JPH0440811Y2 - - Google Patents

Description

[Detailed explanation of the idea] <Industrial application field> The present invention relates to improvements in hole saws.

<Prior art> A hole saw is generally composed of a cylindrical body with a cutting edge provided on the tip edge and a guide drill extending from the inside of the cylindrical body to the tip, and by rotating both in unison, This is to drill a hole in the workpiece under the guidance of a guide drill that has approximately the same external shape as the cylindrical body. At this time, the hole drilled in the object to be cut is, of course, circular. Therefore, when drilling a circular hole, the preconception that it is most preferable for the cylindrical body of the hole saw to be circular has prevailed among those skilled in the art.

<Problems to be Solved by the Invention> However, when a circular hole is drilled in a cylindrical body, the gap between the cut hole and the tube is extremely small. Therefore, chips generated during cutting are not properly discharged, resulting in clogging of the cutting blade. In particular, this clogging becomes more serious when the thickness of the workpiece is large or when a large amount of chips are generated from the workpiece. For example, when the workpiece to be cut is soft iron, this problem becomes apparent when the thickness of the workpiece exceeds 10 mm, or when the workpiece is an ALC plate that generates a lot of chips.

As a general means for solving the problem of the generation of chips, it is known to form spiral grooves for removing chips on the outer periphery of the cylindrical body. However, this groove is usually formed by cutting, which complicates the manufacturing process of the hole saw. Further, the effective depth of the groove for removing chips needs to be 1.0 to 1.5 mm or more, and in order to form the groove, the thickness of the entire cylindrical body needs to be about 3.0 mm. Therefore,
Complicated manufacturing processes and increased plate thickness are factors that push up product costs.

Further, after repeated use, when the cutting blade formed at the tip of the cylindrical body becomes dull, the entire hole saw is discarded. However, since the ALC board has a thickness of about 10 to 20 cm, the length of the cylindrical body must be made as long as the thickness. As a result, if only the cutting edge at the tip deteriorates, and the other parts are also discarded, the amount of waste would be extremely long.

<Means for Solving the Problems> Accordingly, the present invention solves the above problems by providing a modified hole saw having the following configuration.

The modified hole saw of the present invention includes a cylindrical body portion 3, a shank 1 disposed on the proximal side of the body portion and received in a rotary tool, and a guide drill 4 extending from the body portion toward the distal end side. The main body and
It is comprised of a tip cylindrical body 5 that is detachably attached to the tip of the body portion 3 of this main body.

In its cross section, this tip cylindrical body 5 has a plurality of circular arc portions 5a having a radius substantially the same as the radius of the target hole, and is arranged between end portions 5a' and 5a' of the circular arc portions 5a in a radially inward direction. It is composed of a plurality of rectilinear or curved receding portions 5b, 5b', 5b'' which have receded to A cylindrical eggplant whose difference from the shortest distance from the tip is greater than or equal to the thickness of the tip cylindrical body.

The circular arc portion 5a and the retreating portion 5 of this tip cylindrical body
A plurality of cutting blades 51 are provided at the tip edges of each of b, 5b', and 5b''.

On the other hand, at the tip of the body portion 3, an arcuate portion 5a and retreated portions 5b, 5b', 5 of the tip cylindrical body 5 are provided.
A circular arc portion 32a and a recessed portion 32b are formed, respectively, inscribed in ``b''.

<Function> In contrast to conventional hole saws, the cross section of the cylindrical tip is perfectly circular, and the position of the cutting blade formed at the tip of the cylindrical tip is changed. Therefore, in the present invention, the circular arc portion 5a and the retracted portions 5b, 5b', and 5b'' are formed on the tip cylindrical body itself.Therefore, the position of the cutting blade 51 formed at the tip of the tip cylindrical body is The change can be dramatically increased.Therefore, a circular groove with a large width can be cut into the workpiece.

In the present invention, the tip cylindrical body is composed of the arcuate portion 5a and the retracted portions 5b, 5b', and 5b'' as described above, so that the outer circumferential surface of the retracted portion and the inner circumferential surface of the groove formed by cutting are and between the inner peripheral surface of the arc portion and the outer peripheral surface of the groove, there are large gaps 7c, respectively.
is formed. As a result, chips are received in this large gap 7c, and there is no possibility that the chips will become tightly packed between the tip cylindrical body and the groove, and the cutting (rotation) resistance will not increase. do not have.
In particular, since the entire tip cylindrical body (i.e., not only the tip where the cutting blade is provided, but also the entire base end) is composed of the above-mentioned arcuate portion and receding portion, the thickness can be reduced. Even if this hole saw penetrates deeply into a large workpiece, this large gap will continue not only at the tip but also throughout the entire base. Therefore, not only the tip of the cylindrical tip but also the base end, there is no chance of chips becoming tightly packed between the cylindrical tip and the groove, and cutting resistance can be reduced to the end. It becomes possible to make it into a small state.

Moreover, in the present invention, the arcuate portion 5a and the recessed portion 5b provided to improve the cutting ability of the tip cylindrical body 5 are used to prevent rotation, and the arcuate portion 32a and the recessed portion 32a are provided at the tip of the body portion. part 32
By simply forming b, it is possible to prevent the tip cylindrical body from rotating.

<Example> Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a partially sectional side view showing an exploded view of a hole saw according to an embodiment.

This hole saw has a base 2 having a shank 1 connected to a power tool (not shown), a cylindrical body portion 3, and a guide drill 4 attached thereto.

The guide drill 4 has its proximal end 41 inserted into the insertion hole 21 of the base 2, and is fixed by a screw (not shown) inserted into the screw hole 22. A drill blade 42 is formed at the tip of the guide drill 4,
This drill blade 42 protrudes from the tip of the body portion 3 and the tip cylindrical body 5 connected and fixed thereto, and serves as a guide for cutting by the tip cylindrical body 5.

The tip cylindrical body 5 has a large number of cutting blades 5 at its tip.
1, and by rotating it, a circular hole is made in the workpiece. The tip cylindrical body 5 has an arcuate portion 5a and a retreated portion 5b in a cross section perpendicular to its axial direction.
(See FIG. 2, which is a sectional view showing a state in which the distal end cylindrical body 5 is inserted into the insertion portion 32 at the distal end of the body portion 3). The arcuate portion 5a has a circumference that is approximately the same as the target hole diameter. The retreating portion 5b is
It has a substantially linear shape that recedes in the radial direction compared to the arcuate portion 5a, and the ends 5a', 5 of the arcuate portion 5a
It is coordinated between a′.

Therefore, as shown in FIG. 3, a circular groove that is wider than a normal cylindrical hole saw is cut into the workpiece, and the outer periphery 7a of the groove, the inner periphery 7b, and the tip cylindrical body 5. There is a gap 7c between the two, and chips are allowed to escape into the gap 7c. As a result, the ALC board, which generates a large number of chips, is not clogged with chips and can be drilled.

This tip cylindrical body 5 is inserted and fixed to the tip of the body portion 3. Therefore, a flange part 31 and an insertion part 32 are formed at the distal end of the body part 3, and the distal end cylindrical body 5 has its base connected to the insertion part 3.
2 and abuts against the flange portion 32. The insertion portion 32 has an outer circumferential shape corresponding to the inner circumferential shape of the distal end cylindrical body 5 . That is, as shown in Figure 2,
The outer circumferential shape of the insertion portion 32 has three circular arc portions 32.
a and three setback portions 32b. In this embodiment, the retreated portion 32b was formed by cutting the outer periphery of the cylindrical body portion at three locations, but it may also be formed by bending.

Furthermore, as shown in FIG. 1, a locking groove 33 extending in the circumferential direction is formed in the arcuate portion 32a of the insertion portion 32, and on the other hand, on the inner periphery of the arcuate portion 5a of the tip cylindrical body 5, A protrusion 52 is formed. By engaging the protrusion 52 with the locking groove 33, the tip tubular body 5 is prevented from coming off. however,
As long as the distal end cylindrical body 5 and the insertion portion 32 are perfectly fitted, it is not necessary to provide such a locking means, and it is also possible to change to other locking means.

Next, the flange portion 31 has an outer diameter approximately equal to the outer diameter of the tip cylindrical body 5. And insert part 3
The part following the retreating part 32b of No. 2 is a slope 31b cut diagonally so as to be smoothly continuous. Note that this slope 31b does not necessarily need to be formed. Conversely, the outer circumferential shape of the flange portion 31 may be made the same as the outer circumferential shape of the tip cylindrical body 5.

The outer diameter of the body portion 3 is made smaller than the outer diameter of the flange portion 31, thereby securing a space between the body portion 3 and the inner wall of the borehole that can receive chips. They may be the same.

Furthermore, the cross-sectional shape of the body is free,
In addition to a circle, it may be shaped to match the cross-sectional shape of the cylindrical tip, or it may be polygonal.

As described above, with this hole saw, the cylindrical tip can perform drilling while ensuring good discharge of chips, and since the cylindrical tip can be attached to and removed from the body, the cylindrical tip can be removed from the body. It is possible to convert only

In the embodiment described above, the tip cylindrical body 5 has a central angle.
Three 70-degree circular arc portions 5a and three receding portions 5b with a center angle of 50 degrees are arranged alternately, but these angles may vary depending on the type of workpiece, thickness, hole saw diameter, etc. Various changes may be made depending on the situation. Similarly, the numbers of the arcuate portions 5a and the recessed portions 5b may be changed as appropriate, such as two each as shown in Fig. 4, four each as shown in Fig. 5, and six each as shown in Fig. 6. The number can be changed as appropriate, such as one by one. Generally, as the diameter of the hole saw increases, it is desirable to increase the number of each hole saw, but if the diameter is small and the material of the workpiece is relatively soft, it is also possible to use one each.

Further, as shown in FIG. 7, vertical grooves 11 or spiral grooves 12 may be provided on the surface of the tip cylindrical body and further on the body portion in order to enhance the chip removal function.

The base portion 2 and the body portion 3 may be integrally molded, or may be molded separately and then fixed by welding or the like. Further, the base portion 2 and the body portion 3 may be made removable, and only the body portion 3 may be replaceable.

Although the retreated portion 5b has a substantially straight shape in the embodiment, it is not limited to this, and may be curved. For example, as shown in FIG. 8, it may have a curvature and recede. Furthermore, the ninth
As shown in Figures 10 and 11, instead of receding with curvature, the diameter of the cylindrical body 5 itself is constructed by combining the circumferences of a plurality of concentric circles with different diameters, It may also form a recessed portion. To be more specific, what is shown in FIG. 9 is the retreating portion 5b.
is made up of a circumference with a constant diameter. What is shown in FIG. 10 is a portion further retreated to the retreating portion 5b (the number is not limited to the number shown in the figure).
That is, it has the last retraction 5b'. The one shown in FIG. 11 has an overhanging portion 5 in the retreated portion 5b with a larger diameter than the others.
b'' (the number is not limited to what is shown in the figure). A more preferred embodiment will be shown again using FIG. The cutting blade 51'' disposed at the smallest diameter portion of the portion 5b is positioned so as to trace on or near a locus drawn by rotation (ie, a circle (0)). This is to cover the part where the number of blades corresponding to a specific part of the surface to be cut is the least, and to reduce the load on the cutting blade at that position. Such considerations are particularly meaningful when the object to be cut is metal. When cutting soft iron, etc., it is common to have a ``crow'' of about 2 mm, and it is desirable that the cutting blade be aligned on a circle with this width. To give an example in detail, when drilling soft iron, the ``clam'' was generally about 2 mm. The number of cutting blades of the cylindrical body 5 having a radius of 2 to 3 cm is approximately 30. Other cutting blades are omitted in FIG.

The cutting blade 51 may be provided by attaching a cutting edge tip.

As described above, the present invention is not limited to the illustrated embodiments, but can be implemented with various modifications.

<Effects of the invention> As described above, the hole saw of the present invention has a cylindrical shape in which at least the tip side portion of the tip cylindrical body is composed of a circular arc portion and a receding portion. A wide circular groove is cut into the workpiece. As a result, a gap is created between the outer and inner circumference of the groove and the cylindrical body, and chips are allowed to escape into the gap.
Chips are properly removed from ALC boards, etc.
This allows for good cutting.

Furthermore, in the present invention, the tip cylindrical body can be replaced, and economical use is possible. Furthermore, as for the structure for attaching and detaching the distal end cylindrical body, it is possible to reliably prevent rotation by simply forming an arcuate portion and a recessed portion at the distal end of the body portion of the main body. Therefore, it is possible to make a large profit with simple processing.

[Brief explanation of drawings]

Fig. 1 is a partially sectional side view showing the disassembled state of the hole saw of one embodiment, Fig. 2 is a sectional view showing the state in which the cylindrical tip body is inserted into the tip of the body portion, and Fig. 3
The figure is an explanatory diagram showing the state of cutting by the tip cylindrical body, FIGS. 4 to 6 are explanatory diagrams of the shape of the tip cylindrical body of other embodiments, and FIG. 7 is an explanatory diagram of the shape of the tip cylindrical body of another embodiment. FIG. Figure 8, Figure 9, Figure 10
11A and 11B are shape explanatory diagrams showing still other embodiments. DESCRIPTION OF SYMBOLS 1...Shank, 3...Body part, 4...Guide drill, 5...Tip-end cylindrical body, 5a...Circular arc portion, 5b...Retreat portion, 5a...End of circular arc portion.

Claims (1)

[Claims for Utility Model Registration] A cylindrical body portion 3 and a shank 1 disposed on the base end side of this body portion and received in a rotating tool.
and a guide drill 4 extending from the body portion toward the tip side, and a tip cylindrical body 5 detachably attached to the tip of the body portion 3. In the cross section, a plurality of circular arc portions 5a having a radius substantially the same as the radius of the target hole, and a plurality of linear or curved portions arranged between the ends 5a', 5a' of the circular arc portion 5a and receding in the radial direction. The difference between the radius of the arcuate portion 5a and the shortest distance from the center of the tip cylindrical body in the retreated portions 5b, 5b', 5b'' is the tip. It has a cylindrical shape with a thickness greater than the thickness of the cylindrical body, and the arc portion 5a and the retreating portion 5 of this tip cylindrical body.
A plurality of cutting blades 51 are provided on the tip edges of each of the body portion 3, and on the other hand, the arcuate portion 5a and the retreated portions 5b, 5b', of the tip cylindrical body 5 are provided at the tip of the body portion 3. 5b'', a circular arc portion 32a and a retreating portion 32, respectively, are inscribed in
A modified hole saw characterized in that b is formed.