JP5890699B2 - Superabrasive tool for drilling and drilling method using the same - Google Patents

Description

  The present invention relates to a superabrasive tool for drilling and a drilling method using the same.

As this type of conventional tool, a ceramic drilling tool is known. The tool life can be extended by making the tip of the cylindrical base metal a convex curved surface. (For example, Patent Document 1)
Another conventional tool of this type is known as a drilling tool for brittle materials. In the case where the tip of the cylindrical base metal is hemispherical and the through hole is formed, the chipping of the edge is prevented when the through hole is pulled out. (For example, Patent Document 2)
As another conventional tool of this type, a drill for forming a stepped hole is known. (For example, Patent Document 3)

JP 2008-296321 A JP 2003-205410 A JP 2005-199619 A

  However, the conventional superabrasive tool for drilling has a problem that chipping occurs when the through hole is pulled out.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to provide a tool in which chipping is unlikely to occur in a workpiece.

A superabrasive tool for drilling according to the present invention includes a base metal rotatable around an axis, a superabrasive electrodeposition portion having a substantially hemispherical portion provided at a tip of the base metal, and electrodeposition. And a projecting electrodeposition portion provided at the tip of the portion. The tip of the protruding electrodeposition part has a planar shape, a spherical shape or an aspherical shape, a cylindrical electrodeposition part is provided on the rear side of the substantially hemispherical part, and the base metal is provided from the rear end part to the tip part. A supply hole for the grinding fluid is provided, and a groove is provided only in the protruding electrodeposition portion so as to divide the protrusion.

  In the superabrasive tool for drilling configured as described above, since the protruding electrodeposition portion is provided at the tip of the electrodeposition portion, chipping of the workpiece can be prevented by the action of this portion. .

  A method of drilling a workpiece according to the present invention is a method of drilling a workpiece while performing helical feeding using the above-described superabrasive tool for drilling.

It is a front view of the superabrasive tool for drilling according to Embodiment 1 of this invention. It is the top view of the superabrasive tool for drilling seen from the direction shown by arrow II in FIG. It is the bottom face of the superabrasive tool for drilling seen from the direction shown by the arrow III in FIG. It is the right view of the superabrasive tool for drilling seen from the direction shown by arrow IV in FIG. It is the left view of the superabrasive tool for drilling seen from the direction shown by the arrow V in FIG. It is sectional drawing along the VV line in FIG. It is a perspective view of the superabrasive tool shown in FIG. It is a front view of the superabrasive tool for drilling according to Embodiment 2 of this invention. It is a top view of the superabrasive tool for drilling seen from the direction shown by arrow IX in FIG. It is the bottom face of the superabrasive tool for drilling seen from the direction shown by the arrow X in FIG. It is the right view of the superabrasive tool for drilling seen from the direction shown by arrow XI in FIG. It is the left view of the superabrasive tool for drilling seen from the direction shown by arrow XII in FIG. It is sectional drawing along the XIII-XIII line | wire in FIG. It is a perspective view of the superabrasive tool shown in FIG. 1 is a diagram showing an experimental apparatus in Example 1. FIG. It is a figure which shows the helical path in Example 1. FIG. It is a graph which shows the relationship between the number of accumulation holes and the maximum chip width of a workpiece in the conventional tool and the tool of the present invention. It is a graph which shows the relationship between the number of accumulation holes and the maximum chip width of a workpiece in the conventional tool and the tool of the present invention. It is a graph which shows the relationship between grinding resistance and the maximum chip width of a workpiece in the conventional tool and the tool of the present invention.

Embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a front view of a superabrasive tool for drilling according to Embodiment 1 of the present invention. FIG. 2 is a plan view of a superabrasive tool for drilling as seen from the direction indicated by arrow II in FIG. FIG. 3 is a bottom view of the superabrasive tool for drilling as seen from the direction indicated by arrow III in FIG. FIG. 4 is a right side view of the superabrasive tool for drilling as seen from the direction indicated by arrow IV in FIG. FIG. 5 is a left side view of the superabrasive tool for drilling as seen from the direction indicated by the arrow V in FIG. FIG. 6 is a cross-sectional view taken along line VV in FIG. FIG. 7 is a perspective view of the superabrasive tool shown in FIG.

  With reference to these drawings, the superabrasive tool 1 for drilling according to the first embodiment includes a base metal 20 that can rotate around an axis 10, and a substantially hemispherical portion provided at the tip of the base metal 20. A superabrasive electrodeposition portion 30 and a protruding electrodeposition portion 40 provided at the tip of the electrodeposition portion 30. In this example, the tip of the protruding electrodeposition part 40 has a curved surface shape, but the tip may have a flat shape. In this example, the tip of the protruding electrodeposit 40 has a spherical shape, but may have an aspherical shape. The electrodeposition part has a hemispherical part 31 on the front end side and a cylindrical part 32 on the rear side.

  The protruding electrodeposition part 40 is provided with a groove 41 extending in the lateral direction so as to divide the protrusion. The coolant sent from the liquid passages 21 and 42 is supplied to the groove 41. Coolant is ejected from the groove 41 during cutting. Liquid passages 21 and 42 are provided so as to penetrate the base metal 20, and the cylindrical base metal 20 has a hollow shape.

  Diamond abrasive grains as superabrasive grains are fixed to the electrodeposition part 30 and the protruding electrodeposition part 40 by electrodeposition. The diamond abrasive grains may be replaced with cBN abrasive grains.

  The protruding electrodeposited portion 40 formed of a spheroid has a radius Ra, an elliptical axial protrusion amount Rb, and a protruding amount t from the tip of the hemispherical electrodeposited portion 30 to the tip of the protruding electrodeposited portion 40. .

  The method of drilling a workpiece according to the first embodiment is a method of drilling a workpiece while performing helical feeding using the above-described superabrasive tool 1 for drilling.

  The drilling superabrasive tool 1 of this embodiment has a shape in which a large-diameter ball end tool and a small-diameter spheroid tool are combined. That is, in making this invention, the following two findings have been obtained in order to reduce the chipping of a workpiece when making a hole in a brittle material while performing helical feeding.

  Knowledge 1: If the workpiece has a pilot hole and is machined with a ball end tool, chipping is greatly suppressed, and the life of the ball end tool is increased several times. However, as a problem of drilling pilot holes, a) the number of processes increases, b) hole processing is performed with a molded body and a temporary sintered body, and the hole position is shifted due to shrinkage during sintering. .

  Knowledge 2: Chips can be reduced by drilling after artificially generating minute chips.

  Based on these findings, the first chipping is generated in the workpiece in the projecting electrodeposition portion 40 which is a spheroid, and the chipping finally generated is reduced as a whole. The protruding electrodeposited portion 40 at the tip portion is a preceding hole-piercing portion, the ball-shaped hemispherical portion 31 is a hole expanding portion, and the columnar portion 32 is a finished portion.

(Embodiment 2)
FIG. 8 is a front view of a superabrasive tool for drilling according to Embodiment 2 of the present invention. FIG. 9 is a plan view of a superabrasive tool for drilling as viewed from the direction indicated by arrow IX in FIG. FIG. 10 is a bottom view of the superabrasive tool for drilling as viewed from the direction indicated by the arrow X in FIG. FIG. 11 is a right side view of the superabrasive tool for drilling as seen from the direction indicated by the arrow XI in FIG. 8. FIG. 12 is a left side view of the superabrasive tool for drilling as seen from the direction indicated by arrow XII in FIG. 13 is a cross-sectional view taken along line XIII-XIII in FIG. FIG. 14 is a perspective view of the superabrasive tool shown in FIG.

  With reference to these drawings, in the superabrasive tool 1 for drilling according to the second embodiment, the diameter of the protruding electrodeposited portion 40 at the tip is the superabrasive tool for drilling according to the first embodiment. It is different from the superabrasive tool 1 for drilling according to the first embodiment in that it is larger than 1.

  In the drilling of ceramic parts, the occurrence of chipping at the exit portion of the through hole is a problem, and it is an important issue to suppress the chipping. Conventional countermeasures include drilling from both the front and back surfaces, increasing the machining allowance of the chipped surface, and grinding after drilling, and reducing the chipping by reducing the processing conditions. However, both methods increase the processing time.

  Therefore, in this study, by analyzing the shape and grinding resistance of the chip that occurred during helical boring, we elucidated the mechanism of chipping and proposed a machining method, grinding wheel shape, and grinding conditions to suppress chipping, The purpose is to drastically reduce costs by simplifying the process, shortening the machining time, and reducing the grinding allowance.

Example 1
FIG. 15 is a diagram illustrating an experimental apparatus according to the first embodiment. FIG. 16 is a diagram illustrating a helical path according to the first embodiment. This invention is premised on helical drilling to reduce tool management and the number of tools used.

  As shown in FIG. 15, a superabrasive tool 1 for drilling is attached to a chuck 120 that can rotate and revolve. The coolant is sprayed from the nozzle 110 to the drilling superabrasive tool 1. Further, the axial coolant is also ejected from the tip of the drilling superabrasive tool 1.

  The workpiece 130 is held by a dynamometer 140. The dynamometer 140 is connected to the charge amplifier 150 and the memory recorder 160, and can store various parameters at the time of cutting.

A drilling test was performed under the following conditions.
Grinding tool (superabrasive tool 1 for drilling): SD100P (diameter of hemispherical electrodeposition portion 30: 10 mm, diameter of protruding electrodeposition portion 40 2 Ra: 4 mm, Rb: 0.5 mm, t: 1 mm, groove 41 width: 1mm)
Super abrasive grain type: Diamond Workpiece: Al ₂ O ₃ (A479) Plate thickness 10 mm
Spindle speed N _s : 5000 min ⁻¹
Revolution direction: C.I. C. W. (Counterclockwise)
Revolving radius _Rre : 2mm
Feed rate V _w : 300 mm / min
Grinding wheel cutting amount Δ: 0.2 mm / rev.
Coolant Soluble JIS W2-1 External and axial center lubrication For comparison, a sample (ball end tool) with no protruding electrodeposited part 40 and hemispherical electrodeposited part 30 is also prepared and tested. Went.

  The test results are shown in FIG. In FIG. 17, □ indicates the number of accumulated holes in the ball end tool as a comparative product, and ◯ indicates the product of the present invention.

  In the product of the present invention, it can be seen that the chip width of the workpiece is kept small even when the number of accumulated holes is increased.

(Example 2)
In Example 2, the test was performed assuming that the revolution radius R _re was 1 mm, and that the rest was the same as Example 1. The results are shown in FIG. 18 and FIG. Referring to FIG. 18, in the conventional ball end tool, the maximum chip width was increased after 30 holes were machined. And the tool reached the end of its life with 50 holes. Referring to FIG. 19, in the conventional ball end tool, when the grinding resistance exceeds 600 N, a significant increase in chipping was observed. In the tool of the present invention, chipping increased only slightly even when the grinding resistance exceeded 600N.

  From FIG. 18 and FIG. 19, it can be seen that the proposed tool which is the product of the present invention keeps the maximum chip width of the workpiece small.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  It can be considered that the present invention is used for drilling high brittle materials such as glass, ceramics, and silicon.

  DESCRIPTION OF SYMBOLS 1 Superabrasive tool for drilling, 10 axis, 20 base metal, 21,42 Liquid passageway, 30 Electrodeposition part, 31 Hemispherical part, 32 Cylindrical part, 40 Protrusion electrodeposition part, 41 Groove.

Claims (2)

A base metal that can rotate around its axis;
An electrodeposition portion of superabrasive grains having a substantially hemispherical portion provided at the tip of the base metal;
A protruding electrodeposition portion provided at the tip of the electrodeposition portion ,
The tip of the protruding electrodeposition part has a planar shape, a spherical shape or an aspherical shape,
A cylindrical electrodeposition portion is provided on the rear side of the substantially hemispherical portion,
The base metal is provided with a grinding fluid supply hole leading from the rear end to the front end,
A superabrasive tool for drilling , in which a groove is provided only in the protruding electrodeposition portion so as to divide the protrusion . A method for drilling a workpiece while performing helical feed using the superabrasive tool for drilling according to claim 1.

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