JP2009236772A - Gear strength inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a gear strength inspection device having no error in a measurement result even in the case of a thin workpiece. <P>SOLUTION: In this gear strength inspection device, a support plate 25 extending toward a detection coil 33, and each ball 27 having a prescribed size and arranged across the support plate 25 are arranged. A highly accurate measurement result can be acquired by preventing deviation of the detection coil 33 by using the balls 27. In addition, each ball 27 is arranged across the support plate 25. The balls 27 can be arranged closer to the detection coil 33, to thereby acquire highly accurate measurement result even in the case of a thin gear 15. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a gear strength inspection apparatus for evaluating the strength of a gear.

  When steel workpieces such as gears are manufactured, it is inspected whether these steel workpieces have a predetermined strength. It is desirable to use a non-destructive inspection method for inspecting such a final product without destroying the steel workpiece.

As a non-destructive inspection method, an inspection apparatus has been proposed in which an eddy current is generated in a steel workpiece and a magnetic field generated by the eddy current is measured (see, for example, Patent Document 1).
JP 2004-108873 A (FIG. 2)

Patent document 1 is demonstrated based on the following figure.
FIG. 15 is a diagram for explaining the basic principle of the conventional technique, in which an excitation coil 102 and a detection coil 103 are wound around a cylindrical workpiece 101. Then, an AC voltage (excitation voltage) is applied to the excitation coil 102 from the AC power source 104. Then, an eddy current is generated on the surface layer of the cylindrical workpiece 101. This eddy current generates an alternating current in the detection coil 103. The voltage (detection voltage) of the generated alternating current is measured by the measuring device 105.

  According to this measurement, if the voltage of the alternating current generated in the detection coil 103 is measured, the strength of the cylindrical workpiece 101 can be measured, and the strength of the workpiece can be measured quickly.

  By the way, when such a measurement is performed manually, the problem described in the next figure arises.

  FIG. 16 is a diagram for explaining a problem in the conventional technique. The distance from the left tooth tip 108L (L is a subscript indicating the left side) of the gear 107 to the excitation and detection coils 102 and 103 is L1, and the gear 107 When the distance from the right tooth tip 108R (R is a suffix indicating the right side) to the excitation and detection coils 102 and 103 is L2, and the strength of the gear 107 is manually measured, L1 and L2 are the same distance. It may not be. If the distance between L1 and L2 is different, an error may occur in the measurement result.

In addition, it is considered that further errors can occur when the gear 107 is tilted.
Therefore, the inventors conducted an experiment on an error caused by the inclination of the gear 107. The voltage detected from the detection coil 103 at that time was measured while changing the angle (insertion angle) facing the excitation and detection coils 102 and 103 using the same gear 107.

FIG. 17 is a diagram for explaining a graph showing the relationship between the gear insertion angle and the voltage measurement value. The horizontal axis shows the gear insertion angle, and the vertical axis shows the voltage measurement value.
In P1 where the voltage measurement value was the highest, the voltage was 1600 mV, and in P2 where the voltage measurement value was the lowest, the voltage was 400 mV. It was found that by changing the insertion angle of the gear, the difference in the voltage measurement value was up to 4 times.

Different voltage measurements result in different measurement results for the same workpiece.
It is desired to provide a gear strength inspection apparatus that is free from errors in measurement results, that is, has high reliability.

It is an object of the present invention to provide a gear strength inspection device that has no error in measurement results.
In addition, an object of the present invention is to provide a gear strength device capable of inspecting gears having different tooth widths with a single device.

The invention according to claim 1 is a gear strength inspection device for evaluating the strength of a gear.
This gear strength inspection device is supported by a structure having a triangular cross section so that the tip faces the tooth bottom, a detection coil embedded in the tip of the structure, and iron cores disposed on both sides of the structure. Excitation coils, an AC power source for applying an AC voltage to these excitation coils, a support plate disposed at the tip of the iron core and extending toward the detection coil, and a predetermined plate disposed via the support plate It comprises a spherical body having a size and a conversion device that obtains detection information from the detection coil and converts it into gear strength.

  The invention according to claim 2 is characterized in that the support plate is detachably attached to the tip of the iron core.

  The invention according to claim 3 is characterized in that the hole diameter of the female screw hole arranged at the tip of the iron core and the hole diameter of the through hole arranged in the support plate are the same.

  The invention according to claim 4 is characterized in that the support plate is made of an electrical insulating material.

  The invention according to claim 5 is the gear strength inspection device according to claim 1, wherein the detection coil is embedded in the tip of a detection coil support having a triangular cross section so that the tip faces the tooth bottom.

  The gear strength inspection apparatus according to claim 1, wherein the gear strength is a carburized depth of the gear.

  In the invention which concerns on Claim 1, the support plate extended toward a detection coil at the front-end | tip of an iron core, and the spherical body of a predetermined magnitude | size are arrange | positioned through this support plate. The detection coil can be positioned by bringing the sphere into contact with the gear. By preventing the detection coil from shaking, a highly accurate measurement result can be obtained.

  In addition, the sphere is disposed at the tip of the iron core via a support plate extending toward the detection coil. Since the support plate extends toward the detection coil, the sphere can be arranged closer to the detection coil. Since the sphere can be disposed near the detection coil, the detection coil can be positioned even with a thin gear. Therefore, a highly accurate measurement result can be obtained even with a thin gear.

  In the invention according to claim 2, the support plate is detachably attached to the tip of the iron core. Since the support plate is detachably attached, the support plate can be replaced according to the thickness of the gear. It is beneficial to measure gears of multiple thicknesses with a single device.

  In the invention which concerns on Claim 3, the hole diameter of the internal thread hole arrange | positioned at the front-end | tip of an iron core and the hole diameter of the through-hole arrange | positioned at a support plate are the same. On the other hand, a spherical body can be made into the structure which arrange | positions a male screw at the front-end | tip, and is screwed together. If the hole diameter of the female screw hole and the hole diameter of the through hole are the same, the sphere can be screwed into the female screw hole after removing the support. If it can be screwed into the female screw hole, gears with various widths can be measured with this gear strength measuring device.

  In the invention which concerns on Claim 4, a support plate is comprised with an electrical insulating material. By configuring the support plate with an electrical insulating material, the support plate does not interfere with the generation of eddy currents. Since the support plate does not hinder the generation of eddy currents, the support plate can be further extended to the vicinity of the detection coil, or can be configured as a bridge with a single plate. The degree of freedom of the shape of the support plate is increased, which is beneficial.

  In the invention according to claim 5, the detection coil has a triangular cross section so that the tip faces the tooth bottom. The detection coil can face the tooth bottom. If it is possible to face the bottom of the tooth, all the parts of the gear teeth can be inspected. By inspecting all parts of the teeth, the reliability of the inspection results can be increased.

  In the invention according to claim 6, when a gear that has been subjected to vacuum carburizing treatment is used, the gear carburization depth is thinnest at the portion of the tooth bottom 45. If the bottom of the carburized depth is measured, it can be known whether the gear has a predetermined strength. That is, only the tooth bottom needs to be inspected, and the measurement time can be shortened.

  The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. The drawings are viewed in the direction of the reference numerals.
FIG. 1 is a principle diagram of a bottom carburization depth measuring device suitable for using the gear strength inspection device of the present invention. A bottom carburizing depth measuring device 10 includes a base 11 and an upper surface of the base 11. A rail 12 provided in the center and extending left and right in the figure, a slider 13 mounted on the rail 12 so as to be movable left and right, and a gear 15 supported on the slider 13 via a bearing 14 so as to be rotatable vertically and rotatably. A workpiece support shaft 16 that supports the workpiece, an index motor 17 that is built in the slider 13 and rotates the workpiece support shaft 16 at a constant pitch, and a cylinder unit 18 that is placed on the base 11 and reciprocates along the rail 12. A control unit 19 for controlling the cylinder unit 18 and the index motor 17, a bracket 21 extending upward from one end (left side in the figure) of the base 11, and the bracket A U-shaped iron core 23 attached to the upper portion of the base 21 with bolts 22, 22, a detection coil support 24 supported by the iron core 23 and extending toward the gear 15, A support plate 25 disposed at the tip, and contact members 28 and 28 (details will be described later) including support portions 26 and 26 disposed from the support plate 25 toward the gear 15 and spheres 27 and 27 such as steel balls; Exciting coils 29 and 29 wound around the tip of the iron core 23, an AC power source 31 for applying an AC voltage to the exciting coils 29 and 29, and a structure such as a resin provided at the tip of the detection coil support 24 A detection coil 33 embedded in the body 32, a conversion device 35 that acquires detection information from the detection coil 33 and converts it into gear strength, and compares the obtained carburized depth with an acceptable reference depth to determine pass / fail. Pass / fail judgment unit 36 and profit The Based on the acceptance judgment, pass, and acceptance display unit 37 for displaying the failure consists.

  Here, the gear strength inspection device 40 includes the structure 32, the detection coil 33, the excitation coils 29 and 29, the AC power source 31, the support plate 25, the contact members 28 and 28, and the carburization depth conversion device 35. Consists of

  When an insulating material such as nylon or resin is used for the support plate 25, the support plate 25 does not interfere with the generation of eddy current. Since the support plate 25 does not hinder the generation of eddy currents, the support plate 25 can be further extended to the vicinity of the detection coil 33, or can be configured as a bridge with a single plate. The degree of freedom of the shape of the support plate is increased, which is beneficial.

  FIG. 2 is a view for explaining a support plate and a structure according to the present invention. The structure 32 is arranged so as to pass through a square hole 41 provided in the support plate 25. By passing the structural body 32 through the square hole 41, the support plate 25 can be constituted by a single plate. If the support plate 25 is a single plate, the support plate 25 can be easily attached and detached.

  FIG. 3 is a front view of the gear strength inspection apparatus. The detection coil support 24 is fixed to the iron core 23 with screws 42 so as to be slidable in the horizontal direction. The support portion 26 includes a conical portion 43 and a base portion 44.

  It is desirable to configure the base 44 in a hexagonal shape so that the abutting member 28 can be easily removed using a spanner or the like. Accordingly, the abutting member 28 can be easily moved in the tooth width direction according to the thickness of the gear. The movement method will be described later.

  FIG. 4 is a cross-sectional view taken along the line 4 in FIG. 3, and the detection coil 33 is supported by the detection coil support 24 via a structure 32 such as nylon having a triangular cross section that is rich in insulation. Since the structure 32 has a triangular cross section, the detection coil 33 can be brought close to the tooth bottom 45 of the gear 15.

  The detection coil 33 has a triangular cross section so that the tip faces the tooth bottom 45. The detection coil 33 can face the tooth bottom 45. If it is possible to face the tooth bottom 45, all parts of the teeth of the gear 15 can be inspected. By inspecting all parts of the teeth, the reliability of the inspection results can be increased.

  Further, when a gear that has been subjected to vacuum carburizing treatment is used for the gear 15, the gear carburizing depth is the thinnest at the portion of the tooth bottom 45. If the bottom of the carburized depth is measured, it can be known whether the gear has a predetermined strength. That is, only the tooth bottom needs to be inspected, and the measurement time can be shortened.

  FIG. 5 is a cross-sectional view taken along line 5 of FIG. 3, and the spherical diameter of the sphere 27 passes between the adjacent tooth tips 48 and the tooth tips 48, but before reaching the tooth bottom 45, the tooth surfaces 49, 49. It is set to the outer diameter that contacts. That is, since the contact points 51 and 51 are in contact, the positions of the sphere 27 in the left-right direction and the up-down direction are defined. At the same time, the center of the sphere 27 coincides with the center of the tooth bottom 45.

  As a result, the distance between the detection coil 33 (FIG. 4) and the excitation coils 29 and 29 (FIG. 3) from the tooth bottom 45 can be made constant. There is no error in the measurement results because the distance is constant. That is, it can be said to be a highly reliable gear strength inspection device.

  FIG. 6 is a view for explaining the structure of the tip portion of the iron core according to the present invention, and a female screw hole 52 is provided at the tip of the iron core 23. The support plate 25 is attached to the iron core 23 by aligning the mounting hole 53 of the support plate 25 with the female screw hole 52 and screwing with the hexagon socket head cap screw 54.

  The base portion 44 of the abutting member 28 supported by the support plate 25 is configured in a hexagonal shape, and a male screw portion 55 configured in a male screw shape is disposed at the tip. The male screw portion 55 is screwed into a through hole 56 provided in the support plate 25.

  If the gear 15 is thick, the hexagon socket bolt 54 is removed and the support plate 25 is removed. After the support plate 25 is removed, the contact member 28 can be directly attached to the female screw hole 52 in accordance with the thickness of the gear 15.

  Since the support plate 25 is detachably attached, it can be replaced with a support plate 25 in which the position of the through hole 56 is different according to the thickness of the gear 15. It is beneficial to measure gears of multiple thicknesses with a single device.

  By the way, it is necessary to memorize | store the conversion table which converts X voltage obtained by measurement into the carburizing depth in the carburizing depth conversion apparatus 35 demonstrated in FIG. Therefore, using the root carburization depth measuring device 10 of FIG. 1, the frequency was set to 1 kHz, and the “X voltage” of the vacuum carburized gear was measured. This measurement corresponds to a nondestructive inspection.

  Next, this gear was cut and the cut surface was polished, and then the “carburizing depth” was measured. This measurement corresponds to destructive inspection.

FIG. 7 is a graph showing the hardness obtained by the measurement.
First, when the frequency was set to 1 kHz using the tooth bottom carburizing depth measuring device 10 and the “X voltage” of the gear that had been vacuum carburized was measured, the X voltage was −67 mV. Next, it cut | disconnected, polished the cut surface, and set this cut surface as a measuring object, the Vickers hardness (Hv) was measured with the micro Vickers hardness meter to 1.0 mm every 0.1 mm from the surface.

  FIG. 7 is a graph showing the hardness obtained by the measurement. (A) is a graph in which raw data is plotted on a graph in which the horizontal axis is the depth from the surface and the vertical axis is the Vickers hardness. It is.

By the way, in this type of gear, a required specification such as “the depth of ◯ mm from the surface and the Rockwell C scale hardness is 50 or more” is often issued. The Rockwell C scale hardness 50 corresponds to Vickers hardness (Hv) 513 according to the conversion table.
Therefore, a plurality of points plotted in (a) are connected by a smooth curve.

  As a result, the graph shown in (b) is obtained. Therefore, a horizontal line is drawn from 513 on the vertical axis, the vertical line is dropped from where it intersects the curve, and the distance at which this vertical line intersects the horizontal axis is read. The distance from the surface was 0.64 mm.

FIG. 8 is a correlation diagram of the X voltage and the carburization depth. In the graph in which the horizontal axis represents the carburization depth (corresponding to the distance from the surface) and the vertical axis represents the X voltage, one piece of data (0.64 mm). , −67 mV) is plotted with ●.
Twenty-one samples obtained by changing the carburizing conditions were prepared, and the carburizing depth and the X voltage were determined for these samples by following the procedures in FIGS. 7 (a) and 7 (b). Twenty-one samples were circled and plotted on a graph.

One ● and 21 ○ are distributed along a straight line going down to the right. If the X voltage on the vertical axis is obtained by measurement, the carburization depth corresponding to the obtained X voltage can be obtained from this correlation diagram.
Although the detailed calculation method is omitted, the correlation coefficient (r ² ) in this dispersion was 0.92.

  As is clear from the above description, the present invention is also characterized by the following points. That is, as described in FIGS. 7A and 7B, the hardness and depth obtained are obtained by connecting the points obtained by plotting the hardness obtained by measurement from the surface of the gear toward the center. Get from the curve. Since the curve is obtained by connecting the points, the number of measurement points can be set small, the measurement time can be shortened, and the measurement cost can be reduced.

  Further, the carburization depth is determined based on the quantitative data of hardness obtained in FIG. That is, as described with reference to FIG. 7, the hardness data by the destructive inspection and the X voltage by the nondestructive inspection are matched. Thereafter, the X voltage is obtained by nondestructive inspection, and converted to the carburization depth based on FIG. Despite the non-destructive inspection, since it is supported by the destructive inspection, the reliability of the carburization depth obtained by the non-destructive inspection is dramatically increased.

Next, in order to identify a suitable frequency, the frequency is changed from 700 Hz to 4 kHz, 22 samples are prepared for each frequency, a correlation diagram similar to FIG. 8 is created, and a correlation coefficient is obtained. It was. The result is shown in the following figure.
FIG. 9 is a graph showing the relationship between the frequency and the correlation coefficient. The maximum is 1 kHz, and the correlation coefficient is small above 2 kHz. On the other hand, at 700-1 kHz, the change is small.
In order to examine the carburizing depth of the tooth bottom of the vacuum carburized gear, it has been found that the frequency is desirably set in the range of 700 to 1 kHz.

Next, the operation of the steel workpiece inspection apparatus having the above-described configuration will be described by taking a case where a gear is used for the steel workpiece as an example.
FIG. 10 is a diagram for explaining the operation of the contact member according to the present invention. When the distance L3 between the contact member 28 and the contact member 28 is longer than the thickness T2 of the gear 15, as shown in FIG. It is necessary to move the abutting member 28 to a position where it comes into contact. When the contact member 28 is moved, the contact member 28 is first removed from the iron core 23.

  Next, as shown in (b), the support plate 25 is aligned with the tip of the iron core 23, and the support plate 25 is attached to the tip of the iron core 23 using a hexagon socket bolt 54.

  FIG. 11 is a view for explaining the action when the abutting member according to the present invention is attached to the gear. After attaching the support plate 25 in FIG. 10 (b), the through holes 56, 56 are formed as shown in FIG. The contact members 28 and 28 are screwed together. At this time, since the distance L4 between the contact member 28 and the contact member 28 is shorter than the thickness T2 of the gear 15, it can be brought into contact with the gear 15.

  When the position of the contact member 28 is determined, the strength of the gear 15 is measured. The method for measuring the strength of the gear will be described in the next figure.

  FIG. 12 is a diagram for explaining the operation of the steel workpiece inspection apparatus according to the present invention. As shown in FIG. 12 (a), the gear 15 is advanced to the stationary detection coil 33 as shown by the arrow (1). As shown in (b), an arbitrary tooth bottom 45 is made to face the detection coil 33, the carburizing depth of the tooth bottom 45 is detected, and whether the carburizing depth is acceptable or not is determined. When finished, the gear 15 is moved backward as indicated by the arrow (2).

  Next, as shown in (c), the gear 15 is rotated by one pitch (one tooth) (arrow (3)). Then, as shown in (d), the adjacent tooth bottom 45 faces the detection coil 33. Thereafter, the process returns to (a) and continues. This continuing operation will be described again in the flow.

  FIG. 13 is a preferred work flow diagram using the steel workpiece inspection apparatus of the present invention, and the acceptance reference depth Ds is determined by a step number (hereinafter abbreviated as ST) 01. For example, the acceptance reference depth Ds is 0.5 mm. This 0.5 mm is input to the pass / fail judgment unit 36 in FIG.

  In ST02, the number N of gear teeth to be measured is input to the control unit 19 in FIG. In order to monitor the number of measurements, first, the number n is set to 1 (ST03). Next, the abutting member 28 is positioned as shown in FIGS. 10 and 11 (ST04).

  When the position of the abutting member 28 is determined, the gear is advanced in the manner of FIG. 12A (ST05). In the manner of FIG. 12B, the X voltage of the tooth bottom is measured (ST06). The X voltage is converted into the carburization depth Da by the carburization depth conversion device 35 in FIG. 1 (ST07). The pass / fail judgment unit 36 in FIG. 1 checks whether or not the carburized depth Da obtained by the measurement is larger than the acceptance reference depth Ds (ST08). If YES, “pass” is displayed (ST09). Next, the gear is moved backward as indicated by the arrow (2) in FIG. 9B (ST10).

  Here, the number of measurements is examined (ST11). N is 1 for the first time. For example, if the number N of gear teeth is 40, since n <N, NO is advanced and 1 is added to n (ST12). Then, as shown in FIG. 12C, the gear is rotated by one tooth (ST13). Then, the carburization depth of the tooth bottom is measured again from ST05.

  If the carburization depth Da is lower than the acceptance standard depth Ds in ST08, NO is advanced and a failure display is performed (ST14). If it fails, the measurement for this gear can be terminated at this point.

  If the number of measurements n reaches the number of teeth N in ST11, the total number of tooth bottoms has been inspected, so that measurement completion is displayed and the measurement is terminated (ST15).

Another embodiment of the gear strength inspection apparatus according to the present invention will be described below.
FIG. 14 is a diagram for explaining another embodiment of FIG. 11. When a material having electrical conductivity such as steel is used for the support plate 25, the support plate 25 obstructs the generation of eddy currents, and the strength of the gears. May not be inspected.

  Therefore, when a material having electrical conductivity such as steel is used for the support plate 25, the two support plates 25 and 25 are attached to the tips of the respective iron cores 23. At this time, the support plates 25 and 25 are separated by L5 to such an extent that the strength of the gear can be inspected without disturbing the generation of eddy current.

  The steel workpiece inspection apparatus of the present invention may measure the carburization depth with an apparatus or tool other than the root carburization depth measurement apparatus 10 shown in FIG. In short, as long as the carburization depth of the tooth base can be measured nondestructively, the form and type of the measuring device are not limited.

  The present invention is suitable for a technique for measuring the carburization depth of a gear that has been vacuum carburized.

It is a principle figure of the bottom carburization depth measuring device suitable for using the gear strength inspection device of the present invention. The figure explaining the support plate and structure which concern on this invention It is a front view of a gear strength inspection apparatus. FIG. 4 is a sectional view taken along line 4 of FIG. 3. FIG. 5 is a sectional view taken along line 5 of FIG. 3. It is a figure explaining the structure of the front-end | tip part of the iron core which concerns on this invention. It is a graph showing the hardness obtained by measurement. It is a correlation diagram of X voltage and carburizing depth. It is a graph which shows the relationship between a frequency and a correlation coefficient. It is action | operation explanatory drawing of the contact member which concerns on this invention. It is a figure explaining the effect | action at the time of attaching the contact member which concerns on this invention to the gearwheel. It is operation | movement explanatory drawing of the inspection apparatus of the steel workpiece which concerns on this invention. It is a suitable work flowchart using the inspection apparatus of the steel workpiece of this invention. It is a figure explaining another Example of FIG. It is a figure explaining the basic principle of the prior art. It is a figure explaining the problem of the prior art. It is a graph which shows the relationship between the insertion angle of a gearwheel, and a voltage measurement value.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Fundamental strength inspection apparatus, 15 ... Gear, 23 ... Iron core, 24 ... Detection coil support body, 25 ... Support plate, 27 ... Sphere, 29 ... Excitation coil, 31 ... AC power supply, 32 ... Structure, 33 ... Detection coil, 35 ... carburized depth conversion device, 40 ... gear strength inspection device, 52 ... female screw hole, 56 ... through hole.

Claims (6)

In a gear strength inspection device that evaluates the strength of a gear,
This gear strength inspection device includes a detection coil embedded in a detection coil support, an excitation coil supported by iron cores disposed on both sides of the structure, and an AC power source that applies an AC voltage to these excitation coils. A support plate that is disposed at the tip of the iron core and extends toward the detection coil, a sphere of a predetermined size that is disposed through the support plate, and obtains detection information from the detection coil to obtain gear strength. A gear strength inspection device comprising: a conversion device for converting into a gear.   The gear strength inspection device according to claim 1, wherein the support plate is detachably attached to a tip of the iron core.   The gear strength inspection device according to claim 2, wherein the hole diameter of the female screw hole disposed at the tip of the iron core is the same as the hole diameter of the through hole disposed in the support plate.   4. The gear strength inspection apparatus according to claim 1, wherein the support plate is made of an electrical insulating material.   2. The gear strength inspection device according to claim 1, wherein the detection coil is embedded in the tip of a detection coil support having a triangular cross section so that the tip faces the tooth bottom.   The gear strength inspection apparatus according to claim 1, wherein the gear strength is a carburization depth of the gear.

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