Method for measuring depth of recessed part

Abstract

To provide a method for measuring depth of a recessed part which can suppress variation in a measurement result depending on a measuring person, and accurately measure the depth of the recessed part.SOLUTION: A method for measuring depth of a recessed part comprises processes of: preparing a base member which has a surface shape in which the recessed part having a semicircular cross section is formed by a tool; manufacturing a transfer material which has a projection part corresponding to the recessed part by transferring the surface shape; measuring width of the projection part; finding length C calculated by a square root of a value obtained by subtracting a squared value of a half of the width B of the projection part from the squared value of a radius A, by means of Pythagorean theorem, by using the radius A of a tip end part of the tool and the width B of the projection part; and regarding the value obtained by subtracting the length C from the radius A as the depth of the recessed part.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for measuring the depth of a recess. [Background technology]

[0002] Patent Document 1 discloses a measuring device that measures the depth of a hole present on the surface of a material and displays the result digitally. This measuring device measures the depth of the hole by the difference in the relative position between the measuring device body and a slide. The measuring device body is equipped with a contact needle that is brought into contact with the bottom of the hole. The slide is equipped with a contact leg that is brought into contact with the surface of the material. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Utility Model Registration No. 3085469 Summary of the Invention [Problem to be solved by the invention]

[0004] In the measuring device disclosed in Patent Document 1, if the force with which the contact needle touches the bottom of the hole differs depending on the person measuring, the measurement results may vary. If the material surface is curved, in the measuring device disclosed in Patent Document 1, the orientation of the contact needle inserted into the hole is not fixed depending on the position of the contact leg relative to the material surface, making it difficult to bring the contact needle into contact with the deepest, lowest point of the hole, and this may result in variation in the measurement results.

[0005] An object of the present invention is to provide a method for measuring the depth of a recess, which is capable of accurately measuring the depth of a recess while preventing variation in measurement results depending on the person who measures the recess. [Means for solving the problem]

[0006] A method for measuring the depth of a recess according to one embodiment of the present invention includes the steps of preparing a base member having a surface shape in which a recess with a semicircular cross-section is formed by a tool, creating a transfer material having a protrusion corresponding to the recess by transferring the surface shape, measuring the width of the protrusion, and using a radius A of the tip of the tool and a width B of the protrusion to determine a length C calculated by Pythagoras' theorem as the square root of the value obtained by subtracting the value obtained by squaring the radius A from the value obtained by squaring half the width B of the protrusion, and considering the value obtained by subtracting the length C from the radius A as the depth of the recess. Effect of the Invention

[0007] In the method for measuring the depth of a recess of the present invention, the depth of the recess can be obtained accurately without using a measuring device that directly measures the depth of the recess as disclosed in Patent Document 1. Since the recess is formed with a tool, there is no problem in calculating the depth of the recess using the radius A of the tip of the tool. Since the protrusions of the transfer material correspond to the dimensions and shape of the recess, and the width of the protrusions is easy to measure consistently regardless of the person measuring as described below, there is no problem in calculating the depth of the recess using the width B of the protrusions. Since the depth of the recess can be derived by calculation, the measurement results are unlikely to vary depending on the person measuring, and the depth of the recess can be obtained accurately.

[0008] In the method of measuring the depth of a recess of the present invention, a transfer material having protrusions corresponding to the recesses can be left as evidence showing the depth of the recesses. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic partial perspective view showing an example of a base member prepared in a recess depth measuring method according to an embodiment. [Diagram 2] FIG. 2 is a cross-sectional view taken along line II-II of FIG. [Diagram 3] FIG. 3 is an explanatory diagram showing a process of preparing a transfer material in the recess depth measuring method according to the embodiment. [Figure 4]FIG. 4 is a cross-sectional view showing a protrusion of a transfer material in the method for measuring the depth of a recessed portion according to the embodiment. [Diagram 5] FIG. 5 is an explanatory diagram showing how to find the depth of a recess in the recess depth measuring method according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The method for measuring the depth of a recess of the present invention will be described with reference to the drawings. The same reference numerals in the drawings indicate the same objects. In each drawing, for the convenience of explanation, some of the configurations may be exaggerated or simplified. The dimensional ratios of each part in the drawings may also differ from the actual ones.

[0011] <Details of the recess depth measurement method> The recess depth measuring method of the embodiment is a method for determining the depth of a recess formed by a tool mainly by calculation. For example, when machining a press die, a recess may be formed on the surface of the die by the tool. In the press die, it is required to form a recess of an accurate depth. Therefore, in the press die, it is required to accurately grasp the depth of the formed recess. Below, an example will be described in which the depth of a recess formed on the surface of the press die is measured.

[0012] The recess depth measuring method of the embodiment includes a first step of preparing a base member 1 (Figures 1 and 2), a second step of making a transfer material 5 (Figure 4), a third step of measuring the transfer material 5, and fourth and fifth steps of calculating the depth of the recess 3 using the dimensions of a tool 9 (Figure 2) and the measurement results of the transfer material 5 (Figure 4).

[0013] ≪First step≫ In the first step, as shown in FIG. 1 and FIG. 2, a base member 1 having a surface shape in which a recess 3 having a semicircular cross section is formed by a tool 9 is prepared. The recess 3 includes a groove having a semicircular cross section and a hemispherical hole. In FIG. 2, the tool 9 for forming the recess 3 is virtually shown by a two-dot chain line. The tool 9 is, for example, a ball end mill or a grindstone. The grindstone may be a spherical grindstone or a rod-shaped grindstone with one end being hemispherical. Such a rod-shaped grindstone can machine a hemispherical hole. The grindstone may be a disk-shaped grindstone. The disk-shaped grindstone has a semicircular cross section at its outer periphery. Such a disk-shaped grindstone can machine a groove having a semicircular cross section. The tool 9 in this example is a ball end mill. The base member 1 in this example is a part of a press die. The recess 3 formed in the base member 1 is, for example, a groove having a length. The base member 1 in this example has a surface shape in which a plurality of grooves are formed in a lattice shape. The recess 3 may have a semicircular cross-sectional shape, and may be other than the groove shown in Fig. 1. The recess 3 may be, for example, a short recess or a hemispherical hole.

[0014] The target value of the depth of the recess 3 is, for example, 0.2 mm or less. The depth of the recess 3 is the length of the perpendicular line from the lowest point of the recess 3 to the straight line connecting the opening edges of the recess 3. The depth of the recess 3 is determined by the diameter of the tip 90 of the tool 9. For a shallow recess 3 of 0.2 mm or less, if a measuring device that directly measures the depth of the recess 3 as disclosed in Patent Document 1 is used, the force with which the contact needle contacts the bottom of the recess 3 is likely to vary depending on the person measuring. In this example, as will be described later, the depth of the recess 3 is not measured directly but is calculated, so that the depth of the recess 3 can be accurately determined even for a shallow recess 3 of 0.2 mm or less.

[0015] The reference surface 2 of the base member 1 on which the recess 3 is formed is, for example, a curved surface. The recess 3 opens on the reference surface 2. The reference surface 2 in this example is a curved surface. In FIG. 2, the curvature of the reference surface 2 is exaggerated. In the case of the recess 3 formed on the curved surface, if a measuring device that directly measures the depth of the recess 3 is used as disclosed in Patent Document 1, the force with which the contact needle contacts the bottom of the recess 3 is likely to vary depending on the person measuring. In the case of the recess 3 formed on the curved surface, if a measuring device that directly measures the depth of the recess 3 is used as disclosed in Patent Document 1, depending on the position of the contact leg with respect to the reference surface 2, the direction of the contact needle inserted into the recess 3 is not fixed, and it is difficult to make the contact needle contact the deepest, lowest point of the recess 3. In this example, as will be described later, the depth of the recess 3 is calculated rather than measured directly, so that the depth of the recess 3 can be accurately known even if the recess 3 is formed on a curved surface. The reference surface 2 may be a flat surface.

[0016] ≪Second process≫ In the second step, as shown in FIG. 3 and FIG. 4, the surface shape of the base member 1 is transferred to prepare a transfer material 5 having protrusions 6 corresponding to the recesses 3 of the base member 1. Corresponding to the recesses 3 means that the transfer material 5 corresponds to the dimensions and shape of the recesses 3. The transfer material 5 is preferably made of a material that has a fluidity that allows the internal shape of the recesses 3 to be transferred before hardening, and that has shape retention of the transferred shape after hardening. The transfer material 5 is, for example, a hardened rubber material 4. The rubber material 4 is filled in the recesses 3 of the base member 1 as shown in FIG. 3. If the rubber material 4 has excellent quick-drying properties, the time required to prepare the transfer material 5 can be shortened. If the rubber material 4 has a high hardness, the shape of the protrusions 6 corresponding to the recesses 3 of the base member 1 can be maintained when the transfer material 5 with the hardened rubber material 4 is peeled off from the base member 1.

[0017] The rubber material 4 is, for example, silicone rubber. If the rubber material 4 is silicone rubber, it is easy to appropriately transfer the surface shape of the base member 1. The rubber material 4 may be a two-part mixed type silicone rubber consisting of a base agent and a curing agent.

[0018] When transferring the surface shape of the base member 1, the rubber material 4 may be pressed against the base member 1 by a base (not shown). The base is, for example, a flat plate having a flat surface. The rubber material 4 is pressed against the base member 1 while placed on the flat surface of the base. In this case, the transfer material 5 in which the rubber material 4 has hardened is supported on the flat surface of the base. In the transfer material 5 supported on the flat surface of the base, the surfaces other than the protrusions 6 are flat. Even if the surfaces other than the protrusions 6 are flat, the dimensions and shape of the protrusions 6 substantially correspond to the shape and dimensions of the recesses 3 of the base member 1, and are acceptable in terms of measurement accuracy.

[0019] ≪Third process≫ In the third step, the width B1 of the protrusion 6 of the transfer material 5 shown in FIG. 4 is measured. The width B1 is the maximum width of the base of the protrusion 6. The width B1 is measured, for example, by a digital microscope. Specifically, the transfer material 5 is placed on a flat surface of a measurement table, the digital microscope is arranged so that the optical axis is perpendicular to the flat surface of the measurement table, and the width B1 of the protrusion 6 of the transfer material 5 is measured by capturing an image of the protrusion 6 from directly above. If the transfer material 5 is supported on a flat surface of a base (not shown), this base may be used as the measurement table. If the measurement is performed using a digital microscope, the width B1 of the protrusion 6 can be easily and appropriately measured regardless of the person who performs the measurement, even if the surface of the transfer material 5 corresponding to the reference surface 2 of the base member 1 is a curved surface.

[0020] ≪Fourth process≫ 5, in the fourth step, the length C of a portion of a straight line connecting the center point P of the circle constituting the recess 3 of the base member 1 and the deepest point Q of the recess 3 is determined. The length C is the length from the center point P to the intersection R of the line connecting the center point P and the lowest point Q with the line connecting the opening edge S. The length of the remaining portion of the straight line connecting the center point P and the lowest point Q is the depth D of the recess 3. In other words, the length from the intersection R to the lowest point Q is the depth D of the recess 3.

[0021] The radius of the circle constituting the recess 3 is the radius A of the tip 90 of the tool 9. The width between the opening edges S of the recess 3 is the width B1 of the protrusion 6 measured in the third process. Therefore, the length between the opening edge S and the intersection point R is half of the width B1. Hereinafter, half of the width B1 is referred to as the half width B2. A right triangle is formed by the center point P, the opening edge S, and the intersection point R. The diameter A is the length of the hypotenuse of the right triangle. The half width B2 is the length of one adjacent side of the right triangle, that is, the long side in this example. The length C is the length of the other adjacent side of the right triangle, that is, the short side in this example. The diameter A and the half width B2 are known. Therefore, the length C can be found by Pythagoras' theorem using the diameter A and the half width B2. In other words, the length C is calculated by the square root of the value obtained by subtracting the value obtained by squaring the half width B2 from the value obtained by squaring the radius A.

[0022] ≪Fifth process≫ In the fifth step, as shown in Fig. 5, the value obtained by subtracting the length C from the radius A is regarded as the depth D of the recess 3. The length of the straight line connecting the center point P and the lowest point Q is the radius A. The length from the center point P to the intersection point R is the length C calculated in the fourth step. The length from the intersection point R to the lowest point Q is the depth D of the recess 3. Therefore, the depth D of the recess 3 can be found by subtracting the length C from the radius A.

[0023] Since the recess 3 is formed with the tool 9, there is no problem in calculating the depth D of the recess 3 using the radius A of the tip 90 of the tool 9. In particular, when the tool 9 is a ball end mill, the recess 3 can be formed with higher precision, so there is no problem in calculating the depth D of the recess 3 using the radius of the tip of the ball end mill. Since the protrusion 6 of the transfer material 5 corresponds to the recess 3, and the width B1 of the protrusion 6 is easy to measure consistently regardless of the person measuring, there is no problem in calculating the depth D of the recess 3 using the width B1 of the protrusion 6.

[0024] <Action and effect> In the recess depth measuring method of the embodiment, the depth D of the recess 3 can be obtained accurately regardless of the measurer. Unlike a measuring device that directly measures the depth D of the recess 3, there is no process of contacting the lowest point Q of the recess 3 with a constant force, and the depth D of the recess 3 is obtained mainly by calculation, so that the measurement results are less likely to vary depending on the measurer. With the recess depth measuring method described above, the depth D of the recess 3 can be obtained accurately regardless of the measurer, even for shallow recesses 3 of 0.2 mm or less, or recesses 3 formed on a curved surface.

[0025] In the method for measuring the depth of a recess in the embodiment, the depth D of the recess 3 can be obtained easily. For example, the base member 1 or the transfer material 5 can be measured from data obtained by scanning the base member 1 or the transfer material 5 with a 3D scanner, but scanning with a 3D scanner takes time. In the case of the transfer material 5, the height of the protrusion 6 of the transfer material 5 is regarded as the depth D of the recess 3. For example, when the base member 1 is a press die, it is difficult to arrange a 3D scanner at the site of machining the press die. With the above-mentioned method for measuring the depth of a recess, it is only necessary to prepare the transfer material 5 at the site of machining the press die, and the width B1 of the protrusion 6 of the transfer material 5 can also be easily measured with a digital microscope. The depth D of the recess 3 can be calculated on a desk.

[0026] In the recess depth measuring method of the embodiment, a transfer material 5 having a protrusion 6 corresponding to the recess 3 can be left as evidence showing the depth D of the recess 3. For example, information on holes in the mold used to mold a lot of molded products can be confirmed on the transfer material 5. A press mold may wear out during use, but if the transfer material 5 from the press mold before use remains, it is possible to evaluate the wear state of the press mold by making a transfer material from the press mold after use.

[0027] <Test Example> A base member having a surface shape in which a groove having a semicircular cross section was formed by a ball end mill was prepared, and the depth of the groove was measured using three methods, and the results were compared.

[0028] In the first method, a transfer material with protrusions corresponding to the grooves was created by transferring a base member, and this transfer material was scanned with a 3D scanner to measure the height of the protrusions on the transfer material. The height of the protrusions is considered to be the depth of the groove. Measurements were taken at three different points along the longitudinal direction of one groove. Three people each performed measurements of the recesses using this first method. With the first method, consistent measurement results were obtained at each measurement point, regardless of the person performing the measurement. The measurement results scanned with a 3D scanner can be considered to be true values. However, scanning with a 3D scanner requires expensive equipment and takes more time than other methods.

[0029] In the second method, a depth gauge was used to directly measure the depth of the groove in the base member. Measurements were taken at three different points along the longitudinal direction of one groove. Five people each performed measurements of the recesses using this second method. With the second method, the measurement results varied depending on the person taking the measurements at each measurement point, and there was also a large deviation from the true value. This is thought to be due to differences in the force used to contact the depth gauge's contact needle with the bottom of the groove depending on the person taking the measurements, and differences in the orientation of the contact needle inserted into the groove.

[0030] In the third method, the second to fifth steps of the recess measurement method of the above embodiment were performed in order. In the second step, a transfer material having a protrusion corresponding to the recess was produced by transferring a base member using a rubber material. A two-liquid mixed type silicone rubber was used as the rubber material. This transfer material is the same as the transfer material produced by the first method. In the third step, the width B1 of the protrusion of the transfer material was measured by a digital microscope. In the fourth step, the length C shown in FIG. 5 was obtained using the dimension of the radius A of the tip of the ball end mill and the width B1. In the fifth step, the value obtained by subtracting the length C from the radius A was obtained, and this value was considered to be the depth of the recess. The measurement was performed at three different points in the longitudinal direction of one groove. Three people each performed the measurement of the recess by this third method. In the third method, a consistent measurement result was obtained at each measurement point regardless of the person who measured it. In addition, the depth of the recess obtained by the third method had an error of 0.001 mm compared to the depth of the recess obtained by the second method. Therefore, it can be said that the third method makes it possible to obtain the depth of the recess accurately regardless of the person who measures.

[0031] The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims. [Explanation of symbols]

[0032] 1 Base material 2 Reference plane 3. Recess 4. Rubber materials 5 Transfer material 6 Protrusion 9 Tools 90 Tip A radius B1 width B2 half width C. Length D Depth P center point Q lowest point R intersection S Opening Edge

Claims

[Claim 1] preparing a base member having a surface shape with a semicircular recess formed therein by a tool; a step of producing a transfer material having protrusions corresponding to the recesses by transferring the surface shape; Measuring the width of the protrusion; a step of calculating a length C by using a radius A of the tip of the tool and a width B of the protrusion, by Pythagoras' theorem, as the square root of a value obtained by subtracting a value obtained by squaring half the width B of the protrusion from a value obtained by squaring the radius A; and determining a value obtained by subtracting the length C from the radius A as the depth of the recess. How to measure recess depth.

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