Disc grinder

Abstract

The present invention provides a disc grinder capable of suppressing the scattering of sparks generated by contact between the grinding disc and the workpiece. [Solution] The disc grinder 1 of the present invention polishes or grinds a workpiece by pressing a rotating polishing disc 2 against the workpiece. The disc grinder 1 is equipped with a spark scattering suppression member 8 to prevent the scattering of sparks generated by the contact between the polishing disc 2 and the workpiece. The spark scattering suppression member 8 is equipped with a group of bristles 31 in which a plurality of flexible and flame-retardant bristles 30 are arranged in the circumferential direction of the polishing disc 2. The group of bristles 31 is arranged radially outward of the polishing disc 2 such that each bristle 30 overlaps with the polishing disc 2 when viewed from the side.

Description

Technical Field

[0001] The present invention relates to a disk grinder which is a portable tool.

Background Art

[0002] FIG. 7 is a perspective view showing the configuration of a conventional disk grinder 101 disclosed in Non-Patent Document 1. The disk grinder 101 includes a polishing disk 102, a main grip 103, a sub grip 104, and a switch 105. An operator holds the main grip 103 and the sub grip 104 with the right hand and the left hand respectively, and presses the switch 105 with the right hand to rotate a motor (not shown) to rotate the polishing disk 102. By pressing the rotating polishing disk 102 against a workpiece, the workpiece can be grinded or polished.

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional disk grinder 101, when grinding or polishing a metal material, sparks generated by the contact between the polishing disk 102 and the workpiece scatter, and sparks fall on combustibles existing around the disk grinder 101, and serious accidents such as fires may occur.

[0005] The present invention has been made in view of the above problems, and aims to provide a disc grinder capable of suppressing the scattering of sparks generated by contact between the abrasive disc and the workpiece. [Means for solving the problem]

[0006] To achieve the above objectives, the present invention encompasses the subject matter described in the following sections.

[0007] Item 1. A disc grinder that polishes or grinds a workpiece by pressing a rotating abrasive disc against the workpiece, The system includes a spark scattering suppression member to prevent the scattering of sparks generated by contact between the polishing disc and the workpiece, The spark scattering suppression member comprises a group of flexible and flame-retardant bristles arranged in the circumferential direction of the polishing disc. The aforementioned group of bristles is arranged radially outward (hereinafter referred to as radially outward) of the polishing disc such that, in a side view, each bristle overlaps with the polishing disc in the disc grinder.

[0008] Item 2. The disc grinder according to Item 1, wherein each of the bristles is formed from brass or stainless steel.

[0009] Item 3. Grinder body and, Equipped with a disc guard, The grinder body has a built-in motor for rotating the grinding disc. The polishing disc is rotatably suspended from the grinder body, The disc guard comprises an upper guard portion that is arc-shaped in plan view and an outer guard portion that extends downward from the outer circumference of the upper guard portion. The inner circumference of the upper guard portion is attached to the outer circumference of the grinder body such that the upper guard portion is located above the rear region of the polishing disc and the outer guard portion is located radially outside the rear region of the polishing disc, so that the front region of the polishing disc is exposed and not covered by the disc guard. The spark scattering suppression member comprises a fastening plate, The fastening plate comprises a width-side portion that is positioned on the upper guard portion and fastened to the upper guard portion, and a width-side portion that, in a plan view, is partly located radially outward of the width-side portion and the remainder is located radially outward of the front region of the polishing disc. The disc grinder according to item 1 or 2, wherein the group of bristles is suspended from the other side of the width such that at least some of the bristles included in the group of bristles are located radially outward in the front region of the polishing disc.

[0010] Item 4. The disc grinder according to Item 3, wherein the width of one side portion is fastened to the upper guard portion so as to be able to change the position of the fastening plate in the radial direction of the abrasive disc. [Effects of the Invention]

[0011] According to the present invention, it is possible to suppress the scattering of sparks generated by contact between the polishing disc and the workpiece. [Brief explanation of the drawing]

[0012] [Figure 1] This is a perspective view of a disc grinder according to one embodiment of the present invention, as seen from the right side. [Figure 2] This is a perspective view of a disc grinder according to one embodiment of the present invention, as seen from the left side. [Figure 3] This is a plan view of a disc grinder according to one embodiment of the present invention. [Figure 4] This is a bottom view of a disc grinder according to one embodiment of the present invention. [Figure 5] This is a side view showing an enlarged view of area A in Figure 1. [Figure 6] This is a schematic diagram showing an example of a circuit configuration for driving a motor. [Figure 7] This is a perspective view showing the configuration of a conventional disc grinder. [Modes for carrying out the invention]

[0013] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the present invention is not limited to the following embodiments, and various modifications are possible without departing from the gist thereof.

[0014] FIG. 1 is a perspective view showing the disk grinder 1 according to an embodiment of the present invention as viewed from the right side. FIG. 2 is a perspective view showing the disk grinder 1 as viewed from the left side. FIG. 3 is a plan view of the disk grinder 1. FIG. 4 is a bottom view of the disk grinder 1. FIG. 5 is a side view showing an enlarged view of the range A in FIG. 1.

[0015] The disk grinder 1 according to an embodiment of the present invention is a hand-held power tool, and includes a polishing disk 2, a grinder body 3, a main grip 4, a sub grip 5, a switch 6, a disk guard 7, and a spark scattering suppression member 8. An operator performs an operation of polishing or grinding a workpiece by pressing the rotating polishing disk 2 against the workpiece. In the present application, the "radial direction of the polishing disk 2" is referred to as the "radial direction", and the "circumferential direction of the polishing disk 2" is referred to as the "circumferential direction". The arrow A in FIG. 4 indicates the above-mentioned "circumferential direction", and the arrow B in the figure indicates an example of the above-mentioned "radial direction" (the arrow B indicates one direction corresponding to the above-mentioned "radial direction").

[0016] The polishing disk 2 is a disk having a circular outer periphery. The polishing disk 2 is disposed below the grinder body 3 and is suspended from the grinder body 3 so as to be rotatable about the center 2a (FIG. 4) of the polishing disk 2. The polishing disk 2 is composed of, for example, an industrial grinding stone formed by molding abrasive grains made of aluminum oxide, zirconium oxide, etc. using a thermosetting resin such as bakelite, or a polishing cloth paper disk in which the same abrasive grains as above are adhered onto a base material made of vulcanized fiber, etc.

[0017] The main grip 4 extends rearward from the grinder body 3, and the sub-grip 5 extends leftward from the grinder body 3. The operator holds the main grip 4 with the right hand and the sub-grip 5 with the left hand to use the disc grinder 1. Note that the sub-grip 5 may extend rightward from the grinder body 3. In this case, the operator holds the main grip 4 with the left hand and the sub-grip 5 with the right hand to use the disc grinder 1.

[0018] The switch 6 is provided on the main grip 4. By operating the switch 6 with the finger of the hand that holds the main grip 4, the on state and the off state of the switch 6 can be switched. In the present embodiment, the switch 6 is provided below the main grip 4, but the position of the switch 6 is not particularly limited as long as the operator can operate the switch 6. For example, the switch 6 may be provided on the sub-grip 5. In this case, by operating the switch 6 with the finger of the hand that holds the sub-grip 5, the on state and the off state of the switch 6 can be switched. Further, it is preferable that the switch 6 is a paddle switch that is in the on state only when it is pressed and is always in the off state when it is not pressed.

[0019] The grinder body 3 incorporates a motor 10 (FIG. 6 described later) that rotates the polishing disc 2. The motor 10 is a rotational power source by an electric motor or a pneumatic fluid machine. When the switch 6 is turned on, power is supplied to the motor 10, and the motor 10 is driven to rotate the polishing disc 2. When the switch 6 is turned off, power supply to the motor 10 is stopped, the drive of the motor 10 stops, and the rotation of the polishing disc 2 stops.

[0020] Figure 6 is a schematic diagram showing an example of a circuit for driving the motor 10. In the example shown in Figure 6, the motor 10 is a universal motor and is driven by power supplied from the power supply 11. Switch 6 is provided between the power supply 11 and the motor 10. When switch 6 is turned ON, power from the power supply 11 is supplied to the motor 10, driving the motor 10 and rotating the polishing disc 2. When switch 6 is turned OFF, power is no longer supplied to the motor 10, the motor 10 stops driving, and the rotation of the polishing disc 2 stops. The power supply 11 is provided in the grinder body 3 or an external device. When the power supply 11 is provided in an external device, for example, the external device and the disc grinder 1 are connected via wires, and when switch 6 is turned ON, power from the power supply 11 is supplied to the motor 10 via the wires, driving the motor 10 and rotating the polishing disc 2.

[0021] The present invention is not limited to the above example for the circuit for driving the motor 10. Various circuits can be applied to the disc grinder of the present invention as the circuit for driving the motor 10, such as one in which the polishing disc 2 is rotated when the switch 6 is turned on and the polishing disc 2 is stopped when the switch 6 is turned off.

[0022] The disc guard 7 comprises an upper guard portion 20 and an outer guard portion 21. The upper guard portion 20 has an arc shape in plan view, and the outer guard portion 21 extends downward from the outer circumference of the upper guard portion 20. The above "plan view" means "a view of the disc grinder 1 in the vertical direction of the polishing disc 2."

[0023] The disc guard 7 is attached to the outer circumference of the grinder body 3 such that the upper guard portion 20 is located above the rear region 2b of the grinding disc 2, and the outer guard portion 21 is located radially outside the rear region 2b of the grinding disc 2. The front region 2c of the grinding disc 2 is exposed and not covered by the disc guard 7. The operator performs the workpiece polishing or grinding by rotating the grinding disc 2 and pressing the front region 2c of the grinding disc 2 against the workpiece. The attachment of the inner circumference of the upper guard portion 20 to the outer circumference of the grinder body 3 can be achieved, for example, by providing a protruding plate that projects radially outward from the outer circumference of the grinder body 3, and bonding, welding, or fastening the inner circumference of the upper guard portion 20 to the protruding plate. However, the present invention is not limited to the above method for attaching the inner circumference of the upper guard portion 20 to the outer circumference of the grinder body 3. In the disc grinder of the present invention, various methods can be applied to attach the inner circumference of the upper guard portion 20 to the outer circumference of the grinder body 3 such that the upper guard portion 20 is located above the rear region 2b of the grinding disc 2, and the outer guard portion 21 is located radially outside the rear region 2b of the grinding disc 2.

[0024] The spark scattering suppression member 8 comprises a group of hairs 31 in which multiple hairs 30 extending in the vertical direction are arranged in the circumferential direction, and a fastening plate 32 for suspending the group of hairs 31. The group of hairs 31 is positioned radially outward of the polishing disc 2 such that, in a side view, each hair 30 overlaps with the polishing disc 2. The above "side view" means "a view of the disc grinder 1 in the radial direction of the polishing disc 2."

[0025] Each of the multiple hairs 30 included in the hair group 31 has flexibility and flame retardancy. Flexibility refers to the property of bending upon contact with a workpiece. Preferably, each hair 30 has the flexibility to return to its pre-load shape by applying a 30N load perpendicularly to the unbundled side of a bundled hair, up to 2 / 5 of its length. Flame retardancy refers to the property of not burning even when exposed to sparks generated by contact between the polishing disc 2 and the workpiece. Preferably, each hair 30 does not ignite at all even when exposed to red-hot grinding chips for 30 minutes or more, and has flame retardancy with a heat resistance temperature of 700°C or higher. Each hair 30 is formed from, for example, brass or stainless steel. For example, brass-plated steel wire can be used as each hair 30.

[0026] The fastening plate 32 comprises a width-one side portion 40 positioned on the upper guard portion 20 and fastened to the upper guard portion 20, and a width-other side portion 41 from which the bristles 31 are suspended. The circumferential length of the width-other side portion 41 is longer than the circumferential length of the width-one side portion 40, and in a plan view, a portion 41a of the width-other side portion 41 is located radially outside the front region 2c of the polishing disc 2. In the illustrated example, the portion 41a of the width-other side portion 41 protrudes from one end of the width-one side portion 40 in the circumferential direction, and the remaining portion 41b of the width-other side portion 41 is located radially outside the width-one side portion 40 (the remaining portion 41b is the portion of the width-other side portion 41 connected to the width-one side portion 40). Of the multiple bristles 30 included in the bristles group 31, some bristles 30 are suspended from a portion 41a of the other width side portion 41 and are located radially outward of the front region 2c of the polishing disc 2, while the remaining bristles 30 are suspended from the remaining portion 41b of the other width side portion 41 and are located radially outward of the rear region 2b of the polishing disc 2.

[0027] According to the disc grinder 1 of the above embodiment, the bristle group 31 is positioned radially outward of the polishing disc 2 such that each bristle 30 in the bristle group 31 overlaps with the polishing disc 2 in a side view. Therefore, each bristle 30 in the bristle group 31 prevents the progression of sparks generated by contact between the polishing disc 2 and the workpiece. Consequently, the scattering of the sparks is suppressed.

[0028] Furthermore, from the viewpoint of suppressing sparks from escaping between two adjacent hairs 30 in the circumferential direction, it is preferable that the distance X between two adjacent hairs 30 in the circumferential direction be 0.05 mm or less, and more preferably 0 mm.

[0029] Furthermore, according to the disc grinder 1 of the above embodiment, each hair 30 contained in the hair group 31 is flexible, so even when the hair group 31 is interposed between the polishing disc 2 and the workpiece when the polishing disc 2 is brought close to the workpiece, the hairs 30 contained in the hair group 31 bend upon contact with the workpiece, allowing the polishing disc 2 to be pressed against the workpiece and polish or grind the workpiece.

[0030] Furthermore, from the viewpoint of avoiding the bristles 30 that have bent due to contact with the workpiece coming into contact with the polishing disc 2, it is preferable to make the distance L (Figure 4) between each bristle 30 in the radial direction and the polishing disc 2 greater than the length T of the bristles 30.

[0031] Furthermore, from the viewpoint of making the above-mentioned distance L adjustable, it is preferable to fasten one side portion 40 of the fastening plate 32 to the upper guard portion 20 so that the position of the fastening plate 32 in the radial direction can be changed. In the illustrated example, a bolt 51 is inserted from the upper side of the fastening plate 32 through a through hole 50 formed in one side portion 40 of the fastening plate 32 and a through hole formed in the upper guard portion 20, and a nut is fastened to the tip of the bolt 51 that extends to the lower side of the upper guard portion 20. The through hole 50 extends in the radial direction, and by changing the radial position of the through hole 51 through which the bolt 51 is inserted, the position of the fastening plate 32 in the radial direction can be changed, thereby making the above-mentioned distance L adjustable.

[0032] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Forms obtained by appropriately combining the technical means disclosed in the embodiments are also included in the technical scope of the present invention.

[0033] For example, in the above embodiment, an example was shown in which some of the bristles 41a included in the bristles 31 are located radially outward of the front region 2c of the polishing disc 2. However, the bristles 31 may be suspended from the other side 41 of the fastening plate 32 such that all of the bristles 30 included in the bristles 31 are located radially outward of the front region 2c of the polishing disc 2.

[0034] Furthermore, the member from which the bristle cluster 31 is suspended is not limited to the fastening plate 32, but can be any member provided on the disc grinder 1. Even when the bristle cluster 31 is suspended from a member other than the fastening plate 32, the multiple bristles 30 included in the bristle cluster 31 are arranged in the circumferential direction, and the bristle cluster 31 is positioned radially outward of the polishing disc 2 such that the bristles 30 overlap with the polishing disc 2 in a side view, thereby suppressing the scattering of sparks generated when the polishing disc 2 and the workpiece come into contact. Also, the disc guard 7 is not necessarily required and may be omitted. In this case, the disc grinder of the present invention is, for example, capable of pressing not only the front region but also the rear region of the polishing disc 2 against the workpiece, and the bristle cluster 31 is provided on the disc grinder to suppress the scattering of sparks generated when any position on the polishing disc 2 comes into contact with the workpiece.

[0035] Furthermore, the means by which the worker grips the object are not limited to the main grip 4 and sub-grip 5 shown in the above embodiment. For example, a single grip may be provided as the means by which the worker grips the object. In this case, for example, a switch 6 for switching the power supply to the motor 10 may be provided on the single grip. [Explanation of symbols]

[0036] 1. Angle grinder 10 motors 2 polishing discs 2a Rear region of the polishing disc 2b Front area of ​​the polishing disc 3. Grinder body 7 Disc Guard 8 Fastening plate 9. Spark scattering suppression member 20 Upper guard section 21 Outer guard section 30 hair 31 hair group 40 Width of one side of the fastening plate 41 Width of fastening plate on the other side 41a Part of the other side of the width 41b Remaining portion of the other side

Claims

1. A disc grinder that polishes or grinds a workpiece by pressing a rotating abrasive disc against the workpiece, The system includes a spark scattering suppression member to prevent the scattering of sparks generated by contact between the polishing disc and the workpiece, The spark scattering suppression member comprises a group of flexible and flame-retardant bristles arranged in the circumferential direction of the polishing disc. The aforementioned group of bristles is arranged radially outward (hereinafter referred to as radially outward) of the polishing disc such that, in a side view, each bristle overlaps with the polishing disc in the disc grinder.

2. The disc grinder according to claim 1, wherein each of the bristles is formed from brass or stainless steel.

3. The grinder body and Equipped with a disc guard, The grinder body has a built-in motor for rotating the grinding disc. The polishing disc is rotatably suspended from the grinder body, The disc guard comprises an upper guard portion that is arc-shaped in plan view and an outer guard portion that extends downward from the outer circumference of the upper guard portion. The inner circumference of the upper guard portion is attached to the outer circumference of the grinder body such that the upper guard portion is located above the rear region of the polishing disc and the outer guard portion is located radially outside the rear region of the polishing disc, so that the front region of the polishing disc is exposed and not covered by the disc guard. The spark scattering suppression member comprises a fastening plate, The fastening plate comprises a width-side portion that is positioned on the upper guard portion and fastened to the upper guard portion, and a width-side portion that, in a plan view, is partly located radially outward of the width-side portion and the remainder is located radially outward of the front region of the polishing disc. The disc grinder according to claim 1, wherein the group of hairs is suspended from the other side of the width such that at least some of the hairs included in the group of hairs are located radially outward in the front region of the polishing disc.

4. The disc grinder according to claim 3, wherein the width of one side portion is fastened to the upper guard portion so as to be able to change the position of the fastening plate in the radial direction of the polishing disc.

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