JPH0743281A - Material testing machine - Google Patents

Abstract

(57) [Summary] [Purpose] A test piece in a desired range is melted and solidified for characteristic evaluation. [Configuration] A load frame LF for loading the test piece TP,
Coil 25 for heating and melting a predetermined area of test piece TP
And a moving mechanism 2 for moving the coil 25 along the test piece TP to heat and melt the test piece TP over a predetermined range.
2 and 23 are provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material testing machine for evaluating characteristics in the process of melting and solidifying a test piece.

[0002]

2. Description of the Related Art From the viewpoint of resource recycling, used metals are collected, melted and solidified for reuse. At this time, it is necessary to know how the characteristics of the metal change due to the process of melting and solidifying the metal.

Conventionally, as a material testing machine for measuring the characteristic change due to the process of melting and solidifying a metal, a plurality of winding numbers (corresponding to the length to be melted and solidified among the metal test pieces held by the material testing machine ( In some cases, a coil having a (turn) is wound around a test piece, and a high frequency voltage is applied to the coil to heat and melt the test piece, and after cooling and solidifying the test piece, the test piece is added.

[0004]

However, in the above-mentioned conventional material testing machine, the test piece is melted by the coil of a plurality of turns corresponding to the length to be melted and solidified. There is a possibility that the melted portion is large at one time and the melted portion flows down, so that the subsequent characteristic evaluation cannot be performed.

An object of the present invention is to provide a material testing machine capable of melting and solidifying a test piece in a desired range and evaluating the characteristics.

[0006]

The present invention is applied to a material testing machine for performing characteristic evaluation in the process of melting and solidifying a test piece, and the above-mentioned object is to apply a load for loading the test piece. Means, heating means for heating and melting a predetermined region of the test piece, and control means for moving the heating means along the test piece to heat and melt the test piece over a predetermined range.

[0007]

The heating means heats and melts a predetermined area of the test piece, and the control means moves the heating means along the test piece to heat the test piece over a predetermined range.
Melt. With this, it is possible to heat and melt the desired range of the test piece while limiting the range of melting at one time to a predetermined area.

[0008]

1 is a schematic view showing the overall construction of an embodiment of a material testing machine according to the present invention, FIG. 2 is a partially cutaway front view of the testing machine body, and FIG. 3 is a partially broken right side of the testing machine body. It is a side view.
In these figures, 10 is a tester main body for loading the test piece TP, and the tester main body 10 includes a load frame LF. The load frame LF is configured by horizontally mounting a yoke 13 on the upper ends of a pair of screw rods 12a and 12b erected on the table 11 and screwing a crosshead 14 onto the screw rods 12a and 12b.

A motor 15 for load is installed on the table 11, and the rotation of the motor 15 is transmitted to a pair of screw rods 12a, 12b via a transmission 16 and the screw rods 12a, 12a, 12b.
The crosshead 14 moves up and down by the rotation of 12b. The crosshead 14 is provided with an upper grip 18a via a load cell 17, and the table 11 is provided with a lower grip 18b. The test piece TP is provided with these upper and lower grips 18a, 18b.
It is loaded in the state of being gripped by.

Reference numeral 20 is a table 11 and screw rods 12a and 12
This is a vacuum furnace arranged in a space surrounded by b and the crosshead 14, and is placed on the table 11 via a fixing member 21. The inside of this vacuum furnace 20 is maintained at a predetermined degree of vacuum by an exhaust means (not shown), and the atmosphere in the vacuum furnace 20 is replaced with an inert gas by introducing an inert gas after being evacuated. To be done.

In the vacuum furnace 20, the upper grip 18 described above is provided.
The tip portions of a and 18b and the test piece TP are housed, and an airtight holding means (not shown) is interposed between the upper and lower grips 18a and 18b and the vacuum furnace 20, so that the inside of the vacuum furnace 20 is kept airtight. Is held. The reason why the periphery of the test piece TP is kept in a vacuum state or in an inert gas atmosphere is that the test piece TP is not oxidized when the test piece TP is melted in a vacuum state or an inert gas atmosphere, but in the atmosphere as well. The vacuum furnace 20 may not be provided as long as the substance is not easily oxidized.

As shown in FIGS. 1 to 4, a screw rod 22 parallel to the screw rod 12a is provided in the vacuum furnace 20, and the screw rod 22 is fixed to the vacuum furnace 20. It is rotationally driven by a motor 23 (only schematically shown in FIG. 1).

As shown in FIGS. 4 and 5, reference numeral 25 is a coil for high frequency heating, which is fixed to a coil holder 26 provided on the upper portion of the vacuum furnace 20 so as to penetrate the vacuum furnace 20. Are arranged. The tip 25a of the coil 25 is wound around the test piece TP only once as shown in FIG. That is, the number of turns of the coil 25 is one. 4 and 5, only the load axis AX of the test piece TP is shown and the grippers 18a and 18b are not shown.

The base portion 25b of the coil 25 is supported by a fixing member 27 as shown in FIGS. 4 and 5, and a female screw portion 27a which is screwed into the above-mentioned screw rod 22 is formed on a side portion of the fixing member 27. Has been done. Therefore, the screw rod 22
The rotation of the coil 25 causes the coil 25 to move up and down along with the coil holder 26 and the fixing member 27 along the load axis AX. For this reason, a metal bellows 28 is interposed between the coil holder 26 and the vacuum furnace 20. Even if the coil holder 26 moves as the coil 25 moves up and down, the vacuum furnace 20 is hermetically sealed. It is configured to retain the sex. In FIG. 5, 29 is a stopper rod that prevents the coil holder 26 from rising above a certain height with respect to the vacuum furnace 20.

Returning to FIG. 1, reference numeral 30 is a thermocouple attached to the test piece TP. The thermocouple 30 is arranged at a position avoiding the range where the test piece TP is melted and solidified as described later, and more specifically, it is a minute distance from the first melted and solidified part of the test piece TP ( They are arranged at positions apart from each other (for example, about 1 mm).

Reference numeral 40 denotes a control device for controlling each part of the main body 10 of the testing machine, which is composed of, for example, a programmable controller. The control device 40 is the load cell 1
7. Input signals from the thermocouple 30 to control the driving of the motors 15 and 23 and the voltage and current applied to the coil 25 according to a predetermined program pattern.

Next, the operation of the material testing machine of this embodiment will be described with reference to FIGS. First, the motor 15 is controlled to adjust the position of the crosshead 14 to adjust the vertical grip 1
After holding the test piece TP by 8a and 18b, the vacuum furnace 2
The inside of 0 is evacuated or replaced with an inert gas to start the test.

Then, the control device 40 drives and controls the motor 23, and as shown in FIG. 6 (a), the coil 25 is provided at the lower end of the range (indicated by R in the figure, 20 mm in length) to be melted and solidified. The coil 25 is moved up and down to adjust the position of the tip 25a of the coil. In this state, the control device 40 applies a high frequency voltage to the coil 25 to induction heat the test piece TP.

The test piece TP heated by the coil 25 expands due to the temperature rise, and if it is left as it is, a compressive load is applied to the test piece TP. Therefore, the control device 40 detects the compressive load due to the thermal expansion of the test piece TP based on the signal from the load cell 17, and controls the motor 15 so that this load is always 0 (zero load holding). Adjust the position of the crosshead 14.

The power applied to the coil 25 is the thermocouple 3
Controlled by the output signal from 0, as shown in FIG.
When the output signal from the thermocouple 30 reaches a predetermined temperature, the test piece T
The heating rate is controlled to be constant until a part of P melts, and the power is kept constant when a part of the test piece TP (shown by M in FIG. 6A) melts. . The output signal from the thermocouple 30 is not used for control while the power is kept constant. The predetermined temperature as a criterion for keeping the power constant is obtained in advance from the output signal from the thermocouple 30 when the test piece TP is melted under the same conditions, and is input into the control device 40. . The test piece TP
Since a compressive load due to thermal expansion is no longer applied when a part of the above is melted, the control device 40 stops the zero load holding control immediately before the output signal from the thermocouple 30 becomes a signal corresponding to the above-mentioned predetermined temperature. .

At this time, since the number of turns of the coil 25 is one, the portion M melted by the coil 25 is limited to a minute region, and is about 5 mm long, for example. When the test piece TP is melted only in such a minute area M, the melted portion M is prevented from flowing down due to surface tension, and further, the melted portion M is formed by the magnetic field formed by the coil 25.
Is further prevented from convection and flowing down.

When the power applied to the coil 25 is kept constant, the controller 40 drives and controls the motor 23 to raise the tip portion 25a of the coil 25 at a constant speed. The rising speed is the test piece T in the range R to be melted and solidified.
P is uniformly melted and solidified, and the portion M, which is melted at one time, is set so as to be contained in the minute region, and the speed is very gentle as a whole (for example, 1 mm /
Minutes). The test piece TP of the portion C separated from the tip portion 25a of the coil 25 is naturally cooled and solidified as shown in FIG. 6 (b).

After the coil 25 is raised by a predetermined length to melt the entire range R of the test piece TP to be melted and solidified, as shown in FIG. 7, the thermocouple is adjusted so as to have a constant temperature decreasing rate. The control device 40 controls the power output to the coil 25 based on the output signal of 30.

After all the melted portions are solidified, the controller 40 controls the motor 15 to raise the crosshead 14 and apply a tensile load to the test piece TP, as in a normal tensile test.

Therefore, according to this embodiment, the coil 2
Since the portion M that melts 5 at one turn is a minute area, the surface tension of the molten portion M and the coil 2
It is possible to prevent the molten portion M from flowing down due to the magnetic field of 5 or the like. Then, the coil 25 is connected to the load axis AX.
Since the desired range R of the test piece is melted and solidified by moving the test piece TP along, the desired range of the test piece TP can be melted and solidified to perform the characteristic evaluation in the process.

The details of the material testing machine of the present invention are not limited to the above-mentioned one embodiment, and various modifications can be made. As one example, in one embodiment, the present invention was applied to a material testing machine that performs a tensile test, but it is also applicable to known material testing machines such as compression testing machines and creep testing machines. Further, although the coil is formed in one turn in the embodiment, a coil having a plurality of turns may be used as long as the portion melted by the coil does not flow down in a minute area.

[0027]

As described above in detail, according to the present invention, heating means for heating and melting a predetermined region of a test piece is moved along the test piece to heat the test piece over a predetermined range. Since it has been melted, it is possible to heat and melt over a desired range of the test piece while limiting the range of melting at one time to a predetermined region. This makes it possible to perform characteristic evaluation by melting and solidifying the test piece over a desired range while preventing the molten portion of the test piece from flowing down.

[Brief description of drawings]

FIG. 1 is a schematic view showing a material testing machine which is an embodiment of the present invention.

FIG. 2 is a partially cutaway front view of a tester main body.

FIG. 3 is a partially cutaway right side view of the testing machine body.

FIG. 4 is a partially cutaway front view showing a coil.

FIG. 5 is a cross-sectional view showing a state in which a coil is attached to a vacuum furnace.

FIG. 6 is a diagram showing melting and solidification of a test piece by a coil.

FIG. 7 is a diagram showing temperature control by a control device.

[Explanation of symbols]

 AX load shaft LF load frame M fusion part TP test piece 10 tester body 12a, 12b, 22 screw rod 14 crosshead 15, 23 motor 25 coil 30 thermocouple 40 controller

Claims (1)

[Claims] 1. A load means for loading a test piece, a heating means for heating and melting a predetermined region of the test piece, and a heating means for moving the heating means along the test piece to set the test piece in a predetermined range. A material testing machine, comprising: a control means for heating and melting the material.