Drill for evaluating thinning

Abstract

To provide a technique that can evaluate accuracy in grinding by a plurality of grindstones, using one drill for evaluating thinning.SOLUTION: A drill for evaluating thinning comprises a drill main body; a first thinning part having a groove formed in a spiral shape on an outer peripheral surface of the drill main body, where the groove has a first surface extending from an outer periphery side toward a shaft center and a second surface extending from an end part at the shaft center side of the first surface toward the outer periphery side, on a cross section that is perpendicular to the shaft center of the drill main body; and a second thinning part which has a third surface extending from an end part at an outer periphery side of the second surface toward the opposite side of the first surface and a fourth surface extending from an end part at an outer periphery side of the third surface toward the opposite side of the second surface, on the cross section that is perpendicular to the shaft center of the drill main body. The first thinning part and the second thinning part can perform thinning processing using different types of grindstones. This can evaluate accuracy in grinding by a plurality of grindstones, using one drill for evaluating thinning.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a drill for thinning evaluation. [Background technology]

[0002] Patent Document 1 discloses a method for grinding a drill, which includes a step of grinding the flank of the drill and a step of performing a thinning process. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 7-032251 Summary of the Invention [Problem to be solved by the invention]

[0004] When the thinning grinding wheel deteriorates, it becomes impossible to properly thin the drill. For this reason, thinning evaluation drills exist for evaluating the grinding accuracy of grinding wheels. Conventionally, thinning evaluation drills have only one location where thinning can be performed, and one thinning evaluation drill can only evaluate the grinding accuracy of one grinding wheel. This specification proposes a technology that can evaluate the grinding accuracy of multiple grinding wheels using one thinning evaluation drill. [Means for solving the problem]

[0005] (Aspect 1) The thinning evaluation drill disclosed in this specification has a drill body and a groove spirally arranged on the outer peripheral surface of the drill body, and the groove is provided with a first thinning portion having, in a cross section perpendicular to the axis of the drill body, a first surface extending from the outer peripheral side toward the axis side and a second surface extending from the axis-side end of the first surface toward the outer peripheral side, and a second thinning portion having, in a cross section perpendicular to the axis of the drill body, a third surface extending from the outer peripheral end of the second surface toward the opposite side of the first surface and a fourth surface extending from the outer peripheral end of the third surface toward the opposite side of the second surface.

[0006] The above-mentioned thinning evaluation drill has a first thinning portion and a second thinning portion. Therefore, the first thinning portion and the second thinning portion can be thinned using different types of grinding wheels. As a result, it is possible to evaluate the grinding accuracy of multiple grinding wheels using a single thinning evaluation drill. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a plan view of a drill for thinning evaluation. [Figure 2] FIG. 2 is a plan view showing the tip surface of a drill for thinning evaluation. [Figure 3] FIG. [Figure 4] FIG. 10 is an explanatory diagram of a first thinning portion grinding step. [Figure 5] FIG. 10 is an explanatory view of a second thinning portion grinding step. DETAILED DESCRIPTION OF THE INVENTION

[0008] The following are examples that can be added to the above-mentioned Example 1. (Aspect 2) A method for evaluating a thinning grinding wheel using the thinning evaluation drill according to aspect 1, the method comprising: a step of grinding a tip face of the thinning evaluation drill so that the tip angle of the thinning evaluation drill is 178 degrees to 182 degrees; a step of grinding the first thinning portion after the step of grinding the tip face; a step of grinding the second thinning portion after the step of grinding the tip face; and a step of observing the tip portion of the thinning evaluation drill after grinding the first thinning portion and the second thinning portion. (Aspect 3) Aspect 3. The method according to aspect 2, wherein in the step of grinding the first thinning portion, the second surface is ground so that a rake angle of the second surface becomes a negative rake angle.

[0009] According to the second aspect, the tip surface of the drill for thinning evaluation is approximately perpendicular to the axis in a cross section parallel to the axis of the drill body, which prevents the camera or the like from becoming out of focus when observing the tip portion of the drill for thinning evaluation, thereby reducing measurement errors.

[0010] According to the third aspect, the grinding allowance of the first thinning portion increases when the tip surface is ground, and therefore, when the first thinning portion is thinned, it is possible to suppress the remaining part of the connecting portion between the first surface and the second surface from being left unprocessed.

[0011] The thinning evaluation drill 100 shown in Figures 1 and 2 is used to evaluate the grinding accuracy of a thinning wheel. The drill body 10 of the thinning evaluation drill 100 has a cylindrical shape and an outer peripheral surface 14. As shown in Figures 1 and 2, two spirally extending grooves 16 are provided on the outer peripheral surface 14. As shown in Figure 1, the tip surface 30 of the drill body 10 is approximately flat. As will be described later, before carrying out the thinning wheel evaluation method, the tip surface 30 is ground so that the point angle A is 178 degrees to 182 degrees.

[0012] FIG. 2 shows the tip surface 30 of the drill body 10. FIG. 2 shows the cross-sectional shape of the flutes 16 in a plane perpendicular to the axis 12. As shown in FIG. 2, in the cross section perpendicular to the axis 12, each flute 16 has a first thinning portion 20 and a second thinning portion 22. The first thinning portion 20 has an L-shaped cross-sectional shape and includes a first surface 20a and a second surface 20b. The first surface 20a is part of the inner surface of the flute 16 and constitutes the front portion of the flute 16 in the rotational direction. The first surface 20a extends from the outer peripheral surface 14 toward the axis 12. The angle of the first surface 20a relative to the tip surface 30 is an obtuse angle. The second surface 20b extends from an end 24 of the first surface 20a on the axis 12 side toward the outer peripheral surface 14. As shown in FIG. 1, the rake angle α of the second surface 20b of the first thinning portion 20 is a negative angle.

[0013] The second thinning portion 22 is disposed adjacent to the first thinning portion 20. The second thinning portion 22 is a surface having an L-shaped cross section and includes a third surface 22a and a fourth surface 22b. The third surface 22a extends from an end 26 on the outer circumferential side of the second surface 20b toward the opposite side of the first surface 20a. The angle of the third surface 22a relative to the tip surface 30 is an obtuse angle. The fourth surface 22b extends from an end 28 on the outer circumferential side of the third surface 22a toward the opposite side of the second surface 20b to the outer circumferential surface 14. The angle of the fourth surface 22b relative to the tip surface 30 is an obtuse angle.

[0014] The drill body 10 may be provided with an oil wheel 32. The oil wheel 32 discharges the grinding oil supplied to the drill body 10 from an oil tube (not shown) to the outside.

[0015] Next, a method for evaluating a thinning wheel using the thinning evaluation drill 100 will be described. First, a tip surface grinding process is carried out. As shown in FIG. 3, in the tip surface grinding process, a rotating thinning wheel 90 is pressed against the tip surface 30 of the drill body 10 to grind the tip surface 30. At this time, the tip surface 30 is ground so that the point angle A of the thinning evaluation drill 100 is 178 degrees to 182 degrees. As described above, since the rake angle α of each second surface 20b is negative, when the tip surfaces 30 are ground, the width Ta between the two second surfaces 20b increases, as shown in FIG. 4.

[0016] Next, the first thinning portion grinding step is carried out. First, as shown in FIG. 4, a rotating thinning grindstone 90 is pressed against the second surface 20b, and the thinning grindstone 90 is moved from the end 26 toward the end 24 to grind the second surface 20b. At this time, the first thinning portion 20 is ground so that the rake angle of the first thinning portion 20 becomes a negative rake angle on the second surface 20b. Next, the thinning grindstone 90 is moved along the first surface 20a from the end 24 toward the outer peripheral surface 14 to grind the first surface 20a. In this way, the first thinning portion 20 is thinned.

[0017] Next, a second thinning portion grinding process is carried out. In the second thinning portion grinding process, a different thinning stone 92 is used than in the first thinning portion grinding process. First, as shown in FIG. 5 , the rotating thinning stone 92 is pressed against the third surface 22a, and the thinning stone 92 is moved from the end 26 toward the end 28 to grind the third surface 22a. Next, the thinning stone 92 is moved along the fourth surface 22b from the end 28 toward the outer peripheral surface 14 to grind the fourth surface 22b. In this way, the second thinning portion 22 is thinned.

[0018] Next, a step of observing the tip portion of the drill body 100 for thinning evaluation is performed. Here, a microscope is positioned above the drill body 10 along the axis 12. Next, the microscope is used to photograph the tip surface 30 of the drill body 10. Using the photographed image of the tip surface 30 of the drill body 10, an evaluation is performed to determine whether the first thinning portion 20 and the second thinning portion 22 have been properly ground. Since the point angle A of the drill body 10 for thinning evaluation is 178 degrees to 182 degrees, the distance between the microscope and the tip surface 30 in the longitudinal direction of the drill body 100 for thinning evaluation is approximately constant regardless of position. Therefore, it is possible to prevent out-of-focus when photographing the tip surface 30 of the drill body 10 using the microscope. As a result, the shape of each flute 16 can be accurately measured, and the grinding accuracy of the thinning grinding wheels 90, 92 can be properly evaluated.

[0019] If the thinning evaluation drill 100 has only the first thinning portion 20, the thinning evaluation drill 100 can evaluate the grinding accuracy of only one thinning grinding wheel. Therefore, the work time required to evaluate the grinding accuracy of multiple thinning grinding wheels increases. Furthermore, a thinning evaluation drill must be prepared for each thinning grinding wheel. In contrast, in the above-described embodiment, the thinning evaluation drill 100 has the first thinning portion 20 and the second thinning portion 22. Therefore, the grinding accuracy of different thinning grinding wheels can be evaluated with a single thinning evaluation drill, thereby shortening the work time. Furthermore, since it is not necessary to prepare a thinning evaluation drill for each thinning grinding wheel, the work space can be saved and the number of management tasks by the worker can be reduced.

[0020] Furthermore, in the above-described embodiment, the rake angle α of the second surface 20b of each flute 16 is negative. Therefore, as described above, when the tip surface 30 of the thinning evaluation drill 100 is ground in the tip surface grinding process, the width Ta between the two second surfaces 20b becomes wider than before the tip surface grinding process (see FIGS. 2 and 4). Therefore, a sufficient grinding allowance for the second surfaces 20b can be secured in the first thinning portion grinding process, and the second surfaces 20b can be properly ground with the thinning grindstone 90. This allows the thinning grindstone 90 to be properly evaluated.

[0021] In the above-described embodiment, the groove 16 has two thinning portions. However, the groove 16 may have three or more thinning portions.

[0022] In the above-described embodiment, the second thinning portion grinding step was performed after the first thinning portion grinding step. However, the first thinning portion grinding step may be performed after the second thinning portion grinding step. Also, the first thinning portion grinding step and the second thinning portion grinding step may be performed simultaneously.

[0023] Although the embodiments have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. The technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of these objectives itself has technical utility. [Explanation of symbols]

[0024] 10: Drill body 14:Outer surface 16: Groove 20: First thinning part 20a: Side 1 20b: 2nd side 22: Second thinning part 22a: 3rd side 22b: 4th side 30:Tip surface 100: Drill for thinning evaluation

Claims

[Claim 1] A drill for thinning evaluation, The drill body and a groove provided spirally on the outer peripheral surface of the drill body; and The groove is a first thinning portion having a first surface extending from an outer periphery toward an axial center in a cross section perpendicular to an axial center of the drill body, and a second surface extending from an end of the first surface on the axial center side toward an outer periphery; a second thinning portion having, in a cross section perpendicular to an axis of the drill body, a third surface extending from an outer peripheral end of the second surface toward an opposite side of the first surface, and a fourth surface extending from an outer peripheral end of the third surface toward an opposite side of the second surface; Equipped with Drill for thinning evaluation.

Images