JPH0732205A - One way boring drill - Google Patents

Abstract

PURPOSE:To prevent a breakage, so-called clam-like chipping, produced on the surface side of a plate glass from which a drill goes through in boring the plate glass for example. CONSTITUTION:A boring tool for a plate-like workpiece W such as glass, ceramics, etc., for example a core drill 20 provided on the tip of a cutting edge 21 with an abrasive grain layer is formed on the outer peripheral edge of the abrasive grain layer on the tip of the cutting edge 21 with a radiused part R. When the cutting edge 21 goes out of the work piece W, the extent of stress applied to the workpiece W around the drill 20 is narrowed. The workpiece W is worked by one-way working feed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a perforated drill capable of preventing the occurrence of a defect called so-called "bilihama" (claw-like chipping) on the side of the drilling surface in the process of drilling plate glass or the like.

[0002]

2. Description of the Related Art Conventionally, a glass punching machine that punches holes from two directions has been widely known as a device for punching glass for construction and furniture. That is, the work efficiency is good if the hole is drilled by processing (one way) from only one direction. However, as shown in FIG. 8, for example, as shown in FIG. When stress is applied to a wide range of the exit surface of the glass W, cracks d such as cracks and chippings easily occur in a range larger than the drill diameter, and the quality is impaired. There is a problem that glass breakage occurs. Therefore, a glass drilling machine is widely used at present, which prevents holes such as chipping from occurring on the drilling surface side by drilling from two directions. The plate is machined to a position of about half, and a hole is drilled from the lower surface side to the plate thickness of the other half to form a through hole. On the other hand, to improve work efficiency while preventing chipping such as chipping, for example, a taper portion that spreads from the distal end side toward the proximal end side is formed on the outer circumference of the blade part made of an abrasive grain layer, and the tip side and the tapered part are ground. A drill (Fujikoshi Co., Ltd.) that changes the grain size of the grain so that chips such as chipping caused by machining at the tip part can be machined in one way while scraping off with the taper part (Fujikoshi Co., Ltd.) There is also known a drill (Asahi Sakae Co., Ltd.) in which a grain portion is provided to make the grain sizes different, and the taper portion chamfers the yarn surface to remove defects such as chipping.

[0003]

However, the machining from two directions, which has been widely used in the past, not only complicates the machine but also requires accurate alignment of the axes of the upper and lower machining axes. There is a problem that a step is formed in the middle part. Further, in the case of locally changing the abrasive grain size of the abrasive layer of the blade portion as in the one-way improved drill, there is a problem that the drill is not easy to manufacture and the drill is expensive.

[0004]

In order to solve the above-mentioned problems, according to the present invention, a core drill having an abrasive grain layer at the tip of a blade is machined in one direction to drill a plate material such as glass or ceramic. In the perforated drill described above, a rounded portion was formed on the outer peripheral edge of the abrasive grain layer at the tip of the blade.

[0005]

[Function] If the tip of the blade is a straight flat surface, the flat surface of the tip of the blade will come out all at once at the time of drilling and chipping will occur in a wide area such as glass around the drill.
By forming the rounded portion on the outer peripheral edge, when the blade portion comes out, the chipping range generated around the drill is narrowed by gradually coming out from the inner edge to the outer peripheral edge. It is thought that this is because the range of stress applied to the glass and the like around the drill when the blade part comes out is narrowed.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of a one-way drilling tool according to the present invention will be described with reference to the accompanying drawings. FIG. 1 is a front view of a drilling machine that employs this drilling machine, FIG. 2 is a side view of the same, FIG. 3 is a plan view of a work positioning state, and FIG. 4 is a sectional view taken along the line AA of FIG.

This drill is constructed as a drill for drilling a work W such as plate glass such as architectural glass and furniture glass, and is used in a drilling machine 1 as shown in FIG.

That is, the perforator 1 has a base 2 provided with a control panel 9, a work table 3 provided at an intermediate height position of the base 2, and an upper part of the base 2 which can be lifted and lowered. A spindle unit 4 is provided, and a plurality of stoppers 5 for positioning the work W are provided on the upper surface of the work table 3, as shown in FIG.

A rectangular cutout hole 6 as shown in FIG. 3 is provided in the center of the work table 3, and a lower clamp 7 as shown in FIG. 4 is provided below the cutout hole 6. It is said that it can be raised and lowered freely.

The lower clamp 7 is provided with a support plate 10 connected to the cylinder unit 8 and a work contact portion 11 mounted on the upper surface of the support plate 10. The part 11 is designed to be able to enter the cutout hole 6 in the center of the work table 3, and the work contact part 11 is made of a soft material such as rubber to damage the work W surface. I try not to.

On the other hand, above the work table 3, an upper clamp 12 is provided.

As shown in FIG. 2, the upper clamp 12 has a pair of left and right clamp arms 1 whose base end is connected to the cylinder unit 13 and whose middle part is pivotally attached to the base 2.
4, a support plate 15 attached to the tip of the clamp arm 14, and a work contact portion 16 attached to the lower surface of the support plate 15. The work contact portion 16 is also made of a soft material such as rubber. It is composed of materials.

By the way, a drill 20 as shown in FIG. 5 is mounted on the spindle unit 4.

The spindle unit 4 is provided with a hollow shaft spindle 17 with little vibration (for example, 3 μ or less), and the drill 20 can be attached to the tip of the spindle 17, and the base end side of the spindle 17 serves as a coolant liquid supply section. The hollow portion 17a is connected to form a coolant passage.

A hollow portion 20a is also provided inside the drill 20 so as to communicate with the hollow portion 17a of the spindle 17. That is, the coolant liquid supplied through the hollow portions 17a and 20a during processing radially spreads from the central portion of the drill 20 to the periphery and flows toward the processing portion.

The tip of the drill 20 is provided with a blade portion 21 made of an abrasive grain layer. Then, as shown in FIG. 6, a rounded portion R is formed at the tip of the blade portion 21 in a state where the outer peripheral edge is chamfered and rounded.

As shown in FIG. 7, the rounded portion R preferably has a slight flat surface h left on the inner edge side of the tip of the blade 21, and in the case of the embodiment, the thickness of the blade 21 is 0.7 mm. On the other hand, the curvature r of the rounded portion R is about 0.5 mm.

The rounded portion R may have an elliptical shape that is long in the axial direction instead of a circular round shape so as to have a large taper.

Next, the bond degree of the abrasive grain layer of the blade portion 21, the grain size of the abrasive grains, and the concentration will be described.

In determining the bond degree of the bond in the abrasive grain layer, the processing rotation speed is closely related. That is, in general, at high speed rotation, a softer coupling degree is more effective in suppressing chipping, and at low speed rotation, a harder coupling degree is more effective in suppressing chipping.

Therefore, there is a problem whether to select a method of processing a bond having a soft bond with high speed rotation or a method of processing a bond with a hard bond with low speed rotation. In the case of the present invention, the latter is selected. did.

That is, when machining at a high speed, heat generation becomes a serious problem, and various conditions such as cooling conditions by coolant, problems of ensuring rigidity, problems of maintaining spindle accuracy, problems of drill accuracy, etc. become severe, and moreover, This is because a bond with a hard bond has a longer life. As a result of various experiments, a metal bond having a high degree of bonding was selected.

Experiments have also revealed that the grain size of the abrasive grains is closely related to the number of revolutions. For example, if drilling is performed with the same grain size, the sizes of chipping on the front surface and the back surface of the work W are different. However, it was found that when processed at high speed, chipping was smaller on the front surface side when the grain size was finer, and this was not necessarily the case on the back surface side.

On the other hand, if processing is performed at a low speed, on the contrary, the finer the grain size, the smaller the chipping on the back surface side.
It turned out that this is not always the case for the front side.

Therefore, although it cannot be asserted that the finer grain size results in smaller chipping in view of the relationship with the rotation speed, it was decided from the experimental results that fine grain size diamond abrasive grains with small chipping at medium speed rotation were adopted. .

Next, regarding the relationship between the concentration (concentration degree) of the abrasive grains and the chipping, it is considered that there is a close relationship with the bond degree of the bond, etc. As a result of repeated tests, the higher the concentration, the less the chipping. I knew that.

It is considered that this is because as the number of abrasive grains (cutting blades) increases, the sharpness becomes better, and when the number of abrasive grains is small, the result is that the chips are cut by the bond, which also affects the occurrence of chipping.

The operation of the hole drill as described above will be described.

When the work W is positioned on the work table 3 and fixed by being sandwiched vertically by the lower clamp 7 and the upper clamp 12, the spindle 17 comes down while rotating and the machining is started. At this time, at the same time, the coolant is supplied to the processing portion through the hollow portions 17a, 20a of the spindle 17 and the drill 20.

Then, in the work W below the tip blade portion 21 of the drill 20, as shown in FIG. 7, a substantially triangular minute volume portion (hatched portion) is generated below the outer peripheral edge portion, and the blade portion 21 is formed. It is possible to narrow the stress range generated around the drill just before the work W is removed. That is, the chipping width is narrowed.

At this time, the hollow portion 20a at the center of the drill 20 is also used.
The coolant liquid supplied from the nozzle is blown out from the gap between the blade portion 21 and the work W surface in four rounds and acts so as to maintain the shape of the rounded portion R, and the rounded portion R does not disappear even if a large number of holes are drilled. Absent.

By drilling with such a drill 20, the length of chipping can be suppressed within 0.6 mm, and the defect d caused by chipping can be reduced. Further, in the case of the present invention, the processing time is reduced to about 70% of the conventional processing time from two directions.

In the present embodiment, the drill 20 is processed while being lowered from above, but of course it may be processed from below, or may be processed from the side with respect to a vertically placed work. Further, it may be processed by an articulated robot.

Further, in the case of the present invention, the lower surface of the work is not supported by the backup material, but a backup material may be provided, and the work may be made of glass, ceramics, stone material, or the like.

[0035]

As described above, in the one-way hole drill of the present invention, chipping can be reduced without machining from two directions as in the conventional case, and the structure of the machine is simplified. Moreover, since it is a one-way method, the time required for drilling work is shortened and work efficiency is improved. Also, regarding the manufacturing of the drill, the core drill of the conventional type is only slightly improved, and the drill can be manufactured inexpensively and easily.

[Brief description of drawings]

1 is a front view of a drilling machine that employs this drilling drill.

FIG. 2 is a side view of the same.

FIG. 3 is a plan view of a work positioning state.

FIG. 4 is a sectional view taken along the line AA of FIG.

[Fig. 5] Front view of the spindle unit

FIG. 6 is an explanatory view showing a processed state of the drill.

FIG. 7 Partially enlarged view

FIG. 8 is an explanatory view showing a processing state of a conventional drill.

[Explanation of symbols]

 20 drill 21 blade R radius part W work

Claims (1)

[Claims] 1. A perforated drill in which a core drill having an abrasive grain layer at the tip of the blade is fed in one direction to drill a plate material such as glass or ceramic. A one-way drilling drill characterized in that a rounded portion is formed on the outer peripheral edge of the.