Rotary cutting tools

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

Technical Field

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[0001] The present disclosure relates to a rotary cutting tool for cutting a circular hole in a workpiece.

Background Art

[0002] In order to drill a circular hole in a workpiece such as a ceiling material, a rotary cutting tool called a "universal cone" is used. The universal cone is composed of a center drill attached to the center of the rotation axis and cutting edges attached to a pair of arms extending in a direction perpendicular to the rotation axis. The user can adjust the cutting radius from the center of the rotation axis to the cutting edge to drill a round hole with a desired radius in the workpiece (see Patent Document 1).

Prior Art Documents

[0007] To solve the above problems, a rotary cutting tool according to one aspect of the present disclosure comprises a rotationally driven shaft component, a pair of arms facing each other on either side of the shaft component, cutting edges fixed to each of the pair of arms, and 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 edges. The adjustment mechanism comprises a sliding mechanism having a pinion rotatably mounted on the shaft component and a pair of racks fixed to each of the pair of arms, with the pair of racks meshing with the pinion, and a fixing mechanism for fixing the pair of arms to the shaft component. [Effects of the Invention]

[0008] According to this disclosure, it becomes possible to firmly fix the arm to the axis of rotation. [Brief explanation of the drawing]

[0009] [Figure 1] This figure shows an example of the structure of a rotary cutting tool according to an embodiment. [Figure 2] This is a bottom view of the adjustable blade unit. [Figure 3] This is a perspective view of the adjustable blade unit. [Figure 4] This is a diagram showing the shape of the arm. [Figure 5] This diagram shows a pinion rotatably mounted on a shaft component. [Figure 6] This diagram shows an example of the structure of a fixing mechanism. [Modes for carrying out the invention]

[0010] Figure 1 shows an example of the structure of a rotary cutting tool 1 according to an embodiment. The rotary cutting tool 1 comprises a main body 2 through which a rotatable spindle 3 is inserted, and a swivel cutting unit 4. The shaft component 30 of the swivel cutting unit 4 is fixed to a fixing part 5 that connects to the spindle 3. Multiple D-cut portions are formed at the rear end of the shaft component 30. The shaft component 30 of the swivel cutting unit 4 is fixed to the fixing part 5 by inserting the rear end of the shaft component 30 into the fixing part 5 and tightening multiple fixing screws at the fixing part 5 against the multiple D-cut portions.

[0011] The adjustable blade unit 4 comprises a rotationally driven shaft component 30, a pair of first arms 12a and second arms 12b facing each other on either side of the shaft component 30, and an adjustment mechanism 60 that allows the first arms 12a and second arms 12b to move in a direction perpendicular to the axis of rotation relative to the shaft component 30. A center drill 10 is fixed to the tip of the shaft component 30, and the central axis of the center drill 10 coincides with the axis of rotation of the shaft component 30.

[0012] The first arm 12a and the second arm 12b have an elongated shape and are positioned so that their longitudinal direction is perpendicular to the axis of rotation. The first cutting edge 14a is fixed to the side end of the first arm 12a by a blade fixing screw 16a, and the second cutting edge 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 mounted as an inner blade and the second cutting edge 14b as an outer blade, both parallel to the center drill 10. In the direction of the axis of rotation, the cutting edges of the first cutting edge 14a and the second cutting edge 14b are positioned behind the cutting edge of the center drill 10.

[0013] The adjustment mechanism 60 has the function of sliding the first arm 12a and the second arm 12b in conjunction with the shaft component 30 and fixing them to the shaft component 30 at any desired position. By sliding the first arm 12a and the second arm 12b in conjunction, the distance between the rotation axis and the first cutting edge 14a and the distance between the rotation axis and the second cutting edge 14b can be made substantially equal (strictly speaking, the distance between the rotation axis and the cutting edge of the first cutting edge 14a and the distance between the rotation axis and the cutting edge of the second cutting edge 14b differ by the difference between the inner and outer cutting edges). The adjustable cutting edge unit 4 can freely change the cutting radius from the rotation axis of the shaft component 30 to the first cutting edge 14a and the second cutting edge 14b using the adjustment mechanism 60, and the user can machine a round hole of a desired radius. Before starting the hole machining, the user moves the first arm 12a and the second arm 12b relative to the shaft component 30 and fixes the first arm 12a and the second arm 12b to the shaft component 30 in a position where the cutting radius is set to the desired length.

[0014] The rear end portion of the spindle 3 forms the shank portion 3a, which is gripped by the chuck of a power tool such as a drill driver or impact driver. During drilling, the user holds the main body 2 with one hand to prevent the rotary cutting tool 1 from tilting, while gripping the power tool with the other hand and operating the power tool's control switch. Since chips are generated from the workpiece during machining, it is preferable to attach a dust collection cover that surrounds the swivel blade unit 4.

[0015] Figure 2 shows a bottom view of the adjustable blade unit 4, and Figure 3 shows a perspective view of the adjustable blade unit 4. A pair of first arms 12a and second arms 12b are positioned opposite each other, with the shaft component 30 in between.

[0016] Figure 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 longitudinal direction of the plate-like member 56a. A second bolt 20b and a first bolt 20a are inserted through the slide hole 54a, and the second bolt 20b and the first bolt 20a are movable within the slide hole 54a. The first arm 12a is provided with a plurality of screw holes 48a, 50a, and 52a.

[0017] In the first arm 12a, a first rack 22a having teeth cut on a flat bar is attached parallel to the slide hole 54a. In the embodiment, the fixing screws 26a and 28a are fastened to the screw holes 48a and 50a, so that the first rack 22a is fixed to the first arm 12a. At the end of the first arm 12a, the blade fixing screw 16a is fastened to the screw hole 52a, and the first cutting blade 14a is fixed to the first arm 12a.

[0018] 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 longitudinal direction of the plate-like member 56b. The first bolt 20a and the second bolt 20b are inserted through the slide hole 54b, and the first bolt 20a and the second bolt 20b are made movable through the slide hole 54b.

[0019] In the second arm 12b, a second rack 22b having teeth cut on a flat bar is attached parallel to the slide hole 54b. In the embodiment, the second rack 22b is fixed to the second arm 12b by the 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 the blade fixing screw 16b.

[0020] The adjustment mechanism 60 of the embodiment includes a slide mechanism 62 and a fixing mechanism 64. The slide mechanism 62 has a pinion 44 rotatably attached to the shaft component 30, and a first rack 22a and a second rack 22b respectively fixed to the first arm 12a and the second arm 12b. The tooth pitch of the pinion 44 is the same as the tooth pitch of the first rack 22a and the second rack 22b, and the first rack 22a and the second rack 22b are respectively meshed with the pinion 44. In the slide mechanism 62, since the movement amounts (slide amounts) of the first rack 22a and the second rack 22b depend on the rotation amount of the pinion 44, it is possible to surely make the movement amount of the first rack 22a coincide with the movement amount of the second rack 22b. Also, in the embodiment, by arranging the pinion 44, the first rack 22a, and the second rack 22b in the lower space of the component body 34, the gear module can be designed to be large, and thereby the gear strength can be ensured. Therefore, the first rack 22a, the second rack 22b, and the pinion 44 may be formed of a resin material to achieve weight reduction.

[0021] FIG. 5 shows a pinion 44 rotatably attached to the shaft component 30. The shaft component 30 includes a component body 34, a rotating shaft 32 protruding from one end side of the component body 34, and a center drill fixing portion 66 protruding from the other end side of the component body 34. The center drill 10 is fixed to the center drill fixing portion 66 such that the rotation axis coincides with the central axis of the center drill 10.

[0022] At the base of the rotating shaft 32, the pinion 44 is rotatably attached, and a retaining component 46 restricts the axial movement of the pinion 44. The pinion 44 is not fixed to the shaft component 30 and can freely rotate with respect to the shaft component 30. In the component body 34, a first insertion hole 36 through which the first bolt 20a is inserted and a second insertion hole 38 through which the second bolt 20b is inserted are formed.

[0023] Connecting screws 42a and 42b are fastened to the third insertion hole 40, loosely connecting the first arm 12a and the second arm 12b to the shaft component 30 so that the shaft component 30 does not separate from the first arm 12a and the second arm 12b. The purpose of connecting with 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 fixing mechanism 64 is released, and not to fix the first arm 12a and the second arm 12b to the shaft component 30. Therefore, with the first arm 12a and the second arm 12b connected to the shaft component 30 by connecting screws 42a and 42b, the first arm 12a and the second arm 12b can slide relative to the shaft component 30.

[0024] The rotating shaft 32 is inserted into the fixed part 5 which is connected to the main spindle 3, and the shaft component 30 is fixed to the fixed part 5 by tightening multiple fixing screws of the fixed part 5 against multiple D-cut portions 32a. As a result, the shaft component 30 rotates in conjunction with the main spindle 3.

[0025] 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.

[0026] Figure 6 shows an example of the structure of the fixing mechanism 64. The fixing mechanism 64 comprises a first handle 18a and a first bolt 20a. The first handle 18a has an operating part 70 that is rotated by the user and a cylindrical part 68 with an internal thread on its inner circumference. The first bolt 20a is a fixing screw and is inserted through 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 screwed into the internal thread formed in the cylindrical part 68 of the first handle 18a. When the user rotates 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, thereby suppressing the movement of the first rack 22a and the second rack 22b relative to the pinion 44.

[0027] The fixing mechanism 64 of the embodiment further comprises 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 through 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 screwed into the female thread formed in the cylindrical portion 68 of the second handle 18b. When the user rotates 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, thereby suppressing the movement of the first rack 22a and the second rack 22b relative to the pinion 44.

[0028] In the fixing mechanism 64, the first handle 18a and the first bolt 20a, and the second handle 18b and the second bolt 20b are provided at positions flanking the shaft component 30. By providing multiple fixing structures using fixing screws in this way, the fixing mechanism 64 can firmly fix the first arm 12a and the second arm 12b 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, thus suppressing the movement of the first arm 12a and the second arm 12b. In this embodiment, the fixing mechanism 64 has two fixing structures, but it may have three or more fixing structures.

[0029] In the fixing mechanism 64, it is preferable to tighten the first handle 18a and the second handle 18b to eliminate the backlash between the first rack 22a and the second rack 22b and the pinion 44, thereby restricting the movement of the first rack 22a and the second rack 22b relative to the pinion 44. When the backlash is eliminated when the handles are tightened, the teeth of the gears interfere with each other and cannot rotate, making it possible to fix the first arm 12a and the second arm 12b more firmly to the shaft component 30.

[0030] The present disclosure has been described above based on embodiments. These embodiments are illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of their components, and that such modifications are also within the scope of the present disclosure. In the embodiments, the overall structure shown in Figure 1 is referred to as the rotary cutting tool 1, but as described above, if the rotary cutting tool 1 has a structure that allows the swivel blade unit 4 to be separated from the main body 2, the swivel blade unit 4 may be referred to as the rotary cutting tool on its own.

[0031] The details of the nature of this disclosure are as follows: A rotary cutting tool (1, 4) in one aspect of the present disclosure includes a rotationally driven shaft component (30), a pair of arms (12a, 12b) facing each other on either side of the shaft component (30), cutting edges (14a, 14b) fixed to each of the pair of arms (12a, 12b), and an adjustment mechanism (60) that allows the pair of arms (12a, 12b) to move relative to the shaft component (30) so as to change the radius from the rotation axis of the shaft component (30) to the cutting edges (14a, 14b). The adjustment mechanism (60) includes a pinion (44) rotatably mounted on the shaft component (30), a pair of racks (22a, 22b) fixed to the pair of arms (12a, 12b), a sliding mechanism (62) in which the pair of racks (22a, 22b) mesh with the pinion (44), and a fixing mechanism (64) for fixing the pair of arms (12a, 12b) to the shaft component (30).

[0032] The fixing mechanism (64) may have fixing screws (20a, 20b) that fix the pair of arms (12a, 12b) to the shaft component (30) and suppress the movement of the pair of racks (22a, 22b) relative to the pinion (44). In the fixing mechanism (64), a plurality of the fixing screws (20a, 20b) may be provided at positions that sandwich the shaft component (30). [Explanation of Symbols]

[0033] 1... Rotary cutting tool, 2... Main body, 3... Spindle, 3a... Shank section, 4... Adjustable blade unit, 5... Fixing section, 10... Center drill, 12a... First arm, 12b... Second arm, 14a... First cutting edge, 14b... Second cutting edge, 16a, 16b... Blade fixing screws, 18a... First handle, 18b... Second handle, 20a... First bolt, 20b... Second bolt, 22a... First rack, 22b... Second rack, 26a, 26b, 28a, 28b... Fixing screws 30... Shaft component, 32... Rotating shaft, 32a... D-cut section, 34... Component body, 36... First insertion hole, 38... Second insertion hole, 40... Third insertion hole, 42a, 42b... Connecting screws, 44... Pinion, 46... Retaining component, 48a, 50a, 52a... Screw holes, 54a, 54b... Slide holes, 56a, 56b... Plate-shaped member, 60... Adjustment mechanism, 62... Slide mechanism, 64... Fixing mechanism, 66... ​​Center drill fixing section, 68... Cylindrical section, 70... Operating section.

Claims

1. A rotating shaft component, A pair of arms facing each other with the aforementioned 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 that the radius from the rotation axis of the shaft component to the cutting edge can be changed, The adjustment mechanism is, The slide mechanism comprises a pinion rotatably mounted on the shaft component about a rotation axis, and a pair of racks fixed to the pair of arms, the pair of racks each meshing with the pinion, The shaft component has a fixing mechanism for fixing the pair of arms, The fixing mechanism includes a handle that is rotated by the user, and a fixing screw that is inserted through the slide holes of each of the pair of arms and screwed into the threaded portion of the handle, wherein the fixing screw being screwed into the threaded portion of the handle suppresses the movement of the pair of racks relative to the pinion. A rotary cutting tool characterized by the following features.

2. In the aforementioned fixing mechanism, a plurality of fixing screws are provided at positions that sandwich the shaft component. The rotary cutting tool according to feature 1.

3. The pinion and the rack are made of a resin material. The rotary cutting tool according to feature 1.

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