JPS62115303A - Measuring instrument for hardening depth of steel material - Google Patents

Abstract

PURPOSE:To measure the depth of hardening by discharging a charged large-capacity capacitor instantaneously and magnetizing a hardened part, and measuring a current induced at a search coil when a core for magnetic path formation is separated from the hardened part. CONSTITUTION:A power switch 8 is closed and switches 18 and 19 for short-circuiting the CR integrator of a measuring circuit 6 for the induced current are closed. At this time, the switch 9 of a switching circuit is connected to the circuit 6 and then the large-capacity capacitor 10 of an exciting circuit 5 is charged. Then, a probe 2 is brought into contact with the hardened part 1a of a sample 1 and then a magnetic path is formed by the magnetic path forming core 3 and hardened part 1a. When the switch 9 is switched to the side of the circuit 5. The charge of the capacitor 10 is discharged instantaneously to the coil 4 and the hardened part 1a is magnetized. When the discharging is completed, the switch 9 is returned to the original position. Then, the switches 18 and 19 are opened and the probe 2 is separated from the hardened part 1a, so that a voltage is induced across the coil owing to variation of magnetic flux. The output of an IC 12 based upon the induced voltage is found and a specific relation is used to find the depth of hardening.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to an apparatus for measuring the depth of quenching of steel materials.

[Background of the invention]

For example, crankshafts for automobiles and the like are hardened and surface-hardened by induction hardening, but when the induction hardening is shallow, it tends to wear easily, and when the induction hardening is deep, it becomes brittle. Therefore, it is necessary to investigate the degree of induction hardening, but the method of polishing the cut surface to detect the hardening boundary line and measuring its dimensions is time-consuming and requires continuous movement of the part to be measured. It cannot be used for assembly line work. For this reason, tests are conducted on a sample basis and pass/fail decisions are made based on the results, so in some cases a large number of processed parts may have to be discarded.

Therefore, attempts have been made to non-destructively measure the quenching depth of steel materials. Some such devices utilize the relationship between the coercive force Hc of the steel material and the hardness of the steel material. In this method, a horseshoe-shaped electromagnet is placed on the surface of a steel material and sufficiently excited with an excitation current to form a permanent magnet including the detector.Then, the direction of the excitation current is changed and the magnetic ends of these permanent magnets are strangely turned off. When a current is passed so that the magnetomotive force of the permanent magnet and the magnetomotive force applied from the outside are balanced, from the relationship of equilibrium, when the number of turns of the coil of the electromagnet (detector) is N and the exciting current is 1c, Fc By utilizing the fact that =N·IC is a function of the depth of the quench-hardened portion, the quench depth can be measured by measuring the excitation current IC.

However, although non-destructive testing is possible with this method, the equipment is quite large and expensive, and measurement requires a considerable amount of time, making it unsuitable for measuring parts during assembly line work. .

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate such drawbacks and to provide a measuring device that can easily measure the hardening depth of steel materials in a short time.

[Summary of the invention]

The present invention provides an apparatus for measuring the hardening depth of a steel material, which includes a means for magnetizing a hardened part formed by hardening on the surface of a steel material, and a means for measuring the magnetization of the magnetized hardened part. a globe having a core for forming a magnetic path, an excitation coil for magnetizing the hardened hardened portion wound around the core for forming a magnetic path, and a probe coil for measuring the magnetization of the hardened hardened portion, and a large capacitor; an excitation circuit of the quench-hardened part that supplies current to the excitation coil while the quench-hardened part is in contact with the quench-hardened part; An induced current measurement circuit consisting of a CR integrator using a high gain DC amplifier to measure the generated current.

an excitation/measurement switching circuit that switches the connection between the excitation coil and the excitation circuit and the connection between the hollow coil and the induced current measurement circuit, an input side of the high gain DC amplifier of the induced current measurement circuit, and the CRfjli The capacitor is characterized by having a short circuit that short-circuits both ends of the capacitor. .

The present invention enables a large current to flow through an excitation coil using a small-capacity power supply by instantaneously discharging the charge accumulated in a large-capacity capacitor, and measures the magnetization of a hardened part magnetized by this large current. The intended purpose was achieved by using the induced current generated in the groping coil when the magnetic path forming core gold was separated from this quenched and hardened portion.

[Embodiments of the invention]

Examples will be described below.

FIG. 1 is a circuit diagram of one embodiment. In this figure, 1 is a sample made of steel whose hardening depth is to be measured, 1a is a hardened part of sample 1, and 2 is a magnetic path forming core 3 and a magnetic path forming core 3. A globe having an excitation/search coil (hereinafter referred to as a coil) 4 which also serves as an excitation coil for exciting the quench-hardened part wound around the core 3 and a search coil for measuring the quench-hardening S; 5 is the coil 4; An excitation circuit for the quench hardened part 1a that supplies current, 6 a measurement circuit for the induced current generated in the coil 4, 7 a power source for the excitation circuit 5 and the induced current measurement circuit 6 for the quench hardened part 1a, 8 a power supply [ 7 The opening/closing switch es, ), 9 indicates a changeover switch (S2) for switching the connection between the excitation circuit 5, the induced current measurement circuit 6, and the coil 4.

The excitation circuit 5 of the quench hardened part 1a has a large capacity capacitor (C) connected in parallel with the power supply 7 and the coil 4.
1) The inductive current measurement circuit 6 has a high gain linear amplifier (hereinafter referred to as IC) 12 and a variable resistor (VR) for zero adjustment. )
A meter 15 is connected to the output terminal of the IC 12. A resistor 1 is placed between the input side and output side of IC12.
A CR integrator consisting of a capacitor (C2) 6 and a capacitor (C2) 17 is provided. 18 (83=) is a switch that shorts the input terminal of IC12, +9 (S3b) is a capacitor (C2)
A switch that short-circuits 17, switch (b 3m) 1
8 and switch (S3b) 19 are operated in conjunction with a short circuit switch (not shown).

FIG. 2 shows the structure of an example of a probe, which includes a rod-shaped body 3a made of pure iron and a disk-shaped head;
e The cylinder 3b serving as the central axis is integrated with the disk-shaped head of the rod-shaped body 3a, the other end of the cylinder 3b forms an annular gap 3C, and a coil is formed around the rod-shaped body 3a inside the cylinder 3b. 4
is wound.

Next, a method of measuring the hardening depth of a steel material using a steel material hardening depth measuring device having such a structure will be described.

When the switch (81) 8 is closed to start the measurement,
A power source 7 is connected to the excitation circuit 5 and the induced current measurement circuit 6. Next, the short-circuit switch of the induced current measuring circuit 60C integrator is closed. At this time, switch of the switching circuit (8
2) 9 is connected to the induced current measurement circuit 6. Then, the meter 15 is zero-adjusted using the variable resistor (Va) 13, and during this time the large capacity capacitor (
Charge is accumulated in C1)10. For example, a 9-inch small dry cell battery is used as the power source 7, and a large-capacity capacitor (C1) 1
0 to Yong! : Use a resistor of 10,000 μF,
) When 510Ω is used for 11, charging is completed in about 30 seconds. Note that a rung is displayed to indicate that the large capacity capacitor (C1) 10 has completed charging.

In this way, the large capacity capacitor (Ct
) When the globe 2 is brought into contact with the quenched hardened part 1a of the sample 1 when charging of the battery 1o is completed, the magnetic path forming core 3 made of the rod-shaped body 3a and the cylinder 3b of the globe 2
A magnetic path is formed by the quenched and hardened portion 1a of the sample 1. If the changeover switch (Sz) 9'r is switched to the excitation circuit 5 side, the large capacity capacitor (C1) l is connected to the coil 4.
When the capacitor (C1) 10 stored in O is finished discharging, the changeover switch (S2) 9 is returned to its original state. The time during this time is less than 1 second, which is a very short time.

Next, when the short circuit switch of the CR integrator of the induction current measurement circuit 6 is opened and the entire bow 1 of the probe 2 that is in contact with the quenched hardened part 1a is released, a voltage is applied to the coil 4 due to the change in magnetic flux dψ(Mx). c, (V) is induced. Between this induced voltage e, (V) and the change in magnetic flux dψ (M),
When the number of turns of the coil is N2, there is the following relationship. Then, the current 1 (A) flowing through the induced current measurement circuit 6 due to this voltage e1 is regarded as 0 in e because the gain of IC12 and the human resistance are large, and is charged to 1.L (F), so that Output voltage 60 (V
), if the capacitor charging voltage is e c (V), then eo” = ee = t = e = ee, so from equations (1), (2), and (3), ψ
is e. Therefore, e determined by the induced current measurement circuit. The quenching depth can be determined by finding ψ from the equation and using the relationship between ψ and the quenching depth.

Note that by using the variable resistor (R2), sensitivity can be adjusted regardless of the thickness of the hardened portion.

FIG. 3 is a perspective view showing the structure of another example of the glove, in which a coil 4 is wound around a horseshoe-shaped magnetic body 20 whose ends 20 a and 20 b are in close contact with the quenched and hardened parts. This glove is effective when the quench-hardened part has curved wrinkles.

In addition, as the probe in the example, an example was shown in which - number of coils were used to both excite the quenched hardened part and measure the induced current. An excitation coil with a large number of turns and a groping coil with a large number of turns of thin wire may be provided separately so that the induced current can be measured with high sensitivity.

In addition, although we have shown an example of using dry batteries as the power source,
It is also possible to use rectified direct current of 0.0 cm for the power source.

The steel quenching depth measuring device of this example uses the discharge of a large capacitor to excite the excitation coil, making it possible to downsize the power supply and measuring the magnetization of the quenched hardened part using induced current. This made it possible to extremely shorten the measurement time.

As a result, the steel quenching depth measuring device of this embodiment can be brought to the measurement location, turned on at the location, and immediately start measurement after zero adjustment and sensitivity adjustment are completed. That is, measurements can be performed simply by pressing the probe against the sample and pulling it away. Therefore, the device is small and lightweight and can be transported to a desired location, and the measurement operation can be performed easily and in a short time, making it possible to measure the hardening depth of parts during assembly operations.

Additionally, it is possible to measure steel materials with different hardening depths using a single device.

〔Effect of the invention〕

The steel quenching depth measuring device of the present invention is easy and quick!
This makes it possible to provide a measuring device that can measure the depth of quenching of steel materials, and is an industrially effective device.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an embodiment of the steel quenching depth measuring device of the present invention, and FIG. 2 is a sectional view showing the structure of the probe.
FIG. 3 is a perspective view showing another structure of the glove. 1... Sample, 1a... Quench hardened part (of the sample), 2
... Probe, 3... Measuring core, 4... Coil, 5... Excitation circuit (of the quenched hardened part), 6... Induced current measurement circuit, 7... Power supply, 9... ...Selector switch (S2), 10...Large capacity capacitor (C1), 1
2...IC113...Variable resistor, 15...Meter, 17...Capacitor (C2), 18.19...
- Switch (S31S3b). ! ! 42 mouth 3 Hisashi 3G 3rd prisoner 2θ6

Claims (1)

[Claims] 1. An apparatus for measuring the hardening depth of a steel material, comprising means for magnetizing a hardened part formed on the surface of a steel material by quenching, and means for measuring the magnetization of the magnetized hardened part. , a probe having a magnetic path forming core, an excitation coil for magnetizing the hardened hardened portion wound around the magnetic path forming core, and a probe having a probe coil for measuring magnetization of the hardened hardened portion, and a large capacitor. an excitation circuit of the quench-hardened part that supplies current to the excitation coil with the probe in contact with the quench-hardened part, and a magnetized excitation circuit that separates the probe from the quench-hardened part. an induced current measuring circuit comprising a CR integrator using a high gain DC amplifier that measures the current generated in the searching coil; a connection between the exciting coil and the exciting circuit; and a connection between the searching coil and the induced current measuring circuit; and a short-circuit circuit that short-circuits both ends of the input side of the high-gain DC amplifier of the induced current measurement circuit and the capacitor of the CR integrator. Steel quenching depth measuring device. 2. The magnetic path forming core of the probe is made of a magnetic material in which a rod-shaped body located at the center and a cylinder having the rod-shaped body as a central axis are connected at one end and form a gap at the other end, and the cylinder 2. The steel quenching depth measuring device according to claim 1, wherein the excitation coil and the searching coil are provided to surround the rod-shaped body. 3. A patent claim in which the magnetic path forming core of the probe is made of a horseshoe-shaped magnetic material whose both ends are in close contact with the quenched hardened portion, and the excitation coil and the search coil are wound around the magnetic material. The steel quenching depth measuring device according to item 1. 4. Claim 1 or 2, wherein the excitation coil and the search coil are used as one coil.
The steel quenching depth measuring device according to item 1 or 3.