Polishing tool and belt sander

Abstract

The invention discloses a polishing tool which comprises a main machine and a battery pack, the main machine comprises a shell, a battery pack connecting part is formed on the shell, the battery pack is detachably arranged on the battery pack connecting part, and the battery pack connecting part is provided with a mounting surface; a main handle connected to the housing; the grinding assembly is connected to the shell and comprises a bottom plate, and the bottom plate forms a supporting plane; the motor is arranged in the shell and used for driving the grinding assembly to work; the battery pack mounting surface is at least partially arranged between the motor and the main handle; when the battery pack combination part is provided with a battery pack, the host and the battery pack form a complete machine, and the projection point of the gravity center of the complete machine on the extension plane of the supporting plane is located in the supporting plane of the bottom plate; in the front-back direction of the shell, the bottom plate is provided with a first center line, and the distance D between the projection point and the first center line is larger than or equal to 0 mm and smaller than or equal to 38 mm. Therefore, when a user conducts grinding operation, the grinding piece can make stable contact with the ground piece, force applied by the hand of the user is reduced, and the grinding effect is guaranteed.

Description

Technical Field

[0001] The present application relates to a grinding tool. Background Art

[0002] A grinding tool in the related art, which uses a motor to drive the grinding piece to rotate to achieve polishing and grinding on the surface of materials such as wood, plastic, stone, and metal. In addition to meeting the grinding function, handheld grinding tools should usually have a smaller size and weight to meet the user's expectations for convenient operation and usage experience. As the power of the grinding tool increases, the motor configured with it usually has a larger size, which causes the size of the entire grinding tool to increase. After the battery pack is installed, the weight of the entire machine increases. When the user holds the grinding tool in hand, there is surface contact between the grinding piece and the piece being polished. Due to the large size and weight of the entire machine, it is difficult to ensure the stability of the grinding tool during use, resulting in poor grinding effect.

[0003] This section provides background information related to the present application which is not necessarily prior art. Summary of the invention

[0004] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide a grinding tool.

[0005] In order to achieve the above-mentioned objectives, the present application adopts the following technical solutions: a grinding tool, comprising a main unit and a battery pack, the main unit comprising: a shell, formed with a battery pack coupling part, the battery pack being detachably arranged at the battery pack coupling part, the battery pack coupling part having a mounting surface for mounting the battery pack; a main handle, connected to the shell; a grinding assembly, connected to the shell, the grinding assembly comprising a base plate, the base plate forming a supporting plane; a motor, arranged in the shell, the motor being used to drive the grinding assembly to operate; the battery pack mounting surface being at least partially arranged between the motor and the main handle; when the battery pack coupling part is installed with the battery pack, the main unit and the battery pack form a whole machine, the projection point of the center of gravity of the whole machine on the extended surface of the supporting plane is located within the supporting plane of the base plate; in the front-to-back direction along the shell, the base plate has a first center line, and the distance D from the projection point to the first center line is greater than or equal to 0 mm and less than or equal to 38 mm.

[0006] In some embodiments, a distance D from the projection point to the first center line is less than or equal to 25 mm.

[0007] In some embodiments, a projection point of the center of gravity of the battery pack on the extended surface of the support plane is substantially located within the support plane.

[0008] In some embodiments, the battery pack can be coupled to the battery pack coupling portion along a first straight line direction, and the first straight line is parallel to an extended surface of the support plane.

[0009] In some embodiments, the battery pack can be coupled to the battery pack coupling portion along a first straight line direction, and the first straight line obliquely intersects with an extended surface of the support plane.

[0010] In some embodiments, the battery pack can be coupled to the battery pack coupling portion along a first straight line direction, the plane where the mounting surface is located is perpendicular to the extended surface of the supporting plane, and the first straight line is perpendicular to the supporting plane.

[0011] In some embodiments, the plane where the mounting surface is located is obliquely intersecting or parallel to the extended surface of the supporting plane.

[0012] In some embodiments, the grinding assembly further includes a speed control switch configured to control the rotation speed of the motor, and the speed control switch is disposed on the first gripping portion of the main handle.

[0013] In some embodiments, the motor rotates around a motor axis, and the battery pack is coupled to a mounting surface of the battery pack along a first linear direction, and the first linear direction is substantially perpendicular to the motor axis direction.

[0014] In some embodiments, the main handle includes a first grip portion, and a rear end of the first grip portion extends obliquely downward relative to the shell.

[0015] In some embodiments, the distance between the rear end of the first grip portion and the extended surface of the support plane is less than or equal to 50 mm.

[0016] In some embodiments, a trigger is provided on the first gripping portion, and a distance between the trigger and an extended surface of the supporting plane is less than or equal to 80 mm.

[0017] In some embodiments, the grinding assembly also includes a driving wheel and a driven wheel, the driving wheel is located on the rear side of the base plate, the driven wheel is located on the front side of the base plate, and the grinding piece is sleeved on the driving wheel and the driven wheel; a trigger is provided on the first gripping portion, and the trigger is between the highest point of the driving wheel and the center of gravity of the battery pack along a direction perpendicular to the supporting plane.

[0018] In some embodiments, along the front-to-rear direction of the housing, the trigger is located behind the driving wheel.

[0019] In some embodiments, along the left-right direction of the housing, the trigger is substantially located in the middle of the base plate.

[0020] A grinding tool includes a main unit and a battery pack, wherein the main unit includes: a shell, on which a battery pack coupling portion is formed, the battery pack is detachably arranged at the battery pack coupling portion, and the battery pack coupling portion has a mounting surface for mounting the battery pack; a main handle, connected to the shell; a grinding assembly, connected to the shell, the grinding assembly includes a base plate, and the base plate forms a supporting plane; a motor, arranged in the shell, the motor is used to drive the grinding assembly to operate; the motor is at least partially located between the mounting surface and the main handle; when the battery pack is installed at the battery pack coupling portion, the main unit and the battery pack form a complete machine, and the projection point of the center of gravity of the complete machine on the extended surface of the supporting plane is located within the supporting plane of the base plate; in the front-to-back direction along the shell, the base plate has a first center line, and the distance D from the projection point to the first center line is greater than or equal to 0 mm and less than or equal to 38 mm.

[0021] A belt sander includes a main unit and a battery pack, wherein the main unit includes: a shell, on which a battery pack coupling portion is formed, and the battery pack is detachably arranged on the battery pack coupling portion, and the battery pack coupling portion has a mounting surface for mounting the battery pack; a main handle, connected to the shell; a grinding assembly, connected to the shell, and the grinding assembly includes a base plate, and the base plate forms a supporting plane; a motor, which is arranged in the shell, and is used to drive the grinding assembly to operate; the motor is at least partially located between the mounting surface and the main handle; when the battery pack is installed on the battery pack coupling portion, the main unit and the battery pack form a complete machine, and the projection point of the center of gravity of the complete machine on the extended surface of the supporting plane is located within the supporting plane of the base plate.

[0022] The benefit of the present application lies in that: through the structural setting of the battery pack, motor, and main handle, the projection point of the center of gravity of the whole machine on the extended surface of the supporting plane is located within the supporting plane of the base plate, and the center of gravity is stable. Therefore, when the user performs the grinding operation, the grinding workpiece can be in stable contact with the grinded workpiece, reducing the user's hand force and ensuring the grinding effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a structural schematic diagram of a grinding tool provided by the present application; Figure 2 It is a front view of a grinding tool provided by the present application; Figure 3 This is a schematic diagram of a grinding tool provided by the present application with some structures omitted. Figure 1 ; Figure 4 This is a schematic diagram of a grinding tool provided by the present application with some structures omitted. Figure 2 ; Figure 5 It is a schematic diagram of the exploded structure of a grinding tool provided by the present application; Figure 6 is a three-dimensional diagram of the grinding tool in the present application removing the grinding piece; Figure 7 It is a structural schematic diagram of another grinding tool provided by the present application; Figure 8 It is a structural schematic diagram of another grinding tool provided by the present application.

[0024] In the figure: 100, main unit; 110, housing; 111, battery pack joint; 120, main handle; 121, first gripping portion; 122, first connecting portion; 130, grinding assembly; 131, bottom plate; 1311, supporting plane; 132, grinding piece; 133, driving wheel; 134, driven wheel; 140, motor; 150, control panel; 160, trigger; 170, auxiliary handle; 200. Battery pack. DETAILED DESCRIPTION

[0025] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above drawings.

[0026] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0027] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0028] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0029] In this application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, etc. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0030] In this application, it will be understood by those skilled in the art that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0031] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0032] like Figures 1 to 4 As shown, this embodiment provides a grinding tool, which can be used for grinding a workpiece to make the surface of the workpiece smooth. The grinding tool includes a main body 100 and a battery pack 200, the main body 100 includes a housing 110, a main handle 120 and a grinding assembly 130, the housing 110 is formed with a battery pack 200 coupling portion, and the battery pack 200 is detachably arranged on the battery pack coupling portion 111; the main handle 120 is connected to the housing 110, and the grinding assembly 130 is connected to the housing 110.

[0033] The housing 110 forms the main outer shell of the grinding tool, and most of the devices of the grinding tool are connected to the housing 110 or are arranged inside the housing 110. The housing 110 forms a first accommodation space, which refers to a closed or incompletely closed space formed by the housing 110 for placing corresponding components, and the first accommodation space is continuous with the housing 110.

[0034] The grinding tool also includes a motor 140, which is disposed in the housing 110, specifically in the first accommodation space of the housing 110, and is used to provide power for the operation of the grinding assembly 130. The motor 140 is a general term for any device that is powered by electrical energy, preferably an electric motor unit, but it is also conceivable that it can also be other configurations that are easily conceived by people in the field, such as pneumatic motors, internal combustion engines, hybrid motors and the like. The motor 140 is connected to the grinding assembly 130 through a transmission device. The motor 140 is basically fixedly arranged in the first accommodation space, and the housing 110 corresponding to the first accommodation space surrounds the motor 140, and is basically the same shape as the motor 140.

[0035] The grinding tool further includes a control panel 150, which is disposed in the housing 110, specifically in the first accommodation space of the housing 110. The control panel 150 is electrically connected to the motor 140 and can be electrically connected to the battery pack 200. The battery pack 200 supplies power to the motor 140 through the control panel 150. A trigger 160 is disposed on the main handle 120, and the trigger 160 is electrically connected to the control panel 150 to control the start and stop of the motor 140.

[0036] The grinding assembly 130 may have different structures depending on the type of grinding tool. Figure 5 As shown, the grinding assembly 130 includes a base plate 131 and a grinding piece 132. A support plane 1311 is formed on the base plate 131. The base plate is used to support the grinding piece 132. The grinding piece 132 is used to grind the workpiece. The support plane 1311 is particularly defined as the largest surface of the base plate 131 and the grinding piece 132 in contact when the grinding tool is in the most common posture. In this embodiment, the base plate 131 is substantially rectangular, and the support plane 1311 is the largest plane of the base plate 131. The extended surface of the support plane 1311 refers to the virtual plane A1 where the support plane 1311 is located and can be extended.

[0037] The grinding piece 132 is a belt-shaped structure with a rough surface and a grinding function. The motor 140 can drive the grinding piece 132 to work, and the motor 140 is configured to rotate around the motor axis 146. Specifically, the grinding assembly 130 also includes a driving wheel 133 and a driven wheel 134, the driving wheel 133 is located on the rear side of the base plate 131, and the driven wheel 134 is located on the front side of the base plate 131. The grinding piece 132 is sleeved on the driving wheel 133 and the driven wheel 134, and the motor 140 is used to drive the driving wheel 133 to rotate, so that the grinding piece 132 rotates around the driving wheel 133 and the driven wheel 134 to achieve grinding. The motor 140 can directly drive the driving wheel 133 to rotate, and can also drive the driving wheel 133 through a transmission mechanism.

[0038] In this embodiment, the front and rear, left and right, and up and down directions of the housing 110 are defined, the main handle 120 is located at the rear side of the housing 110, and an auxiliary handle 170 is also provided at the front side of the housing 110. The polishing assembly 130 is located at the bottom of the housing 110, and the battery pack 200 is provided above the polishing assembly 130 for easy installation and removal.

[0039] The battery pack 200 is detachable. When the battery pack 200 is installed on the battery pack joint 111, the host 100 and the battery pack 200 form a complete machine, and the projection point of the center of gravity G1 of the complete machine on the extended surface of the support plane 1311 is located within the support plane 1311 of the bottom plate 131. The center of gravity G1 is stable, so when the user performs grinding operations, the center of gravity G1 of the complete machine falls within the boundary of the bottom plate 1319, and the support plane 1311 of the bottom plate 131 is in parallel contact with the grinding plane of the workpiece as much as possible, and there will be no uneven grinding surface caused by the shaking of the grinding tool back and forth. On the other hand, when the user operates the sander to grind the workpiece, in order to avoid uneven grinding due to the shaking of the grinding tool, the user will apply external force to the sander to make the supporting plane 1311 of the sander and the grinding plane as parallel as possible. After a long time, the user will be very tired. Through the above setting, while ensuring the grinding effect of the sander, it can also reduce the user's hand force, making it easier for the user to operate.

[0040] Please refer to Figures 5 and 6, along the front-to-back direction of the shell 110, the bottom plate 131 has a first center line 102, and the center of gravity G1 of the whole machine has a projection point G3 on the extension surface of the support plane 1311, and the distance D from the projection point G3 to the first center line 102 is greater than or equal to 0mm and less than or equal to 38mm. That is to say, the projection point G3 of the center of gravity G1 of the whole machine basically falls on the left and right sides less than 38mm from the first center line. This setting can make the center of gravity G1 of the whole machine as close to the first center line 102 of the bottom plate as possible. Through the above setting, the bottom plate 131 is subjected to balanced force, avoiding the front end of the bottom plate 131 from warping during use, thereby avoiding the grinding tool from shaking back and forth and causing uneven grinding, ensuring the stability of the sanding machine, and improving the grinding effect of the sanding machine. Further, the distance D from the projection point G3 to the first center line 102 is greater than or equal to 0mm and less than or equal to 25mm. The distance D from the projection point G3 to the first center line 102 is set in the above range, and the grinding effect is better, and the user is more labor-saving. In this way, when the user holds the grinding tool to grind the workpiece, he only needs to pay attention to the surface to be grinded and control the sander to grind, which is convenient for the user to operate and can also improve the grinding effect of the sander. The first center line 102 is basically located in the middle of the bottom plate 131, that is, in the left-right direction, the first center line 102 is basically located in the middle of the width direction of the bottom plate 131.

[0041] The battery pack joint 111 has a mounting surface for mounting the battery pack 200, the mounting surface is in surface contact with the battery pack 200, and the mounting surface is obliquely intersecting, perpendicular or parallel to the extension surface A1 of the support plane 1311. In other words, the battery pack 200 can be arranged vertically, horizontally or obliquely to adapt to various shape requirements of the housing 110.

[0042] In some embodiments, Figure 2 As shown, the mounting surface extends in the vertical direction, and A2 represents the mounting surface. The mounting surface is perpendicular to the extension surface of the supporting plane 1311 . Further, the mounting surface is perpendicular to the supporting plane 1311 .

[0043] The battery pack 200 can be coupled to the battery pack coupling portion 111 along a first straight line, and the first straight line is parallel to the mounting surface. The first straight line is represented by O1 in the drawings. In some embodiments, Figure 2 As shown, the first straight line is parallel to the installation surface, the first straight line is perpendicular to the extension surface of the support plane 1311, the first straight line extends in the vertical direction, and the battery pack 200 is inserted from top to bottom. In other embodiments, such as Figure 7 As shown, the first straight line extends in the horizontal direction, and the battery pack 200 is inserted from the front to the back. If space permits, the battery pack 200 can be inserted and removed in the left and right directions. Figure 8As shown, the mounting surface extends in the vertical direction, the mounting surface is perpendicular to the extension surface of the support plane 1311, the first straight line is parallel to the extension surface of the support plane 1311, the first straight line extends in the horizontal direction, and the battery pack 200 can be plugged in and out in the left and right directions.

[0044] In some embodiments, the first straight line O1 is parallel to, obliquely intersecting with, or vertically arranged with the extended surface A1 of the support plane, so that the battery pack can be horizontally inserted into the battery pack joint 111 along the front-to-back direction and the left-to-right direction, and the battery pack can also be inserted into the battery pack joint 111 along multiple inclined angles such as the forward direction, the rearward direction, the left direction, and the right direction, and the battery pack can also be inserted into the battery pack joint 111 along the up-down direction.

[0045] When the battery pack 200 is installed on the battery pack installation surface along the first straight line O1, wherein the first straight line O1 is substantially perpendicular to the motor axis 146 of the motor 140, the opening direction of the battery pack coupling portion 111 is toward the main handle 120. In this way, whether the battery pack coupling portion 111 is coupled with a battery pack with a heavier battery capacity or a battery pack with a lighter capacity, the projection point of the center of gravity of the whole device on the supporting plane 1311 can be as close to the first center line 102 as possible.

[0046] When the battery pack is installed on the battery pack joint 111, the projection point of the center of gravity G2 of the battery pack 200 on the extended surface of the support plane 1311 is located within the support plane 1311 of the bottom plate 131, ensuring the stability of the battery pack 200 and avoiding imbalance during use. In actual operation, users will choose different capacity battery packs 200 for sanding according to different working conditions. It can be understood that different battery capacities, that is, battery packs 200, correspond to different weights of the battery pack 200. The weight of the battery pack 200 is relatively heavy relative to the weight of the main body of the sanding machine, so the weight of the battery pack 200 will affect the center of gravity G1 of the whole machine. Through the above-mentioned setting of the battery pack joint 111, no matter which capacity of battery pack 200 the user chooses, or the angle at which the battery pack 200 is inserted into the battery pack joint 111, the projection of the center of gravity G2 of the battery pack installed on the main body on the extended surface of the support plane 1311 can be located within the support plane of the bottom plate.

[0047] like Figure 2 As shown, the battery pack 200 is at least partially disposed between the motor 140 and the main handle 120. In other embodiments, such as Figures 7 and 8As shown, the motor 140 is at least partially disposed between the battery pack 200 and the main handle 120. The layout of the battery pack 200, the motor 140 and the main handle 120 ensures that the projection of the center of gravity of the whole machine on the support plane 1311 is located within the boundary of the bottom plate 131, and the center position of the bottom plate 131 is basically located to ensure that the projection of the center of gravity of the battery pack 200 on the support plane 1311 is located within the boundary of the bottom plate 131.

[0048] like Figure 2 As shown, the main handle 120 includes a first gripping portion 121 , the tail end of which extends obliquely downward relative to the housing 110 , and can apply a forward and downward force to the main handle 120 when gripped to prevent the tool from tilting during operation.

[0049] Specifically, the distance between the rear end of the first gripping portion 121 and the extended surface of the supporting plane 1311 is less than or equal to 50 mm. Figure 2 L1 represents the distance between the tail end of the first grip 121 and the support plane 1311. In some embodiments, the distance between the tail end of the first grip 121 and the extended surface of the support plane 1311 is equal to 50 mm, 40 mm, 30 mm, 20 mm, etc. This arrangement allows the grinding tool to occupy less space in the height direction of the entire machine, which is more convenient.

[0050] A trigger 160 is disposed on the first grip portion 121, and the distance between the trigger 160 and the extended surface of the support plane 1311 is less than or equal to 80 mm. Figure 2 L2 represents the distance between the rear end of the first grip 121 and the extended surface of the support plane 1311. In some embodiments, the distance between the trigger 160 and the extended surface of the support plane 1311 is equal to 80mm, 70mm, 60mm, 50mm, etc. This arrangement allows the grinding tool to occupy less space in the height direction of the entire machine, which is more convenient.

[0051] In the direction perpendicular to the extension surface of the support plane 1311, the trigger 160 is between the highest point of the driving wheel 133 and the center of gravity of the battery pack 200. The setting position of the trigger 160 is convenient for holding, because it is lower than the center of gravity of the battery pack 200 and higher than the driving wheel 133, making it easy to control the balance when holding.

[0052] In some embodiments, along the front-to-back direction of the housing 110, the trigger 160 is located behind the driving wheel 133. In some embodiments, along the left-to-right direction of the housing 110, the trigger 160 is substantially located in the middle of the bottom plate 131. Such a configuration is to ensure the balance of the whole machine.

[0053] The first gripping portion 121 is provided with a first connecting portion 122 at one end close to the housing 110. The first connecting portion 122 is integrally formed with the housing 110 or is detachably connected. The first gripping portion 121 extends substantially along the second straight line, and the first connecting portion 122 extends substantially along the third straight line. The angle between the second straight line and the third straight line is an acute angle. Figure 2 In the figure, O2 represents the second straight line, and O3 represents the third straight line.

[0054] The grinding tool is also provided with a speed switch 123, which is used to control the rotation speed of the motor 140. The speed switch 123 is arranged on the first connecting part 122. In this way, when the user holds the first holding part 121, he can turn the speed switch 123 at the same time, which is convenient for the user to operate.

[0055] In the present application, the grinding tool may be a belt sander.

[0056] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above embodiments do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. A grinding tool, comprising a main unit and a battery pack, wherein the main unit comprises: A housing is formed with a battery pack coupling portion, the battery pack is detachably arranged on the battery pack coupling portion, and the battery pack coupling portion has a mounting surface for mounting the battery pack; a main handle connected to the housing; A grinding assembly connected to the housing, the grinding assembly comprising a base plate, the base plate forming a support plane; A motor is disposed in the housing, and is used to drive the grinding assembly to operate; Features: The battery pack mounting surface is at least partially disposed between the motor and the main handle; When the battery pack is installed on the battery pack combination portion, the host and the battery pack form a complete machine, and the projection point of the center of gravity of the complete machine on the extended surface of the support plane is located within the support plane of the bottom plate; In the front-to-back direction of the shell, the bottom plate has a first center line, and a distance D from the projection point to the first center line is greater than or equal to 0 mm and less than or equal to 38 mm.

2. The grinding tool according to claim 1, characterized in that: A distance D from the projection point to the first center line is less than or equal to 25 mm.

3. The grinding tool according to claim 1, characterized in that: The projection point of the center of gravity of the battery pack on the extended surface of the support plane is basically located within the support plane.

4. The grinding tool according to claim 1, characterized in that: The battery pack can be coupled to the battery pack coupling portion along a first straight line direction, and the first straight line is parallel to an extension surface of the support plane.

5. The grinding tool according to claim 1, characterized in that: The battery pack can be coupled to the battery pack coupling portion along a first straight line direction, and the first straight line obliquely intersects with an extended surface of the support plane.

6. The grinding tool according to claim 1, characterized in that: The battery pack can be coupled to the battery pack coupling portion along a first straight line direction, the plane where the mounting surface is located is perpendicular to the extended surface of the supporting plane, and the first straight line is perpendicular to the supporting plane.

7. The grinding tool according to claim 1, characterized in that: The plane where the mounting surface is located is obliquely intersecting or parallel to the extended surface of the supporting plane.

8. The grinding tool according to claim 1, characterized in that: The motor rotates around the motor axis, and the battery pack is coupled to a mounting surface of the battery pack along a first straight line direction, wherein the first straight line direction is substantially perpendicular to the motor axis direction.

9. The grinding tool according to any one of claims 1 to 8, characterized in that: The main handle comprises a first gripping portion, wherein a rear end of the first gripping portion extends downwardly at an angle relative to the housing.

10. The grinding tool according to claim 9, characterized in that: The distance between the tail end of the first gripping portion and the extended surface of the supporting plane is less than or equal to 50 mm.

11. The grinding tool according to claim 9, characterized in that: The first gripping portion is provided with a trigger, and the distance between the trigger and the extended surface of the supporting plane is less than or equal to 80 mm.

12. The grinding tool according to claim 9, characterized in that: The grinding assembly further comprises a driving wheel and a driven wheel, wherein the driving wheel is located at the rear side of the bottom plate, the driven wheel is located at the front side of the bottom plate, and the grinding piece is sleeved on the driving wheel and the driven wheel; A trigger is provided on the first gripping portion, and along a direction perpendicular to the supporting plane, the trigger is located between the highest point of the driving wheel and the center of gravity of the battery pack.

13. The grinding tool according to claim 12, characterized in that: Along the front-to-rear direction of the housing, the trigger is located behind the driving wheel.

14. The grinding tool according to claim 12, characterized in that: Along the left-right direction of the housing, the trigger is basically located in the middle of the base plate.

15. A belt sander, comprising a main unit and a battery pack, wherein the main unit comprises: A housing is formed with a battery pack coupling portion, the battery pack is detachably arranged on the battery pack coupling portion, and the battery pack coupling portion has a mounting surface for mounting the battery pack; a main handle connected to the housing; A grinding assembly connected to the housing, the grinding assembly comprising a base plate, the base plate forming a support plane; A motor is disposed in the housing, and is used to drive the grinding assembly to operate; Features: The motor is at least partially located between the mounting surface and the main handle; When the battery pack is installed on the battery pack combining portion, the host and the battery pack form an integrated machine, and the projection point of the center of gravity of the integrated machine on the extended surface of the supporting plane is located within the supporting plane of the bottom plate.

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