Die Grinder

The present application claims priority to Japanese patent application Nos. 2024-044580 filed on Mar. 21, 2024 and 2025-005915 filed on Jan. 16, 2025. The contents of the foregoing applications are hereby fully incorporated herein by reference.

The present disclosure relates to a die grinder.

A rotary tool (such as a die grinder and a disc grinder) is known that is configured to perform an operation such as grinding and polishing a workpiece by rotationally driving a tool accessory coupled to a spindle. For example, Japanese Unexamined Patent Application Publication No. 2024-076277 discloses a disc grinder that has a grip part to be held by a user and is configured to rotate a spindle by a motor being rotated by power supplied from a battery.

A rotary tool can be improved in workability if a grip part can be suitably held by a user. If, for example, the length of the grip part in a front-rear direction is increased, however, the whole length of the rotary tool may be increased and thus the size of the rotary tool may be increased. It is therefore desired to provide a rotary tool configured such that a grip part can be suitably held by a user, while suppressing increase in size of the rotary tool. A die grinder is generally more often used in a narrow place than a disc grinder. It is therefore more strongly desired to solve the above-described problem in a die grinder.

It is accordingly a non-limiting object of the present disclosure to provide a die grinder configured such that a grip part can be suitably held by a user, while suppressing increase in size of the die grinder.

According to a non-limiting aspect of the present disclosure, a die grinder is provided. The die grinder includes a motor, a spindle and a main housing. The motor is driven by power supplied from a battery. The spindle is rotated by power of the motor around a drive axis that defines a front-rear direction of the die grinder. The main housing includes a motor housing, a handle housing and a battery housing. The motor housing houses the motor. The handle housing is connected to a rear end of the motor housing and has an elongate grip part configured to be held by a user. The battery housing is connected to a rear end of the handle housing and has a battery mounting part configured such that the battery is mounted thereto. The battery mounting part is arranged in a position through which the drive axis passes and configured such that the battery is mounted in a direction orthogonal to the drive axis. A center axis of the grip part is arranged outward of the drive axis in a radial direction.

In the die grinder according to this aspect, compared with a structure in which the battery is obliquely mounted to the battery mounting part, the length of the battery housing in the front-rear direction can be shortened to secure the length of the grip part easy to hold. Thus, the die grinder is provided and configured such that the grip part can be suitably held by a user, while suppressing increase in size of the die grinder.

According to another non-limiting aspect of the present disclosure, a die grinder is provided. The die grinder includes a motor, a spindle and a main housing. The motor is driven by power supplied from a battery. The spindle is rotationally driven by power of the motor around a drive axis that defines a front-rear direction of the die grinder. The main housing includes a motor housing, a handle housing, a tool housing and a battery housing. The motor housing houses the motor. The handle housing is connected to a rear end of the motor housing and has an elongate grip part configured to be held by a user. The tool housing is connected to a front end of the motor housing, and the spindle is arranged in the tool housing. The battery housing is connected to a rear end of the handle housing and has a battery mounting part that is configured such that the battery is mounted thereto. The length of the main housing from a rear end of the battery housing to a front end of the tool housing in the front-rear direction is 400 mm or less.

In the die grinder according to this aspect, the length of the main housing in the front-rear direction is 400 mm or less and is shorter than that of a main housing of a general die grinder. Thus, the die grinder is provided that can be suitably used for operation even in a narrow place.

Representative, non-limiting examples of the present invention are described in detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the invention. Furthermore, each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide improved tools and manufacturing and using methods of the tools.

Moreover, combinations of features and steps disclosed within the following detailed description may not be necessary to practice the invention in the broadest sense, and are instead taught merely to particularly describe representative examples of the invention. Furthermore, various features of the representative examples described above and below, as well as the various independent and dependent claims below, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

In at least one non-limiting embodiment according to the present disclosure, when a direction in which the battery is mounted to the battery mounting part is defined as an up-down direction of the die grinder, the drive axis may be arranged to pass a middle point between an upper end and a lower end of the battery mounted to the battery mounting part when the die grinder is viewed from the side.

According to this embodiment, a user can easily move the die grinder along the drive axis and operate the die grinder in a well-balanced manner. Therefore, the workability of the die grinder is improved.

In addition or in the alternative to the preceding embodiment, the die grinder may further have a controller configured to control driving of the motor. The controller may be arranged in a position through which the drive axis passes. The controller may extend in a direction orthogonal to the drive axis when the die grinder is viewed from the side.

According to this embodiment, the arrangement of the controller on the drive axis suppresses or restricts increase in size of the main housing in the radial direction. Further, the length of the main housing in the front-rear direction can be shortened compared with a structure in which the controller is arranged obliquely to the drive axis.

In addition or in the alternative to the preceding embodiments, the controller may be housed behind the grip part within the main housing.

According to this embodiment, by housing the controller in the battery housing in which a space is more easily formed inside than in the motor housing and the handle housing, the controller is efficiently arranged in the main housing, and increase in size of the main housing is suppressed or prevented.

In addition or in the alternative to the preceding embodiments, the main housing may have an air inlet from which outside air is led into the main housing. The controller may be arranged to overlap at least part of the air inlet when the die grinder is viewed from the side.

According to this embodiment, the length of the main housing in the front-rear direction can be shortened, compared with a structure in which the controller is arranged in a different position through the air inlet in the front-rear direction, while the controller is cooled by air.

In addition or in the alternative to the preceding embodiments, the motor may include a stator having a stator core, a rotor and a motor shaft that rotates together with the rotor. The motor may be housed in the motor housing such that a rotation axis of the motor shaft extends in parallel to the front-rear direction. A length of the stator core in the front-rear direction may be 30 mm or less.

According to this embodiment, the length of the motor in the front-rear direction is relatively short. Therefore, the length of the grip part in the front-rear direction can be increased, while increase in length of the die grinder in the front-rear direction is suppressed.

In addition or in the alternative to the preceding embodiments, the die grinder may further have a shaft locking mechanism that locks the spindle while the spindle is stopped rotating.

According to this embodiment, the die grinder is provided that is convenient in replacement of the tool accessory.

In addition or in the alternative to the preceding embodiments, the die grinder may further have a coupling that connects a motor shaft of the motor and the spindle such that a rotation axis of the motor shaft coincides with the drive axis. The shaft locking mechanism may be configured to lock the spindle by engagement between the shaft locking mechanism and the coupling.

According to this embodiment, by utilizing the coupling, increase of the number of parts of the die grinder is prevented, and increase in length of the die grinder in the front-rear direction is prevented.

In addition or in the alternative to the preceding embodiments, the die grinder may further have a switch that turns on and off the motor according to user's operation of a first operation part. The switch may be housed in the grip part.

According to this embodiment, compared with a structure in which the switch is housed in the motor housing or the battery housing, increase in length of the die grinder in the front-rear direction is prevented.

In addition or in the alternative to the preceding embodiments, the die grinder may have a second operation part that adjusts the rotation speed of the motor. The second operation part may be arranged behind the grip part

According to this embodiment, by housing the dial in the battery housing in which a space is more easily formed inside than in the motor housing and the handle housing, the dial is efficiently arranged in the main housing, and increase in size of the main housing is suppressed or prevented.

In addition or in the alternative to the preceding embodiments, a length from a rear end to a front end of the grip part in the front-rear direction may be 60 mm or more.

According to this embodiment, the grip part is longer than a grip part of a general die grinder. Therefore, a user can suitably hold the grip part, so that the die grinder is improved in usability.

In addition or in the alternative to the preceding embodiments, a circumferential length of the grip part in a cross section orthogonal to the drive axis may be 150 mm or less.

According to this embodiment, the grip part is thinner than a grip part of a general die grinder. Therefore, a user can suitably hold the grip part, so that the die grinder is improved in usability.

In addition or in the alternative to the preceding embodiments, a length of the main housing from the rear end of the battery housing to a front end of the motor housing in the front-rear direction may be 260 mm or less.

According to this embodiment, the length from the rear end of the battery housing to the front end of the motor housing in the front-rear direction is shorter than that of a general die grinder. A rear half of the main housing is relatively short, so that a user can operate the die grinder in a well-balanced manner by holding the grip part.

A1. The structure of elements forming the outer appearance of a die grinder:

A die grinderaccording to a first embodiment of the present disclosure is now described with reference to. The die grinderis a representative example of a rotary tool that rotationally drives a tool accessory that is removably held on a front end. The die grinderrotates a spindlearound a drive axis TX with rotational power generated by driving a motor. A tool accessory TA is mounted to a front end of the spindleand rotated by rotation of the spindle. The die grinderis also referred to as a hand grinder or a straight grinder.

In the example shown in, the tool accessory TA is a generally cylindrical grinding stone with a shank. A side face TS of the tool accessory TA functions as a grinding face. A user can perform an operation such as grinding and polishing by operating the die grinderto rotate the tool accessory TA while pressing the side face TS of the tool accessory TA onto a workpiece. The shape of the tool accessory TA is not limited to a cylindrical shape, and it may be appropriately changed to other various shapes, such as a pyramid shape including a cone shape, according to the kind of a workpiece or the purpose of the operation. The tool accessory TA is not limited to a grinding stone, and it may be other tool accessories such as a flap wheel with sanding paper adhered thereon.

The die grinderhas a generally cylindrical main housingextending in an extending direction of the drive axis TX. The main housingincludes a battery housing, a handle housing, a motor housingand a tool housing.

A2. The structure of the battery housing:

As shown in, the battery housingis arranged in a rear end part of the main housing. An air inletis formed in a side of the battery housing. Air for cooling a motoris led into the main housingthrough the air inlet.

As shown in, the battery housinghas a battery mounting partconfigured such that a rechargeable battery BT is removably mounted thereto. The battery BT is, for example, a known secondary battery such as a lithium-ion battery including cells.

The battery mounting partis arranged in a position through which the drive axis TX passes in a rear end part of the handle housing. In, for the sake of convenience of illustration, the battery BT is not shown. The battery mounting parthas a pair of rails and a terminal that can be electrically connected to a terminal of the battery BT. The pair of rails of the battery mounting partare physically engaged with a pair of grooves of the battery BT, so that the battery BT is guided in a direction orthogonal to the drive axis TX and removably mounted to the battery mounting part.

In this specification, for the sake of convenience of explanation, the extending direction of the drive axis TX is defined as a front-rear direction of the die grinder. In the front-rear direction, a side on which the spindleis disposed is defined as a front side of the die grinder, and the opposite side is defined as a rear side of the die grinder. A direction orthogonal to the front-rear direction and in which the battery BT is mounted on and removed from the battery mounting partis defined as an up-down direction. A direction orthogonal to the front-rear direction and the up-down direction is defined as a left-right direction of the die grinder. Further, any direction orthogonal to the drive axis TX is defined as a radial direction of the die grinder, and in the radial direction, a direction away from the drive axis TX and a direction toward the drive axis TX are defined as a radially outward direction and a radially inward direction, respectively.

As shown in, a mounting/removing direction of the battery BT is a direction orthogonal to the drive axis TX and is defined as the up-down direction of the die grinder. A user can remove the battery BT from the battery mounting partby pulling out the battery BT upward. Further, the user can mount the battery BT to the battery mounting partby pushing in the battery BT downward. The battery BT mounted to the battery mounting partcan supply power to the motorand a controller.

In this embodiment, the mounting/removing direction of the battery BT is set orthogonal to the drive axis TX. This prevents the battery mounting partand the battery BT from protruding rearward compared with a structure in which the mounting/removing direction of the battery BT is set oblique to the drive axis TX. Thus, the length of the battery housingin the front-rear direction can be shortened compared with the structure in which the battery BT is obliquely mounted to the battery mounting part. Therefore, the length of the grip partcan be increased by the shortened length of the battery housing, while suppressing increase in length of the die grinderin the front-rear direction. Thus, the die grinderis provided and configured such that the grip partcan be suitably held by a user. If the length of the grip partis sufficiently secured, the length of the die grindermay be shortened.

In the die grinderof this embodiment, as shown in, the drive axis TX is arranged to pass a middle point BC between an upper end BU and a lower end BD of the battery BT mounted to the battery mounting partwhen viewed from the side. With this arrangement, a user can easily move the die grinderalong the drive axis TX and operate the die grinderin a well-balanced manner. Further, compared with a structure in which the middle point BC of the battery BT is offset radially outward from the drive axis TX, the battery BT is prevented from protruding radially outward from the main housing. Thus, the die grinderis suppressed or restricted from being increased in size radially outward around the drive axis TX. Further, in this embodiment, although not specifically shown, the drive axis TX is also arranged to pass a middle point between a left end and a right end of the battery BT.

As shown in, a dialand the controllerare further arranged in the battery housing. As shown in, the dialis exposed to the outside from the battery housingand configured to be rotated by user's manual operation. The dialoutputs a signal for setting the rotation speed of the motor to the controlleraccording to the rotation position.

As shown in, the controllercomprises a computer having a central processing unit CPU and memories such as a RAM and a ROM. The controlleris a plate-like member including a circuit substrate. The controllercontrols driving of the motorand other various operations in the die grinder.