JP4647057B2 - Pilot hole correction tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a pilot hole correction tool used to correct a pilot hole provided through a work material in advance, and in particular, a pilot hole provided in a work material made of a high hardness material. Even when it is distorted, etc., it is characterized in that the pilot hole can be corrected straight.
[0002]
[Prior art]
Conventionally, various methods have been used to provide a threaded hole penetrating a work material made of a high hardness material obtained by heat-treating a steel material to increase its hardness.
[0003]
In the first method, a through hole is provided in the work material having a low hardness before the heat treatment, and a threading process is performed on the work hole using a tap, and then the work material is heat treated. In the second method, after providing a pilot hole penetrating the work material in a low hardness state before heat treatment, the work material is heat treated to increase its hardness. Then, threading is performed using a tap in the prepared hole as described above, and in the third method, the workpiece penetrated through the heat-treated workpiece with increased hardness. After providing a pilot hole, threading was performed on the pilot hole using a tap.
[0004]
Here, in the first method, after the screw hole is provided in the work material in a low hardness state before the heat treatment, the work material is heat treated. There was a problem that the hole was deformed and the screw could not be properly inserted into the screw hole.
[0005]
In the second method, the prepared hole is provided in the work material by the heat treatment in order to heat the work material after providing the prepared hole in the work material in a low hardness state before the heat treatment. When the threading process is performed on the prepared hole by using the tap, the tap may be broken and the work material provided with the prepared hole is heat treated. There is also a problem that the work material becomes troublesome because it is necessary to remove the work material from the apparatus and set the work material again in the apparatus after the heat treatment.
[0006]
For this reason, it is thought that said 3rd method is preferable as a method of providing a screw hole in the work material which consists of high hardness material.
[0007]
However, as shown in the third method, in the case of providing a through hole in the work material that has been heat-treated to increase the hardness, the shape of the work material is not a flat plate, As shown in FIG. 1, when the lower surface 1a of the work material 1 is inclined, if the prepared hole 2 is provided in the work material 1 using a drilling tool such as a drill, the work material Since the hardness of No. 1 is high, the drilling tool escapes in the direction where the thickness is small, and there is a problem that the pilot hole 2 provided in the work material 1 is inclined and distorted.
[0008]
Then, when threading is performed on the distorted pilot hole 2 using a tap, there arises a problem that the tap is broken.
[0009]
Here, in the past, a finishing tool such as a reamer has generally been used to cut and finish the periphery of the prepared hole 2 provided in the work material 1 with a drilling tool such as a drill.
[0010]
However, in the case of a finishing tool such as a reamer, a chip discharge groove for discharging chips is provided long in the circumferential direction through a required interval, so that the rigidity of the finishing tool is reduced, as described above. When cutting around the pilot hole 2 provided in the work material 1 having high hardness, the finishing tool is bent along the pilot hole 2 distorted as described above, and the straight pilot hole 2 is provided. There was a problem that it could not be done or the finishing tool was bent and bent.
[0011]
[Problems to be solved by the invention]
An object of the present invention is to solve the above-described problem when a pilot hole previously penetrating through a work material is distorted, and in particular, a work made of a high-hardness material. Even when the pilot hole provided in the material is distorted, it is an object to make it possible to correct the pilot hole straight.
[0012]
[Means for Solving the Problems]
In the prepared hole correcting tool according to the present invention, the tip of the columnar tool body 10 is provided in order to solve the above-described problem in correcting the prepared hole 2 penetrating through the work material 1 in advance. multiple provided with a cutting edge 13 of the required width d on the outer peripheral portion, a chip pocket 12 which is inclined toward the outer peripheral side from the center side of the tool body 10 in the rotational direction front side of the tool body 10 in the cutting edge 13 the tool The angle θ1 formed between the surface orthogonal to the central axis of the tool main body 10 and the bottom surface 12a of the inclined chip pocket 12 is provided only at the tip of the main body 10 and the surface orthogonal to the central axis of the tool main body 10 The angle θ2 formed with the cutting edge 13 is smaller than the angle θ2.
[0013]
And if the chip pocket 12 is provided only at the tip of the tool body 10 as in the pilot hole correcting tool in the present invention, the tool body 10 has a larger length than a reamer provided with many long grooves for discharging chips. Increases rigidity.
[0014]
And when correcting the prepared hole 2 provided beforehand penetrating to the work material 1 with the prepared hole correcting tool in this invention, each cutting edge 13 provided in the front-end | tip outer peripheral part of the tool main body 10 WHEREIN: Since the periphery of the tool body 10 is cut and the rigidity of the tool body 10 is high as described above, even when the prepared hole 2 provided in the work material 1 made of a high-hardness material is distorted, the tool body 10 is Bending along the pilot hole 2 is suppressed, and the distorted pilot hole 2 is straightened.
[0015]
In the pilot hole correcting tool of the present invention, the angle θ1 formed by the surface perpendicular to the central axis of the tool body 10 and the bottom surface 12a of the inclined chip pocket 12 as described above is the center of the tool body 10. Since the angle θ2 formed by the surface perpendicular to the axis and the cutting blade 13 is smaller than the angle θ2, when the chips cut by the cutting blade 13 hit the bottom surface 12a of the chip pocket 12, the cutting The scrap is pushed out to the tip end side of the tool body 10 and is discharged to the outside through the prepared hole 2 provided therethrough. For this reason, even if it does not enlarge the chip pocket 12 in the front-end | tip part of the tool main body 10, a chip will not be clogged and the rigidity of a prepared hole correction tool can be improved.
[0016]
Further, in the prepared hole correcting tool according to the present invention, as shown in claim 2, the contracted portion 14 in which the diameter D of the tool body 10 contracts rearward from the tip end portion of the tool body 10 provided with the chamfered portion 11. When provided, even when the tool body 10 is slightly shaken when the prepared hole 2 provided in advance through the work material 1 is corrected by the prepared hole correcting tool, the prepared hole cut by the cutting edge 13 is used. 2 is rubbed by the outer peripheral portion of the tool main body 10 on the rear side of the cutting blade 13 to prevent the periphery of the pilot hole 2 from being hardened, and threading is performed on the pilot hole 2 using a tap. When this is done, the periphery of the pilot hole 2 becomes too hard to prevent the tap from being broken.
[0017]
Further, as shown in claim 3, when the concave portion 15 is provided in the contracted portion 14 so as to be recessed on the axial center side of the tool body 10, the pilot hole 2 is formed using a pilot hole correction tool having a large diameter of the tool body 10. Even in the case of correction, the periphery of the pilot hole 2 cut by the cutting edge 13 is prevented from being rubbed and cured by the outer peripheral portion of the tool body 10 on the rear side of the chamfered portion 11.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a pilot hole correcting tool according to an embodiment of the present invention will be specifically described with reference to the accompanying drawings.
[0019]
In the prepared hole correcting tool in this embodiment, as shown in FIGS. 2 and 3, two chamfers are formed so that the outer peripheral portion of the tip of the tool body 10 in a columnar shape is symmetrical with respect to the center of the tool body 10. In the two chamfered portions, a chip pocket 12 inclined from the center side to the outer peripheral side of the tool body 10 is provided on the front side in the rotational direction of the tool body 10, and the cutting edge 13 having the required width d is provided. Two are provided so as to be symmetric with respect to the center of the tool body 10, and two flank surfaces 11 a and 11 b are successively formed from the two cutting edges 13 on the rear side in the rotation direction of the tool body 10. ing.
[0020]
Here, in the prepared hole correction tool in this embodiment, the two cutting blades 13 are provided on the outer peripheral portion of the tip of the tool body 10 as described above, and the tool body 10 is further forward in the rotational direction than the two cutting blades 13. In providing the chip pocket 12 inclined from the center side of the tool body 10 toward the outer peripheral side, the angle θ1 formed by the surface perpendicular to the central axis of the tool body 10 and the bottom surface 12a of the inclined chip pocket 12 is provided. However, it is made to become smaller than angle (theta) 2 which the surface orthogonal to the central axis of the tool main body 10 and said cutting blade 13 make.
[0021]
Further, in the prepared hole correction tool of this embodiment, an appropriate angle α is formed with the central axis of the tool body 10 from the tip of the tool body 10 provided with each of the cutting blades 13 to the rear. Thus, a contracted portion 14 in which the diameter D of the tool body 10 contracts is provided in a tapered shape.
[0022]
Then, using the prepared hole correcting tool of this embodiment, as shown in FIG. 1, in correcting the distorted prepared hole 2 provided in the work material 1 in which the lower surface 1a is inclined, The main body 10 is rotated, and the tool main body 10 is pushed into the prepared hole 2 while cutting the periphery of the prepared hole 2 by the respective cutting blades 13 at the outer periphery of the tip.
[0023]
In this way, the chips cut by the respective cutting blades 13 are pushed out to the tip side of the tool body 10 at the bottom surface 12a of the chip pocket 12, and are discharged to the outside through the prepared hole 2 provided therethrough. At the same time, the tool body 10 is only provided with a chip pocket 12 at its tip, and is not formed with a long groove for discharging chips like a reamer. Even when the rigidity of the main body 10 is high and the pilot hole 2 is deformed, the tool main body 10 is restrained from being deformed along the pilot hole 2 and a straight pilot hole 2 can be obtained.
[0024]
Further, in the prepared hole correction tool of this embodiment, since the contraction portion 14 contracted in a taper shape from the tip end portion of the tool body 10 provided with the respective cutting blades 13 as described above is provided, Even if the tool body 10 is slightly shaken, the periphery of the pilot hole 2 cut by the cutting blade 13 is suppressed from being rubbed by the outer peripheral portion of the tool body 10 on the rear side of the cutting blade 13. The periphery of the hole 2 is not hardened.
[0025]
In the prepared hole correction tool of this embodiment, only the contracted portion 14 contracted in a taper shape from the tip end portion of the tool body 10 toward the rear is provided, but as shown in FIG. When the concave portion 15 is provided in the contracted portion 14 of the tool main body 10 so as to be recessed on the axial center side, even when the diameter D of the tool main body 10 is increased, the periphery of the pilot hole 2 cut by the cutting blade 13 is Scraping by the outer peripheral portion of the tool body 10 on the rear side of the cutting blade 13 is suppressed, and the periphery of the pilot hole 2 is not hardened.
[0026]
Next, the case where the distorted pilot hole 2 provided in the work material 1 is corrected using the pilot hole correcting tool of the specific embodiment of the present invention will be described, and the pilot hole of the embodiment is thus described. Comparative example that when the distorted pilot hole 2 provided in the work material 1 is corrected with a correction tool, the tap is prevented from being broken when the tap hole is used for the pilot hole 2. To clarify.
[0027]
Here, as the work material 1 in which the pilot hole 2 is provided, the steel material of SCM440 is oil-quenched at 900 ° C. for 45 minutes and then tempered at 520 ° C. for 80 minutes, and the Rockwell hardness C scale (HRC) is 40. 1 to 45, and the lower surface 1a of the work material 1 is inclined 60 ° with respect to the horizontal plane as shown in FIG.
[0028]
(Example 1 and Comparative Example 1)
Here, in providing the prepared hole 2 for the work material 1, a high-speed drill having a diameter of 2.1 mm is used, the cutting speed is set to 12 m / min, the feed is set to 0.022 mm / rev, and the work material is cut. A pilot hole 2 in which the length of the short hole portion was 10 mm with respect to the material 1 was provided.
[0029]
Here, when the pilot hole 2 is provided in this way, the curvature of the pilot hole 2 is in the range of 0.1 to 0.15 mm, and the surface roughness in the vicinity of the through portion of the pilot hole 2 is calculated. The average roughness Ra was determined to be in the range of 12.5 to 6.3 μmRa.
[0030]
And in Example 1, it was comprised with the cemented carbide, the diameter D was 2.15 mm, the width d of the cutting blade 13 was 0.2 mm, the surface orthogonal to the central axis of the tool main body 10, and said inclined chip The angle θ1 formed by the bottom surface 12a of the pocket 12 is 25 °, the angle θ2 formed by the surface orthogonal to the central axis of the tool body 10 and the cutting blade 13 is 45 °, and the angle formed by the contraction portion 14 and the central axis of the tool body 10 Using the prepared hole correction tool shown in FIG. 2 and FIG. 3 in which α is 1 ° and the clearance angle of the flank 11a is 10 °, the cutting speed is 30 m / min, the feed is 0.015 mm / rev, The pilot hole 2 provided in the work material 1 was corrected.
[0031]
As a result, the pilot hole 2 provided in the work material 1 is penetrated straight, and the surface roughness in the vicinity of the through portion of the pilot hole 2 is about 1.6 μmRa.
[0032]
And after correcting the pilot hole 2 provided in the work material 1 using the pilot hole correction tool of Example 1 in this way, a M2 tap is used for the pilot hole 2 and screwed at a rotational speed of 100 rpm. On the other hand, in Comparative Example 1, the pilot hole 2 provided in the work material 1 is not modified, but the M2 tap is used for the pilot hole 2 as it is, and threading is performed at a rotational speed of 100 rpm. Went.
[0033]
As a result, in the case of Comparative Example 1 in which the threading process is performed as it is without correcting the pilot hole 2 provided in the work material 1, the tap is formed when the threading process is performed 30 to 34 times. Damaged. On the other hand, when the pilot hole 2 provided in the work material 1 is corrected using the pilot hole correcting tool of the first embodiment, the threading process is performed 180 to 200 times before the tap is broken. Was done.
[0034]
(Examples 2 and 3 and Comparative Example 2)
In Examples 2 and 3 and Comparative Example 2, when providing the prepared hole 2 for the work material 1, a high-speed drill having a diameter of 4.3 mm was used, the cutting speed was 12 m / min, and the feed was 0.045 mm. The prepared hole 1 in which the length of the short hole portion is 15 mm is provided in the work material 1.
[0035]
Here, when the pilot hole 2 is provided in this way, the curvature of the pilot hole 2 is in the range of 0.1 to 0.15 mm, and the surface roughness in the vicinity of the through portion of the pilot hole 2 is calculated. The average roughness Ra was determined to be in the range of 12.5 to 6.3 μmRa.
[0036]
And in Example 2, it was comprised with the cemented carbide, the diameter D was 4.35 mm, the width d of the cutting blade 13 was 0.5 mm, the surface orthogonal to the central axis of the tool main body 10, and said inclined chip The angle θ1 formed by the bottom surface 12a of the pocket 12 is 25 °, the angle θ2 formed by the surface orthogonal to the central axis of the tool body 10 and the cutting blade 13 is 45 °, and the angle formed by the contraction portion 14 and the central axis of the tool body 10 Using the prepared hole correction tool shown in FIGS. 2 and 3 in which α is 1 ° and the clearance angle of the flank 11a is 10 °, the cutting speed is 30 m / min, the feed is 0.03 mm / rev, The pilot hole 2 provided in the work material 1 was corrected.
[0037]
As a result, the pilot hole 2 provided in the work material 1 is penetrated straight, and the surface roughness in the vicinity of the through portion of the pilot hole 2 is about 1.6 μmRa. However, in this case, the periphery of the pilot hole 2 was rubbed and hardened by the outer peripheral portion of the tool body 10.
[0038]
Further, in the third embodiment, the prepared hole correction in which the contracted portion 14 of the prepared hole correction tool used in the second embodiment is provided with a recessed portion 15 recessed on the axial center side of the tool body 10 as shown in FIG. Other than that, the pilot hole 2 provided in the work material 1 was corrected in the same manner as in Example 2 above.
[0039]
As a result, the pilot hole 2 provided in the work material 1 is penetrated straight, and the surface roughness in the vicinity of the through portion of the pilot hole 2 is about 1.6 μmRa. The periphery of the hole 2 was not rubbed and hardened by the outer periphery of the tool body 10.
[0040]
And after correcting the pilot hole 2 provided in the work material 1 using the pilot hole correction tool of Example 2 and 3 as mentioned above, each M2 tap is used for each pilot hole 2, While threading is performed at a rotation speed of 100 rpm, in Comparative Example 2, the M5 tap is used for the pilot hole 2 as it is without correcting the pilot hole 2 provided in the work material 1. Threading was performed at 100 rpm.
[0041]
As a result, in the case of the comparative example 2 in which the threading process is performed as it is without correcting the pilot hole 2 provided in the work material 1, the tap is formed when the threading process is performed 30 to 34 times. Damaged. On the other hand, when the pilot hole 2 provided in the work material 1 is corrected using the pilot hole correcting tool of the second embodiment, the threading process is performed 70 to 80 times before the tap is broken. In addition, when the pilot hole 2 provided in the work material 1 is corrected using the pilot hole correcting tool of the third embodiment, the threading process is performed 200 to 240 times before the tap is broken. I did it.
[0042]
【The invention's effect】
As described above in detail, when the pilot hole provided through the work material in advance using the pilot hole correcting tool according to the present invention is corrected, the rigidity of the pilot hole correcting tool is increased, Even when a pilot hole provided in a work material made of a high-hardness material is distorted, the pilot hole has been corrected so that a straight pilot hole can be obtained.
[0043]
As a result, even if the pilot hole provided in the work material made of a high hardness material is distorted, the pilot hole is corrected and straightened, and threading is performed on the pilot hole using a tap. When doing so, the tap is now prevented from breaking easily.
[0044]
In the pilot hole correcting tool according to the present invention, the angle θ1 formed between the surface orthogonal to the center axis of the tool body and the bottom surface of the inclined chip pocket is such that the surface orthogonal to the center axis of the tool body and the cutting blade Since it is made smaller than the angle θ2 formed, when the chips cut by the cutting blade hit the bottom surface of the chip pocket, the chips are pushed out to the tip end side of the tool body and pass through the prepared through hole. It came to be discharged outside.
[0045]
As a result, in the pilot hole correcting tool of the present invention, the chips are not clogged without increasing the chip pocket at the tip of the tool body, and the rigidity of the pilot hole correcting tool can be increased.
[0046]
Further, in the prepared hole correcting tool according to the present invention, when a contracted portion having a diameter contracted rearward from the tip of the tool body provided with the cutting blade is provided, the prepared material is previously penetrated into the work material by the prepared hole correcting tool. When the prepared pilot hole is modified, it is prevented that the periphery of the pilot hole is rubbed and hardened by the outer periphery of the tool body on the rear side of the cutting blade, and the tap hole is used to thread the pilot hole. When processing, the tap is further prevented from breaking.
[0047]
Furthermore, in the pilot hole correcting tool according to the present invention, when a concave portion recessed on the axial center side of the tool body is provided in the contracted portion, the pilot hole is corrected using a pilot hole correcting tool having a large tool body diameter. However, the periphery of the pilot hole is prevented from being rubbed and hardened by the outer peripheral portion of the tool body on the rear side of the chamfered portion.
[Brief description of the drawings]
FIG. 1 is an explanatory cross-sectional view showing a state in which a prepared hole is inclined and distorted when a prepared hole is provided in a work material having an inclined lower surface.
FIG. 2 is a partial side view of a prepared hole correcting tool according to an embodiment of the present invention.
FIG. 3 is a front view of the prepared hole correcting tool according to the embodiment.
FIG. 4 shows that the tool hole correction tool according to the embodiment is recessed toward the axial center side of the tool body in a contracted part in which the diameter of the tool body contracts rearward from the tip part of the tool body provided with the chamfered part. It is a partial side view of the example of a change of the prepared hole correction tool which provided the recessed part.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Work material 2 Pilot hole 10 Tool main body 12 Chip pocket 12a Bottom face 13 of chip pocket 14 Cutting edge 14 Shrinkage part 15 Recessed part θ1 Angle (theta) 2 formed by the surface orthogonal to the central axis of a tool main body, and the bottom face of a chip pocket The angle d between the surface perpendicular to the central axis of the body and the cutting edge d The width of the cutting edge

Claims (3)

A prepared hole correcting tool used for correcting a prepared hole 2 provided through the work material 1 in advance, and a cutting edge 13 having a required width d at the outer periphery of the tip of a cylindrical tool body 10. Are provided, and a chip pocket 12 inclined from the center side of the tool body 10 toward the outer peripheral side is provided only at the tip of the tool body 10 on the front side in the rotation direction of the tool body 10 at each cutting edge 13. The angle θ1 formed between the surface orthogonal to the central axis of the tool body 10 and the bottom surface 12a of the inclined chip pocket 12 is the angle between the surface orthogonal to the central axis of the tool body 10 and the cutting blade 13 described above. A prepared hole correcting tool characterized by being smaller than an angle θ2 formed. The prepared hole correction tool according to claim 1, wherein a contracted portion 14 in which the diameter D of the tool body 10 contracts is provided rearward from the tip of the tool body 10 provided with the cutting edge 13. Prepared hole correction tool. 3. A pilot hole correcting tool according to claim 2, wherein a concave portion 15 is provided in the contracted portion 14 so as to be recessed on the axial center side of the tool body 10.

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