JPS6334005B2 - - Google Patents

Description

[Detailed description of the invention] (Industrial application field) The present invention relates to a drilling expansion drill.

(Prior Art) A conventional drill of this type is known in which the cutting tip is expanded in the radial direction by a taper of a cutting tip guide rod attached to a guide bar (Japanese Patent Application No. 3616/1983). Specification). However, with this drill, chips get stuck between the cutting tip and the guide rod, it cannot be applied to drills with a very small diameter due to the strength of the cutting tip guide rod, and the cutting tip breaks. The disadvantage is that the entire drill must be replaced with a new one if something like this occurs.

(Problems to be solved by the invention) Therefore, the present invention eliminates the drawbacks of the prior art and provides an expansion mechanism that does not cause chip clogging during hole expansion work using a drill and can be applied even when the diameter of the drill is small. The task is to create a drilling expansion drill.

(Means for Solving the Problems) According to the present invention, the above problems are solved by the features set forth in claim 1.

(Effects of the Invention) According to the present invention, the drill is not clogged with chips during drilling and expanding work, and can be suitably applied to small-diameter drills, and the cutter blade moves through the guide bar during the work to remove chips. For example, even if the cutter blade breaks, only the cutter blade needs to be replaced, and there is no need to replace the guide bar itself, and it is also possible to partially replace only the cutting tip. This is an advantage.

(Example) Embodiments of the present invention will be described based on the drawings.

In FIG. 1, a guide bar 1 is fitted into a sleeve 2, and its rear end is fitted into a hole 4 of a drill shank 3 and fixed to the drill shank 3 by a pin 5. The cutter blade 6 cuts into the groove 1 of the guide bar 1 near the tip of the guide bar 1.
The guide bar 1 is rotatably supported by a pivot pin 7 that is inserted into the cutter blade 6 and passes through the hole 6b of the cutter blade 6. A cemented carbide chip 8 is brazed to the tip of the cutter blade 6. Near the rear end of the cutter blade 6, when the drill is not rotating (hereinafter referred to as the "starting position"), cam surfaces 6a, 6a' are deviated laterally with respect to the axis of the guide bar 1 and toward the tip 8. It is formed. Both cam surfaces 6a, 6
a′ runs approximately parallel. The stationary abutment pins 9 attached to the guide portions 2a at the lower end of the sleeve 2 facing each other are in contact with the stationary abutment cam surface 6a in the starting position, and when in operation, the abutment pins 9' in operation are in contact with the abutment cam surface 6a at rest. The tip comes into contact with the cam surface 6a' of the cutter blade 6 and serves to restrict the amount of lateral protrusion of the cutter blade 6. During the retracting process of the drill and the starting position, the center of gravity of the cutter blade is located on the side where the tip 8 is located with respect to the axis of the guide bar 1 so that the tip of the abutment pin 9 and the cam surface 6a come into contact when the drill is at rest. It is set as follows. A compression spring 1 is installed inside the sleeve 2 and outside the guide bar 1.
One end of the compression spring 10 is supported by the inner end of the sleeve 2, and the other end is supported by the end surface of the drill shank 3. In order to prevent the guide bar 1 and the drill shank 3 from being disengaged from the sleeve 2, a stop ring 11 is fitted in the region of the upper end of the sleeve 2, and the stop ring 11 rests against the upper surface of the flange 3a of the drill shank 3. The area of the drill shank 3 protruding from the sleeve 2 is clamped by the chuck of a hammer drill or vibratory drill.

(Action of invention) The drill according to the invention works as follows.

Before using the drill according to the present invention, a straight hole is previously drilled in concrete or rock using a conventional drill (FIG. 4). The guide bar 1 is inserted into this straight hole by operating a hammer drill or a vibration drill. The lower end surface of the sleeve 2 is supported by a concrete surface or a rock surface and remains stationary regardless of the movement of the guide bar. In such a rotating state of the drill, due to the centrifugal force of the cutter blade 6, the operating abutting cam surface 6a' of the cutter blade 6 comes into contact with the tip of the operating abutting pin 9', and the drill shank 3
Therefore, as the amount of feed of the guide bar 1 into the sleeve 2 increases against the force of the compression spring 10, the cam for operating the cutter blade 6 against the tip of the abutting pin 9' during operation increases. According to the inclination of the surface 6a', the tip 8 can be brought into contact so as to move clockwise, whereby the cutter blade 6 is rotated clockwise around the pivot pin 7. The result is a pre-drilled straight hole (fourth
The inner wall of the straight hole is gradually cut to a larger diameter as it goes deeper into the straight hole, thus forming a tapered hole whose diameter increases as it goes deeper from the entrance of the hole (FIG. 5). During the retracting process of the drill and the starting position, the tip of the stationary abutment pin 9 slides into contact with the stationary abutment cam surface 6a of the cutter blade 6 due to the gravity of the cutter blade 6, and thereby the cutter blade 6 is swung back counterclockwise around pivot pin 7 (FIG. 1).

According to the drill according to the present invention, drilling of a lower enlarged hole in concrete, rock, etc. can be performed optimally.

[Brief explanation of the drawing]

FIG. 1 is a front view showing a drill according to the present invention in cross section, FIG. 2 is a side view of the guide bar portion, and FIG.
The figures show a front view of the cutter blade, FIG. 4 a straight hole, and FIG. 5 a cross-sectional view of an enlarged hole formed by a drill according to the invention. Symbols in the figure 1... Guide bar, 2... Sleeve, 3... Drill shank, 6... Cutter blade, 6a... Cam surface for contact when stationary, 6a'... Cam surface for contact during operation, 7... ...Pivot pin, 8...Tip, 9...Pin for abutment when stationary, 9'...Pin for abutment during operation, 10...Compression spring.

Claims (1)

[Claims] 1 At the tip of the drill shank 3, there is a sleeve 2 whose rear end is slidably fitted in the axial direction of the drill shank, and a guide bar 1 whose rear end is fixed to the drill shank 3 through the sleeve 2. The sleeve is provided with a compression spring 10 for urging the sleeve away from the drill shank, and the tip of the sleeve is provided with a pin 9 for abutting the cutter blade 6 at rest, and a pin 9 for abutting the cutter blade 6 when in operation. and the guide bar 1 are provided facing each other.
A pivot pin 7 is provided near the tip of the cutter blade 6, and the cutter blade 6 is rotatably supported on the pivot pin. Near the rear end of the blade 6, on the side where the tip is provided, there is provided a cam surface 6a for stationary contact that contacts the tip of the stationary contact pin 9 of the sleeve at the starting position, and the tip 8 is provided. A cam surface 6a' for abutment during operation, which comes into contact with the tip of the pin 9' for abutment during operation of the sleeve when the drill rotates, is provided on the opposite side to the side where the sleeve is abutted during operation, and both cam surfaces 6a, 6 are provided.
a' is both on the tip side 8 with respect to the axis of the guide bar 1.
A drilling expansion drill characterized by being biased.