JP3567085B2 - Core drill - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a core drill, and more particularly, to a core drill used for drilling a hole having a relatively large diameter in a hollow shape.
[0002]
[Prior art]
Conventionally, a wide variety of core drills have been developed and marketed as core drills for drilling relatively large-diameter holes, and in order to smoothly perform drilling work, a center drill and a core body are combined to form a center drill. Core drills, in which a center hole precedes and a large-diameter hole formed by a core body is drilled thereafter, are also widely used.
[0003]
A core drill of this type in which a base having a shank supported by a chuck of a drive shaft and a core body are detachably connected to each other is separated from each other after the drilling, and a cut-out waste material remaining in the core body is extracted. It is possible to replace the broken core body with a new core body, and prepare multiple core bodies with different types of drill blades made according to the properties of the object to be drilled However, it is convenient when these core bodies are exchanged to pierce a pierced object having different physical properties.
[0004]
As a specific example of the core drill in which the base body and the core body are detachably connected as described above, a core body mounting portion is formed on a base body having a shank, and a peripheral surface of the core body mounting portion is formed from a lower end of the core body mounting portion in a generatrix direction. A hook-shaped engaging groove formed by connecting a lateral groove in the circumferential direction following the vertical groove formed in the groove is formed in the core body mounting portion, and a ball that protrudes and retracts in the engaging groove is biased by a spring. There is a configuration in which a mounting cylinder portion in which the core body mounting portion is inserted is provided on the upper portion of the core body, and an engagement protrusion that engages with and disengages from the engagement groove is provided on the inner surface of the mounting cylinder portion. . With the core drill configured as described above, when the base and the core body are joined, the engaging projections ride over the ball projecting into the engaging groove against the spring, and when the engaging projection reaches the end of the engaging groove, the ball is moved. The engagement projection is held at the end of the engagement groove by projecting into the engagement groove under the bias of the spring, so that the connection between the base and the core body does not loosen during the drilling operation. (For example, see Japanese Utility Model Publication No. 7-39527 as prior art)
[0005]
[Problems to be solved by the invention]
As described above, with a core drill in which the base and the core body are detachably connected, a ball that protrudes and retracts in the engagement groove to connect the base and the core body and hold the engagement protrusion at the end of the engagement groove, In a configuration in which a spring for biasing the spring is provided, the number of components increases accordingly. Further, the number of processing steps for assembling these components in the core body mounting portion also increases.
[0006]
Therefore, an object of the present invention is to reduce the number of components without requiring a ball or a component such as a spring for biasing the ball, simplify the configuration capable of securely connecting the base and the core by coupling the base and the core. It is intended to provide a core drill.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, an invention according to claim 1 of the present invention is a core drill in which a boss portion of a core body is fitted into a coupling hole of a base and coupled via coupling holding means, The holding means comprises a plurality of engaging projections protruding from the inner wall of the coupling hole of the base, and engaging grooves formed on the peripheral surface of the boss corresponding to the engaging protrusions. One of, forming a boss top Rutotomoni provided on the outer surface of the elastic pieces that form set by cutting a slit in the axial direction, the base of the elastic piece, the groove-like thin wall portion to cause deformation of the elastic pieces to the base circumferential direction A protruding portion is provided in the middle of the engaging groove, and the elastic piece is elastically deformed from the groove-shaped thin portion toward the center of the boss portion to move over the protruding portion when the engaging protrusion of the base crosses the protruding portion. And
[0008]
Here, the base has a shank supported by the chuck of the drive shaft at the center of the upper surface, and a center drill or a center pin is attached at the center of the lower surface. The core body has a cylindrical shape, a plurality of cutting blades are formed at the lower opening edge, and a chip discharge groove is provided in the core body corresponding to the cutting blade. The configuration in which the center drill or the center pin is pierced prior to drilling is the same as a known configuration.
[0009]
In the core drill according to the present invention, a downwardly opened coupling hole is formed in the base, and when the base and the core are coupled, the boss portion of the core is fitted into the coupling hole, and the elastic piece is elastically deformed in the fitting process. Then, the elastic piece is finally returned to the original shape, and the connection relationship between the base and the core body is securely maintained. Therefore, in keeping the base and the core united together, the elastic piece formed in the boss portion has the same function as the conventional ball and the spring for biasing the same, thereby reducing the number of parts and reducing the configuration. Can be simplified.
[0010]
In the above configuration, the engagement groove serving as the coupling holding means is formed in a hook shape by connecting a horizontal groove portion in the circumferential direction following the vertical groove portion formed in the generatrix direction from the upper surface of the boss portion and the elastic piece, It is preferable that the raised portion provided in the middle of the engaging groove provided near the entrance of the lateral groove is provided.
[0011]
With this configuration, when the base and the core body are joined, the engagement protrusion moves in the axial direction along the longitudinal groove of the engagement groove, and the lower surface of the base comes into contact with the top surface of the core body. When the body is relatively rotated in the circumferential direction, the engagement protrusion moves to the lateral groove portion. Here, the engagement protrusion deforms the elastic piece from the base against the elasticity of the groove-shaped thin portion of the elastic piece base. Over the ridge to settle at the end of the engagement groove. In this manner, unless the base and the core body are turned artificially in the circumferential direction in opposite directions, the base and the core body do not separate from each other, and the connection relationship between the base and the core body is securely maintained. Therefore, even if it is used for a rotary hammer drill or the like that drills by simultaneously giving both the vibrating impact force and the rotating action, the connection between the base and the core body may loosen during the drilling operation. Since it does not occur, it is suitable for drilling work on concrete, stone and the like.
[0012]
In addition, the elastic piece formed on the boss portion is a general-purpose rotary cutting blade that is formed by slitting the boss portion, after cutting the boss portion, including cutting of the engagement groove, etc. It can be easily formed simply by adding a device. Further, in a state where the base and the core body are separated from each other, the elastic piece is always noticeable as a part of the boss portion, so that it is easy to find an abnormality of the elastic piece.
[0013]
Also, the deformation of the elastic piece when the core body is attached to and detached from the base body is bent from the groove-shaped thinly formed elastic piece base regardless of the presence or absence of the engaging groove recessed on the outer surface of the elastic piece. Is morphologically stable over a long period of time as a coupling holding means or as a part of a boss part or as a part of a boss part.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.
[0015]
FIG. 1 is an exploded front view of the core drill of the present invention, with a part thereof removed, FIG. 2 is a cross-sectional view taken along line AA of FIG. 1, FIG. 3 is a cross-sectional view taken along line BB of FIG. It is a front view of the elastic piece part of the boss | hub part which shows embodiment of invention.
[0016]
In the drawings, reference numeral 1 denotes a base, 2 denotes a core body detachably connected to the base, and 3 denotes a center drill attached to a lower portion of the base.
[0017]
A coupling hole 4 opened downward is formed in the base 1, a shank 5 supported by a chuck of a drive shaft is provided in the center of the upper surface of the base 1, and a center drill is provided in a drill mounting hole 3 a provided in the center of the lower surface of the base 1. 3 is detachably attached by a hit screw 3b which is fitted into the base of 3 and screwed from the side.
[0018]
The core body 2 is formed in a cylindrical shape having a top plate 6, a plurality of cutting blades 7 are formed at an opening edge of a lower end, and a chip discharge groove 8 is provided in the core body 2 corresponding to the cutting blade 7. A boss 9 is provided on the upper surface of the board 6 to be fitted into the coupling hole 4 of the base 1. The boss 9 has a straight slit of an appropriate width cut from the upper surface of the boss to the base of the boss in parallel to the axial direction. An elastic piece 11 is formed at 11a, and is elastically deformable toward the center of the boss. In this embodiment, in order to cause the deformation (bending) of the elastic piece 11 from the base of the elastic piece, a groove-shaped thin portion 12 is formed in the circumferential direction of the base of the elastic piece 11 in the embodiment.
[0019]
Engagement projections 13 are protruded at three locations on the inner wall of the coupling hole of the base 1 as coupling holding means 10 for maintaining the coupling relationship between the base 1 and the core body 2. The engagement groove 14 is provided at two places and on the outer surface of the elastic piece. The engaging groove 14 of the embodiment is formed in a hook shape by connecting a vertical groove 14a formed in the generatrix direction from the upper surface of the boss 9 and the elastic piece 11 to a horizontal groove 14b in the circumferential direction. A raised portion 15 is provided near the entrance of the lateral groove portion of the 11 engaging grooves 14. Further, the engagement protrusion 13 of the embodiment is formed by drilling a bottomed hole 13a of an appropriate size (diameter) from the outside of the base at a corresponding position of the base 1, and punching the bottom of the hole toward a coupling hole. As a result, an engagement projection 13 which protrudes spherically from the inner wall of the coupling hole is formed.
[0020]
In the above-described configuration, in order to connect the base 1 and the core body 2, the boss 9 is fitted into the connecting hole 4 of the base 1. The lower surface of the base 1 is moved into the groove 14 a so that the lower surface of the base 1 contacts the top surface of the core body 2. Thus, when the base 1 and the core body 2 are relatively rotated in the circumferential direction, the engagement protrusions 13 that move through the engagement holes 14 of the elastic pieces 11 are separated from the groove-shaped thin portions 12 provided at the base of the elastic pieces 11. The elastic piece 11 is settled at the end of the engaging groove over the raised portion 15 against the elasticity of the bending, and the bending of the elastic piece 11 immediately returns to the original state, so that the connection relationship between the base 1 and the core body 2 is securely maintained. In this way, unless the base 1 and the core body 2 are turned in the circumferential direction in a direction opposite to the direction in which the base body 1 and the core body 2 are joined, the base 1 and the core body 2 do not separate from each other, and the base 1 and the core body 2 are integrally formed. Is kept.
[0021]
【The invention's effect】
The present invention is implemented in the form described above, and according to the present invention, the elastic piece formed in the boss portion securely holds the connection relationship between the base and the core body. Using a core body with a cutting blade made of a carbide tip, it is used for rotary hammer drills and the like to realize stable and reliable drilling. In addition, since the elastic piece can be easily formed by cutting the boss portion of the core body, it can be provided at low cost without increasing the number of parts.
[Brief description of the drawings]
FIG. 1 is an exploded front view of a core drill according to an embodiment of the present invention, in which a part of a core drill is omitted.
FIG. 2 is a cross-sectional view taken along line AA of FIG.
FIG. 3 is a sectional view taken along line BB of FIG. 1;
FIG. 4 is a front view of an elastic piece of a boss showing the embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Base 2 Core body 3 Center drill 3a Drill mounting hole 3b Hit screw 4 Connection hole 5 Shank 6 Top plate 7 Cutting blade 8 Debris discharge groove 9 Boss part 10 Coupling holding means 11 Elastic piece 11a Straight slit 12 Thin part 13 Mating projection 13a bottomed hole 14 engagement groove 14a vertical groove 14b horizontal groove 15 ridge

Claims (1)

A core drill in which a boss portion of a core body is fitted to a coupling hole of a base and coupled via coupling and holding means, wherein the coupling and holding means comprises a plurality of engaging projections projecting from an inner wall of the coupling hole of the substrate. An elastic groove formed of an engaging groove formed on the peripheral surface of the boss corresponding to the engaging protrusion, wherein one of the engaging grooves is formed by cutting a slit in the axial direction from the upper surface of the boss. Rutotomoni provided in the outer surface, the base of the elastic piece, the groove-like thin wall portion to cause deformation of the elastic piece is formed in the base circumferential direction, a raised portion provided in the middle of the engagement groove, the the raised portion substrate A core drill, wherein an elastic piece is elastically deformed from a groove-shaped thin portion toward the center of a boss portion when the engaging projection gets over, so as to get over the elastic piece.

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