the break-in step of inserting the stylus 211 into the constant temperature bath 30 may be performed, and the provisional detection step may not be performed.

In particular, in the above embodiment, in order to detect the first surface 11 and the second surface 12 of the step gauge 10, the stylus 211 is inserted into the constant temperature bath 30 through the opening 33 on one side of the constant temperature bath 30. After the contact detection of the first surface 11, the stylus 211 is inserted into the constant temperature bath 30 through the opening 33 on the other side of the constant temperature bath 30, and the second surface 12 is contact-detected. However, if the tentative detection step is not performed, the break-in step simply inserts the stylus 211 into the constant temperature bath 30 through the same opening 33 of the constant temperature bath 30 or through different openings 33 in sequence. There may be.

In the above embodiment, the length dimension of the step gauge 10 is used as the detection result by the provisional detection step, and the detection step is started after the temporal transition of the length dimension of the step gauge 10 is stable. The present invention is not limited to this.
For example, as the detection result by the provisional detection step, the three-dimensional coordinates of either the first surface 11 or the second surface 12 of the step gauge 10 may be used instead of the length dimension of the step gauge 10.

Further, in the above embodiment, the start time of the detection step is determined based on the detection result of the provisional detection step, but the start time of the detection step may be determined by other means. For example, it may be determined whether or not the temperature inside the constant temperature bath 30 is stable, or whether or not the waiting time obtained by an experiment or the like has elapsed in advance, and if it is determined to be Yes, the detection step may be started. .. If the detection result obtained by the provisional detection step is not used, the detection result may be discarded after performing the provisional detection step.

In the above embodiment, the lid 34 is opened and closed according to the measurement operation command while the temperature inside the constant temperature bath 30 is changing, but the present invention is not limited to this. For example, the lid 34 may be in a constantly open state.

Further, in the above embodiment, the next provisional measurement is started after a predetermined waiting time tw has elapsed from the end of the provisional measurement, but the present invention is not limited to this. For example, the linear expansion coefficient measuring device 1 may have an adjusting means for adjusting the waiting time tw (time interval of the break-in step) between the provisional measurements.
For example, based on the temperature difference between the ambient temperature outside the constant temperature bath 30 and the temperature inside the tank (or the set temperature), the larger the temperature difference, the shorter the standby time tw may be adjusted. Further, based on the rate of change of the temperature in the tank with respect to time, the standby time tw may be adjusted to be shorter as the rate of change in temperature is larger. As a result, the larger the temperature difference between the environmental temperature and the set temperature (or the set temperature), or the larger the temperature change rate of the temperature inside the tank with respect to time, the more frequently the provisional measurement is performed. It can be acclimated to the internal temperature.
Further, based on the measurement result by the provisional measurement, the waiting time tw may be adjusted so that the smaller the difference between the measurement result between the previous provisional measurement and the current provisional measurement, the longer the waiting time tw. As the measurement result of the tentative measurement becomes stable, the frequency of performing the tentative measurement decreases and the time for closing the lid 34 of the constant temperature bath 30 becomes longer, so that the temperature inside the tank can be stabilized at an early stage.

In the above embodiment, the dimensions of the step gauge 10 are comparatively measured based on the dimensions of the reference block gauge 40, but the present invention is not limited to this, and the dimensions may be measured by the scale measuring function of the coordinate measuring machine 20.
Further, in the above embodiment, the coefficient of linear expansion of the step gauge 10 is measured as the object to be measured, but the present invention is not limited to this, and the present invention can be applied to measure the coefficient of linear expansion of various objects to be measured. ..
Further, in the above embodiment, the coordinate measuring device 20 of the present invention is used, but the present invention is not limited to this, and various types of coordinate measuring devices can be used as long as it is a contact type having a stylus. it can.

1 ... Linear expansion coefficient measuring device, 10 ... Step gauge, 11 ... First surface, 12 ... Second surface, 13 ... Main body, 14 ... Convex, 20 ... Coordinate measuring machine, 21 ... Probe, 211 ... Stylus, 22 ... moving mechanism, 23 ... surface plate, 24 ... column, 25 ... crossbar, 26 ... head, 27 ... ram, 30 ... constant temperature bath, 31 ... accommodating part, 32 ... top plate part, 33 ... opening, 34 ... Lid, 35 ... Temperature sensor, 36 ... Temperature adjustment mechanism, 37 ... Lid opening / closing mechanism, 40 ... Reference block gauge, 41 ... First reference surface, 42 ... Second reference surface, 50 ... Support unit, 51 ... Bottom plate , 52 ... Measured object support, 53 ... Reference gauge support, 60 ... Control device, 61 ... Calculation unit, 62 ... Storage unit, 63 ... Probe control unit, 64 ... Linear expansion coefficient calculation unit, 65 ... Temperature command unit , 66 ... Lid body control unit.

Claims (5)

A method for measuring the coefficient of linear expansion of an object to be measured, which is a method for measuring the coefficient of linear expansion.
A setting step to sequentially set the set temperature for the constant temperature bath, and
A detection step of inserting the stylus of the coordinate measuring device into the constant temperature bath to detect the object to be measured while the temperature inside the constant temperature bath is stable at the set temperature.
A method for measuring a coefficient of linear expansion, which comprises performing a break-in step of inserting the stylus into the constant temperature bath while the temperature inside the constant temperature bath is changing. The method for measuring a coefficient of linear expansion according to claim 1.
While the temperature inside the constant temperature bath is changing, the break-in step of inserting the stylus into the constant temperature bath and the evacuation step of retracting the stylus from the constant temperature bath are alternately performed. Method for measuring the coefficient of linear expansion. The method for measuring a coefficient of linear expansion according to claim 1 or 2.
A method for measuring a coefficient of linear expansion, which further performs a provisional detection step of detecting an object to be measured by using the stylus while the stylus is inserted into the constant temperature bath by the break-in step. The method for measuring a coefficient of linear expansion according to claim 3.
The method for measuring a coefficient of linear expansion, characterized in that the detection step is started after the temporal transition of the detection result by the provisional detection step is stable. A linear expansion coefficient measuring device that measures the linear expansion coefficient of an object to be measured.
A constant temperature bath that adjusts the temperature inside the tank to the set temperature and houses the object to be measured, and
A probe inserted into the constant temperature bath to detect the object to be measured,
A moving mechanism for moving the probe and
A control unit that controls the movement mechanism is provided.
The control unit is a linear expansion coefficient measuring device that controls the moving mechanism so as to insert the stylus of the probe into the constant temperature bath while the temperature inside the constant temperature bath is changing.

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