Die grinding machine

Abstract

The invention provides a mold grinding machine. A mold grinder has a motor, a spindle, and a main housing. The main shaft rotates around a drive axis defining the front-back direction of the die grinder by the power of the motor. The main housing includes a motor housing, a handle housing, and a battery housing. The motor housing accommodates the motor. The handle housing is connected to a rear end portion of the motor housing, and has a long gripping portion configured to be gripped by a user. The battery shell is connected to the rear end part of the handle shell and is provided with a battery mounting part capable of mounting a battery; the battery mounting portion is disposed at a position through which the drive axis passes, and is capable of mounting a battery in a direction orthogonal to the drive axis. The central axis of the grip portion is disposed radially outward of the drive axis. Therefore, the holding part can be properly held while the large size of the die grinder is inhibited.

Description

Technical Field

[0001] The present invention relates to a die grinder. Background Art

[0002] Rotary tools (e.g., die grinders and disc grinders) are known that perform grinding, polishing, or other processing operations on a workpiece by rotating a tool tip mounted on a spindle. For example, Japanese Patent Application Laid-Open No. 2024-076277 discloses a disc grinder having a grip for a user to hold, and utilizing power supplied by a battery to rotate a motor to rotate the spindle. Summary of the Invention

[0003] When the user can properly grip the handle, the operability of the rotary tool can be improved. However, simply extending the handle in the front-to-back direction, for example, increases the overall length of the rotary tool, potentially increasing the size of the rotary tool. Therefore, a rotary tool that can properly grip the handle while suppressing the tool's size increase is desired. Compared to disc grinders, die grinders are generally easier to use in confined spaces. Therefore, such technical issues may become more pronounced in die grinders.

[0004] One of the non-limiting objects of the present invention is to provide a die grinder capable of appropriately gripping a gripping portion while suppressing an increase in size of the die grinder.

[0005] According to one non-limiting embodiment of the present invention, a mold grinder is provided. The mold grinder includes a motor, a spindle, and a main housing. The motor is driven by electricity supplied by a battery. The spindle rotates around a drive axis that defines the front-to-back direction of the mold grinder by the power of the motor. The main housing includes a motor housing, a handle housing, and a battery housing. The motor housing accommodates the motor. The handle housing is connected to the rear end of the motor housing and has an elongated grip configured for a user to hold. The battery housing is connected to the rear end of the handle housing and has a battery mounting portion on which the battery can be mounted. The battery mounting portion is arranged at a position where the drive axis passes, and the battery can be mounted in a direction orthogonal to the drive axis. The central axis of the grip is arranged at a position radially outward of the drive axis.

[0006] According to the mold grinder of this embodiment, the length of the battery case in the front-to-back direction can be shortened compared to a case where the battery is installed at an angle on the battery mounting portion, while ensuring a grip length that is easy to hold. Therefore, it is possible to provide a mold grinder that can appropriately hold the grip portion while suppressing the size of the mold grinder.

[0007] According to another non-limiting embodiment of the present invention, a mold grinder is provided. The mold grinder has a motor, a spindle and a main housing. The motor is driven by electricity supplied by a battery. The spindle is driven to rotate around a drive axis that defines the front-to-back direction of the mold grinder by the power of the motor. The main housing includes a motor housing, a handle housing, a tool housing and a battery housing. The motor housing accommodates the motor. The handle housing is connected to the rear end of the motor housing and has an elongated gripping portion configured for a user to hold. The tool housing is connected to the front end of the motor housing and is used to configure the spindle. The battery housing is connected to the rear end of the handle housing and has a battery mounting portion on which the battery can be mounted. In the front-to-back direction, the length of the main housing from the rear end of the battery housing to the front end of the tool housing is less than 400 mm.

[0008] According to the die grinder of this embodiment, the length of the main housing in the front-back direction is less than 400 mm, which is shorter than the main housing of a general die grinder. Therefore, it is possible to provide a die grinder that can be properly operated even in a narrow space. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a perspective view showing the external appearance structure of the die grinding machine according to the first embodiment. Figure 2 It is a cross-sectional view showing the internal structure of the die grinding machine according to the first embodiment. Figure 3 It is a cross-sectional view showing the internal structure of the handle case and the battery case. Figure 4 It is a cross-sectional view showing the internal structure of the motor housing and the tool housing. Figure 5 It is a cross-sectional view showing the structure of a shaft lock mechanism. Figure 6 It is an explanatory diagram showing the length of the die grinder in the front-back direction. Figure 7 Yes Figure 6 Cross-sectional view at position VII-VII. Figure 8 It is a cross-sectional view showing the structure of a die grinding machine according to a second embodiment. [Explanation of Reference Numerals] 10: Main housing; 14: Switch; 20: Motor; 21: Motor body; 22: Motor shaft; 26: Fan; 30: Motor housing; 32: Motor bearing holder; 34: Switch button; 34S: Outer surface; 34b: Paddle switch; 40: Handle housing; 42: Grip; 50: Tool housing; 58: Air vent; 60: Cylindrical portion; 66: Bearing holder; 70: Shaft locking mechanism; 72: Button; 74: Pin; 76: Force-applying member; 78: Fitting portion; 80: Battery housing; 82: Air inlet; 84: Controller; 86: Battery mounting portion; 88: Dial; 90: Spindle; 92: Chuck Cone; 94: Collet nut; 100, 100b: Die grinder; 201: Front bearing; 202: Rear bearing; 204: Coupling; 212: Stator; 212C: Stator core; 214: Rotor; 322: Opening; 342: Coil spring; 601: Front bearing; 602: Rear bearing; 604: Recess; 606: Through hole; 721: First connecting portion; 724: Recess; 742: Second connecting portion; 744: Limiting portion; 746: Top; BT: Battery; HX: Center axis; MX: Motor rotation axis; TA: Top tool; TS: Side; TX: Drive axis. DETAILED DESCRIPTION

[0010] Representative and non-limiting examples of the present invention are described in detail below with reference to the accompanying drawings. This detailed description is intended only to provide those skilled in the art with details of preferred embodiments of the present invention and is not intended to limit the scope of the present invention. Furthermore, the additional features and inventions disclosed below may be used alone or in combination with other features and inventions to provide further improved devices, methods of making the same, and methods of using the same.

[0011] In addition, the combinations of features and steps disclosed in the following detailed description are not necessarily required to practice the present invention in the broadest sense, but are provided solely to illustrate representative embodiments of the present invention. Furthermore, the various features of the representative embodiments described above and below, as well as the various features described in the independent and dependent claims, do not need to be combined as described in the examples herein, or in the order in which they are listed, to provide additional and useful embodiments of the present invention.

[0012] Except for the structures of features described in the embodiments and / or technical solutions, all features described in this specification and / or technical solutions are intended to be disclosed individually or independently of each other as limitations of the original disclosed and claimed specific matters. Furthermore, the description of all numerical ranges and groups or groups is intended to disclose intermediate structures thereof as specific matters originally disclosed and claimed.

[0013] In a non-limiting embodiment of the present invention, it can also be configured that, when the direction in which the battery is installed on the battery mounting portion is defined as the up and down direction, when the mold grinder is viewed from the side, the drive axis passes through the midpoint between the upper end of the battery mounted on the battery mounting portion and the lower end of the battery. According to this embodiment, the user can easily move the die grinder along the drive axis and operate the die grinder with good balance, thereby improving the operability of the die grinder.

[0014] In addition to or in lieu of the above embodiments, the mold grinder may further include a controller configured to control the driving of the motor. The controller may be positioned so that the drive axis passes through it. The controller may extend in a direction perpendicular to the drive axis when viewing the mold grinder from the side. According to this embodiment, since the controller is arranged on the drive axis, it is possible to suppress or prevent the main housing from being enlarged in the radial direction. In addition, the length of the main housing in the front-rear direction can be shortened compared to the case where the controller is arranged obliquely with respect to the drive axis.

[0015] In addition to or instead of the above embodiment, the controller may be housed in the main housing at a position rearward of the grip portion. According to this embodiment, by accommodating the controller in the battery case, which has a space easier to form inside than the motor case and the handle case, the controller can be efficiently arranged in the main case, thereby suppressing or preventing the main case from being enlarged.

[0016] In addition to or in lieu of the above embodiment, the main housing may have an air inlet capable of introducing external air into the interior of the main housing. Alternatively, the controller may be arranged at a position overlapping at least a portion of the air inlet when viewing the mold grinder from the side. According to this embodiment, the controller can be air-cooled while the length of the main housing in the front-rear direction can be shortened compared to a case where the controller and the air intake holes are arranged at different positions.

[0017] In addition to or in lieu of the above embodiment, the motor may include a stator, a rotor, and a motor shaft that rotates together with the rotor, wherein the stator includes a stator core. Alternatively, the motor may be housed in the motor housing such that the rotation axis of the motor shaft is parallel to the front-to-back direction. Alternatively, the length of the stator core in the front-to-back direction may be 30 mm or less. According to this embodiment, the length of the motor in the front-back direction is relatively short. Therefore, the length of the gripping portion in the front-back direction can be extended while suppressing the length of the die grinder in the front-back direction.

[0018] In addition to or in place of the above-described embodiment, a shaft locking mechanism capable of fixing the main shaft in a state where the rotation of the main shaft is stopped may be further provided. According to this embodiment, a die grinder that facilitates replacement of a tip tool can be provided.

[0019] In addition to or in lieu of the above embodiment, the motor may further include a coupling that connects the motor shaft and the main shaft so that the rotation axis of the motor shaft is coaxial with the drive axis. The shaft locking mechanism may also be configured to secure the main shaft by locking the shaft locking mechanism and the coupling. According to this embodiment, by utilizing the coupling, it is possible to prevent an increase in the number of parts of the die grinder and to prevent an increase in the length of the die grinder in the front-rear direction.

[0020] In addition to or in place of the above embodiment, a switch may be further provided for switching the start and stop of the motor in response to a user's operation of the first operating portion. The switch may be accommodated in the grip portion. According to this embodiment, compared with a case where the switch is housed in a motor case or a battery case, it is possible to prevent the length of the die grinder in the front-rear direction from being increased.

[0021] In addition to or in place of the above embodiment, a second operating portion capable of adjusting the rotational speed of the motor may be further provided. The second operating portion may be provided at a position further rearward than the grip portion. According to this embodiment, by providing a dial in the battery case, which has a smaller internal space than the motor case and the handle case, the dial can be efficiently arranged in the main case, thereby suppressing or preventing the main case from becoming larger.

[0022] In addition to or instead of the above embodiment, the length from the rear end to the front end of the grip portion in the front-back direction may be 60 mm or more. According to this embodiment, the grip portion is longer than that of a general die grinder, so the user can properly grip the grip portion, thereby improving the usability of the die grinder.

[0023] In addition to or instead of the above embodiment, the circumference of the grip portion in a cross section perpendicular to the drive axis may be 150 mm or less. According to this embodiment, the grip portion is thinner than that of a general die grinder, so the user can grip the grip portion appropriately, thereby improving the usability of the die grinder.

[0024] In addition to or instead of the above embodiment, the length of the main housing from the rear end of the battery housing to the 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-to-back direction is shorter than that of a typical die grinder. Since the rear half of the main housing is shorter, the die grinder can be operated with good balance by gripping the handle.

[0025] A. First embodiment: A1. Appearance and structure of mold grinding machine 100: like Figure 1 As shown, the die grinder 100 is an example of a rotary tool that rotates a tip tool removably held at its tip. The die grinder 100 utilizes the rotational force generated by a motor to rotate a spindle 90 about a drive axis TX. The tip tool TA is mounted at the tip of the spindle 90 and rotates as the spindle 90 rotates. The die grinder 100 is sometimes referred to as a "manual grinder" or "straight grinder."

[0026] exist Figure 1 In the example, the tip tool TA is a roughly cylindrical grindstone with a shaft. The side surface TS of the tip tool TA functions as a grinding surface. The user, for example, operates the mold grinder 100 to rotate the tip tool TA and presses the side surface TS of the tip tool TA against the workpiece to perform grinding, polishing, and other processing operations. In addition, the shape of the tip tool TA can also be switched to various shapes, including a conical shape, corresponding to the type of workpiece and the purpose of the processing operation. The tip tool TA is not limited to grindstones, and tools other than grindstones, such as a flap grinding wheel with sandpaper bonded thereto, can also be used.

[0027] The die grinder 100 includes a substantially cylindrical main housing 10 extending in the direction in which the drive axis TX extends. The main housing 10 includes a battery housing 80 , a handle housing 40 , a motor housing 30 , and a tool housing 50 .

[0028] A2. Structure of the battery housing 80: like Figure 1As shown, the battery case 80 is provided at the rear end portion of the main case 10. An air intake hole 82 is formed at a side portion of the battery case 80. The air intake hole 82 guides air for cooling the motor 20 and the like into the main case 10.

[0029] like Figure 2 As shown, the battery case 80 has a battery mounting portion 86 for detachably mounting a rechargeable battery BT. The battery BT is, for example, a well-known secondary battery such as a lithium-ion battery including a plurality of cells.

[0030] The battery mounting portion 86 is provided at a position where the drive axis TX passes through the rear end of the handle housing 40. Figure 2 For ease of illustration, the battery BT is omitted. The battery mounting portion 86 includes a pair of rails and terminals electrically connectable to the terminals of the battery BT. The pair of rails of the battery mounting portion 86 physically engage with a pair of grooves formed in the battery BT. As a result, the battery BT is guided in a direction perpendicular to the drive axis TX and can be attached and detached from the battery mounting portion 86.

[0031] In this specification, for the sake of convenience, the extension direction of the drive axis TX is defined as the front-to-back direction of the mold grinder 100. In the front-to-back direction, the side where the main shaft 90 is arranged is defined as the front side of the mold grinder 100, and the opposite side is defined as the rear side of the mold grinder 100. The direction perpendicular to the front-to-back direction and in which the battery BT is installed and removed relative to the battery mounting portion 86 is defined as the up-down direction. The direction perpendicular to the up-down direction and the left-right direction is defined as the left-right direction of the mold grinder 100. In addition, any direction perpendicular to the drive axis TX is defined as the radial direction of the mold grinder 100, the direction away from the drive axis TX is defined as the radial outer direction, and the direction close to the drive axis TX is defined as the radial inner direction.

[0032] like Figure 3 As shown, the battery BT is installed in a direction perpendicular to the drive axis TX and defines the vertical direction of the die grinder 100. The user can remove the battery BT from the battery mounting portion 86 by pulling the battery BT upward. Alternatively, the user can install the battery BT in the battery mounting portion 86 by pressing the battery BT downward. The battery BT installed in the battery mounting portion 86 can supply power to the motor 20, the controller 84, and the like.

[0033] In the present embodiment, the installation direction of the battery BT is configured to be orthogonal to the drive axis TX. Compared to the case where the installation direction of the battery BT is tilted relative to the drive axis TX, the battery mounting portion 86 and the battery BT are prevented from protruding to the rear side. Therefore, compared to the case where the battery BT is installed at an angle on the battery mounting portion 86, the length of the battery housing 80 in the front-to-back direction can be shortened. Therefore, it is possible to suppress the extension of the length of the mold grinder 100 in the front-to-back direction, and at the same time, the length of the holding portion 42 can be extended by the amount by which the length of the battery housing 80 is shortened. Therefore, it is possible to provide a mold grinder 100 that can appropriately hold the holding portion 42. In addition, while fully ensuring the length of the holding portion 42, the length of the mold grinder 100 in the front-to-back direction can also be shortened.

[0034] like Figure 3 As shown, in the mold grinder 100 of this embodiment, when the mold grinder 100 is viewed from the side, the drive axis TX passes through the midpoint BC between the upper end BU of the battery BT mounted on the battery mounting portion 86 and the lower end BD of the battery BT. With this structure, the user can easily move the mold grinder 100 along the drive axis TX and operate the mold grinder 100 with good balance. In addition, compared with a case where the midpoint BC of the battery BT deviates radially outward from the drive axis TX, the battery BT can be prevented from protruding radially outward from the main housing 10. Therefore, it is possible to suppress or prevent the mold grinder 100 from growing radially outward with the drive axis TX as the center. In addition, in this embodiment, the drive axis TX is also configured to pass through the midpoint between the left and right ends of the battery BT, but the specific illustration is omitted.

[0035] like Figure 3 As shown, the battery housing 80 is also provided with a dial 88 and a controller 84. Figure 1 As shown, the dial 88 is exposed to the outside of the battery case 80 and is provided so as to be rotatable by manual operation of the user. The dial 88 outputs a signal for setting the rotation speed of the motor to the controller 84 according to the rotation position.

[0036] like Figure 3 As shown, the controller 84 is composed of a computer having a CPU as a central processing unit and memory such as RAM and ROM. The controller 84 is a plate-shaped component including a circuit board. The controller 84 controls various operations in the die grinding machine 100, such as the drive control of the motor 20.

[0037] The controller 84 is arranged at a position where the drive axis TX passes. This configuration can suppress or prevent the main housing 10 from increasing in size in the radial direction, compared to a case where the controller 84 is arranged radially outward from the drive axis TX.

[0038] The controller 84 is arranged in the battery housing 80 which is located on the rear side of the handle housing 40. By accommodating the controller 84 in the battery housing 80, which has a space easier to form inside than the motor housing 30 or the handle housing 40, the controller 84 can be efficiently arranged in the main housing 10, thereby suppressing or preventing the main housing 10 from being enlarged.

[0039] The controller 84 is configured to extend in a direction perpendicular to the drive axis TX. Specifically, the circuit board constituting the controller 84 is configured to extend in the vertical direction and the horizontal direction. This configuration allows the length of the main housing 10 in the front-to-back direction to be shortened compared to a case where the controller 84 is configured to be tilted relative to the drive axis TX.

[0040] The controller 84 is positioned approximately at the same position as the air inlet 82 in the front-to-back direction. Specifically, when viewing the mold grinder 100 from the side, the controller 84 is positioned so as to overlap at least a portion of the air inlet 82 in the front-to-back direction. This configuration allows the controller 84 to be cooled using air introduced through the air inlet 82, while also shortening the length of the main housing 10 in the front-to-back direction compared to a case where the controller 84 and the air inlet 82 are positioned at different positions in the front-to-back direction.

[0041] A3. Structure of the handle housing 40: like Figure 2 As shown, the handle housing 40 is arranged between the motor housing 30 and the battery housing 80. The handle housing 40 includes a grip portion 42. In addition, the boundary between the handle housing 40 and the battery housing 80 in the front-to-back direction is the position of the front end of the components such as the controller 84 and the dial 88 that are accommodated in the battery housing 80. In this embodiment, the position of the front end of the dial 88 is the boundary between the handle housing 40 and the battery housing 80.

[0042] The grip portion 42 has a long, cylindrical shape extending in the front-to-back direction. The grip portion 42 is thinner than the motor housing 30 and the battery housing 80 and is designed to be gripped by the user. The grip portion 42 is designed with a thickness (outer diameter), length, and cross-sectional shape that is easily grasped by the user. The detailed structure of the grip portion 42 will be described later.

[0043] A4. Structure of the motor housing 30: like Figure 2 As shown, the motor housing 30 is disposed between the handle housing 40 and the tool housing 50. The motor housing 30 is a long cylindrical housing extending in the front-to-back direction and houses the motor 20. The boundary between the motor housing 30 and the handle housing 40 in the front-to-back direction is, for example, the rear end of the motor 20.

[0044] like Figure 2As shown, a switch button 34 is provided above the motor housing 30. The switch button 34 moves between an off position and an on position in response to manual operation by the user. The switch button 34 is operably connected to the switch 14. The switch 14 is disposed on the grip 42. The switch 14 is turned on and off in response to the user's operation of the switch button 34, thereby switching the motor 20 on and off. The motor 20 is driven while the switch 14 is in the on state.

[0045] like Figure 4 As shown, the motor 20 is a brushless DC motor driven under the control of the controller 84. The motor 20 includes a motor body 21, a motor shaft 22, and a fan 26 mounted on the motor shaft 22.

[0046] The motor body 21 includes a stator 212 and a rotor 214. The stator 212 includes a stator core 212C. The stator core 212C is formed by laminating multiple electromagnetic steel sheets. The stator 212 rotates the rotor 214 using a magnetic field generated by a DC current supplied by a battery. The rotation of the rotor 214 causes the motor shaft 22 to rotate about the motor rotation axis MX. The volume of the stator core 212C affects the output (rotational speed, torque) of the motor 20.

[0047] Considering its intended use, the mold grinder 100 of this embodiment can be designed so that the output of the motor 20 is lower than that of a handheld electric disc grinder. An electric disc grinder is a rotary tool that uses a grinding stone, a cutting stone, a blade, a brush, or the like as a tool tip to perform operations such as grinding, grinding, and cutting. Electric disc grinders are sometimes also referred to as angle grinders.

[0048] The die grinding machine 100 of this embodiment is configured as follows: Figure 4 As shown, the distance LC of the stator core 212C in the front-to-back direction, that is, the thickness of the stator core 212C is relatively thin. Specifically, in the motor used in a general electric disc grinder, the thickness of the stator core is, for example, thicker than 30 mm (millimeter) and less than 80 mm. In the motor 20 used in the mold grinder 100 of this embodiment, the thickness of the stator core 212C is 24.15 mm, which is less than 30 mm. As a result, the length of the motor housing 30 in the front-to-back direction is shortened compared to the electric disc grinder. In this way, the mold grinder 100 of this embodiment is constructed so that the output of the motor 20 required by the mold grinder 100 is ensured, and at the same time, the length of the motor 20 in the front-to-back direction becomes relatively short.

[0049] like Figure 4As shown, the motor shaft 22 is rotatably supported by the motor housing 30 via a front bearing 201 and a rear bearing 202 provided in the motor housing 30. The front bearing 201 is supported in the motor housing 30 while being restricted in movement by the motor bearing holder 32. The motor bearing holder 32 has an air outlet 58 (see FIG. 1 ) formed therein, which is similar to the air outlet 58 formed in the tool housing 50. Figure 1 ) connected opening portion 322.

[0050] The motor shaft 22 rotates together with the rotor 214 about the motor rotation axis MX. In this embodiment, the motor shaft 22 is connected to the main shaft 90 via the coupling 204. The motor shaft 22 and the main shaft 90 are connected via the coupling 204 so that the motor rotation axis MX and the drive axis TX are coaxial. By arranging the motor rotation axis MX and the drive axis TX coaxially, it is possible to suppress or prevent the mold grinder 100 from becoming larger in the radial direction. However, the motor rotation axis MX and the drive axis TX do not necessarily have to be coaxial. For example, the drive axis TX and the motor rotation axis MX can be configured so that they are close to each other and parallel.

[0051] The fan 26 rotates together with the motor shaft 22. The fan 26 generates an air flow for cooling the motor 20. More specifically, Figure 2 As shown, the external air is guided into the battery housing 80 from the air inlet 82 formed in the battery housing 80 by the rotation of the fan 26. The air guided into the battery housing 80 flows forward inside the handle housing 40 and is guided into the motor housing 30. The air guided into the motor housing 30 passes through the opening 322 and is discharged from the air outlet 58 (see FIG. 1 ) formed in the tool housing 50. Figure 1 ) is sent to the outside.

[0052] Furthermore, the space defined within the grip 42 serves as a flow path for airflow cooling the motor 20 and controller 84. Therefore, the thickness of the grip 42, more specifically, the shape of the grip 42 in a cross-section perpendicular to the drive axis TX, influences the size of the flow path. In the mold grinder 100 of this embodiment, as described above, the output of the motor 20 is lower than that of a typical electric disc grinder. Therefore, the temperature rise of the motor 20 when using the mold grinder 100 is lower than that of an electric disc grinder. Therefore, the cooling performance of the motor 20 and controller 84, achieved by air cooling using the fan 26, can be set lower than that of an electric disc grinder. Therefore, in this embodiment, the grip 42 is designed to be thinner than that of an electric disc grinder to ensure a comfortable grip for the user. However, the grip 42 may also be of the same thickness as that of an electric disc grinder. Furthermore, the cooling performance of the die grinder 100 by air cooling may be equal to the cooling performance of an electric disc grinder.

[0053] A5. Structure of the tool housing 50: like Figure 2 As shown, the tool housing 50 is provided at the front end of the main housing 10. The tool housing 50 is connected to the front end of the motor housing 30. The tool housing 50 accommodates the spindle 90. The tool housing 50 is configured to have a thickness (outer diameter), length, and cross-sectional shape that is easy for the user to grip.

[0054] like Figure 4 As shown, the tool housing 50 houses a cylindrical portion 60. The cylindrical portion 60 houses a spindle 90. The spindle 90 is rotatably supported by the cylindrical portion 60 via a front bearing 601 and a rear bearing 602 held within the cylindrical portion 60. The front bearing 601 is secured by a bearing holder 66, restricting its movement in the front-to-back direction.

[0055] A collet cone 92 and a collet nut 94 are provided at the front end of the spindle 90 for fixing the tool TA to the spindle 90. The tool TA is inserted into the collet cone 92 and is non-rotatably mounted to the spindle 90 by tightening the collet nut 94.

[0056] When the user manually operates the switch button 34 to start the motor 20 , the motor shaft 22 is driven. The main shaft 90 and the tip tool TA rotate integrally with the motor shaft 22 via the coupling 204 .

[0057] A6. Shaft lock mechanism: like Figure 5As shown in FIG. 1 , the mold grinder 100 of this embodiment includes a shaft locking mechanism 70. The shaft locking mechanism 70 fixes the spindle 90 when the spindle 90 stops rotating. The shaft locking mechanism 70 prevents the collet nut 94 and the spindle 90 from rotating together relative to the main housing 10 when the top tool TA is replaced. Figure 5 As shown, the shaft locking mechanism 70 includes a button 72 , a pin 74 , a biasing member 76 , and an engaging portion 78 .

[0058] The button 72 functions as an operating unit that switches between activation and deactivation of the shaft locking mechanism 70. The outer surface of the button 72 is exposed to the outside of the tool housing 50. The inner surface of the button 72 faces the cylindrical portion 60. A recess 724 is formed on the inner surface of the button 72 to receive the biasing member 76.

[0059] The urging member 76 is a metal coil spring and is disposed in a recessed portion 604 formed on the outer surface of the cylindrical portion 60. The urging member 76 urges the recessed portion 604 and the recessed portion 724 of the button 72 in directions away from each other.

[0060] The pin 74 has an elongated, substantially cylindrical shape. The pin 74 is inserted into the through hole 606 formed in the cylindrical portion 60. Figure 5 In the example shown, the through hole 606 extends in the vertical direction. However, the through hole 606 may extend in any direction perpendicular to the drive axis TX, such as the left-right direction. The pin 74 is arranged in the through hole 606 so that the tip 746 of the pin 74 faces the coupling 204.

[0061] The pin 74 includes a second connection portion 742 and a restriction portion 744. The second connection portion 742 is a groove formed in the pin 74. The second connection portion 742 of the pin 74 is locked with the convex first connection portion 721 of the button 72, so that the button 72 and the pin 74 are integrally connected.

[0062] The limiting portion 744 is a portion of the pin 74 that is enlarged in diameter. The limiting portion 744 cannot enter the through hole 606, thereby limiting the pin 74 from moving upward from a predetermined position. Figure 5 As shown, when the button 72 is not pressed, the pin 74 is arranged at an initial position where the restriction portion 744 contacts the inner surface of the cylindrical portion 60 due to the biasing force of the biasing member 76 .

[0063] The interlocking portion 78 is configured to be interlocked with the top end 746 of the pin 74. In the present embodiment, the interlocking portion 78 is formed on the coupling 204. The interlocking portion 78 is a recessed portion formed on the surface of the coupling 204. The shaft locking mechanism 70 is configured to fix the main shaft 90 by locking the pin 74 and the coupling 204. In the mold grinder 100 of the present embodiment, by using the coupling 204 as part of the shaft locking mechanism 70, the provision of new components is avoided, thereby suppressing or preventing an increase in the number of components of the mold grinder 100. In addition, compared to a case where the components used for the shaft locking mechanism 70 are provided on the main shaft 90, etc., the length of the mold grinder 100 in the front-to-back direction can be prevented from increasing.

[0064] like Figure 5 As shown, when the button 72 is not pressed, the pin 74 is arranged in the initial position. In the initial position, the fitting portion 78 and the tip 746 of the pin 74 are not fitted. When the user presses the button 72 against the biasing force of the biasing member 76, the pin 74 moves to a position (hereinafter also referred to as the "fitted position") where the tip 746 fits with the fitting portion 78 formed on the coupling 204.

[0065] While the button 72 is pressed, the engagement between the pin 74 and the engaging portion 78 restricts the coupling 204 from rotating about the drive axis TX, that is, the spindle 90 from rotating about the drive axis TX. Therefore, while the button 72 is pressed, the collet nut 94 and the spindle 90 are prevented from rotating together. The user can stop the rotation of the spindle 90 by a simple method, such as pressing the button 72, thereby easily replacing the tip tool TA.

[0066] A7. Length of the mold grinder 100 in the front and rear directions: like Figure 6 As shown, in the mold grinder 100 of this embodiment, the length in the front-to-back direction is relatively short due to the structures of the various components described above. The length of the main housing in the front-to-back direction of a typical mold grinder is longer than 400 mm. The so-called "length of the main housing 10" refers to the length from the rear end of the battery housing 80 to the front end of the tool housing 50 in the front-to-back direction. The front end of the tool housing 50 does not include the chuck cone 92, chuck nut 94, and tip tool TA. The rear end of the battery housing 80 does not include the battery BT.

[0067] In contrast, in the mold grinder 100 of this embodiment, the length LA of the main housing 10 in the front-to-back direction is 382.1 mm, which is less than 385 mm. In other words, the mold grinder 100 of this embodiment is shorter than the main housing of a typical mold grinder. Due to its relatively short front-to-back length, the mold grinder 100 of this embodiment can be used appropriately even in confined spaces.

[0068] In addition, in the mold grinder 100 of the present embodiment, the length LB from the rear end of the battery housing 80 to the front end of the motor housing 30 in the main housing 10 in the front-to-back direction is relatively short. In a general mold grinder, the length from the rear end of the battery housing 80 to the front end of the motor housing 30 in the front-to-back direction is longer than 260 mm. In the present embodiment, the so-called front end of the motor housing 30 refers to the front end of the area where the motor housing 30 and the motor bearing holder 32 are in contact. However, in the case where the mold grinder 100 does not have a motor bearing holder 32, the front end of the motor housing 30 may be, for example, the front end of the motor shaft 22 or the front end of the area where the motor housing 30 and the tool housing 50 are in contact.

[0069] In contrast, in the mold grinder 100 of this embodiment, the length LB from the rear end of the battery housing 80 to the front end of the motor housing 30 in the front-to-back direction is 246.5 mm. In other words, the length from the rear end of the battery housing 80 to the front end of the motor housing 30 in the front-to-back direction is shorter than that of a typical mold grinder. In the front-to-back direction, the load on the rear half of the main housing 10 tends to increase due to the battery BT and motor 20 mounted on the battery mounting portion 86. In the mold grinder 100 of this embodiment, since the portion of the main housing 10 where the load tends to increase is relatively short, the mold grinder 100 can be carried with good balance by gripping the grip 42. In addition, by gripping the grip 42, the user can easily operate the front half of the main housing 10, thereby enabling the top tool TA to perform processing operations appropriately.

[0070] A8. Structure of the gripping portion 42: In the die grinder 100 of this embodiment, the gripping portion 42 has the following structure.

[0071] (1) Figure 3 As shown, in the mold grinding machine 100 of this embodiment, the center axis HX of the gripping portion 42 is arranged radially outside the drive axis TX. In this embodiment, the center axis HX is arranged above the drive axis TX. In the mold grinding machine 100 of this embodiment, the center axis HX is substantially parallel to the drive axis TX, and any position of the gripping portion 42 in the front-to-back direction is arranged above the drive axis TX. In addition, as shown in FIG. Figure 7 As shown in FIG. 1 , the central axis HX of the grip portion 42 is arranged directly above the drive axis TX.

[0072] The so-called "center axis HX of the gripping portion 42" refers to a straight line based on the center of the cross-sectional shape of the gripping portion 42. The so-called "cross-sectional shape of the gripping portion 42" refers to the outer shape of the gripping portion 42 in the cross-sectional area perpendicular to the drive axis TX. The "center of the cross-sectional shape" includes the centroid of the cross-sectional shape or the center of gravity of the cross-sectional shape. In the present embodiment, the center of gravity of the cross-sectional area of ​​the gripping portion 42 is defined as the center of the cross-sectional shape of the gripping portion 42. In addition, in the present embodiment, a straight line connecting the center of the cross-sectional shape of the gripping portion 42 at the front end of the gripping portion 42 and the center of the cross-sectional shape of the gripping portion 42 at the rear end of the gripping portion 42 is defined as the center axis HX of the gripping portion 42. In addition, the center of the cross-sectional shape in the gripping portion 42 may be extracted from a plurality of locations, and a straight line derived from the extracted plurality of centers using linear regression analysis or the like may be defined as the center axis HX of the gripping portion 42.

[0073] As described above, in the die grinder 100, grinding, polishing, and other machining operations can be performed by pressing the side surface TS of the tool tip TA against the workpiece. Therefore, when performing such machining operations, the user tilts the die grinder 100 so that its front end is located vertically below the motor housing 30, or moves the entire die grinder 100 downward toward the workpiece. In this embodiment, the die grinder 100 is configured so that the center axis HX of the grip 42 is located above the drive axis TX. Therefore, when the user performs machining operations by gripping the grip 42 with one hand and the tool housing 50 with the other, the die grinder 100 can be easily tilted so that its front end is located below the rear end. This improves the operability of the die grinder 100.

[0074] (2) The upper end of the grip 42 is substantially coplanar with the upper end of the motor housing 30. This configuration allows the user to properly grip the grip 42. Furthermore, the user can easily operate the switch button 34 provided on the motor housing 30 while gripping the grip 42.

[0075] (3) The perimeter of the gripping portion 42 is shorter than that of a general die grinder. The so-called "perimeter of the gripping portion 42" refers to the length of the outer shape of the gripping portion 42 in a cross section perpendicular to the drive axis TX. Figure 7 The dotted line schematically illustrates the circumference of the grip 42. In the present invention, the circumference of the grip 42 is sometimes referred to as the "thickness of the grip 42." However, the circumference of the grip 42 does not include any portion that the user does not contact when gripping the grip 42, or any local irregularities such as through-holes, threaded holes, grooves, and decorations formed in the grip 42 that do not affect the function of the grip 42.

[0076] In the mold grinder 100 of this embodiment, the average circumference of the grip 42 is less than 150 mm. In other words, the grip 42 is thinner than the grips of typical mold grinders. Therefore, the user can grip the grip 42 more comfortably. In the mold grinder 100 of this embodiment, the average circumference of the grip 42 is approximately 146 mm.

[0077] (4) The length of the gripping portion 42 in the front-back direction is longer than that of a general die grinder. More specifically, in the die grinder 100 of this embodiment, the length of the gripping portion 42 in the front-back direction is approximately 80 mm.

[0078] The length of the grip 42 in the front-to-back direction refers to the length from the front end of the grip 42 to the rear end of the grip 42. In the present invention, the "front end of the grip 42" refers to the portion at the front end of the handle housing 40 where the circumference of the grip 42 is greater than the average value of the circumference of the grip 42 by a specified value or more. The "rear end of the grip 42" refers to the portion at the rear end of the handle housing 40 where the circumference of the grip 42 is greater than the average value of the circumference of the grip 42 by a specified value or more.

[0079] In the present embodiment, the front end of the grip portion 42 is defined as a portion at the front end portion of the handle housing 40 where the circumference of the grip portion 42 becomes larger than 150 mm. In other words, the front end of the grip portion 42 is set to a portion where the circumference of the grip portion 42 is approximately 3% larger than the average value of the circumference of the grip portion 42. The rear end of the grip portion 42 is similarly defined as a portion at the rear end portion of the handle housing 40 where the circumference of the grip portion 42 is larger than 150 mm. In other words, the rear end of the grip portion 42 is set to a portion where the circumference of the grip portion 42 is approximately 3% larger than the average value of the circumference of the grip portion 42.

[0080] In a typical mold grinder, the length of the grip portion in the front-to-back direction is shorter than 60 mm. In the mold grinder 100 of this embodiment, the length of the grip portion 42 in the front-to-back direction is 80 mm, which fully ensures the length of the grip portion 42. Therefore, the user does not need to grip any portion of the main housing 10 other than the grip portion 42, such as the motor housing 30 or the battery housing 80, and can operate the mold grinder 100 by simply gripping the grip portion 42. Therefore, the user can properly grip the grip portion 42, thereby improving the usability of the mold grinder 100. In addition, the length of the grip portion 42 is approximately 20% or more of the length LA of the main housing 10 in the front-to-back direction. In other words, the grip portion 42 occupies a relatively large area of ​​the main housing 10. With respect to the length of the grip portion 42, in a typical mold grinder, the grip portion is approximately 15% of the length LA of the main housing 10. In the die grinder 100 of this embodiment, the grip 42 occupies a relatively large area of ​​the main housing 10 , thereby making it easy for the user to grip the grip 42 . Furthermore, by gripping the grip 42 , the die grinder 100 can be carried with good balance.

[0081] (5) The circumference of the grip portion 42 in the front-to-back direction is substantially uniform. More specifically, the dimensional error in the circumference of the grip portion 42 from the front end to the rear end is less than 3%. The uniform thickness of the grip portion 42 allows the user to grip the grip portion 42 appropriately.

[0082] As described above, according to the die grinder 100 of this embodiment, the battery mounting portion 86 is positioned so that the drive axis TX passes through it, allowing the battery BT to be mounted perpendicular to the drive axis TX. The central axis HX of the grip 42 is positioned radially outward of the drive axis TX. This shortens the length of the battery case 80 in the front-to-back direction compared to a case where the battery BT is mounted at an angle to the battery mounting portion 86. This prevents the die grinder 100 from extending in the front-to-back direction, while also increasing the length of the grip 42 in the front-to-back direction by the same amount as the battery case 80. Consequently, a die grinder 100 can be provided that allows for convenient gripping of the grip 42 while minimizing size. Furthermore, since the central axis HX of the grip 42 is positioned radially outward of the drive axis TX, the user can easily tilt the die grinder 100 so that the front end of the die grinder 100 is vertically below the rear end when operating the die grinder 100, thereby improving the operability of the die grinder 100.

[0083] In the die grinder 100 of this embodiment, when viewed from the side, the drive axis TX passes through the midpoint BC between the upper end BU of the battery BT mounted on the battery mounting portion 86 and the lower end BD of the battery BT. This makes it easy for the user to move the die grinder 100 along the drive axis TX and operate the die grinder 100 with good balance. This improves the operability of the die grinder 100. Furthermore, it is possible to suppress or prevent the die grinder 100 from growing radially outward about the drive axis TX.

[0084] In the mold grinder 100 of this embodiment, the controller 84 is positioned so as to extend vertically at a position along which the drive axis TX passes when viewing the mold grinder 100 from the side. This positioning of the controller 84 on the drive axis TX can suppress or prevent radial enlargement of the main housing 10. Furthermore, the length of the main housing 10 in the front-to-back direction can be shortened compared to a case where the controller 84 is positioned at an angle relative to the drive axis TX.

[0085] In the mold grinder 100 of this embodiment, the controller 84 is housed in the main housing 10 at a position further back than the grip 42. By housing the controller 84 in the battery housing 80, which has a greater internal space than the motor housing 30 and the handle housing 40, the controller 84 can be efficiently arranged within the main housing 10, thereby suppressing or preventing an increase in the size of the main housing 10.

[0086] In the mold grinder 100 of this embodiment, the controller 84 is positioned so as to overlap at least a portion of the air inlet 82 when the mold grinder 100 is viewed from the side. This allows air cooling of the controller 84 while shortening the length of the main housing 10 in the front-to-rear direction compared to a case where the controller 84 and the air inlet 82 are positioned at different locations.

[0087] In the mold grinder 100 of this embodiment, the stator core 212C of the motor 20 in the front-to-back direction is 30 mm or less. This configuration ensures a relatively short length of the motor 20 in the front-to-back direction. This prevents the mold grinder 100 from extending in the front-to-back direction while simultaneously extending the length of the gripping portion 42 in the front-to-back direction.

[0088] The die grinder 100 of this embodiment includes a shaft locking mechanism 70 utilizing a coupling 204. Utilizing the coupling 204 avoids the need for a new component as the shaft locking mechanism 70. This prevents an increase in the number of components of the die grinder 100 and prevents an increase in the length of the die grinder 100 in the front-rear direction.

[0089] In the die grinder 100 of this embodiment, the switch 14 is housed in the grip 42. Compared to a case where the switch 14 is housed in the motor case 30 or the battery case 80, the die grinder 100 can be prevented from being lengthened in the front-rear direction.

[0090] In the die grinder 100 of this embodiment, the dial 88 is provided in the battery housing 80 further rearward than the grip 42. By providing the dial 88 in the battery housing 80, which has a greater internal space than the motor housing 30 and the handle housing 40, the dial 88 can be efficiently arranged in the main housing 10, thereby suppressing or preventing the main housing 10 from increasing in size.

[0091] In the mold grinder 100 of this embodiment, the grip 42 has a length of 80 mm in the front-to-back direction, which is sufficient compared to the grip length of conventional mold grinders. This allows the user to grip the grip 42 appropriately, thereby improving the usability of the mold grinder 100.

[0092] In the mold grinder 100 of this embodiment, the grip 42 has a circumference of 146 mm, which is thinner than that of a typical mold grinder. Therefore, the user can grip the grip 42 appropriately, thereby improving the usability of the mold grinder 100.

[0093] In the mold grinder 100 of this embodiment, the length LA of the main housing 10 in the front-to-back direction is 382.1 mm, which is shorter than that of the main housings of conventional mold grinders. Therefore, due to the relatively short front-to-back length of the mold grinder 100, it can be operated appropriately even in confined spaces.

[0094] In the die grinder 100 of this embodiment, the length LB from the rear end of the battery housing 80 to the front end of the motor housing 30 in the front-to-back direction is 246.5 mm, which is also shorter than that of conventional die grinders. Because the rear half of the main housing 10 is relatively short, the die grinder 100 can be operated with good balance by gripping the grip 42.

[0095] B. Second embodiment: like Figure 8 As shown, the mold grinding machine 100b according to the second embodiment differs from the mold grinding machine 100 according to the first embodiment in that a paddle switch 34b is provided in place of the switch button 34. Other than this, the structures are identical. Even with this structure, the same effects as those of the first embodiment can be achieved.

[0096] The paddle switch 34b is provided at the lower end of the grip 42. The paddle switch 34b is urged toward the outside of the grip 42 by the coil spring 342 and is normally located at the stop position where the motor 20 is stopped. When the user overcomes the biasing force of the coil spring 342 and pushes the paddle switch 34b toward the inside of the grip 42, the paddle switch 34b moves toward the start position for starting the motor 20. Figure 8 3. The paddle switch 34b is shown in the park position.

[0097] exist Figure 8 FIG2 schematically illustrates the outer surface 34S of the paddle switch 34b when the paddle switch 34b is moved to the activated position. The outer surface 34S in the activated position is substantially coplanar with the lower end of the grip 42. In the mold grinder 100b thus configured, when defining the circumference of the grip 42, the outer surface 34S of the paddle switch 34b in the activated position may be considered part of the grip 42.

[0098] The following shows the correspondence between the various components (features) of the above-mentioned embodiment and the various components (features) of the present disclosure or the present invention. However, the various components of the embodiment are merely examples and do not limit the various components of the present disclosure or the present invention.

[0099] The mold grinder 100 and the mold grinder 100b are examples of a "mold grinder." The motor 20 is an example of a "motor." The stator core 212C is an example of a "stator core." The stator 212, the rotor 214, and the motor shaft 22 are examples of a "stator," a "rotor," and a "motor shaft." The motor rotation axis MX is an example of a "rotation axis of the motor shaft." The drive axis TX is an example of a "drive axis." The spindle 90 is an example of a "spindle." The main housing 10 is an example of a "main housing." The motor housing 30 is an example of a "motor housing." The handle housing 40 is an example of a "handle housing." The battery mounting portion 86 is an example of a "battery mounting portion." The battery housing 80 is an example of a "battery housing." The grip 42 is an example of a "grip portion." The controller 84 is an example of a "controller." The air inlet 82 is an example of an "air inlet." The shaft lock mechanism 70 is an example of a "shaft lock mechanism." The coupling 204 is an example of a "coupling." The switch button 34 and the paddle switch 34b are examples of a "first operating unit." The switch 14 is an example of a "switch." The dial 88 is an example of a "second operating unit."

[0100] The mold grinding machine according to the present invention is not limited to the mold grinding machines 100 and 100b of the above-described embodiments. For example, the following non-limiting modifications are possible. Furthermore, at least one of these modifications may be employed in combination with the mold grinding machines 100 and 100b of the embodiments and at least one of the features described in the technical claims.

[0101] (C1) In the first embodiment described above, the mold grinder 100 includes a switch button 34. Furthermore, in the second embodiment, the mold grinder 100b includes a paddle switch 34b. Alternatively, a trigger switch that activates the motor 20 by a user's depressing operation may be provided in place of the switch button 34 and the paddle switch 34b. The trigger switch may be provided, for example, at the lower end of the grip 42.

[0102] (C2) In the first embodiment described above, the drive axis TX is configured so that, when the mold grinder 100 is viewed from the side, the drive axis TX passes through the midpoint BC between the upper end BU of the battery BT mounted on the battery mounting portion 86 and the lower end BD of the battery BT. Alternatively, the drive axis TX may be configured so as to pass through the center of gravity of the battery BT mounted on the battery mounting portion 86. Furthermore, the drive axis TX may be configured so as to pass through the center (also referred to as the centroid) of the outer shape of the battery BT in a cross section perpendicular to the drive axis TX. Even with such a configuration, the user can easily move the mold grinder 100 along the drive axis TX and operate the mold grinder 100 with good balance.

[0103] The present invention is not limited to the above-described embodiments and can be implemented in various configurations without departing from the scope of the present invention. For example, in order to solve some or all of the above-described technical problems or achieve some or all of the above-described effects, the technical features in the embodiments corresponding to the technical features in the various embodiments described in the "Summary of the Invention" column can be appropriately replaced or combined. In addition, if the technical features are not described as essential in this specification, they can be appropriately deleted.

Claims

1. A mold grinding machine, characterized in that, It has a motor, a main shaft and a main housing, wherein The motor is driven by electricity supplied by a battery; The main shaft is rotated by the power of the motor about a drive axis defining the front-rear direction of the mold grinder; The main housing includes a motor housing, a handle housing and a battery housing, wherein: The motor housing accommodates the motor; The handle housing is connected to the rear end portion of the motor housing and has an elongated grip portion configured for a user to grip; The battery housing is connected to the rear end portion of the handle housing and has a battery mounting portion for mounting the battery. The battery mounting portion is arranged at a position where the drive axis passes, and is capable of mounting the battery in a direction perpendicular to the drive axis. The central axis of the grip portion is arranged radially outward of the drive axis.

2. The mold grinding machine according to claim 1, characterized in that When the direction in which the battery is installed in the battery mounting portion is defined as the up and down direction, the drive axis is configured so that, when the mold grinder is viewed from the side, the drive axis passes through the midpoint between the upper end of the battery mounted on the battery mounting portion and the lower end of the battery.

3. The mold grinding machine according to claim 1 or 2, characterized in that: A controller is further provided, the controller being configured to control the driving of the motor, The controller is arranged at a position where the drive axis passes through. When the die grinder is viewed from the side, the controller extends in a direction orthogonal to the drive axis.

4. The mold grinding machine according to claim 3, characterized in that The controller is housed in the main housing at a position rearward of the grip portion.

5. The mold grinding machine according to claim 3 or 4, characterized in that: The main housing has an air inlet, which can introduce external air into the interior of the main housing. When the die grinder is viewed from the side, the controller is arranged at a position overlapping with at least a portion of the air inlet hole.

6. The mold grinding machine according to any one of claims 1 to 5, characterized in that The motor includes a stator, a rotor, and a motor shaft rotating together with the rotor, wherein the stator includes a stator core. The motor is housed in the motor housing such that the rotation axis of the motor shaft is parallel to the front-rear direction. The length of the stator core in the front-to-back direction is less than 30 mm.

7. The mold grinding machine according to any one of claims 1 to 6, characterized in that The invention further includes a shaft locking mechanism capable of fixing the main shaft in a state where the rotation of the main shaft is stopped.

8. The mold grinding machine according to claim 7, characterized in that A coupling is further provided for connecting the motor shaft and the main shaft in such a manner that the rotation axis of the motor shaft of the motor and the drive axis are coaxial. The shaft locking mechanism is configured to be able to fix the main shaft by locking the shaft locking mechanism and the coupling.

9. The mold grinding machine according to any one of claims 1 to 8, characterized in that A switch is further provided, which switches the start and stop of the motor in response to the user's operation of the first operating part. The switch is accommodated in the grip portion.

10. The mold grinding machine according to any one of claims 1 to 9, characterized in that A second operating unit is provided, which can adjust the rotation speed of the motor. The second operating portion is provided at a rear side relative to the grip portion.

11. The mold grinding machine according to any one of claims 1 to 10, characterized in that In the front-back direction, the length from the rear end to the front end of the grip portion is 60 mm or more.

12. The mold grinding machine according to any one of claims 1 to 10, characterized in that In a cross section perpendicular to the drive axis, the circumference of the grip portion is 150 mm or less.

13. A mold grinding machine, characterized in that: It has a motor, a main shaft and a main housing, wherein The motor is driven by electricity supplied by a battery; The main shaft is driven to rotate around a drive axis defining the front-rear direction of the mold grinder by the power of the motor; The main housing includes a motor housing, a handle housing, a tool housing and a battery housing, wherein: The motor housing accommodates the motor; The handle housing is connected to the rear end portion of the motor housing and has an elongated grip portion configured for a user to grip; The tool housing is connected to the front end of the motor housing and is used to configure the spindle; The battery housing is connected to the rear end of the handle housing and has a battery mounting portion capable of mounting the battery. In the front-to-rear direction, a length of the main housing from the rear end of the battery housing to the front end of the tool housing is 400 mm or less.

14. The mold grinding machine according to claim 13, characterized in that In the front-to-back direction, the length of the main housing from the rear end of the battery housing to the front end of the motor housing is 260 mm or less.

15. The mold grinding machine according to claim 13 or 14, characterized in that: In the front-to-back direction, the length from the rear end to the front end of the grip portion is greater than or equal to 60 mm.

16. The die grinding machine according to any one of claims 13 to 15, characterized in that In a cross section perpendicular to the drive axis, the circumference of the grip portion is 150 mm or less.

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