JPH0715307U - Woodworking drill - Google Patents

Abstract

(57) [Summary] [Purpose] The contact area of the twisting blade is reduced during drilling, and the rigidity is increased at the lower end to prevent chipping. [Structure] A twist shaft having a twist side and a twist groove is integrally provided on the tip side of the shank, and a twist blade having a larger diameter and a shorter length than the twist shaft is formed at the tip of the twist shaft, and the tip of the twist blade is formed. Is formed into a taper blade having a smaller diameter toward the tip, and the tip end portion of the taper blade is cut, and a flat blade extending in the radial direction is formed in the cut portion.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a woodworking drill for making holes in wooden columns, beams, and the like.

[0002]

[Prior art]

 As a conventional technique, there is one shown in FIG. In FIG. 4, reference numeral 1 denotes a woodworking drill, which has two twist blades 2 formed on the tip (lower end) side of a cylindrical shank (not shown). The twisted blade 2 is formed to have the same diameter over the entire length, and a center blade 3, a pulling blade 4 and a flat blade 5 are formed at the tip thereof. The center blade 3 is formed in a conical shape and protrudes downward from the axial center of the twisting blade 2. Further, the bristle pulling blade 4 is formed in a tongue shape and protrudes downward from an outer peripheral end of one of the spiral blades 2a of the twisting blade 2. The flat blade 5 is formed by extending in the radial direction at the lower end of the other strip blade 2a of the spiral blade 2. The bristle cutting blade 4 is formed so as to be 180 degrees out of phase with the flat blade 5 in the circumferential direction and protrudes downward from the flat blade 5, and the center blade 3 is lower than the flat blade 5. To project.

[0003]

[Problems to be solved by the device]

 In the above-mentioned conventional type, since the twisting blade 2 has the same diameter over the entire length, the twisting blade 2 comes into full contact with the inner peripheral surface of the hole of the workpiece during drilling. When the center blade 3 is in contact with the work piece, the lower part of the twisting blade 2 is supported by the work piece via the center blade 3, so that the resistance of nodes of the work piece or the like is received. Even if the lower part of the twisting blade 2 is slightly biased to the side, the twisting blade 2 contacts the inner peripheral surface of the hole with a substantially uniform pressure, and the occurrence of vibration is suppressed. However, when the center blade 3 comes out of the work piece downward, the entire surface of the laterally biased twisting blade 2 hits the inner peripheral surface of the hole of the work piece, violently vibrates, and is damaged. was there. In addition, since the hair pulling blade 4 is formed on one side in the radial direction and the flat blade 5 is formed on the other side and is asymmetric with respect to the center of rotation, it is easily affected by wood grain, knots, etc. There was a defect that burr was likely to occur on the exit side when high-speed holes were drilled. The present invention relates to a novel woodworking drill that overcomes the above drawbacks.

[0004]

[Means for Solving the Problems]

 The present invention is configured as follows to achieve the above object. That is, a twist shaft having a twist side and a twist groove is integrally provided on the tip side of the shank, and a twist blade having a larger diameter and a shorter length than the twist axis is formed at the tip of the twist shaft, and the tip of the twist blade is formed. Is formed into a taper blade having a smaller diameter toward the tip, and the tip portion of the taper blade is cut, and a flat blade extending in the radial direction is formed in the cut portion.

[0005]

【Example】

 An embodiment of the present invention will be described below with reference to the drawings. In the drawings, FIG. 1 is a side view showing an embodiment of the present invention, FIG. 2 is a bottom view thereof, and FIG. 3 is a view A shown in FIG. In FIG. 1, reference numeral 10 is a woodworking drill, and a twist shaft 12 is integrally formed on the lower (tip) side of a cylindrical shank 11. The twisted shaft 12 has a diameter D1 of 11 mm, and has two twisted sides 12a and a twisted groove 12b.

A twisting blade 13 having a diameter larger than that of the twisted shaft 12 is formed in the lower portion (tip portion) of the twisted shaft 12. The spiral blade 13 has a diameter D2 of 15 mm and a length L1 of 10 mm, and has two blades 13a and 13b which are continuous with the spiral side 12a and the spiral groove 12b of the spiral shaft 12 described above. Further, a taper blade 14 is formed in the lower part of the twisting blade 13 so as to be inclined downward from the lower end of each blade 13a and in the axial direction. Each inclination angle α of these tapered blades 14 is set to 25 degrees.

The taper blade 14 has a vertical length L2 of 8.6 mm and cuts a lower end portion thereof, and a pair of flat blades extending in mutually opposite radial directions are cut at the cut portion, as shown in FIG. The blade 15 is formed, and the axial center of each flat blade 15 is connected by a chisel blade 16. The ratio of the diameter D2 of the twisting blade 13 to the diameter D1 of the twisting shaft 12, the length L1 of the twisting blade 13 and the inclination angle α of the taper blade 14 are the wood to be punched (workpiece). It is appropriately set according to the material, hole diameter, etc.

According to the above-described embodiment, the large-diameter twist blade 13 comes into contact with the inner peripheral surface of the hole of the workpiece during drilling, and the small-diameter twist shaft 12 does not come into contact with the hole. When the tapered blade 14 is in contact with the workpiece, the helical blade 13 is supported by the workpiece via the tapered blade 14, and each blade 13a of the helical blade 13 has an inner peripheral surface of the hole. It comes into contact with the surface at a substantially equal pressure and smoothly cuts. Further, since the taper blades 14 and the flat blades 15 are symmetrical about the rotation axis, the straightness at the time of drilling becomes high. Further, the chips generated during cutting pass through the groove 13b of the spiral blade 13 and the spiral groove 12b of the spiral shaft 12 and are smoothly discharged upward.

Further, even when the twisting blade 13 is slightly deviated to the side due to the resistance of the node of the workpiece during drilling, the twisting shaft 12 does not contact the inner peripheral surface of the hole of the workpiece, and When the drill 10 is moved in the removal direction after the completion, only the twisting blade 13 having a small contact area hits the inner peripheral surface of the hole, which reduces the load and suppresses the occurrence of vibration.

[0010]

[Effect of device]

 As is apparent from the above description, the present invention has a large-diameter or short-length helix blade formed at the tip of the helix shaft, and a tapered blade formed at the tip of the helix blade for punching. Vibration at the time of drilling is reduced and straightness is improved. Further, since the flat blade extending in the radial direction is formed at the lower end of the taper blade, the rigidity of the lower end portion of the drill is increased, and the effect of preventing chipping is obtained.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of the present invention.

FIG. 2 is a bottom view according to the present invention.

FIG. 3 is a view shown in FIG. 2A.

FIG. 4 is a side view showing a conventional example.

[Explanation of symbols]

 10 Woodworking Drill 11 Shank 12 Twisting Shaft 12a Twisted Edge 12b Twisting Groove 13 Twisting Blade 13a Blade 13b Groove 14 Tapered Blade 15 Flat Blade 16 Chisel Blade

Claims (1)

[Scope of utility model registration request] 1. A twist shaft having a twist side and a twist groove is integrally provided on the tip side of the shank, and a twist blade having a diameter and a shorter length than the twist shaft is formed at the tip of the twist shaft. A woodworking drill characterized in that a tip portion is formed into a tapered blade having a smaller diameter toward the tip, the tip portion of the tapered blade is cut, and a flat blade extending in a radial direction is formed in the cutting portion.