JP2024018195A - rotary cutting tool - Google Patents

Abstract

To provide a technique for firmly fixing an arm to a rotary shaft.SOLUTION: A universal blade unit 4 includes: a first arm 12a and a second arm 12b which face each other across a shaft component 30; a first cutting blade 14a and a second cutting blade 14b which are fixed to the first arm 12a and the second arm 12b, respectively; and an adjustment mechanism 60 which makes the first arm 12a and the second arm 12b movable with respect to the shaft component 30. The adjustment mechanism 60 has a slide mechanism 62 and a fixing mechanism 64. The slide mechanism 62 has a pinion 44 which is rotatably mounted in the shaft component 30, and a first rack 22a and a second rack 22b which are fixed to the first arm 12a and the second arm 12b, respectively. Each of the first rack 22a and the second rack 22b is engaged with the pinion 44. The fixing mechanism 64 fixes the first arm 12a and the second arm 12b to the shaft component 30.SELECTED DRAWING: Figure 2

Description

The present disclosure relates to a rotary cutting tool that cuts a circular hole in a workpiece.

A rotary cutting tool called a "swivel drill" is used to drill circular holes in work materials such as ceiling materials. The adjustable drill has a center drill attached to the center of the rotation axis, and cutting blades attached to a pair of arms extending in a direction perpendicular to the rotation axis. A user can drill a round hole with a desired radius in a workpiece by adjusting the cutting radius from the center of the rotation axis to the cutting edge (see Patent Document 1).

Japanese Patent Application Publication No. 5-318459

The adjustable drill has a mechanism in which a pair of arms interlock and slide relative to the rotating shaft.The user adjusts the sliding amount of the arms to obtain the desired cutting radius, and then slides the arms relative to the rotating shaft. Fix it. During drilling, the arms are not allowed to move relative to the rotation axis, and the pair of arms must be firmly fixed to the rotation axis.

A conventional fixing mechanism fixes an arm to a rotating shaft by using frictional force between the arm and the rotating shaft when a user manually tightens a bolt. However, since there is a limit to the manual torque of the user, when driving the adjustable drill with a high-power drill driver to drill a round hole in a hard workpiece, the arm may move relative to the rotation axis.

Therefore, the present disclosure provides a technique for firmly fixing an arm to a rotating shaft.

In order to solve the above problems, a rotary cutting tool according to an aspect of the present disclosure includes a rotatably driven shaft component, a pair of arms facing each other with the shaft component in between, and a cutting blade fixed to each of the pair of arms. and an adjustment mechanism that makes the pair of arms movable relative to the shaft component so as to change the radius from the axis of rotation of the shaft component to the cutting edge. The adjustment mechanism includes a pinion rotatably attached to the shaft component and a pair of racks each fixed to a pair of arms. It has a fixing mechanism that fixes the pair of arms.

According to the present disclosure, it is possible to firmly fix the arm to the rotating shaft.

It is a figure showing an example of the structure of the rotary cutting tool of an embodiment. FIG. 3 is a bottom view of the adjustable blade unit. FIG. 3 is a perspective view of the adjustable blade unit. It is a figure showing the shape of an arm. It is a figure which shows the pinion rotatably attached to the shaft component. It is a figure which shows the example of the structure of a fixing mechanism.

FIG. 1 shows an example of the structure of a rotary cutting tool 1 according to an embodiment. The rotary cutting tool 1 includes a main body 2 into which a rotatable main shaft 3 is inserted, and a free blade unit 4, and a shaft component 30 of the free blade unit 4 is fixed to a fixed part 5 connected to the main shaft 3. A plurality of D-cut portions are formed at the rear end of the shaft component 30, and the rear end of the shaft component 30 is inserted into the fixing portion 5, and the plurality of fixing screws are inserted into the plurality of D-cut portions in the fixing portion 5. By tightening the shaft component 30 of the adjustable blade unit 4 to the fixing portion 5.

The adjustable blade unit 4 includes a shaft component 30 that is rotationally driven, a pair of first arms 12a and a second arm 12b facing each other with the shaft component 30 in between, and a pair of first arms 12a and second arms 12b that are connected to the shaft component 30. In contrast, an adjustment mechanism 60 is provided that allows movement in a direction perpendicular to the rotation axis. A center drill 10 is fixed to the tip of the shaft component 30, and the center axis of the center drill 10 coincides with the rotational axis of the shaft component 30.

The first arm 12a and the second arm 12b have an elongated shape, and are arranged so that their longitudinal direction is perpendicular to the axis of rotation. A first cutting blade 14a is fixed to the side end of the first arm 12a by a blade fixing screw 16a, and a second cutting blade 14b is fixed to the side end of the second arm 12b by a blade fixing screw 16b. . In this example, the first cutting edge 14a is an inner cutting edge, and the second cutting edge 14b is an outer cutting edge, which are respectively attached in parallel to the center drill 10. In the direction of the rotation axis, the cutting edges of the first cutting edge 14a and the second cutting edge 14b are arranged at positions further back than the cutting edge of the center drill 10.

The adjustment mechanism 60 has a function of sliding the first arm 12a and the second arm 12b relative to the shaft component 30 in conjunction with each other, and fixing them to the shaft component 30 at an arbitrary position. By sliding the first arm 12a and the second arm 12b in conjunction with each other, the distance between the rotation axis and the first cutting blade 14a and the distance between the rotation axis and the second cutting blade 14b can be substantially changed. (Strictly speaking, the distance between the rotational axis and the cutting edge of the first cutting blade 14a and the distance between the rotational axis and the cutting edge of the second cutting blade 14b are different by the difference between the inner cutter and the outer cutter. ). The adjustable blade unit 4 can freely change the cutting radius from the rotational axis of the shaft component 30 to the first cutting edge 14a and the second cutting edge 14b by the adjustment mechanism 60, and the user can cut a round hole with a desired radius. can be processed. Before starting hole machining, the user moves the first arm 12a and the second arm 12b relative to the shaft component 30, and rotates the first arm 12a and the second arm 12b at a position where the cutting radius is adjusted to the desired length. It is fixed to the part 30.

The rear end portion of the main shaft 3 constitutes a shank portion 3a, and the shank portion 3a is held by a chuck of a power tool such as a drill driver or an impact driver. During drilling, the user holds the main body 2 with one hand to prevent the rotary cutting tool 1 from tilting, grips the power tool with the other hand, and operates the operation switch of the power tool. Note that since chips are generated from the workpiece during machining, it is preferable that a dust collection cover surrounding the free blade unit 4 be attached.

2 shows a bottom view of the adjustable blade unit 4, and FIG. 3 shows a perspective view of the adjustable blade unit 4.
A pair of first arms 12a and second arms 12b are arranged at opposing positions with the shaft component 30 in between.

FIG. 4 shows the shape of the first arm 12a. The first arm 12a has an elongated plate-like member 56a, and a slide hole 54a is formed in the plate-like member 56a in the longitudinal direction. The second bolt 20b and the first bolt 20a are inserted through the slide hole 54a, so that the second bolt 20b and the first bolt 20a are movable in the slide hole 54a. A plurality of screw holes 48a, 50a, and 52a are provided in the first arm 12a.

In the first arm 12a, a first rack 22a, which is a flat rod with gears, is attached in parallel to the slide hole 54a. In the embodiment, the first rack 22a is fixed to the first arm 12a by fastening the fixing screws 26a, 28a into the screw holes 48a, 50a. At the end of the first arm 12a, a blade fixing screw 16a is fastened to the screw hole 52a, and the first cutting blade 14a is fixed to the first arm 12a.

The second arm 12b may have the same shape as the first arm 12a. The second arm 12b has an elongated plate-like member 56b, and a slide hole 54b is formed in the plate-like member 56b in the longitudinal direction. The first bolt 20a and the second bolt 20b are inserted through the slide hole 54b, so that the first bolt 20a and the second bolt 20b are movable in the slide hole 54b.

In the second arm 12b, a second rack 22b, which is a flat bar with gears, is attached in parallel to the slide hole 54b. In the embodiment, the second rack 22b is fixed to the second arm 12b by fixing screws 26b and 28b. At the end of the second arm 12b, the second cutting blade 14b is fixed to the second arm 12b by a blade fixing screw 16b.

The adjustment mechanism 60 of the embodiment includes a slide mechanism 62 and a fixing mechanism 64. The slide mechanism 62 includes a pinion 44 rotatably attached to the shaft component 30, and a first rack 22a and a second rack 22b fixed to the first arm 12a and the second arm 12b, respectively. The pitch of the teeth of the pinion 44 is the same as the pitch of the teeth of the first rack 22a and the second rack 22b, and the first rack 22a and the second rack 22b are meshed with the pinion 44, respectively. In the slide mechanism 62, since the amount of movement (slide amount) of the first rack 22a and the second rack 22b depends on the amount of rotation of the pinion 44, the amount of movement of the first rack 22a and the amount of movement of the second rack 22b are It is possible to ensure a match. Furthermore, in the embodiment, by arranging the pinion 44, the first rack 22a, and the second rack 22b in the lower space of the component main body 34, the gear module can be designed to be large, thereby ensuring the strength of the gear. Therefore, the first rack 22a, the second rack 22b, and the pinion 44 may be made of resin material to realize weight reduction.

FIG. 5 shows a pinion 44 rotatably mounted to the shaft part 30. The shaft component 30 includes a component body 34, a rotating shaft 32 protruding from one end of the component body 34, and a center drill fixing portion 66 protruding from the other end of the component body 34. The center drill 10 is fixed to the center drill fixing part 66 so that the rotation axis and the center axis of the center drill 10 coincide.

A pinion 44 is rotatably attached to the base of the rotating shaft 32, and a retaining component 46 restricts movement of the pinion 44 in the axial direction. The pinion 44 is not fixed to the shaft component 30 and can freely rotate relative to the shaft component 30. The component body 34 is formed with a first insertion hole 36 into which the first bolt 20a is inserted, and a second insertion hole 38 into which the second bolt 20b is inserted.

Connecting screws 42a and 42b are fastened to the third insertion hole 40, and the first arm 12a and the second arm are connected to the shaft component 30 so that the shaft component 30 is not separated from the first arm 12a and the second arm 12b. 12b are loosely connected. The purpose of the connection using the connecting screws 42a and 42b is to prevent the first arm 12a and the second arm 12b from falling off the shaft component 30 when the fixation by the fixing mechanism 64 is released. The first arm 12a and the second arm 12b are not fixed. Therefore, the first arm 12a and the second arm 12b can slide with respect to the shaft component 30 in a state where the first arm 12a and the second arm 12b are connected to the shaft component 30 by the connecting screws 42a and 42b.

The rotating shaft 32 is inserted into the fixed part 5 connected to the main shaft 3, and the plurality of fixing screws of the fixed part 5 are tightened to the plurality of D-cut parts 32a, so that the shaft component 30 is fixed to the fixed part 5. . This causes the shaft component 30 to rotate in conjunction with the main shaft 3.

The fixing mechanism 64 fixes the first arm 12a and the second arm 12b to the shaft component 30. By fixing the first arm 12a and the second arm 12b to the shaft component 30, the first arm 12a and the second arm 12b rotate together with the shaft component 30.

FIG. 6 shows an example of the structure of the fixing mechanism 64. The fixing mechanism 64 includes a first handle 18a and a first bolt 20a. The first handle 18a has an operating section 70 that is rotated by the user, and a cylindrical section 68 that is internally threaded. The first bolt 20a is a fixing screw, and is inserted into the slide hole 54b of the second arm 12b, the first insertion hole 36, and the slide hole 54a of the first arm 12a, and is formed in the cylindrical portion 68 of the first handle 18a. It is screwed into the female thread. When the user turns the operating part 70 in the tightening direction, the first handle 18a and the first bolt 20a fix the first arm 12a and the second arm 12b to the shaft component 30, and the first rack 22a relative to the pinion 44. And the movement of the second rack 22b is suppressed.

The fixing mechanism 64 of the embodiment further includes a second handle 18b and a second bolt 20b. The second handle 18b and the second bolt 20b may have the same shape as the first handle 18a and the first bolt 20a. The second bolt 20b is a fixing screw, and is inserted into the slide hole 54a of the first arm 12a, the second insertion hole 38, and the slide hole 54b of the second arm 12b, and is formed in the cylindrical portion 68 of the second handle 18b. It is screwed into the female thread. When the user turns the operating part 70 in the tightening direction, the second handle 18b and the second bolt 20b fix the first arm 12a and the second arm 12b to the shaft component 30, and the first rack 22a relative to the pinion 44. And the movement of the second rack 22b is suppressed.

In the fixing mechanism 64, a first handle 18a and a first bolt 20a, and a second handle 18b and a second bolt 20b are provided at positions sandwiching the shaft component 30. Since the fixing mechanism 64 includes a plurality of fixing structures using fixing screws in this way, the first arm 12a and the second arm 12b can be firmly fixed to the shaft component 30. Even if the first bolt 20a loosens due to insufficient tightening of the first handle 18a by the user, the pinion 44 cannot rotate as long as the second handle 18b and the second bolt 20b are fixed. Therefore, movement of the first arm 12a and the second arm 12b can be suppressed. Although the fixing mechanism 64 includes two fixing structures in the embodiment, it may include three or more fixing structures.

In the fixing mechanism 64, by tightening the first handle 18a and the second handle 18b, the backlash between the first rack 22a and the second rack 22b and the pinion 44 is reduced to zero, and the first rack 22a and the second rack relative to the pinion 44 are tightened. It is preferable to limit the movement of the two racks 22b. Since the backlash becomes zero when the handle is tightened, the teeth of the gears interfere with each other and cannot rotate, so the first arm 12a and the second arm 12b are more firmly fixed to the shaft component 30. becomes possible.

The present disclosure has been described above based on the embodiments. It will be understood by those skilled in the art that this embodiment is an example, and that various modifications are possible in the combination of each component thereof, and that such modifications are also within the scope of the present disclosure. In the embodiment, the overall structure shown in FIG. 1 is referred to as a rotary cutting tool 1, but if the rotary cutting tool 1 has a structure in which the adjustable blade unit 4 can be separated from the main body 2 as described above, it is referred to as a rotary cutting tool 1. The unit 4 may also be called a rotary cutting tool by itself.

A summary of aspects of the disclosure is as follows.
A rotary cutting tool (1, 4) according to an aspect of the present disclosure includes a rotationally driven shaft component (30), a pair of arms (12a, 12b) facing each other with the shaft component (30) in between, and the pair of arms (12a, 12b) facing each other across the shaft component (30). cutting blades (14a, 14b) fixed to each of the arms (12a, 12b), and a radius from the rotation axis of the shaft component (30) to the cutting blades (14a, 14b), It includes an adjustment mechanism (60) that allows the pair of arms (12a, 12b) to move relative to the shaft component (30). The adjustment mechanism (60) includes a pinion (44) rotatably attached to the shaft component (30), and a pair of racks (22a, 22b) fixed to the pair of arms (12a, 12b), respectively. The pair of racks (22a, 22b) each have a slide mechanism (62) meshed with the pinion (44), and the pair of arms (12a, 12b) are connected to the shaft component (30). It has a fixing mechanism (64) for fixing.

The fixing mechanism (64) fixes the pair of arms (12a, 12b) to the shaft component (30) to suppress movement of the pair of racks (22a, 22b) with respect to the pinion (44). It may have screws (20a, 20b). In the fixing mechanism (64), a plurality of fixing screws (20a, 20b) may be provided at positions sandwiching the shaft component (30).

DESCRIPTION OF SYMBOLS 1... Rotary cutting tool, 2... Main body, 3... Main shaft, 3a... Shank part, 4... Free blade unit, 5... Fixed part, 10... Center drill, 12a ...First arm, 12b...Second arm, 14a...First cutting blade, 14b...Second cutting blade, 16a, 16b...Blade fixing screw, 18a...First handle , 18b...second handle, 20a...first bolt, 20b...second bolt, 22a...first rack, 22b...second rack, 26a, 26b, 28a, 28b...・Fixing screw, 30... Shaft component, 32... Rotating shaft, 32a... D cut part, 34... Component body, 36... First insertion hole, 38... Second insertion hole , 40... Third insertion hole, 42a, 42b... Connection screw, 44... Pinion, 46... Retaining part, 48a, 50a, 52a... Screw hole, 54a, 54b... Slide hole, 56a, 56b... Plate member, 60... Adjustment mechanism, 62... Slide mechanism, 64... Fixing mechanism, 66... Center drill fixing part, 68... Cylindrical part, 70...Operation unit.

Claims (3)

A rotationally driven shaft part,
a pair of arms facing each other with the shaft component in between;
a cutting blade fixed to each of the pair of arms;
A rotary cutting tool comprising: an adjustment mechanism that allows the pair of arms to move relative to the shaft component so as to change the radius from the rotation axis of the shaft component to the cutting edge,
The adjustment mechanism is
A slide mechanism comprising a pinion rotatably attached to the shaft component and a pair of racks respectively fixed to the pair of arms, and the pair of racks are each meshed with the pinion;
a fixing mechanism that fixes the pair of arms to the shaft component;
A rotary cutting tool characterized by: The fixing mechanism includes a fixing screw that fixes the pair of arms to the shaft component and suppresses movement of the pair of racks with respect to the pinion.
The rotary cutting tool according to claim 1, characterized in that: In the fixing mechanism, a plurality of the fixing screws are provided at positions sandwiching the shaft component,
The rotary cutting tool according to claim 2, characterized in that:

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