JP3632288B2 - Rotary cutting tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a rotary cutting tool used for drilling a hole for installation such as an outlet installed on a wall surface or the like.
[0002]
[Prior art]
A conventional rotary cutting tool of this type is shown in FIG. The grip a and the cover b form an outer shell, and a rotary shaft c is rotatably inserted into the center of the grip a, and the cutting blade d and the rotary shaft arranged in the cover b. c. The cutting blade body d is formed in a U-shape with a horizontal hook e perpendicular to the rotation axis c and blade portions f attached to both ends of the horizontal hook e, and the center of the horizontal hook e and the tip of the rotation axis c are connected to each other. It is connected. A center drill g is attached to the center of the recumbent e. Accordingly, the center drill g and the cutting blade body d are rotationally driven by rotationally driving the rotary shaft c, and a circular hole centered on the center drill g is drilled by pressing against the workpiece.
[0003]
[Problems to be solved by the invention]
However, in the above conventional example, since the driving force is always transmitted from the rotating shaft to the cutting blade body, the cutting blade body may rotate unexpectedly and cause injury. In addition, when two cutting blades are provided instead of one cutting blade as described above so that two circular holes can be opened simultaneously, the cutting blade hits the workpiece when not cutting, and rotates. When the is locked, there is a problem that a hand having a grip is twisted by a force that rotates the outer shell body from the cutting blade side and the hand is injured.
[0004]
The present invention has been made in view of the description, and it is an object of the present invention to ensure safety by interrupting transmission of a driving force from the rotating shaft to the cutting blade except when drilling is performed. .
[0005]
[Means for Solving the Problems]
In order to solve the above problems, a rotary cutting tool according to the present invention supports a rotary body block comprising a cutting blade that is rotationally driven, a rotary shaft that rotationally drives the cutting blade, and a rotary body block that is slidably and rotatably supported. In a rotary cutting tool comprising an outer shell having a grip that can be held by hand, a pair of drive shafts are rotatably mounted so as to be rotationally symmetric about the rotary shaft, and cutting blades are respectively provided at the ends of the pair of drive shafts. The gears provided around the rotary shaft and the gears provided on the pair of drive shafts are meshed with each other, and the gears provided on the pair of drive shafts are meshed with each other to rotate around the rotary shaft. When the cutting blade is pressed against the workpiece , the gear and the rotary shaft around the rotary shaft are connected so as to transmit power by sliding when the cutting blade is pressed against the workpiece . gear and rotation Characterized in that it comprises providing a clutch which is spring-loaded so as to slide in the direction of separating the transmission of the. With this configuration, the cutting blade is not driven even when the clutch is normally disengaged and the rotary shaft is driven to rotate, and the clutch is engaged only when the cutting blade is pressed against the workpiece and cutting is performed. Then, the rotation of the rotating shaft is transmitted to the cutting blade and cutting is performed. For this reason, there is no risk of the cutting blade rotating unexpectedly and injury, and safety can be ensured.
[0006]
It is also preferable that the rotation trajectories of the pair of cutting blades are partially overlapped. In this case, the pair of cutting blades can be drilled so that a pair of circular holes are continuous. Of course, the cutting blade does not rotate when not cutting with the cutting blade, so the cutting blade unexpectedly hits the workpiece. Even the outer shell is not swung around.
[0007]
It is also preferable that a center drill is provided on the cutting blade, and the tip of the center drill protrudes from the tip of the cutting blade. Even if the cutting blade starts to rotate after being pressed against the workpiece, only the center drill hits first and then the cutting blade hits. A small motor for driving the shaft is sufficient.
[0008]
It is also preferable that the clutch is constituted by serrations. In this case, when the clutch is engaged, the rotation can be reliably transmitted by serration, and since the clutch can be engaged and disengaged smoothly, the force for pressing the cutting blade against the workpiece when cutting is small.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The rotary cutting tool A of the present invention is used by being mounted on the electric rotary tool B. The outer shell housing 1 of the rotary cutting tool A is composed of a cylindrical grip 2 on the base side and a cover 3 having a large diameter on the tip side. A mechanism case 4 is housed inside the cover 3, and a spring receiving member 5 and a spring receiving body 6 are housed inside the grip 2. The mechanism case 4 is prevented from rotating with respect to the cover 3 by a rotation-preventing ridge 8 and a rotation-preventing groove 7, but is movable in the axial direction. The spring receiving member 5 is provided integrally with the housing 1. The spring receiving body 6 is prevented from rotating with respect to the grip 2 but is movable in the axial direction. The rotating shaft 9 is disposed at the center of the rotary cutting tool A, and is inserted into the shaft hole of the spring receiving body 6, the shaft hole of the spring receiving member 5, and the mechanism case 4. It is free to slide. Locking rings 10 and 11 are attached to the rotating shaft 9 to restrict sliding of the spring receiving member 5 and the mechanism case 4 in one axial direction with respect to the rotating shaft 9. A coil spring 12 is interposed between the spring receiving member 5 and the spring receiving body 6 on the outer periphery of the rotating shaft 9 and biased in a direction in which the spring receiving member 5 and the spring receiving body 6 are separated from each other. A cylindrical body 13 is fitted on the outer periphery of the base side of the rotating shaft 9, and the cylindrical body 13 is coupled to the rotating shaft 9 with a pin 14, and a spring receiver 6 is attached to an end surface on the distal end side of the cylindrical body 13. Is in contact.
[0010]
A drive shaft 15 a and a drive shaft 15 b are rotatably mounted on the mechanism case 4 so as to be 180 ° rotationally symmetric about the rotation shaft 9. Cutting blades 16a and 16b and center drills 17a and 17b are attached to the tips of the drive shafts 15a and 15b, respectively. The cutting blades 16a and 16b are formed in a substantially U shape. As shown in FIG. 4, the center drills 17a and 17b have a drill portion 18 at the distal end, a polygonal portion 19 at the base side, an attachment screw portion 20 at the base end, and insertion of the cutting blades 16a and 16b. The mounting screw portion 20 is inserted into the hole 21, and the mounting screw portion 20 is screwed into the mounting hole 22 of the drive shafts 15a and 15b, whereby the cutting blades 16a and 16b and the center drills 17a and 17b are joined to the drive shafts 15a and 15b together. It is attached to. The cutting blade 16a and the cutting blade 16b are attached in an orthogonal direction. The tips of the center drills 17a and 17b are protruded to the tip side from the tips of the cutting blades 16a and 16b. In the mechanism case 4, a gear 24 is rotatably disposed on the outer periphery of the rotating shaft 9, and a rotating member 25 and a gear 24 that are rotatably mounted on the tip of the rotating shaft 9 are disposed on the outer periphery of the rotating shaft 9. The coil spring 26 is connected. A clutch made of serration is provided between the gear 24 and the rotary shaft 9. That is, a serration portion 27a is provided on the inner periphery of the shaft hole of the gear 24, and a serration portion 27b that meshes with the serration portion 27a is provided on the outer periphery of the rotary shaft 9, and the gear 24 slides against the coil spring 12 toward the base side. As a result, the serration portions 27a and 27b are engaged with each other, and the gear 24 is slid to the front end side by the coil spring 12 so that the engagement of the serration portions 27a and 27b is released. A gear 28 is integrally provided on the base side of the drive shaft 15a, and the gear 28 and the gear 24 are engaged with each other. A gear 29 is attached to the distal end side of the drive shaft 15a, a gear 30 is attached to the distal end side of the drive shaft 15b, and the gear 29 and the gear 30 are engaged with each other. Thus, when the gear 24 is driven by the rotary shaft 9, the drive shaft 15a is driven through the gears 24 and 28, the drive shaft 15b is driven through the gears 29 and 30, and the cutting blades 16a and 16b and the center are driven. Drills 17a and 17b are driven.
[0011]
Further, as shown in FIG. 1, the electric rotary tool B such as an electric screwdriver is formed by incorporating a motor 34, a speed reducer 35, a clutch 36, and an output shaft 37 in a main body housing 33 having a grip 32. The chuck 38 can be rotationally driven via the speed reducer 35, the clutch 36, and the output shaft 37. When the rotary cutting tool A is attached to the electric rotary tool B, the base of the rotary shaft 9 is gripped by the chuck 38.
[0012]
Next, the operation of the rotary cutting tool A configured as described above will be described. When the hole is not cut, the clutch is disengaged as shown in FIGS. 1 and 2, and the serration portions 27a and 27b are not engaged. That is, the mechanism case 4 is biased by the coil spring 12 so as to go to the tip side, and the serration portions 27a and 27b are not engaged with each other. For this reason, even if the rotary shaft 9 is rotationally driven by the electric rotary tool B, the rotary shaft 9 only rotates idle, and the cutting blades 16a and 16b and the center drills 17a and 17b are not driven. When the tips of the center drills 17a and 17b, the tips of the cutting blades 16a and 16b, and the tip of the cover 3 are pressed against the workpiece in order to make a hole in the workpiece, the mechanism case 4 and the cover 3 resist the coil spring 12. Move to the base side. Then, the gear 24 moves to the base side, and as shown in FIG. 3, the serration portions 27a and 27b are engaged to engage the clutch. If the rotary shaft 9 is rotating at this time, the drive shafts 15a and 15b are driven via the gears 24, 28, 29 and 30, and the cutting blades 16a and 16b and the center drills 17a and 17b are driven to rotate. Drilling is performed. At this time, the mechanism case 4 moves to the base side to a position where the serration portions 27a and 27b are engaged with each other, but the further movement does not move and the drilling proceeds. The cover 3 moves relatively to the base side against the coil spring 12 as the drilling proceeds. In the case of the present invention, since the tips of the center drills 17a and 17b protrude from the tips of the cutting blades 16a and 16b, the center drills 17a and 17b come in contact with the workpieces before the cutting blades 16a and 16b. For this reason, even if the rotating shaft 9 is driven after being pressed against the workpiece, the starting torque is small and the rotation is not locked. By rotating the pair of cutting blades 16a and 16b to pierce the holes as described above, a sag-like hole formed by connecting two circular holes is drilled. When the rotary cutting tool A is extracted from the hole after the hole has been drilled, the cover 3 and the mechanism case 4 are moved to the distal end side by the coil spring 12, the clutch is disconnected, and the cutting blades 16a and 16b and the center drills 17a and 17b are rotated. Stops.
[0013]
【The invention's effect】
In the present invention, as described above, a pair of drive shafts are rotatably mounted so as to be rotationally symmetric about the rotation shaft, and cutting blades are detachably mounted at the ends of the pair of drive shafts, respectively. And the gears provided on the pair of drive shafts are meshed with each other, and the gears provided on the pair of drive shafts are meshed with each other, and between the gears provided around the rotary shaft and the rotary shafts. When the cutting blade is pressed against the workpiece, the gear around the rotating shaft and the rotating shaft are connected so as to transmit power by sliding and the transmission between the gear around the rotating shaft and the rotating shaft is normally separated. A spring-biased clutch is provided so that the cutting blade is normally disengaged and the cutting blade is not driven even when the clutch is disengaged and the rotary shaft is driven to rotate. Only when trying to cut the clutch Rotation of the rotary shaft be those cutting is transmitted to the cutting edge is made I, in which can be secured there is no fear safety injured rotates and unexpectedly cutting edge.
[0014]
In the invention according to claim 2 of the present invention, since the rotation trajectories of the pair of cutting blades are partially overlapped, the pair of cutting blades are drilled so that the pair of circular holes are continuous. Of course, since the cutting blade does not rotate when it is not cut with the cutting blade, the outer shell body is not swung even if the cutting blade unexpectedly hits the workpiece.
[0015]
In the invention according to claim 3 of the present invention, the center drill is provided on the cutting blade, and the tip of the center drill protrudes from the tip of the cutting blade, so that the rotation is performed after pressing the cutting blade against the workpiece. Even when starting, only the center drill hits first and then the cutting blade hits. Therefore, the starting torque can be reduced, the rotation is not locked, and the motor for driving the rotating shaft can be small.
[0016]
In the invention according to claim 4 of the present invention, since the clutch is constituted by serrations, the rotation can be reliably transmitted by serrations when the clutch is engaged, and the clutch slides smoothly and the clutch. Therefore, when cutting, the force for pressing the cutting blade against the workpiece is small.
[Brief description of the drawings]
FIG. 1 is a partially omitted sectional view showing a rotary cutting tool and an electric rotary tool according to an embodiment of the present invention, with a clutch disengaged.
FIG. 2 is a cross-sectional view in a state where a clutch for enlarging the rotary cutting tool portion is disengaged.
FIG. 3 is a cross-sectional view of the rotary cutting tool portion of the above in a state where a clutch is engaged.
FIG. 4 is a perspective view of the above center drill.
FIG. 5 is a cross-sectional view of a conventional example.
[Explanation of symbols]
A Rotary cutting tool 2 Grip 9 Rotating shaft 12 Coil spring 16a Cutting blade 16b Cutting blade 17a Center drill 17b Center drill

Claims (4)

Rotational cutting comprising a rotary body block comprising a cutting blade that is rotationally driven and a rotary shaft that rotationally drives the cutting blade, and an outer shell body having a grip that supports the rotary body block in a slidable and rotatable manner and that can be held by hand. In the tool, a pair of drive shafts are rotatably mounted so as to be rotationally symmetric about the rotation shaft, and a cutting blade is detachably mounted at the tip of the pair of drive shafts, and is provided around the rotation shaft. The gear and the gear provided on the pair of drive shafts are meshed, the gears provided on the pair of drive shafts are meshed with each other, and the cutting blade is disposed between the gear provided on the rotation shaft and the rotation shaft. The gear around the rotating shaft and the rotating shaft are connected by the slide so as to transmit the power when pressing the workpiece against the work piece, and the sliding is normally performed in a direction separating the transmission between the gear around the rotating shaft and the rotating shaft. As Rotary cutting tool, characterized by comprising providing a biased clutch. 2. The rotary cutting tool according to claim 1, wherein the rotation trajectories of the pair of cutting blades are partially overlapped. The rotary cutting tool according to claim 1 , wherein the tip of the center drill protrudes from the tip of the cutting blade. The rotary cutting tool according to claim 1 , wherein the clutch is composed of serrations.

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