CN114871915B

CN114871915B - Sanding machine

Info

Publication number: CN114871915B
Application number: CN202210516970.1A
Authority: CN
Inventors: 钱雪江
Original assignee: Changzhou Jinmao Electric Tool Manufacture Co ltd
Current assignee: Changzhou Jinmao Electric Tool Manufacture Co ltd
Priority date: 2022-05-12
Filing date: 2022-05-12
Publication date: 2023-06-06
Anticipated expiration: 2042-05-12
Also published as: CN114871915A

Abstract

The invention provides a sander, which comprises a shell, a motor, a sand bottom plate, a connecting shaft, cooling fan blades, a locking mechanism, a dust collection assembly, an annular gear and 1 sand bottom plate connecting screw, wherein the motor is fixedly arranged in the shell and provided with a motor shaft; the sand bottom plate comprises an eccentric block arranged in the sand bottom plate and an outer gear ring matched with the inner gear ring; the outer gear ring is fixedly arranged on the periphery of the upper end of the eccentric block; when the sand bottom plate is installed, the outer gear ring is sleeved with the inner gear ring, and the eccentric block is inserted into the connecting shaft and fixedly connected with the connecting shaft through 1 sand bottom plate connecting screw. The sander has the advantages of small vibration and noise during working, convenience and high efficiency for installing and replacing sand bottom plates with different shapes, and good dust collection effect.

Description

Sanding machine

Technical Field

The invention relates to the technical field of electric tools, in particular to a sander with a sanding bottom plate convenient to replace.

Background

The sander is an electric tool for sanding wood products, metal products, plastic products, walls and other surfaces. The hand-held sander mainly comprises a machine body and two parts of a sand bottom plate connected with the machine body, sand paper is interchangeably arranged on the sand bottom plate, and a motor in the machine body enables the sand bottom plate to do reciprocating swing motion through an eccentric block (also called a balancing weight) fixedly arranged on a motor rotating shaft during working, so that sand paper on the sand bottom plate is utilized to polish and sand an operation object. In order to adapt to different operation objects and save equipment cost, a hand-held sander is provided with sand bottom plates with different shapes such as round, square, triangle and the like, and when in use, the sand bottom plates with different shapes are arranged on a machine body according to different working conditions, for example, a sander disclosed in Chinese patent literature with an authorized bulletin number of CN209970387U is the existing common sander. The problems with such hand-held sanders that are common today are: firstly, an eccentric block for driving the sand bottom plate to do rotary motion or reciprocating swing motion is fixedly arranged on a motor rotating shaft in a machine body, the eccentric block can only work optimally for the sand bottom plate with a certain shape (such as a round shape), and when the sand bottom plate is replaced by a square, triangular or other shapes, as the eccentric block is not designed for the adaptability, the handle on the mobile phone body of the sanding machine is large in vibration and noise when the sanding machine works after the replacement, the hand feeling of an operator is poor, and the working efficiency and the physical and mental health of the operator are influenced when the sanding machine works for a long time; secondly, the sand bottom plate is generally fixedly connected with a connecting seat (also called a connecting flange) arranged in the machine body through 4 screws, and a bearing is fixedly arranged in the connecting seat and is fixedly arranged on a motor rotating shaft; thirdly, only one double-sided fan blade driven by a motor rotating shaft is arranged in the machine body of the existing handheld sander, the upper fan blade of the double-sided fan blade is used for air cooling of the motor, and the lower fan blade bears the dust collection function (dust collection is sent out from a dust outlet on the machine body) during working, and due to limited structure and mounting position, the dust collection effect is poor, and the health and the working quality of operators are affected. Therefore, aiming at the technical problems, the technical improvement of the existing sanding machine is necessary.

Disclosure of Invention

The purpose of the invention is that: in order to solve the technical problems existing in the prior art, a sanding machine with improved structure is provided.

The technical scheme of the invention is as follows: the sander comprises a shell, a motor with a motor shaft fixedly arranged in the shell, and a sanding bottom plate arranged below the shell and driven by the motor, and is structurally characterized in that: the motor also comprises a connecting shaft fixedly connected with the motor shaft, a cooling fan blade fixedly arranged on the motor shaft and used for cooling the motor, a locking mechanism used for locking the connecting shaft when the sand bottom plate is installed or replaced, a dust collection assembly used for collecting dust when working, an annular gear fixedly arranged on the connecting shaft and used for assisting in positioning when the sand bottom plate is installed or replaced, and 1 sand bottom plate connecting screw used for fixing the sand bottom plate; the sand bottom plate comprises an eccentric block arranged in the sand bottom plate and an outer gear ring matched with the inner gear ring; the outer gear ring is fixedly arranged on the periphery of the upper end of the eccentric block; when the sand bottom plate is installed, the outer gear ring is sleeved with the inner gear ring, and the eccentric block is inserted into the connecting shaft and fixedly connected with the connecting shaft through the sand bottom plate connecting screw.

The further scheme is as follows: the connecting shaft is a structural member formed by integrally or fixedly connecting a round rod-shaped shaft main body and a circular ring protruding part arranged on the periphery of the middle lower part of the shaft main body, the connecting shaft is fixedly connected with the motor shaft through the upper end of the shaft main body, a screw hole recessed upwards from the lower end surface is arranged in the shaft main body, and a connecting shaft supporting bearing arranged on the connecting shaft is rotatably arranged in the shell; the sand bottom plate connecting screw is matched with a screw hole of the shaft main body of the connecting shaft; the inner gear ring is fixedly connected with the lower end face of the annular protruding part of the connecting shaft.

The further scheme is as follows: the locking mechanism comprises a locking ring, a locking pin button and a reset spring; the lock ring is a structural member which is round as a whole, a group of radial inward concave slotted holes are formed in the periphery of the lock ring at intervals and serve as pin holes, and the lock ring is fixedly arranged on the connecting shaft and positioned below the cooling fan blade; the lock pin is a rod-shaped structural member matched with a pin hole of the lock ring, the lock pin button is a plate body member, the outer end of the lock pin is integrated with or fixedly connected with the lock pin button, and the reset spring is used for driving the inner end of the lock pin to automatically recover to a separation state from a pin hole plugging locking state of the lock ring after the lock pin button is loosened; the lock pin and the reset spring are movably arranged in the shell, and the lock pin button is movably arranged on the shell.

The further scheme is as follows: the dust collection assembly comprises dust collection fan blades, a dust collection cover and a dust outlet nozzle; the dust collection fan blade is fixedly arranged on the lower side of the connecting shaft and is arranged close to the sand bottom plate; the wind collecting cover is a cylindrical structural member and is fixedly arranged in the shell, and the dust outlet nozzle is arranged on the shell; one port of the air collecting cover is arranged close to the dust collection fan blade, and the other port of the air collecting cover is communicated with the dust outlet nozzle.

The further scheme is as follows: the sand bottom plate further comprises a bottom plate, a bracket fixedly arranged at the upper end of the bottom plate, and an eccentric block supporting bearing fixedly arranged in the bracket, wherein the eccentric block is sleeved with an inner ring of the eccentric block supporting bearing so as to be rotatable, an axial connecting hole which penetrates up and down is formed in the eccentric block, a screw hole which penetrates up and down is formed in the middle of the bottom plate, the position of the screw hole is matched with the position of the axial connecting hole of the eccentric block, and the integral structure and the shape of the eccentric block are matched with the shape of the bottom plate; the eccentric block is inserted into the connecting shaft through a shaft connecting hole and fixedly connected with the connecting shaft through a screw hole of the bottom plate by the sand bottom plate connecting screw.

The further scheme is as follows: the bottom plate of the sand bottom plate is a circular plate body, and correspondingly, the sand bottom plate is a circular sand bottom plate.

The further scheme is as follows: the bottom plate of the sand bottom plate is a triangular plate body or a square plate body piece, and correspondingly, the sand bottom plate is a triangular sand bottom plate or a square sand bottom plate; the shell also comprises 4 swinging brackets which are arranged in the shell in an integral or fixed connection way with the shell; the triangular sand bottom plate and the square sand bottom plate also comprise 4 positioning columns which are fixedly or integrally arranged on the support, and the 4 positioning columns are correspondingly inserted with 4 swinging supports of the shell during installation.

The invention has the positive effects that: (1) According to the sanding machine, through the improved design of the integral structure, particularly, the eccentric blocks are arranged in the sand bottom plate, so that the eccentric blocks can adopt the structural design with optimal adaptability aiming at the sand bottom plates with different shapes, vibration and noise of the sanding machine during use can be greatly reduced, and the technical problems that in the prior art, only 1 eccentric block is fixedly arranged on a motor rotating shaft in a machine body and cannot be simultaneously and optimally adapted to the circular, triangular and square sand bottom plates, the sanding machine is large in vibration and noise during working, operators feel bad, and working efficiency and physical and mental health of the operators are influenced during long-time working can be effectively solved. (2) According to the sander, the connecting shaft is fixedly arranged on the motor rotating shaft, the screw hole is arranged at the lower end of the connecting shaft, the inner gear ring which is used for assisting in positioning is fixedly arranged on the connecting shaft, the outer gear ring matched with the inner gear ring is arranged on the sand bottom plate, the connecting shaft is inserted with the eccentric block arranged on the sand bottom plate, and the locking mechanism is used for locking the connecting shaft to enable the connecting shaft to be unable to rotate when the sand bottom plate is installed or replaced, so that the sander is convenient and quick to operate when the sander is installed and replaced, time and labor are saved, the efficiency of installing and replacing the sander bottom plate is high, and the technical problems that in the prior art, the sand bottom plate is difficult to align and position the screws through 4 screws and 4 screw holes which are fixedly connected with the connecting seat arranged in the sander body are solved. (3) Compared with the prior art, the sander has the advantages that only one double-sided fan blade driven by a motor rotating shaft is arranged in the sander body (the upper fan blade is used for air cooling the motor and the lower fan blade is used for dust collection during working), and the double-sided fan blade is used for air cooling and dust collection of the motor, so that the sander cannot be arranged close to the motor or close to the sanding bottom plate; the dust collection fan blade is arranged close to the sand bottom plate, so that dust collection efficiency can reach more than 3 times that of the prior art, dust collection effect is better, and the dust collection fan blade is beneficial to the health of operators and improves construction quality.

Drawings

FIG. 1 is a schematic view of an external structure of the present invention;

FIG. 2 is a schematic view of the structure with a front cover of the housing of FIG. 1 removed and portions of the components shown in cross-section;

FIG. 3 is a schematic perspective view of the front cover of the housing of FIG. 1, with the locking mechanism shown in an unlocked state, i.e., in a locked configuration during normal use;

FIG. 4 is an enlarged schematic view of the structure shown at A in FIG. 3;

FIG. 5 is a schematic perspective view of the front cover of the housing of FIG. 1, with the locking mechanism in a locked position, i.e., a position of the locking mechanism when the sand bottom plate is replaced;

FIG. 6 is an enlarged schematic view of the structure shown at B in FIG. 5;

FIG. 7 is a schematic view of the structure of FIG. 3 with a portion of the components removed from the housing shell;

fig. 8 is a schematic structural view of the ring gear of fig. 2;

FIG. 9 is a schematic view of the construction of a round sand bottom plate of one of the sand bottom plates of the present invention;

FIG. 10 is a C-C cross-sectional view of FIG. 9;

FIG. 11 is a schematic view of the outer ring gear of FIG. 10;

FIG. 12 is a schematic view of the construction of a triangular sand bottom plate of one of the sand bottom plates of the present invention;

FIG. 13 is a D-D sectional view of FIG. 12;

FIG. 14 is a schematic view of the structure of a square sand bottom plate of one of the sand bottom plates of the present invention;

FIG. 15 is an E-E cross-sectional view of FIG. 14;

FIG. 16 is a schematic view of an exploded structure of three sand bed connection modes of the present invention.

The reference numerals in the above figures are as follows:

a housing 1, a front cover 11, a shell 12, and a swing bracket 13; a motor 2, a motor shaft 21; the connecting shaft 3, the shaft main body 3-1, the annular protruding part 3-2, the connecting shaft support bearing 31, the cooling fan blade 4, the locking mechanism 5, the locking ring 51, the locking pin 52, the locking pin button 53 and the reset spring 54; the dust collection assembly 6, dust collection fan blades 61, a wind collection cover 62 and a dust outlet 63; an inner gear ring 7; the sand bottom plate 8, the bottom plate 81, the bracket 82, the eccentric block supporting bearing 83, the eccentric block 84, the shaft connecting hole 84-1, the outer gear ring 85, the screw hole 86 and the positioning column 87; the sand bottom plate is connected with a screw 9.

Detailed Description

The invention will be described in further detail with reference to the drawings and the detailed description.

Example 1

Referring to fig. 1 to 3, the sander of the present embodiment mainly comprises a housing 1, a motor 2, a connecting shaft 3, cooling fan blades 4, a locking mechanism 5, a dust collection assembly 6, an inner gear ring 7, a sand bottom plate 8 and a sand bottom plate connecting screw 9.

The housing 1 includes a front cover 11, a case 12 detachably connected to the front cover 11, and 4 swing brackets 13 provided in the housing 1 integrally or fixedly connected to the housing 1. The motor 2 is fixedly arranged in the housing 1, and the motor 2 is provided with a motor shaft 21. The descriptions in this paragraph are prior art and are not described in detail.

Referring to fig. 3, the connecting shaft 3 is a structural member formed by integrally or fixedly connecting a circular rod-shaped shaft main body 3-1 and a circular ring protruding part 3-2 provided at the outer periphery of the middle lower portion of the shaft main body 3-1, the upper end of the shaft main body 3-1 is fixedly connected with a motor shaft 21 and follows the motor shaft 21, a screw hole (not shown) recessed upward from the lower end surface is provided in the shaft main body 3-1, and a connecting shaft supporting bearing 31 provided with the connecting shaft 3 is rotatably provided in the housing 1.

Unlike the prior art, which only sets a double-sided blade driven by the motor shaft (the upper blade cools the motor, the lower blade bears the dust-absorbing function during working), in this embodiment, the cooling blade 4 and the dust-absorbing blade 61 of the dust-absorbing component 6 are set separately. The cooling fan blade 4 is fixedly arranged on the motor shaft 21 and is close to the motor 2, and compared with the mode that the double-sided fan blade bearing two functions in the prior art cannot be close to the motor 2, the cooling fan blade 4 of the embodiment has better heat dissipation effect on the motor 2 during working, and the service life of the motor 2 is prolonged.

Referring to fig. 2 to 7, the locking mechanism 5 is used to lock the connecting shaft 3 from rotating when the sand bottom plate 8 is installed or replaced. The locking mechanism 5 includes a lock collar 51, a lock pin 52, a lock pin button 53, and a return spring 54; the locking ring 51 is a whole circular structural member, a group of radial inward concave slotted holes are formed in the outer periphery of the locking ring 51 at intervals to serve as pin holes, and the locking ring 51 is fixedly arranged on the connecting shaft 3 and positioned below the cooling fan blade 4. The lock pin 52 is a rod-shaped structural member matched with the pin hole of the lock ring 51, the lock pin button 53 is a plate body member, the outer end of the lock pin 52 is integrated with or fixedly connected with the lock pin button 53, and the reset spring 54 is used for driving the inner end of the lock pin 52 to automatically restore to a separation state from a plugging locking state with the pin hole of the lock ring 51 after the lock pin button 53 is released. The lock pin 52 and the return spring 54 are both movably provided in the housing 1, and the lock pin button 53 is movably provided on the housing 1.

The dust collection assembly 6 is used for sucking working dust in the using process of the sander of the embodiment. The dust collection assembly 6 comprises dust collection fan blades 61, a dust collection cover 62 and a dust outlet nozzle 63; the dust collection fan blade 61 is a self-suction fan blade, the dust collection fan blade 61 is fixedly arranged on the connecting shaft 3, and the dust collection fan blade 61 is positioned at the lower side of the connecting shaft 3 and is close to the sand bottom plate 8. The wind collecting cover 62 is a cylindrical structural member, the wind collecting cover 62 is fixedly arranged in the shell 1, the dust outlet nozzle 63 is arranged on the shell 1, one port of the wind collecting cover 62 is arranged close to the dust collecting fan blade 61, and the other port of the wind collecting cover 62 is communicated with the dust outlet nozzle 63. Unlike the prior art that only one double-sided fan blade driven by the motor rotating shaft is arranged in the machine body (the upper fan blade is used for carrying out air cooling on the motor, and the lower fan blade is used for carrying out dust collection function during working), in the embodiment, the dust collection fan blade 61 and the cooling fan blade 4 are respectively arranged, so that the dust collection fan blade 61 of the embodiment can be arranged closer to the sand bottom plate 8 relative to the prior art, dust collection efficiency can reach more than 3 times that of the prior art, dust collection effect is better, and the dust collection device is beneficial to the health of operators and improves working quality.

The inner gear ring 7 is used for assisting in positioning during installation or replacement of the sand bottom plate 8; the structure of the ring gear 7 is shown in fig. 8. The ring gear 7 is fixedly connected with the lower end face of the annular protruding part 3-2 of the connecting shaft 3 through one opening end thereof, and the lower end of the shaft main body 3-1 of the connecting shaft 3 penetrates through the ring gear 7 to extend downwards.

Referring to fig. 9 to 16, the sand base plate 8 mainly comprises a bottom plate 81, a bracket 82 fixedly arranged at the upper end of the bottom plate 81, an eccentric block supporting bearing 83 arranged in the bracket 82, an eccentric block 84 sleeved with the inner ring of the eccentric block supporting bearing 83 so as to be rotatable, and an outer ring gear 85 fixedly arranged at the periphery of the upper end of the eccentric block 84 and used for being matched with the inner ring gear 7 for inserting and assisting in positioning when the sand base plate 8 is installed. The eccentric block 84 is provided with a shaft connecting hole 84-1 which penetrates up and down; the middle of the bottom plate 81 is provided with screw holes 86 which are vertically penetrated and are used for being matched with the sand bottom plate connecting screws 9 to fix the sand bottom plate 8, and the positions of the screw holes 86 are matched with the positions of the shaft connecting holes 84-1 of the eccentric blocks 84. In use, sandpaper (not shown) is secured to the lower end surface of the bottom plate 81. The sand bottom plate 8 is exemplified by a round sand bottom plate, a triangular sand bottom plate and a square sand bottom plate in this embodiment, depending on the shape of the bottom plate 81 thereof. As is well known in the art, the round sand bottom plate rotates during operation, and the triangular sand bottom plate and the square sand bottom plate oscillate during operation, so when the triangular sand bottom plate or the square sand bottom plate is adopted as the sand bottom plate 8, the brackets 82 are also respectively provided with 4 positioning posts 87 which are in plug-in fit with 4 oscillating brackets 13 fixedly arranged in the shell 1, which is the same as the prior art and is not described in detail. In this embodiment, when the sand base plate 8 is a round sand base plate, a triangular sand base plate or a square sand base plate, the structure and shape of the eccentric block 84 are adapted to the shape of the sand base plate 8, so as to optimize vibration and noise. When the sand bottom plate 8 is installed, the lock pin button 53 of the locking mechanism 5 is pressed firstly to enable the lock pin 52 to be inserted into the lock ring 51 so that the connecting shaft 3 is locked and cannot rotate (as shown in fig. 6), then the outer gear ring 85 of the sand bottom plate 8 is sleeved with the inner gear ring 7, at the moment, the lower end of the connecting shaft 3 is inserted into the shaft connecting hole 84-1 of the eccentric block 84, after the sand bottom plate connecting screw 9 passes through the screw hole 86 in the middle of the bottom plate 81 from bottom to top, the sand bottom plate connecting screw 9 is matched and screwed with the screw hole of the shaft main body 3-1 of the connecting shaft 3, when the sand bottom plate 8 is a triangular sand bottom plate and a square sand bottom plate, when the outer gear ring 85 is sleeved with the inner gear ring 7, the 4 positioning posts 87 are inserted into the 4 swinging brackets 13 in the shell 1, so that the installation of the three sand bottom plate 8 can be completed, and finally, the lock pin button 53 of the locking mechanism 5 is pressed so that the lock pin 52 is loosened with the lock ring 51 under the action of the reset spring 54 (as shown in fig. 4), so that the connecting shaft 3 can rotate, and the sander can be used. When the sand bed 8 needs to be replaced, the operation of removing the sand bed 8 is reverse to the above-described mounting operation sequence. From the foregoing, it can be seen that, when the sand bottom plate 8 of the sanding machine of this embodiment is installed and replaced, the operation is convenient and fast, the time and effort are saved, the efficiency of installing and replacing the sand bottom plate 8 is higher, and thus the technical problems that in the prior art, the sand bottom plate is difficult to align and locate the screws through 4 screws and 4 screw holes which are fixedly connected with the connecting seat in the machine body, and the efficiency of replacing the sand bottom plate is lower can be solved.

The sanding machine of the embodiment can adopt the structural design with optimal adaptability aiming at the sand bottom plates 8 with different shapes because the eccentric blocks 84 are arranged in the sand bottom plates 8, thereby greatly reducing the vibration and noise of the sanding machine during use, and effectively solving the technical problems that in the prior art, only 1 eccentric block is fixedly arranged on a motor rotating shaft and cannot be simultaneously and optimally adapted to round, triangular and square sand bottom plates, so that the sanding machine has large vibration and noise during working, operators feel bad, and the working efficiency and the physical and mental health of the operators are influenced during long-time working.

The above embodiments are illustrative of the specific embodiments of the present invention, and not restrictive, and various changes and modifications may be made by those skilled in the relevant art without departing from the spirit and scope of the invention, and all such equivalent technical solutions are intended to be included in the scope of the invention.

Claims

1. The utility model provides a grinder, includes the shell, the fixed motor that locates in the shell has the motor shaft, locates the shell below by motor drive's sand bottom plate, its characterized in that: the motor also comprises a connecting shaft fixedly connected with the motor shaft, a cooling fan blade fixedly arranged on the motor shaft and used for cooling the motor, a locking mechanism used for locking the connecting shaft when the sand bottom plate is installed or replaced, a dust collection assembly used for collecting dust when working, an annular gear fixedly arranged on the connecting shaft and used for assisting in positioning when the sand bottom plate is installed or replaced, and 1 sand bottom plate connecting screw used for fixing the sand bottom plate; the sand bottom plate comprises an eccentric block arranged in the sand bottom plate and an outer gear ring matched with the inner gear ring; the outer gear ring is fixedly arranged on the periphery of the upper end of the eccentric block; when the sand bottom plate is installed, the outer gear ring is sleeved with the inner gear ring, and the eccentric block of the sand bottom plate is spliced with the connecting shaft and fixedly connected with the connecting shaft through the sand bottom plate connecting screw;

the locking mechanism comprises a locking ring, a locking pin button and a reset spring; the lock ring is a structural member which is round as a whole, a group of radial inward concave slotted holes are formed in the periphery of the lock ring at intervals and serve as pin holes, and the lock ring is fixedly arranged on the connecting shaft and positioned below the cooling fan blade; the lock pin is a rod-shaped structural member matched with a pin hole of the lock ring, the lock pin button is a plate body member, the outer end of the lock pin is integrated with or fixedly connected with the lock pin button, and the reset spring is used for driving the inner end of the lock pin to automatically recover to a separation state from a pin hole plugging locking state of the lock ring after the lock pin button is loosened; the lock pin and the reset spring are movably arranged in the shell, and the lock pin button is movably arranged on the shell.

2. A sander as set forth in claim 1, wherein: the connecting shaft is a structural member formed by integrally or fixedly connecting a round rod-shaped shaft main body and a circular ring protruding part arranged on the periphery of the middle lower part of the shaft main body, the upper end of the shaft main body of the connecting shaft is fixedly connected with the motor shaft, a screw hole recessed upwards from the lower end surface is arranged in the shaft main body, and the connecting shaft is rotatably arranged in the shell through a connecting shaft supporting bearing arranged on the connecting shaft; the sand bottom plate connecting screw is matched with a screw hole of the shaft main body of the connecting shaft; the inner gear ring is fixedly connected with the lower end face of the annular protruding part of the connecting shaft.

3. A sander as set forth in claim 1, wherein: the dust collection assembly comprises dust collection fan blades, a dust collection cover and a dust outlet nozzle; the dust collection fan blade is fixedly arranged on the lower side of the connecting shaft and is close to the sand bottom plate; the air collecting cover is a cylindrical structural member and is fixedly arranged in the shell, and the dust outlet nozzle is arranged on the shell; one port of the air collecting cover is arranged close to the dust collection fan blade, and the other port of the air collecting cover is communicated with the dust outlet nozzle.

4. A sander as set forth in any one of claims 1 to 3, wherein: the sand bottom plate further comprises a bottom plate, a bracket fixedly arranged at the upper end of the bottom plate, and an eccentric block supporting bearing fixedly arranged in the bracket, wherein the eccentric block is sleeved with an inner ring of the eccentric block supporting bearing so as to be rotatable, the eccentric block is provided with a shaft connecting hole which penetrates up and down, the middle of the bottom plate is provided with a screw hole which penetrates up and down and is matched with the position of the shaft connecting hole of the eccentric block in the set position, and the overall structure and the shape of the eccentric block are matched with the shape of the bottom plate; the eccentric block is inserted into the connecting shaft through a shaft connecting hole of the eccentric block and fixedly connected with the connecting shaft through a screw hole of the bottom plate, and the connecting screw penetrates through the bottom plate through a connecting screw of the sand bottom plate.

5. The sander as set forth in claim 4, wherein: the bottom plate of the sand bottom plate is a circular plate body piece, and correspondingly, the sand bottom plate is a circular sand bottom plate.

6. The sander as set forth in claim 4, wherein: the bottom plate of the sand bottom plate is a triangular plate body or a square plate body piece, and correspondingly, the sand bottom plate is a triangular sand bottom plate or a square sand bottom plate; the shell also comprises 4 swinging brackets which are arranged in the shell in an integral or fixed connection way with the shell; the triangular sand bottom plate and the square sand bottom plate also comprise 4 positioning columns which are fixedly or integrally arranged on the support, and the 4 positioning columns are correspondingly inserted with 4 swinging supports of the shell during installation.