JP6027430B2 - Oil film thickness measurement method during reciprocating wear test - Google Patents

Description

  The present invention relates to a method for measuring an oil film thickness during a reciprocating wear test.

  Conventionally, metal parts that slide through lubricating oil, such as engine pistons and bearings, have been widely used in automobiles, etc., but it is extremely important to evaluate the wear of these metal parts by testing, For example, as schematically shown in FIG. 5, the working piece 1 is reciprocated by a reciprocating device comprising a metal working piece 1 and a pin 2 and a motor or a crank mechanism (not shown). A reciprocating wear test is known in which the pin 2 is held by a test jig 3 and slidably contacted with a piece 1 from above.

  Such a reciprocating wear test is performed while lubricating between the working piece 1 and the pin 2, but the evaluation of the test greatly fluctuates due to the difference in the lubrication conditions. In order to grasp it, it is necessary to measure the thickness of the oil film between the sliding contact surfaces of the working piece 1 and the pin 2, and conventionally, measurement methods such as capacitance type, X-ray type, laser type, and ultrasonic type are used. Is used to measure the thickness of the oil film between the sliding contact surfaces of the operating piece 1 and the pin 2.

  The prior art document information related to the oil film thickness measuring method during this type of reciprocating wear test includes the following Patent Document 1.

Japanese Patent Laid-Open No. 10-26581

  However, even when using any of the measurement methods of capacitance type, X-ray type, laser type, and ultrasonic type, the oil film that lubricates between the working piece 1 and the pin 2 during the reciprocating wear test is used. In measuring the thickness, there is a problem that a large measuring equipment is required and the cost is increased, and a complicated procedure is required for the preliminary preparation, which requires a lot of labor and time.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for measuring an oil film thickness during a reciprocating wear test capable of reducing the cost and reducing the time and labor required for preparation in advance. And

The present invention relates to a method for measuring the thickness of an oil film that lubricates between a working piece and a pin during a reciprocating wear test performed by sliding a metal pin against a reciprocating metal working piece. An eddy current film thickness sensor is embedded in a position retracted by a wear allowance set within a range of 0.2 mm ± 0.05 mm from the sliding surface of the pin, and the coil of the eddy current film thickness sensor A high-frequency current is caused to flow to generate a high-frequency magnetic field, and when the eddy current is induced on the surface of the working piece by the high-frequency magnetic field, the impedance change of the coil is detected, and the change amount is converted to obtain the thickness of the oil film It is characterized by this.

  That is, when a high-frequency magnetic field is generated by flowing a high-frequency current through the coil of the eddy-current film thickness sensor embedded in the pin, an eddy current due to electromagnetic induction is generated on the surface of the operating piece by the high-frequency magnetic field, and this eddy current is counteracted. An electromagnetic field is formed, and the impedance of the coil changes in correlation with the distance from the high frequency magnetic field source (eddy current type film thickness sensor) to the surface of the operating piece by the action of the demagnetizing field. The oil film thickness is obtained by converting the amount of change.

  At this time, the sliding surface of the pin gradually wears due to sliding on one side as the test time becomes longer, but the eddy current film thickness sensor is moved back from the sliding surface of the pin by the required wear allowance. The test data is collected before the tip of the eddy current film thickness sensor is damaged. Can be achieved.

  In addition, in the present invention, it has been found by the inventor's research results that the wear allowance for retreating the eddy current film thickness sensor from the sliding surface of the pin should be set in the range of 0.2 mm ± 0.05 mm. If the wear allowance is set within this range, it is possible to ensure the test time as long as possible while maintaining the sensitivity with which an accurate oil film thickness can be measured.

  According to the oil film thickness measuring method during the reciprocating wear test of the present invention described above, various excellent effects as described below can be obtained.

  (I) According to the invention described in claim 1 of the present invention, the thickness of the oil film between the operating piece and the pin is determined during the reciprocating wear test by the eddy current film thickness sensor embedded in the pin as the specimen. Since measurement can be performed, large-scale measuring equipment is not required and costs can be kept low. In addition, labor and time can be greatly reduced compared to conventional methods because no complicated procedures are required for the preparation. .

According to the invention described in claim 1, (II) the present invention, by setting the wear allowance to retract the eddy current film thickness sensor from the sliding surface of the pin in the range of 0.2 mm ± 0.05 mm, The test time can be ensured as long as possible while maintaining the sensitivity capable of accurately measuring the thickness of the oil film.

It is a typical enlarged view which shows an example of the form which implements this invention. FIG. 2 is a circuit diagram schematically showing an electrical system of the eddy current film thickness sensor of FIG. 1. It is a front view which shows the arrangement | positioning state of the eddy current type film thickness sensor with respect to the pin of FIG. FIG. 4 is a detailed view showing a main part of FIG. It is the schematic which shows the mode of a general reciprocating abrasion test.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows an example of an embodiment for carrying out the present invention. As in the example described with reference to FIG. 5, a metal working piece 1 and a pin 2 are used as specimens, and a motor or crank (not shown) is shown. A reciprocating wear test in which the operating piece 1 is reciprocated by a reciprocating device composed of a mechanism, while the pin 2 is held by the test jig 3 to be in sliding contact with the operating piece 1 from above. The thickness of the oil film 4 that lubricates between the working piece 1 and the pin 2 is measured during the reciprocating wear test. In FIG. 1, the sliding contact surface between the working piece 1 and the pin 2 is measured. A state in which the oil film 4 is interposed therebetween is shown as a schematic enlarged view.

  In this embodiment, an eddy current film thickness sensor 5 is embedded at the tip of the pin 2, and a coil built in the eddy current film thickness sensor 5 is schematically shown in FIG. 6 is connected to a power source 7 via a high-frequency current generator 8 so that the high-frequency current generator 8 can cause a high-frequency current to flow through the coil 6 to generate a high-frequency magnetic field. A voltage / ammeter 9 for detecting a voltage value and a current value is interposed at an appropriate position of the electric circuit for supplying a high-frequency current. Thus, a change in impedance of the coil 6 is detected, and the amount of change is converted into the thickness of the oil film 4 to be obtained.

  Here, as shown in FIGS. 3 and 4, the pin 2 is formed in a cylindrical shape with a hollow shaft center portion, and an eddy current film thickness sensor 5 is fitted and mounted on the tip side of the hollow portion. However, the wear margin x is embedded in a position retracted from the sliding contact surface of the pin 2 by a required wear allowance x. More specifically, the wear allowance x is 0.2 mm ± 0.05 mm. It is set in the range. In the example shown in FIGS. 3 and 4, a slit 11 for releasing the coil 6 of the eddy current film thickness sensor 5 is formed on the side surface of the pin 2. It extends from the proximal end to the vicinity of the distal end, and the end has an arc shape.

  Thus, in this case, when a high frequency current is caused to flow through the coil 6 of the eddy current film thickness sensor 5 embedded in the pin 2 by the high frequency current generator 8, a high frequency magnetic field is generated by the high frequency magnetic field. An eddy current due to electromagnetic induction is generated on the surface of the operating piece 1, and this eddy current forms a demagnetizing magnetic field. Due to the action of the demagnetizing magnetic field, the impedance of the coil 6 becomes a high frequency magnetic field generating source (eddy current type film thickness Since it changes in relation to the distance from the sensor 5) to the surface of the working piece 1, the amount of change in impedance is obtained by the arithmetic unit 10 based on the voltage value and current value detected by the voltmeter / ammeter 9, and this is calculated. The thickness of the oil film 4 is obtained by conversion.

  At this time, the sliding contact surface of the pin 2 gradually wears due to sliding on the working piece 1 side as the test time becomes longer, but the eddy current film thickness sensor 5 is required to wear from the sliding contact surface of the pin 2. Since it is buried at a position retracted by a margin x, a sufficient test time is secured until the tip of the eddy current film thickness sensor 5 is worn, and the eddy current film thickness sensor 5 is damaged. It becomes possible to collect the test data required before.

  Therefore, according to the above embodiment, the thickness of the oil film 4 between the working piece 1 and the pin 2 is measured during the reciprocating wear test by the eddy current film thickness sensor 5 embedded in the pin 2 as the specimen. Therefore, it is possible to reduce the cost at a low cost by eliminating the need for a large-scale measuring facility, and it is possible to significantly reduce labor and time as compared with the prior art because no complicated procedure is required for the preliminary preparation.

  Further, it has been found by the inventor's research results that the wear allowance x for retracting the eddy current film thickness sensor 5 from the sliding contact surface of the pin 2 should be set in the range of 0.2 mm ± 0.05 mm. If the wear allowance x is set within this range, the test time can be secured as long as possible while maintaining the sensitivity with which the accurate thickness of the oil film 4 can be measured.

  In addition, the oil film thickness measuring method during the reciprocating wear test of the present invention is not limited to the above-described embodiments, and it is needless to say that various changes can be made without departing from the scope of the present invention. .

1 Operating piece 2 Pin 4 Oil film 5 Eddy current film thickness sensor 6 Coil x Wear allowance

Claims (1)

During a reciprocating wear test performed by sliding a metal pin against a reciprocating metal working piece, a method of measuring the thickness of the oil film lubricating between the working piece and the pin, An eddy current film thickness sensor is embedded in a position retracted by a wear allowance set within a range of 0.2 mm ± 0.05 mm from the sliding surface of the pin, and a high frequency current is applied to the coil of the eddy current film thickness sensor. Generating a high-frequency magnetic field, detecting an impedance change of the coil when an eddy current is induced on the surface of the operating piece by the high-frequency magnetic field, and converting the amount of change to obtain the thickness of the oil film. Oil film thickness measurement method during reciprocating wear test.

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