JPH1038504A - Inspection gauge for radial alignment of cutting face of hob - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inspection gauge for radial alignment of cutting face with which the radial alignment of cutting face of a hob is easily inspected. SOLUTION: To the end part 40 of the first member 32 whose profile is almost a C-shape, the second member 34 is attached. At the end part 40 and the second member 34, the first plane 46 and the third plane 56 are formed respectively, in tight contact. At an end part 42 of the first member 32, the second plane 48 is so formed as to be positioned flush with the first plane 46. As a result, the second and third planes 48 and 56 are flush, their orientation reversed. With these two flat surfaces contact to a corresponding rake face 16, a gap between the two planes and the rake face 16 is visually observed by an operator, so that inspection of the radial alignment of cutting face of a sample hob 10 of a rake angle 0 is easily performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gauge for inspecting the degree of centripetality indicating the degree of deviation of an actual rake face of a hob from a theoretical rake face.

[0002]

2. Description of the Related Art The degree of centroid of a hob is one type of accuracy of the hob.
That is, it is problematic because it affects the pressure angle. The centripetal degree is represented by a difference between an intersection line (referred to as an actual line) between a plane perpendicular to the axis of the hob and the rake face and a theoretical line. In particular, in a hob having a rake angle of 0, a straight line group orthogonal to the hob axis has the highest degree of coincidence between an intersection line of a plane perpendicular to the hob axis and a rake face (this straight line is ideally used). Can be regarded as a line) and the intersection line. This difference can be specifically expressed, for example, by the angle formed by the straight line and the intersection line.

[0003] Conventionally, the inspection of the centripetality has been performed using a special measuring device. As shown in FIG. 17, the hob 100 is mounted on the arbor 102, the arbor 102 is supported at both centers, and one of two diametrically spaced rake faces is aligned with a horizontal plane, and the other rake face is provided. 104
To the contact 106 in the direction of the arrow, and
A measuring machine that determines the amount of deviation of the angle formed by the trace trajectory obtained based on the measurement result 08 from the horizontal line from the theoretical angle has been used. It is also possible to obtain the degree of centering by making the contactor trace at least one of the two rake faces in a state where the tip cutting edges of the two rake faces separated in the diametrical direction are both located on the horizontal plane. it can. In such a conventional inspection of the degree of centripetality, ambiguity may remain in the inspection result. For example, when the flatness of the rake face 104 is poor, the value of the centripetal degree varies depending on the position of the contact 106. Therefore, it is desirable that the distance over which the contact 106 traces the rake face 104 be as long as possible.

[0004]

It is troublesome to obtain the degree of centripetality using the above-mentioned measuring instrument. In particular, when grinding a raked surface for re-grinding of the hob, if the quality of the grinding result is to be determined by inspection using a conventional measuring machine, the hob is removed from the grinding machine and set on the measuring machine. It is indispensable, and if this is repeated several times, it is very troublesome. In addition, for example, in the above-described conventional measuring instrument, a mechanism is required that enables the micrometer 108 to slide in a direction perpendicular to the hob axis with high accuracy in one plane including the hob axis. However, there is also a problem that the cost becomes complicated and the equipment cost increases. The first invention according to claim 1 of the present application has been made with an object to obtain a means which can easily inspect the centripetality of a hob and can be manufactured at a low cost, with this situation as a background. It is. A second object of the present invention is to make the centripetal inspection gauge according to the first invention as small and easy to use as possible, and a third object of the present invention. The object of the present invention is to make the centripetal inspection gauge according to the first invention easy to manufacture.

[0005]

Means for Solving the Problems, Functions and Effects of the Invention
An object of the first invention is to inspect a centripetal degree, which is a difference between an actual surface and a theoretical surface of a rake face in a cross section perpendicular to an axis of a hob, with a gauge.
This problem is solved by connecting two reference portions each having a reference surface corresponding to a theoretical surface of two rake surfaces separated in the diameter direction of the hob while avoiding interference with the hob by a connecting portion.

[0006] An operator checks a hob (simply,
The two reference surfaces of the centripetality inspection gauge of the first invention are brought into contact with a pair of rake faces that face each other with the axis of the hob to be inspected interposed therebetween, and whether the two sets of contact surfaces are in close contact with each other. It is visually determined whether the centroid of the inspected hob is normal or not. The centripetal inspection gauge of the present invention is configured on the assumption that the number of blades located on one circumference of the inspected hob is an even number, and that the shapes of the rake faces of the blades are the same. However, this precondition is often satisfied. The number of blades located on one circumference of the hob is generally an even number.For example, in the case of the above-described re-grinding, the axis of the hob is attached to a mounting portion of a machine tool used for grinding. Usually, a jig such as an indexing disc having a function of accurately determining the angle of rotation is used. In this case, the hob is N times rotationally symmetrical about the axis (N is formed in the hob). (Equal to the number of grooves)
It becomes. The centripetal inspection gauge of the present invention was devised by effectively utilizing such a situation, and the centripetal inspection can be performed by a simple operation as compared with the above-described conventional measuring machine. , And can be manufactured at low cost.

The two reference portions on which the respective reference surfaces are formed are connected to each other by a connecting portion so that they cannot move relative to each other. Since the connecting portion has a shape that does not interfere with each portion of the hob to be inspected, the two reference surfaces can be brought into contact with the hob to be inspected. If the rake face of the inspected hob is processed normally, the reference plane, which is the theoretical plane, and the actual rake face are in contact without any gap.If the processing is not performed normally, the gap between the reference plane and the rake face A thin wedge-shaped gap results. By a simple operation of visually recognizing whether or not a gap exists and the size of the gap, the centripetal degree can be inspected. Also, based on the shape of the gap, for example, it can be confirmed whether or not the rake face is processed into a flat plane. Note that, as described above, this test depends on the ability of the human eye to recognize the presence or absence of a gap and the size of the gap, but the human eye has sufficient accuracy for such a test. Have cognitive ability. The centripetal test gauge of the present invention plays a role as an auxiliary device that effectively brings out the high performance of the human eye. If it is difficult to directly observe the gap between the reference surface and the rake surface with the naked eye, apply a contact confirming agent such as Komitsutan or Blue Paste to one of the reference surface and the rake surface. After the contact, the state of adhesion of the contact confirmation agent to the other side can be visually observed to indirectly inspect the degree of concentricity.

[0008] In the second invention, the above-mentioned problem is caused by extending the connecting portion of the centripetal test gauge according to the first invention along a plane including the axis of the hob when the centripetal test gauge is in use. The problem is solved by forming a C-shape and connecting each of the two reference portions at both ends of the C-shape. In this centripetal inspection gauge, the connecting portion has a simple C shape that does not interfere with the hob to be inspected. Here, the C shape may be a literal C shape, or may be a shape (for example, an affine-transformed shape) obtained by deforming the C shape within a range that does not lose basic properties. . In addition, a shape that should be referred to as a U-shape or a U-shape is also included in the C-shape. The C-shaped connecting portion has one concave portion, and the inspection hob is positioned in the concave portion during the inspection, so that interference between the connecting portion and the inspected hob can be avoided. Because the connecting portion has such a simple shape, the centripetal inspection gauge of the present invention is small-sized,
It is lightweight and easy to use.

In the third invention, the above object is achieved by providing the centripetal test gauge according to the first invention in a C-shape extending along a plane including the axis of the hob in a use state,
A first member having a first plane and a second plane parallel to each other at both ends of the U-shape, and a third plane, and a part of the third plane being in close contact with the first plane of the first member. And a second member fixed to the first member, wherein a portion of the third plane deviating from the first plane and the first plane respectively constitute the reference plane.

In the centripetal test gauge of the present invention, the second plane of the first member and the third plane of the second member define
A reference plane is configured. The first member has a first plane and a second plane which are parallel to each other, and these planes are important only in the degree of flatness of each plane, the degree of parallelism between the two planes, and the accuracy of the separation distance in the normal direction. Therefore, it can be easily formed. For example, if the hob to be inspected has a rake angle of 0, the normal separation distance between the first plane and the second plane is 0, and the first and second planes are on the same plane. Since these two surfaces can be manufactured as a part, for example, these two surfaces may be ground simultaneously by a surface grinder. When the hob to be inspected has a rake angle other than 0, the distance between the first plane and the second plane in the normal direction is not 0, but is parallel to each other. The height of the grindstone may be changed by a grinder to grind both surfaces, and the height of the grindstone can be easily changed using the high-precision adjustment mechanism of the surface grinder. In any case, when forming both planes, there is no need to change the setup such as the change of material to a machine tool such as a surface grinder, so that extremely simple processing can be completed as a whole.

When processing the second member, only the flatness of the third plane is important, and the second member can be easily formed. The first and third planes, which can be easily formed in this way, are brought into close contact with each other, so that the second and third planes are parallel and opposite to each other and cannot be moved relative to each other. Will be done. It is necessary to keep the first and third planes in close contact with each other, but it is necessary to select and employ an appropriate means from among the means for mechanically coupling the first and second members, such as bolting. Can be.

[0012]

Preferred embodiments of the present invention can be carried out in the following embodiments in addition to the embodiments described in the above claims. The embodiments are conveniently described as an embodiment of the same type as the claims. (1) The centripetal inspection gauge according to claim 3, wherein the first member has a flat plate shape, and the first plane and the second plane are located on the same plane. (2) The centripetal gauge according to claim 3, wherein the first member has a flat plate shape, and the first plane and the second plane are located on each of two planes parallel to each other. (3) The centripetal test gauge according to any one of claims 1 and 2, wherein the second member is fixed to the first member by bolts. If the first member and the second member are fixed with bolts in a state where the first plane and the third plane are in close contact with each other, both members can be easily fixed, and
When the reference surface is worn or damaged, it can be easily repaired by disassembling and grinding the two members. (4) The centripetal inspection gauge according to claim 1, wherein the connecting portion has a shape that connects the two reference portions through an outer peripheral surface of the hob in a use state. Since the connecting portion extends along a plane perpendicular to the reference plane, manufacturing is more complicated than when the connecting portion extends along a plane including the axis of the hob when the centripetal test gauge is used. Although it is likely to be, the usability is the same or better. As will be described later in the embodiment section, in use, it is possible to visually check the contact state of the two reference surfaces with the two rake faces without being disturbed by the connecting portion or the hand holding the same. This is because it becomes easy. (5) The centripetality test gauge is further disposed between at least one of the two reference portions and the corresponding connection portion, and at least one of the reference portions and the corresponding connection portion. 5. The centripetal inspection according to claim 1, further comprising a relative position adjusting means for adjusting a relative position of the reference plane in a normal direction. gauge. As described later in embodiments of the present invention, this is an aspect in which a plurality of hobs having different rake angles can be inspected.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A centripetal test gauge which is an embodiment common to the first to third inventions will be described with reference to the drawings. 1 and 2 are a front view and a partially sectional left side view of an inspected hob 10 (one-gear hob for a gear), which is an example of a hob to be inspected. Cutting blade 12 of hob 10 to be inspected
Are formed as straight grooves, and
The rake face 16 lies on a plane containing the axis of the hob. That is, the rake angle is zero. The hob as shown in FIGS. 1 and 2 can extend the tool life by re-grinding the rake face 16, but at that time, the centripetal degree needs to be kept at zero. The eccentricity is the difference between the actual line and the theoretical line of the line of intersection between the plane orthogonal to the axis and the rake face 16, and the eccentricity inspection gauge of the present embodiment allows the operator to visually check this difference. To make it recognizable.

FIGS. 3 to 5 are a front view, a right side view and a plan view, respectively, of the centripetal test gauge 30 of the present embodiment. The centrifugal inspection gauge 30 of the present embodiment is configured by fixing a second member 34 to two C-shaped first members 32 with two bolts 36. First member 32
Is a plate-shaped member, and the left side surface 38 is finished to a smooth plane by grinding with a surface grinder.
The right side surface 39 does not necessarily need to be finished by grinding. The end portion 40 and the end portion 42 of the first member 32 are thicker than the other portions, and the first flat surface 46 protrudes outward from the right side surface 39 in the normal direction.
And a second plane 48 serving as a reference plane are formed. The first and second planes 46 and 48 are parallel to the left side 38 and the first and second planes 4 after the above-described left side 38 has been finished into a smooth plane by grinding.
6, 48 are finished smoothly so as to be on the same plane. The grinding on the left side surface 38 is performed as a pretreatment for finishing the first and second planes 46 and 48, whereby the first plane 46 and the second plane 48 are formed.
Are very easily formed as a smooth plane on the same plane.

The end portion 40 is formed with two screw holes 52, which are screwed together with the two bolts 36 described above to form a reference surface formed on the first plane 46 and the second member 34. The third flat surface 56, which is a surface, is fixed in close contact with the third flat surface 56. As a result, the second plane 48 and the third plane 56 formed on the same plane as the first plane 46 are planes on the same plane and opposite to each other. As described above, in the centripetal inspection gauge 30 of the present embodiment, the second plane 48 and the third plane 56, which are reference planes, can be easily formed.

FIG. 6 shows the centripetal inspection gauge 3 of this embodiment.
0 is a front view showing a situation where the hob 10 to be inspected shown in FIGS. FIG. 7 is a left side view showing the situation shown in FIG.
FIGS. 6 and 7 show a case where the centroid of the inspected hob 10 is zero. If the centripetality is zero,
As described above, a set of rake faces 16 located on opposite sides of the axis of the hob 10 to be inspected is included in one plane including the axis. Therefore, the centripetal inspection gauge 30
The second plane 48 and the third plane 56 can be brought into close contact with the corresponding rake face 16. A person checks with naked eyes whether or not these are in close contact with each other from the direction shown in FIG. At this time, it is desirable to illuminate the inspected hob 10 and the centripetality inspection gauge 30 from the side opposite to the naked eye, or to place white paper or the like on the opposite side to facilitate recognition of the gap by the naked eye.

The centripetal inspection gauge 30 of the present embodiment is used.
Is such that the size of the second plane 48 and the third plane 56 can be in contact with one or two rake faces 16. In the state shown in FIG. 7, one rake face 16 is in contact with the third plane 56 and two rake faces 16 are in contact with the second plane 48. In this state, the gap between the third plane 56 and one rake face 16 is larger than that of the second plane 4.
Compared to the gap between the rake face 8 and the two rake faces 16, the confirmation is easier and the inspection is easier. The inspected hob 10 and the centrifugal inspection gauge 30 are moved relative to each other in the axial direction of the inspected hob 10, and are moved to the second plane 48 or the third plane 56,
If only one rake face 16 is sequentially contacted and the presence or absence of a gap between each rake face 16 and the face contacting the rake face 16 is sequentially confirmed, all the rake faces 16 can be easily inspected.

If the centripetality is not zero, the second plane 48 and the third plane 56 are replaced by their corresponding rake face 1
When each of them is brought into contact with each other, the parts that should be in close contact do not adhere. For example, when the rake angle of the rake face 16 becomes a positive value other than 0 by re-grinding, as shown in FIG. 8, the second plane 48 and the third plane 56 and the corresponding rake face 16 Cannot be brought into close contact with the tooth bottom side (inner peripheral side). On the other hand, if the rake angle is a negative value,
As shown in FIG. 9, the second plane 48 and the third plane 56 cannot be brought into close contact with the corresponding rake face 16 on the tooth tip side (outer peripheral side). 8 and 9, the two-dot chain line indicates the position of a virtual plane including the second plane 48 and the third plane 56. As is clear from these figures, according to the inspection using the centripetalness inspection gauge 30 of the present embodiment, in addition to the inspection whether the centripetality is zero, the rake angle of the rake face 16 is determined. You can also know the sign. Also, if you get used to it, you can know the approximate size of the rake angle from the size of the gap. As described above, the centripetal inspection gauge 30 of the present embodiment performs the inspection of the centroid of the inspected hob 10 by the inclination of two straight lines intersecting at one point (from the directions shown in FIGS. 6, 8, and 9). When the contact surface between the second plane 48, the third plane 56 and the rake face 16 is seen, it looks like this).

It should be noted that the centripetal inspection gauge 30 of this embodiment is
Does not mean that the inspection of the centripetality is impossible even when viewed from a direction other than the direction shown in FIG. For example, the inspection can be performed by confirming whether there is a gap between the second plane 48 and the third plane 56 and the cutting blade 12 from a direction slightly obliquely deviated from the direction shown in FIG. Each cutting edge 12 is formed as a very sharp outer edge of the rake face 16 having a generally trapezoidal shape. Therefore, when the degree of centroid is not zero, the cutting edge 12 corresponds to the hypotenuse of the trapezoid. A gap is also formed between the portion and the second plane 48 or the third plane 56.
This gap can naturally be confirmed from the direction shown in FIG. 6 and the like, but can also be confirmed from a direction slightly obliquely deviated from that direction.

In addition, the centripetal inspection gauge 30 of the present embodiment
Can be used for inspection of a hob having a rake angle of 0. However, in order to reduce cutting resistance, there is a hob having a positive rake angle of, for example, about 6 to 8 degrees. In order to check the centripetality, it is necessary that the above-mentioned second plane 48 and third plane 56 are not on the same plane. This is because a pair of diametrically spaced rake faces 16 no longer lie on the same plane, as can be seen from FIG. 8 as a front view of the hob with a positive rake angle. Therefore, for example, the end portion 42 may be made thicker or the end portion 40 may be made thinner. In addition, the thickness of the end portion 40 is reduced, and a parallel plate can be sandwiched between the second member 34 and the end portion 40. By selectively sandwiching a plurality of parallel plates having different thicknesses. Alternatively, a mode may be adopted in which a plurality of hobs having different rake angles can be inspected.

Further, another embodiment may be provided in which at least one of these ends 40, 42 is provided with a relative position adjusting means for adjusting the relative position between the third plane 56 and the second plane 46. For example, as shown in FIG. 10, a micrometer head 62 is attached to the end 40 via a bracket 60, and the inspection surface 64 of the micrometer head 62 (the end surface of the spindle disk 68 attached to the tip of the spindle 66) is Instead of the third plane 56. That is, the position of the third plane 56 can be finely adjusted in μm units using the spindle feed mechanism of the micrometer head 62. The adjustment of this fine adjustment mechanism
For example, this can be performed by making the second plane 48 and the inspection surface 64 and two rake surfaces 16 separated in the diameter direction of the hob which are known to be good products come into close contact with each other. FIG. 10 shows a case where the hob 10 to be inspected is a non-defective product. In this state, the spindle 66 is fixed so as not to move by the clamp 70 and used for the inspection of the centripetal degree.

The centripetal inspection gauge 3 shown in FIG.
0, the thimble 7 of the micrometer head 62
By using the thimble graduation 74 normally provided in 2, the size of the rake angle can also be obtained. The value obtained by dividing the distance in the normal direction between the pair of rake faces 16 facing each other across the axis of the inspection hob 10 obtained based on the reading of the thimble scale 74 by the outer diameter of the inspection hob 10 is the rake. This is because the sine of the angle is obtained.

FIG. 11 is a drawing showing still another embodiment of the centripetal test gauge of the present invention. In the centrifugal inspection gauge 30 of the present embodiment, the second plane 48 and the third plane 56, which are reference planes, are longer than the blade width of the hob 10 to be inspected, and the two grooves 14 facing each other with the axis interposed therebetween. Rake face 1
The entire surface 6 is the surface to be inspected, and a smaller number of rake surfaces 16, for example, two rake surfaces 16 may be the surfaces to be inspected. In these cases, the eccentricity inspection of the rake face of the blade at the end of the hob 10 to be inspected in the axial direction can be easily performed directly with the naked eye, but the internal blade is difficult to directly inspect with the naked eye. Therefore, in this case, the second plane 48 and the third plane 56 and the rake face 16
After applying a contact confirming agent such as Gwangmyeongtan or Blue Paste to one of them and bringing it into contact with the other, the state of adhesion of the contact confirming agent to the other is visually observed to indirectly determine the degree of centripetality. Inspection is desirable.

FIGS. 12 and 13 are a front view and a left side view, respectively, showing still another embodiment of the centripetal test gauge of the present invention. FIG. 14 is a front view showing a state where an inspection using the centripetality inspection gauge 30 of the present embodiment is being performed. As is clear from these figures, the centroid test gauge 30 of the present embodiment has a cylindrical outer peripheral surface of the hob 10 to be inspected when the first member 32 serving as the connecting portion is being inspected. It is configured to pass through the outside. Therefore, the state of contact between the rake face 16 of the hob 10 to be inspected and the second plane 48 and the third plane 56 serving as reference planes is obstructed by the first member 32 or the hand of an operator holding the first member 32. There are few advantages. In the centripetal inspection gauge 30 of the present embodiment, the second plane 4
8 is not formed directly on the first member 32, but is formed on an auxiliary member 76 that is attached to the first member 32 using the bolt 36. The end surface 78 of the end portion 42 of the first member 32 is formed parallel to the first plane 46, and the second plane 48 of the auxiliary member 76 is formed by grinding or the like so as to ensure sufficient flatness. You. It is not an essential condition that the second plane 48 is formed directly on the first member 32 as described above, and it is sufficient that the second plane 48 and the third plane 56 are kept parallel to each other. .

FIGS. 15 and 16 correspond to FIGS.
The end portion 42 where the second plane 48 is formed and the second member 34 where the third plane 56 is formed are the embodiments shown in FIGS. 3 and 4 and the like. In the same manner as described above, the length of the hob 10 to be inspected is shortened in the axial direction (individual rake faces 16
FIGS. 9A and 9B are a front view and a left side view showing another embodiment in which the third plane 56 is further shortened than the second plane 48. Centripetality inspection gauge 30 of the present embodiment
Since the third plane 56 is considerably shortened in the axial direction of the hob 10 to be inspected, it is easy to confirm the gap between the third plane 56 and the corresponding rake face 16 when the degree of centroid is not zero. This makes it easier to check the degree of centripetality. The third plane 56 is formed such that both sides of the surface of the second member 34 on which the third plane 56 is formed are shaved off to form the flank 80 so that the third plane 56 is considerably shortened in the axial direction. In the present embodiment, in the inspection state, the inspection of the centripetal degree is performed mainly by confirming whether or not there is a gap between the third plane 56 and the corresponding rake face 16.

Although some embodiments of the present invention have been described above, these are merely examples, and the present invention can be implemented in various modified and improved forms without departing from the scope of the claims. can do.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of a hob serving as a gear cutting tool.

FIG. 2 is a left side view of the hob of FIG.

FIG. 3 is a front view showing a centripetal inspection gauge which is an embodiment common to the first to third inventions of the present application;

FIG. 4 is a right side view of the centripetal test gauge of FIG. 3;

FIG. 5 is a plan view of the centripetal test gauge of FIG. 3;

FIG. 6 is a front view showing a state where the centripetal inspection gauge of FIGS. 3 to 5 is used for inspection of the centripetal degree;

FIG. 7 is a left side view showing a state where the centripetal inspection gauge of FIGS. 3 to 5 is used for inspection of the centripetal degree;

FIG. 8 is a diagram illustrating a case where the centroid or the rake angle of the hob to be inspected is not zero.

FIG. 9 is a diagram showing another case where the centroid or rake angle of the hob to be inspected is not zero.

FIG. 10 is a front view showing a centripetal inspection gauge as another embodiment common to the first and second inventions of the present application.

FIG. 11 is a left side view showing a centripetal test gauge as still another embodiment common to the first to third inventions of the present application.

FIG. 12 is a front view showing a centripetality inspection gauge which is still another embodiment of the first invention of the present application.

FIG. 13 is a left side view of the centripetal test gauge of FIG. 12;

FIG. 14 is a front view showing a state where the centripetal inspection gauge shown in FIGS. 12 and 13 is used for inspection of the centripetal degree.

FIG. 15 is a front view showing a centripetality inspection gauge which is still another embodiment of the first invention of the present application.

FIG. 16 is a left side view of the centripetal test gauge of FIG. 15;

FIG. 17 is a diagram showing an outline of a configuration of a general centripetal measuring device.

[Explanation of symbols]

10: Single hob for gear (hob to be inspected) 12: Cutting blade
14: groove 16: rake face 30: centripetal inspection gauge 32:
First member 34: Second member 36: Bolt 38: Left side
39: Right side surface 40, 42: End 46: First plane 48: Second plane 52: Screw hole 56: Third plane 60: Bracket 62: Micrometer head 64: Inspection surface 66: Spindle 68: Spindle disk 70: Clamp 72: thimble 74: thimble scale 76: auxiliary member 78: end face 80: flank face

Claims (3)

[Claims] 1. A gauge for inspecting the degree of eccentricity which is a difference between an actual surface and a theoretical surface of a rake face in a cross section perpendicular to an axis of a hob, wherein two rakes which are opposite to each other and are spaced apart in a diameter direction of the hob. A centripetal test gauge, wherein two reference portions each having a reference surface corresponding to a theoretical surface of a surface are connected by a connecting portion while avoiding interference with a hob. 2. The connecting portion forms a C-shape extending along a plane including the axis of the hob in a use state of the centripetal test gauge, and the reference portion is provided at both ends of the C-shape. The centripetality test gauge according to claim 1, wherein the gauges are connected. 3. A C-shape which extends along a plane including the axis of the hob in a use state, and is formed at both ends of the C-shape.
A first member having a first plane and a second plane parallel to each other, a third member having a third plane, and a part of the third plane;
A second member fixed to the first member in close contact with the first plane of the member, and a portion of the third plane that deviates from the first plane and the first plane respectively constitute the reference plane. The centripetal inspection gauge according to claim 1.