Sander

Abstract

A sander (100), comprising a housing (1), a driving assembly (2), a fan assembly (3), and a bottom plate assembly (4). The driving assembly (2) has a motor axis. The fan assembly (3) is provided with a partially thickened first counterweight area (3a), and the ratio of the mass of the first counterweight area (3a) to the mass of the fan assembly (3) is less than or equal to 13%. A balance block (5) is provided between the fan assembly (3) and the bottom plate assembly (4), the balance block (5) is provided with a center-of-mass adjustment portion (51) protruding from the periphery, and the center-of-mass adjustment portion (51) and the first counterweight area (3a) are located on a same side of the motor axis. By means of a counterweight mode in which the fan assembly (3) and the balance block (5) are combined, the sander achieves the balance of heat dissipation, dust collection, vibration reduction, economy and manufacturability.

Description

sander

Technical field

[0001] The present invention relates to a sanding machine, in particular to a sanding machine comprising a balancing weight. [Background Technology]

[0002] Sanders are commonly used as grinding and polishing tools, primarily used for cleaning, deburring, and leveling large surfaces in applications such as building renovation, furniture painting, and bathroom fixtures. A sander primarily consists of a housing, drive assembly, fan assembly, eccentric element, and base assembly. The housing houses the drive assembly, motor assembly, and eccentric element. The base assembly is at least partially external to the housing and is used to connect sandpaper. The eccentric element drives the base assembly into an oscillatory motion about the drive assembly's motor axis, thereby enabling the sandpaper to grind and polish the workpiece.

[0003] To reduce vibration during operation, sanders often incorporate a balancing structure to counteract the eccentric force of the baseplate assembly. To facilitate installation and simplify the structure, two main balancing layouts are available: one is to directly connect the balancing structure to the fan element or form it integrally; the other is to use an independent balancing block structure.

[0004] However, in the prior art sanding machine, reference can be made to Chinese invention patent No. CN1899765A, published on January 24, 2007, which further discloses: a sanding machine having at least two balancing weights for balancing an eccentric cutter of the sanding machine, the balancing weights comprising a first balancing weight, a second balancing weight, and a third balancing weight, the first balancing weight and the third balancing weight being integrally formed with each other and fixedly connected to or integrated with a fan impeller, the second balancing weight being non-rotatably connected to the shaft via a shaft support unit or an inner bearing ring of the shaft support unit. However, the balancing weights are not described in detail (such as the material of the balancing weights, the ratio of the balancing weights to each other, the structural design of the balancing weights, and the connection between the balancing weights and the base plate assembly). Only the structural layout of the balancing weights is disclosed. Moreover, the structural process is complex, which is not conducive to achieving good control of heat dissipation, dust collection, and balancing weights in the sanding machine.

[0005] In view of this, it is necessary to provide a sanding machine to overcome the defects of the prior art.

[0006] [Summary of the invention]

[0007] In view of the deficiencies in the prior art, an object of the present invention is to provide a sanding machine with good balance and low vibration.

[0008] The present invention solves the existing technical problems by adopting the following technical solutions: a sanding machine comprises a casing, a driving assembly installed in the casing, a fan assembly connected to the driving assembly and a base plate assembly driven by the driving assembly, the driving assembly having a motor axis, the fan assembly comprising a mounting plate connected to the driving assembly and heat dissipation fan blades and dust collecting fan blades integrated in the mounting plate, the mounting plate having a first surface and a second surface arranged on opposite sides, the heat dissipation fan blades being arranged on the first surface, and the dust collecting fan blades being arranged on the second surface; the fan assembly has a partially thickened first counterweight area, the first counterweight area is integrated in the second surface, the ratio of the mass of the first counterweight area to the mass of the fan assembly is less than or equal to 13%, a balancing block is provided between the fan assembly and the base plate assembly, the balancing block has a center of mass adjustment portion protruding from the periphery, the center of mass adjustment portion and the first counterweight area are located on the same side of the motor axis.

[0009] A further improvement is as follows: the first counterweight area includes a first counterweight blade thickened from the dust collecting fan blade and a first counterweight block protruding from the periphery of the mounting plate. There is at least one first counterweight blade, and the first counterweight blade and the first counterweight block are located on the same side of the motor axis.

[0010] A further improvement is that the first counterweight is an arc-shaped counterweight, the ratio of the radial width of the arc-shaped counterweight to the diameter of the mounting plate is less than or equal to 11%, and the ratio of the height of the arc-shaped counterweight to the height of the dust collecting fan blade is less than or equal to 30%.

[0011] A further improved solution is: A further improved solution is: the first counterweight area forms an angle with the second surface, and the angle is less than or equal to 120°.

[0012] A further improved solution is: the base plate assembly has a circular groove recessed from the center, the balancing weight is installed in the circular groove, and the ratio of the area of ​​the circular groove to the area of ​​the base plate assembly is less than or equal to 7.5%.

[0013] A further improved solution is: the first surface has a meandering hole passing through the mounting plate, the second surface has a circular hole passing through the mounting plate, and the meandering hole is connected to the circular hole.

[0014] A further improvement is that the balancing block includes a through hole for installing the drive assembly, the circular hole is coaxial with the through hole, and the torque of the balancing block from the center of the through hole accounts for between 40% and 50% of the torque of the first counterweight area from the center of the circular hole.

[0015] A further improvement is as follows: the fan assembly also has an eccentric element protruding from the second surface, the eccentric element includes an eccentric shaft connected to the drive assembly and a recessed portion recessed from the axial end of the eccentric shaft, the balancing block also has a snap-fit ​​portion protruding from the end face, the snap-fit ​​portion and the center of mass adjustment portion are arranged along both sides of the motor axis, and the snap-fit ​​portion is combined with the recessed portion.

[0016] A further improvement is as follows: the eccentric element has a first axis in a radial direction, the first axis coincides with the center point of the recessed portion, and the mass of the first counterweight blade intersecting the first axis is greater than the mass of the other first counterweight blades.

[0017] A further improved solution is: the end surface of the serpentine hole has a second axis facing the second counterweight, and the first axis is parallel to or colinear with the second axis.

[0018] A further improvement is as follows: the heat dissipation fan blade has a partially thickened second counterweight fan blade, the other side of the mounting plate has a second counterweight block protruding from the periphery, the second counterweight fan blade and the second counterweight block form a second counterweight area, and the second counterweight area is integrated into the first surface.

[0019] A further improved solution is that the first counterweight area and the second counterweight area are arranged along both sides of the motor axis.

[0020] Compared with the prior art, the present invention has the following beneficial effects: by utilizing the counterweight method combining the fan assembly and the independent counterweight, the sander achieves a good balance in functionality (heat dissipation, dust collection and balance), economy and processability. Specifically, due to the presence of the counterweight, the ratio of the sum of the mass of the first counterweight blade and the first counterweight to the mass of the fan assembly is less than or equal to 13%, thereby reducing the mass of the counterweight on the fan assembly and having little effect on the dust collection or heat dissipation effect. In addition, the first counterweight is an arc-shaped counterweight, the radial width of the arc-shaped counterweight is less than or equal to 11% of the diameter of the mounting plate, and the ratio of the height of the arc-shaped counterweight to the height of the dust collecting blade is less than or equal to 30%, which has little effect on the dust collection effect of the dust collecting end of the dust collecting fan; secondly, the center of mass adjustment portion on the counterweight, the first counterweight blade and the first counterweight are relatively close to each other. The weight blocks are arranged on the same side of the motor axis, which has good balance and reduces the influence of centrifugal force on the operation of the whole machine. Then, the ratio of the area of ​​the circular groove of the base plate assembly to the area of ​​the base plate assembly is less than or equal to 7.5%, the volume of the balance block is reduced, the strength of the base plate assembly is increased, its buffering capacity is improved, and the operating comfort of the sander during operation is improved. Finally, the balancing weight is a balancing method in which the weight of the fan assembly is combined with an independent balancing block. The independent balancing block has a certain axial overlap on the base plate assembly, which has a significant effect on the downward shift of the center of mass position of the main balancing assembly.

Brief Description of the Drawings

[0021] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0022] FIG1 is a schematic structural diagram of a sanding machine according to the present invention;

[0023] FIG2 is a schematic cross-sectional view of the sanding machine shown in FIG1 ;

[0024] FIG3 is an exploded schematic diagram of a portion of the structure of the sanding machine shown in FIG2 ;

[0025] FIG4 is a schematic structural diagram of a fan assembly and a balancing block of the sanding machine shown in FIG3 ;

[0026] FIG5 is a schematic structural diagram of the fan assembly of the sanding machine shown in FIG4 ;

[0027] FIG6 is a structural schematic diagram of the fan assembly of the sanding machine shown in FIG5 from another perspective;

[0028] FIG7 is a schematic structural diagram of the balance block of the sanding machine shown in FIG3 ;

[0029] FIG8 is a schematic structural diagram of the bottom plate assembly and the balancing block of the sanding machine shown in FIG1 ;

[0030] FIG9 is a cross-sectional schematic diagram of the bottom plate assembly and the balancing block of the sanding machine shown in FIG8 . [Specific implementation method]

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0032] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. For example, terms such as "upper," "lower," "front," and "rear" indicating orientation or positional relationships are based solely on the orientation or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the disclosure. They do not indicate or imply that the device or element referred to must have a specific orientation or be constructed or operated in a specific orientation. Therefore, they should not be construed as limiting the disclosure.

[0033] 1 to 3 , an embodiment of the present invention relates to a sanding machine 100, comprising a housing 1, a drive assembly 2 installed in the housing 1, a fan assembly 3 connected to the drive assembly 2, a base assembly 4 driven by the drive assembly 2, and a switch 6 for controlling the operation of the sanding machine 100. The housing 1 has a grip 11 for a user to hold and a housing 12 for accommodating the drive assembly 2 and the fan assembly 3. One end of the grip 11 is connected to the housing 12, and the other end is used to connect to a power cord 7 of the sanding machine 100 or to form a connection seat for installing a portable DC power supply such as a battery pack. In this embodiment, the sanding machine 100 uses AC power provided by the power cord 7.

[0034] The switch 6 is mounted on the housing 1 , specifically, the switch 6 is mounted on the grip 11 . When the user's palm covers the grip 11 , the user's fingers can conveniently toggle the switch 6 , thereby controlling the start and stop of the sander 100 .

[0035] The drive assembly 2 includes a motor axis L and a motor 21 that rotates along the motor axis L. The motor 21 serves as the prime mover of the sanding machine 100 and is disposed within the housing 12. The motor 21 includes a motor shaft 211 for transmitting power to the fan assembly 3. The motor shaft 211 rotates along the motor axis L, and the motor axis L extends generally in the vertical direction.

[0036] The housing 1 is formed with an air inlet, an air outlet, and a dust outlet. The fan assembly 3 is fixedly connected to the motor shaft 211, that is, when the motor 21 rotates, the fan assembly 3 also operates. When the fan assembly 3 rotates, air enters from the air inlet, flows through the motor 21 and other components, and finally flows out from the air outlet, thereby achieving the effect of cooling the motor 21 and other components in the housing 1. On the other hand, the airflow can also effectively blow the dust processed on the base plate assembly 4 to the dust outlet, and finally enter the dust collection box (not shown in the figure), thereby achieving the dust collection effect.

[0037] The fan assembly 3 includes a mounting plate 31 connected to the drive assembly 2, and heat dissipation blades 32 and dust collection blades 33 integrated into the mounting plate 31. The mounting plate 31 is sleeved around the outer periphery of the motor shaft 211. When the motor 21 rotates via the energy source provided by the power cord 7, the fan assembly 3 is driven to rotate about the motor axis L, generating a dust collection airflow and / or a heat dissipation airflow.

[0038] The heat dissipation fan blades 32 and the dust collection fan blades 33 are integrated together to form a double-sided fan, which is beneficial to shortening the height of the sanding machine 100 in the vertical direction, making the entire machine structure more compact and reducing the weight of the sanding machine 100.

[0039] As shown in Figures 5 and 6 , the mounting plate 31 has a first surface 311 and a second surface 312 disposed on opposite sides. The heat dissipation blades 32 are disposed on the first surface 311, and the dust collection blades 33 are disposed on the second surface 312. The blades of both the heat dissipation blades 32 and the dust collection blades 33 are curved. When viewed upward from the base plate assembly 4, the arc of the dust collection fan 33 is distributed counterclockwise with the motor axis L as the centerline, facilitating dust collection. The heat dissipation blades 32, on the other hand, are distributed clockwise with the motor axis L as the centerline, drawing air to cool the motor 21 and other components within the housing 1, achieving a heat dissipation effect.

[0040] 2 and 5 , the fan assembly 3 further includes an eccentric element 34 protruding from the second surface 312. The eccentric element 34 is mounted on the motor shaft 211 and is eccentrically disposed relative to the motor shaft 211. The eccentric element 34 is fixedly connected to the mounting plate 31. It should be noted that the eccentricity of the eccentric element 34 relative to the motor shaft 211 means that the eccentric element 34 has an eccentric axis L3. The eccentric axis L3 is parallel to the motor axis L and an eccentric distance e is present between the two. The eccentric distance e enables the eccentric element 34 to transfer the rotation of the motor shaft 211 into the rotation and revolution of other components connected to the eccentric element 34 when the motor shaft 211 rotates.

[0041] Please refer to FIG. 2 , FIG. 8 and FIG. 9 . The base plate assembly 4 at least partially covers the housing 12 . The motor shaft 211 can drive the base plate assembly 4 to move, thereby enabling the base plate assembly 4 to perform eccentric grinding relative to the housing 1 .

[0042] Specifically, the eccentric element 34 is connected to the base plate assembly 4, and the motor shaft 211 transmits power to the base plate assembly through the eccentric element 34. The base plate assembly 4 includes an upper surface 41 and a lower surface 42 disposed on opposite sides. The upper surface 41 is located on the side closer to the fan assembly 3 relative to the lower surface 42. The lower surface 42 is used to mount a polishing element such as sandpaper. The upper surface 41 has a circular groove 43 recessed from the center, and the eccentric weight 5 is mounted within the circular groove 43. Driven by the motor shaft 211 and the eccentric element 34, the eccentric weight 5 drives the base plate assembly 4 to perform eccentric motion, thereby causing the sandpaper to continuously rub against the surface of the workpiece being processed, achieving functions such as polishing and grinding.

[0043] In this embodiment, the base plate assembly 4 also includes a support ring 49 mounted within the circular groove 43. The support ring 49 is used to mount the balancing weight 5, thereby reducing the impact force generated by the eccentric movement of the balancing weight 5, providing a certain buffering effect, thereby reducing the vibration of the entire machine. Without the support ring 49, the height of the entire machine would increase. In particular, for the sanding machine 100 in this embodiment, the increased height would cause the center of gravity to shift upward, affecting the vibration effect.

[0044] 2 , the base plate assembly 4 further includes a bearing seat 44 mounted on the fan assembly 3, a first bearing 45 mounted within the bearing seat 44, and a bearing pressure plate 46 connected to the bearing seat 44. The bearing seat 44 is used to reduce the friction coefficient between the motor shaft 211 and the eccentric element 34 disposed on the motor shaft 211 during rotation, thereby ensuring the rotational accuracy and parallelism of the motor shaft 211.

[0045] Furthermore, the bearing seat 44 and the bearing pressure plate 46 form an accommodating space, the first bearing 45 is arranged in the accommodating space, the motor shaft 211 is sleeved on the inner ring of the first bearing 45, and the outer ring of the first bearing 45 is connected to the inner wall of the bearing seat 44. The balls in the first bearing 45 enable the outer ring of the first bearing 45 to move relative to the inner ring of the first bearing 45.

[0046] In this embodiment, the bearing seat 44 is fixedly connected to the outer ring of the first bearing 45, i.e., the two are synchronously connected. The bearing seat 44 is also fixedly connected to the base plate assembly 4, i.e., the base plate assembly 4 is capable of synchronous movement with the bearing seat 44 and the outer ring of the first bearing 45. It should be noted that the fixed connection between the bearing seat 44 and the base plate assembly 4 means that the base plate assembly 4 includes at least one fastening screw 40, which passes through the mounting hole 401 of the base plate assembly 4 and penetrates the bearing pressure plate 46, thereby securing it to the bearing seat 44.

[0047] Furthermore, the bearing seat 44, the bearing pressure plate 46, the first bearing 45, and the washer 47 attached to the surface of the first bearing 45 are axially locked by a locking screw 48, so that the balancing weight 5 is fixedly connected to the motor shaft 211. In other words, the balancing weight 5 can form a synchronous movement with the motor shaft 211. Through the above arrangement, when the motor shaft 211 rotates, it drives the fan assembly 3 to rotate, thereby driving the eccentric movement of the eccentric weight 5. Because the eccentric weight 5 is installed in the bearing seat 44, and the bearing seat is fixedly connected to the base plate assembly 4, efficient grinding of the base plate assembly 4 can be achieved.

[0048] Please refer to Figures 3 and 4. The balancing block 5 is used to balance the base plate assembly 4. In the direction along the motor axis L, the balancing block 5 is arranged between the fan assembly 3 and the base plate assembly 4. The balancing block 5 and the eccentric element 34 are detachably connected, that is, the eccentric element 34 and the balancing block 5 constitute synchronous movement, and the balancing block 5 can rotate around the motor axis L with the eccentric element 34.

[0049] As shown in Figures 7 to 9 , the balancing weight 5 has a center of mass adjustment portion 51 protruding from its periphery. In this embodiment, the center of mass adjustment portion 51 is integrally formed with the balancing weight 5. However, it should be noted that the center of mass adjustment portion 51 can also be fixedly connected to the balancing weight 5. The size of the center of mass adjustment portion 51 is adjusted accordingly based on the difference between the weight of the dust collection fan 33 and the total balancing weight, thereby adjusting the position of the center of mass and achieving a balance between the weight and torque of the base plate assembly 4.

[0050] In this embodiment, the balancing block 5 is at least partially arranged in the base plate assembly 4. A circular groove 43 recessed downward from the upper surface 41 allows the balancing block 5 to move. The circular groove 43 is coaxial with the motor axis L. The balancing block 5 and the base plate assembly 4 partially overlap in their axial direction, which significantly reduces the center of mass position of the fan assembly 3, thereby reducing the vibration of the entire machine.

[0051] Specifically, the ratio of the area of ​​the circular groove 43 to the area of ​​the base plate assembly 4 is less than or equal to 7.5%. On the one hand, by setting a reasonable range of the thinned area on the base plate assembly 4, the balancing weight 5 is ensured to have sufficient space for movement, while at the same time avoiding the situation where the thinned area of ​​the circular groove 43 is too large, which would increase the radial size of the transmission assembly. The strength of the base plate assembly 4 is increased, its buffering capacity is enhanced, and the user experience of the sanding machine 100 during operation is improved. On the other hand, the balancing weight 5 is arranged as close to the base plate assembly 4 as possible, so that the center of mass of the balancing weight 5 is shifted downward, which reduces the torque and the vertical size of the entire machine, making the overall structure more compact.

[0052] 2 to 5 , the eccentric element 34 is integrally formed with the mounting plate 31 of the fan assembly 3 , that is, the eccentric element 34 is formed on the mounting plate 31 , and the fan assembly 3 is mounted on the motor shaft 211 and can be driven by the motor shaft 211 to rotate.

[0053] In this embodiment, the mounting plate 31 has a first counterweight 313 extending from its periphery. The ratio of the combined mass of the first counterweight blades 331 and the first counterweight 313 to the mass of the fan assembly 3 is less than or equal to 13%. This means that the counterweight on the dust collection fan 33 is relatively light, resulting in a low weight for the fan assembly 3. This means that the fan assembly 3 generates a low moment of inertia and eccentric force during rotation, resulting in smoother operation and significantly improved user comfort.

[0054] Specifically, when the motor 21 drives the fan assembly 3 to rotate, the fan assembly 3 will generate rotational inertia, and a restraining force will be formed during rotation to keep the fan assembly 3 rotating around the motor axis L. This restraining force will cause the sander 100 to move in the opposite direction of its movement direction. In this way, the user needs to apply more force to overcome the restraining force, thereby increasing the user's operating fatigue. If the sander 100 is used for a long time, the numbness of the hands caused by the vibration will greatly affect the work efficiency.

[0055] Furthermore, within the internal structure of the sander 100, the motor 21 and fan assembly 3 are relatively heavy compared to the other components, meaning the weight of the sander 100 is primarily concentrated in the motor 21 and fan assembly 3. The structural design of the fan assembly 3 significantly reduces the weight of the fan assembly 3, thereby reducing the moment of inertia and weight of the sander 100, improving user comfort and work efficiency.

[0056] As shown in Figures 3 to 6 , the mounting plate 31 is fixedly connected to the motor shaft 211. Specifically, the motor shaft 211 is sleeved onto the outer ring of the motor shaft 211, achieving synchronous rotation. The first surface 311 has a circular hole 3111 extending through the mounting plate 31, and the second surface 312 has a circular hole 3121 extending through the mounting plate 31. The circular hole 3111 and the circular hole 3121 are interconnected. Furthermore, the motor shaft 211 passes through the circular hole 3111 on the first surface 311 and exits through the circular hole 3121 on the second surface 312, thereby driving the fan assembly 3 to rotate synchronously.

[0057] The mounting disc 31 is arranged substantially symmetrically relative to the motor axis L. The heat dissipation blades 32 and dust collection blades 33 are evenly distributed along the circumference of the motor axis L on the first and second surfaces 311, 312 of the mounting disc 31, respectively. When the motor shaft 211 rotates the mounting disc 31, the sander simultaneously collects dust and dissipates heat. Specifically, the airflow generated by the rotating heat dissipation blades 32 dissipates heat from the entire machine, while the airflow generated by the rotating dust collection blades 33 draws dust generated during machining toward the dust outlet, effectively collecting dust.

[0058] 5 and 6 , the dust collecting fan blade 33 has a partially thickened first counterweight fan blade 331 and a plurality of first ordinary fan blades 332. The thickness of the first counterweight fan blade 331 is greater than that of the first ordinary fan blade 332, and the thickness of the plurality of first ordinary fan blades 332 is equal. There is at least one first counterweight fan blade 331, and its thickness can be designed to be equal or unequal according to actual needs. In this embodiment, the thickness of the first counterweight fan blade 331 is designed to be unequal, and there is one blade that is the thickest.

[0059] Specifically, there is at least one first counterweight blade 331, and the number of first counterweight blades 331 is an odd number, such as 1, 3, or 5. It should be noted that in this embodiment, the number of counterweight blades 331 is 5. This minimizes the impact on the dust collection efficiency of the dust collection fan 33 after achieving counterweight balance. Furthermore, it can also adjust the operational stability of the fan assembly 3, thereby improving the operating efficiency of the sander 100.

[0060] In this embodiment, the first counterweight 313 is an arc-shaped counterweight. The ratio of the radial width d of the arc-shaped counterweight 313 to the diameter D of the mounting plate 31 is less than or equal to 11%, and the ratio of the height h of the arc-shaped counterweight 313 to the height H of the dust-collecting blades 33 is less than or equal to 30%. This configuration significantly reduces the weight of the arc-shaped counterweight 313, resulting in a smaller weight of the first counterweight region 3a and a lower moment of inertia, thereby improving operator comfort. Furthermore, the first counterweight 312 at the dust-collecting end of the dust-collecting blades 33 is designed as an annular structure, which minimizes the impact on dust collection by the fan assembly 3.

[0061] The eccentric element 34 includes an eccentric shaft 341 connected to the drive assembly and a recessed portion 342 recessed from the end of the eccentric shaft 341. The eccentric shaft 341 is fixedly connected to or integrally formed with the mounting plate 31. In this embodiment, the eccentric shaft 341 and the mounting plate 31 are integrally formed. A circular hole 3121 extends all the way through the eccentric shaft 341, and the motor shaft 211 is mounted to the eccentric shaft 341 to achieve synchronous rotation.

[0062] The balancing block 5 also has a snap-fitting portion 52 protruding from the end face. The snap-fitting portion 52 and the center of mass adjustment portion 51 are arranged along both sides of the motor axis L. The snap-fitting portion 52 is combined with the recessed portion 342, which can constitute the synchronous rotation of the motor shaft 211 and the eccentric element 34, and then drive the base plate assembly 4 to oscillate with the motor axis L as the rotation center, thereby realizing the grinding and polishing of the workpiece by sandpaper.

[0063] 5 and 6 , the first counterweight blade 331 and the first counterweight block 313 form a first counterweight area 3a, which is integrated into the second surface 311 to achieve moment balance and mass center overlap on the dust collecting blade 33.

[0064] In this embodiment, the first counterweight region 3a is formed at an angle θ with the second surface 311, and the angle θ is less than or equal to 120°. It should be noted that when the angle θ is less than or equal to 120°, it means that the first counterweight region 3a is not bisected by the plane formed by the motor axis L and the eccentric axis L3, and that within this range of the angle θ, center of mass overlap is achieved while also preventing dust from accumulating in the dust collecting blades 33, thereby not affecting the dust collection effect of the dust collecting end of the dust collecting blades 33.

[0065] The heat dissipation blades 32 include a partially thickened second counterweight blade 321 and a plurality of second ordinary blades 322. The second counterweight blade 332 is thicker than the second ordinary blade 322, and the thickness of the plurality of second ordinary blades 322 is equal. There is at least one second counterweight blade 321, and its thickness can be designed to be equal or unequal according to actual needs. In this embodiment, the thickness of the second counterweight blades 321 is unequal, with one blade being the thickest.

[0066] The number of blades of the heat dissipation fan blades 32 is greater than the number of blades of the dust collecting fan blades 33. When the heat dissipation fan blades 32 are within a reasonable range, the more blades there are, the more parts the airflow is dispersed into, the friction between the airflow and the fan blades is correspondingly reduced, the air output is greater, and the heat dissipation effect is better; the distribution spacing of the dust collecting fan blades 33 is large, which avoids dust accumulation during dust removal and affects the service life of the sander 100.

[0067] Furthermore, the thickness of the first counterweight blade 331 is greater than the thickness of the second counterweight blade 321. It should be noted that since the first counterweight blade 331 is arranged in the opposite direction of the eccentric element 34, in order to reduce the eccentric force generated by the eccentric element 34 and to offset this eccentric force, a counterweight is required on the dust collecting blade 33; while the second counterweight blade 321 on the heat dissipation fan 32 is used to adjust the center of mass, keeping the center of mass of the fan assembly 3 in an overlapping state.

[0068] The other side of the mounting plate 31 has a second counterweight block 314 protruding from the periphery. The height of the second counterweight block 314 is less than the height of the second counterweight blade 321, so as to achieve the heat dissipation effect of the sander 100 when working while the center of mass of the heat dissipation blade 32 overlaps.

[0069] The second counterweight blades 321 and the second counterweight block 314 form a second counterweight region 3b, which is integrated with the first surface 311. Furthermore, the first counterweight region 3a and the second counterweight region 3b are arranged along either side of the motor axis L, with the first counterweight region 3a and the second counterweight region 3b facing away from each other, achieving the dual effects of counterweight balance and center of mass overlap for the fan assembly 3.

[0070] Referring again to Figures 3 and 4 , the sander 100 further includes a second bearing 212 mounted above the fan assembly 3. The second bearing 212 is mounted on the motor shaft 211, supporting the motor shaft 211 and driving the fan assembly 3 in oscillatory motion. It should be noted that the eccentric motion of the components connected to the second bearing 212 creates a significant eccentric force, which can cause numbness in the sander 100 during grinding, thereby affecting operator comfort.

[0071] In this embodiment, the center of mass adjustment portion 51, the first counterweight blade 331 and the first counterweight block 313 are arranged on the same side of the motor axis L and arranged in the opposite direction of the eccentric axis L3 of the eccentric element 34, so as to reduce the impact of centrifugal force on the operation of the whole machine.

[0072] As shown in Figures 5, 7, and 9, the balancing weight 5 includes a through hole 53 for mounting the motor shaft 211. The circular hole 3121 is coaxial with the through hole 53, thereby ensuring synchronous motion between the motor shaft 211 and the balancing weight 5. The balancing weight 5 rotates eccentrically about the motor axis L, driving the base plate assembly 4 in a yaw motion, thereby performing the grinding process.

[0073] In this embodiment, the balancing block 5 is used to achieve dual balance of mass balance and torque balance of the base plate assembly 4. Specifically, the torque of the balancing block 5 from the center of the through hole 53 accounts for between 40% and 50% of the torque of the first counterweight area 3a from the center of the circular hole 3121. It should be noted that torque is equal to the product of the applied force and the lever arm. In this embodiment, the lever arm length of the balancing block 5 is the length from the center of the through hole 53 to the outer edge of the balancing block 5, while the lever arm length of the first counterweight area 3a is the length from the center of the circular hole 3121 to the outer edge of the fan assembly 3. The above-mentioned structural arrangement allows the overall size of the balancing block 5 to be significantly reduced, avoiding an excessively large thinning area of ​​the circular groove 43. As a result, when the sanding machine 100 is performing grinding and polishing operations, due to the reduced stiffness of the base plate assembly 4, its buffering capacity is also reduced, resulting in large vibration of the entire machine, affecting the user's hand feel and causing fatigue.

[0074] Referring again to Figures 5 and 6 , the eccentric element 34 has a first radial axis L1, which coincides with the center point of the recessed portion 342. The mass of the first counterweight blade 331a intersecting the first axis L1 is greater than the mass of the other first counterweight blades 331b. It should be noted that the first counterweight blade 331a is located at the highest point of the center of mass. Without affecting dust collection efficiency, the thickness of the first counterweight blade 331a is designed to be greater than that of the other first counterweight blades 331b, thereby achieving the dual effects of center of gravity balance and center of mass overlap.

[0075] The end surface of the serpentine hole 3111, facing the second counterweight 314, has a second axis L2. The first axis L1 and the second axis L2 form a phase angle, which is as close to zero as possible. It should be noted that the existence of the phase angle affects the eccentric counterweight problem caused by the eccentric element 34 during actual processing. The closer the phase angle approaches zero, the higher the counterweight balance and the more effective the force dissipation. Furthermore, the best effect is achieved when the first axis L1 and the second axis L2 are parallel or collinear.

[0076] The fan assembly 3 is made of metal. In this embodiment, the fan assembly 3 is made of aluminum alloy. First, the larger counterweight volume caused by the pure aluminum alloy fan counterweight can be reduced, which affects the cooling and dust collection effect of the fan assembly 3. Secondly, if a zinc alloy fan with a higher density is used, although the counterweight volume is reduced, the high cost of zinc alloy leads to a higher cost of the entire machine, affecting the cost performance of the entire machine. Then, if a plastic-embedded metal block fan is used, although both volume and cost can be taken into account, the fan rigidity is poor, which can cause resonance and numbness. Finally, if an independent balancing block structure is used, the unbalanced force is large, resulting in a larger volume of the balancing block, and then a larger diameter of the support ring 49 of the sealing balancing block 5. The bottom plate assembly 4 needs to avoid the increase of the support ring 49, resulting in an increase in the thickness of the circular groove 43 in the axial direction of the bottom plate assembly 4, affecting the buffering capacity of the bottom plate assembly 4 and ultimately affecting the vibration effect.

[0077] In this embodiment, the counterweight system utilizes a fan assembly 3 and an independent counterweight 5, distributing the counterweight to the first counterweight region 3a and the counterweight 5. This achieves overall counterweight balancing for the entire machine. This also prevents the fan assembly 3 and / or counterweight 5 from being excessively bulky, which could affect the machine's dust collection efficiency. Through this arrangement, the sanding machine 100 achieves a good balance between functionality (heat dissipation, dust collection, and balance), cost-effectiveness, and processability.

[0078] The present invention is not limited to the above-described specific embodiments. Those skilled in the art will readily appreciate that many alternatives to the sanding machine of the present invention exist without departing from the principles and scope of the present invention. The scope of protection of the present invention shall be determined by the claims.

Claims

1. A sanding machine, comprising a housing, a driving assembly installed in the housing, a fan assembly connected to the driving assembly, and a bottom plate assembly driven by the driving assembly, wherein the driving assembly has a motor axis, the fan assembly comprises a mounting plate connected to the driving assembly and a heat dissipation fan blade and a dust collection fan blade integrated in the mounting plate, the mounting plate has a first surface and a second surface arranged on opposite sides, the heat dissipation fan blade is arranged on the first surface, and the dust collection fan blade is arranged on the second surface; characterized in that: The fan assembly has a partially thickened first counterweight area, which is integrated with the second surface. The ratio of the mass of the first counterweight area to the mass of the fan assembly is less than or equal to 13%. A balancing block is provided between the fan assembly and the base plate assembly. The balancing block has a center of mass adjustment portion protruding from the periphery, and the center of mass adjustment portion and the first counterweight area are located on the same side of the motor axis.

2. The sanding machine according to claim 1, characterized in that: The first counterweight area includes a first counterweight blade thickened from the dust collecting blade and a first counterweight block protruding from the periphery of the mounting plate. The number of the first counterweight blade is at least one, and the first counterweight blade and the first counterweight block are located on the same side of the motor axis.

3. The sanding machine according to claim 2, characterized in that: The first counterweight block is an arc-shaped counterweight block, the ratio of the radial width of the arc-shaped counterweight block to the diameter of the mounting plate is less than or equal to 11%, and the ratio of the height of the arc-shaped counterweight block to the height of the dust collecting fan blade is less than or equal to 30%.

4. The sanding machine according to claim 1, characterized in that: The first counterweight area forms an angle with the second surface, and the angle is less than or equal to 120°.

5. The handheld tool according to claim 1, characterized in that: The bottom plate assembly has a circular groove sunken from the center, the balancing weight is installed in the circular groove, and the ratio of the area of ​​the circular groove to the area of ​​the bottom plate assembly is less than or equal to 7.5%.

6. The sanding machine according to claim 2, characterized in that: The first surface has a meandering hole penetrating the mounting plate, the second surface has a circular hole penetrating the mounting plate, and the meandering hole is connected to the circular hole.

7. The sanding machine according to claim 6, characterized in that: The balancing block includes a through hole for mounting the driving assembly, the circular hole is coaxial with the through hole, and the moment of the balancing block from the center of the through hole accounts for between 40% and 50% of the moment of the first counterweight area from the center of the circular hole.

8. The sanding machine according to claim 7, characterized in that: The fan assembly also has an eccentric element protruding from the second surface, and the eccentric element includes an eccentric shaft connected to the driving assembly and a recessed portion recessed from the axial end of the eccentric shaft. The balancing block also has a clamping portion protruding from the end surface, and the clamping portion and the center of mass adjustment portion are arranged along both sides of the motor axis, and the clamping portion is combined with the recessed portion.

9. The sanding machine according to claim 8, characterized in that: The eccentric element has a first axis in a radial direction, the first axis coincides with the center point of the recessed portion, and the mass of the first counterweight blade intersecting the first axis is greater than the mass of the other first counterweight blades.

10. The sanding machine according to claim 9, characterized in that: An end surface of the serpentine hole has a second axis facing the second counterweight, and the first axis is parallel to or colinear with the second axis.

11. The sanding machine according to claim 1, characterized in that: The heat dissipation fan blade has a partially thickened second counterweight fan blade, and the other side of the mounting plate has a second counterweight block protruding from the periphery. The second counterweight fan blade and the second counterweight block form a second counterweight area, and the second counterweight area is integrated with the first surface.

12. The sanding machine according to claim 11, characterized in that: The first counterweight area and the second counterweight area are arranged along two sides of the motor axis.

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