ELECTRIC TOOL GRINDING MACHINE WITH STATIC ELECTRICITY DISSIPATION

An electric tool grinding machine with static electricity dissipation, the electric tool grinding machine includes a machine tool body, a motor disposed in the machine tool body, a power supply unit disposed in the machine tool body and connected to the motor, a grinding disc rotating with the motor, and a dust collecting element facing the grinding disc and assembled with the machine tool body. The power supply unit includes a power ground wire. The machine tool body includes a charge conducting element contacting the dust collecting element, and the charge conducting element is electrically connected to the power ground wire by one of the following: direct connection and indirect connection, when an electrostatic charge is generated on the dust collecting element, the charge conducting element conducts the electrostatic charge to the power ground wire.

FIELD OF THE INVENTION

The invention relates to an electric tool grinding machine, and more particularly to an electric tool grinding machine with static electricity dissipation.

BACKGROUND OF THE INVENTION

Grinding tools remove the surface material of a ground object by driving abrasive materials (such as sandpaper, grinding disc, grinding belt, grinding wheel). The grinding process will generate dust, which will pollute the surrounding environment, and frequent inhalation of dust into the human body will also cause harm to health, so when tool grinding is implemented, dust collection operation is generally carried out at the same time.

The common dust collecting operation is implemented by a dust collecting element disposed on the grinding tool, a dust collecting pipe connected with the dust collecting element, and a dust suction device communicating with the dust collecting element through the dust collecting pipe. When the dust suction device is in operation, suction force is generated to make the dust pass through the dust collecting element and the dust collection pipe, and finally be collected in the dust suction device.

Although this method can effectively reduce the pollution of dust to the surrounding environment, when the dust moves at a high speed in the dust collecting element and the dust collecting pipe by suction, the dust will rub against the inner wall of the dust collecting element and/or the dust collecting pipe to generate static electricity. When static electricity is in an environment with high relative humidity, the electrostatic voltage may be only a few hundred volts, but when static electricity is in an environment with low relative humidity, the electrostatic voltage can be as high as thousands of volts. When the relative humidity of the environment is below 20%, the electrostatic voltage is more likely to exceed 10,000 volts. Such a high electrostatic voltage is likely to generate spark discharge instantaneously when the worker touches the grinding tool, causing shock or injury to the worker, and the instantaneous discharge may also cause damage to the electronic components in the grinding tool. In order to solve the aforementioned problems, there are mainly two existing implementation solutions. One of the implementation solutions is to use the dust suction device with anti-static function, and an anti-static dust suction pipe. The anti-static dust suction pipe has one of the following: a conductive wire is wound inside the pipe and a conductive material is coated on the surface, such as in CN114986287A. The aforesaid dust collection device is provided with a ground point at a communication port used to connect with the anti-static dust suction pipe. When the anti-static dust suction pipe is connected to the communication port, the ground point forms an electrical connection with the conductive wire. Thereby, static electricity can be guided to the ground through the ground point.

Although this implementation mode seems simple, the anti-static dust suction pipe is expensive, and it needs to be implemented with the dust suction device that can be connected to the anti-static dust suction pipe, which greatly reduces the desire of users to buy. In addition, there are even incompatibility issues among various brands.

The second implementation solution is to make the dust collecting element possess electrostatic conductivity. The dust collecting element can be made of metal to avoid static electricity accumulation through the conductive ability of metal. However, the configuration of the dust collecting element is not a simple straight line, which leads to complicated processing. The processing costs of metal parts are much higher than the costs of plastic injection molding. In addition, grinding operation is different from cutting operation, workers generally need to hold the grinding tool for a long time. Implementation with metal parts will cause the grinding tool to become heavy, which is not conducive to long-term use.

In addition to the foregoing, CN113453846A discloses a dust collecting hood for power tools, the dust collecting hood or its inner wall is made of a conductive base material that transfers electrostatic charges from the dust collecting hood to a suction hose, which ensures that electrostatic charges are dissipated via the dust suction device. It can be known that although the dust collecting hood of CN113453846A has the ability to guide electrostatic charges due to the static dissipative material, it still needs to be implemented with the dust suction device with anti-static function and the anti-static dust suction pipe, and therefore the above-mentioned problems still exist.

SUMMARY OF THE INVENTION

A main object of the invention is to solve the problem that conventional electric tool grinding machines easily accumulate static electricity when collecting dust.

A secondary object of the invention is to solve the problems caused by all static electricity elimination solutions must be implemented with specific devices.

Another secondary object of the invention is to implement static electricity dissipation without excessively modifying a framework of an electric tool grinding machine.

In order to achieve the above objects, the invention provides an electric tool grinding machine with static electricity dissipation. The electric tool grinding machine includes a machine tool body, a motor disposed in the machine tool body, a power supply unit disposed in the machine tool body and connected to the motor, a grinding disc rotating with the motor, and a dust collecting element facing the grinding disc and assembled with the machine tool body. The power supply unit includes a power ground wire. The machine tool body includes a charge conducting element contacting the dust collecting element, and the charge conducting element is electrically connected to the power ground wire by one of the following: direct connection and indirect connection. When an electrostatic charge is generated on the dust collecting element, the charge conducting element conducts the electrostatic charge to the power ground wire.

In one embodiment, a surface resistance value of the dust collecting element is between 103ohms and 107ohms.

In one embodiment, the power supply unit comprises a circuit board and a heat sink, the circuit board includes a grounding part thereon connected to the power ground wire, the heat sink is electrically connected to the grounding part, the charge conducting element is electrically connected to the heat sink, and the charge conducting element is indirectly connected to the power ground wire via the heat sink.

In one embodiment, the machine tool body includes a linking block for assembling the dust collecting element, the dust collecting element includes a connecting block assembled with the linking block, the charge conducting element is disposed on the linking block, and the dust collecting element includes a contact surface disposed on the connecting block and facing the charge conducting element.

In one embodiment, one of the linking block and the connecting block is shaped as a groove-like structure for snapping in.

In one embodiment, the linking block is the groove-like structure, and the charge conducting element is disposed on a terminal of the groove-like structure.

In one embodiment, the dust collecting element includes an auxiliary conducting element disposed on the contact surface and contacts the charge conducting element.

In one embodiment, the machine tool body is divided into a grasping part and a gripping part connected with the grasping part, in and the linking block is located on the gripping part.

In one embodiment, the dust collecting element is connected with a dust collecting pipe.

In one embodiment, materials of the dust collecting element comprise a static dissipative material.

In one embodiment, the static dissipative material is less than 30% of all materials used to make the dust collecting element.

Through the aforementioned implementation of the invention, the invention has the following characteristics compared with the prior art.

1. The dust collecting element of the invention is electrically connected to the power ground wire through the charge conducting element on the machine tool body, so that the dust collecting element is always grounded and static electricity can be specifically dissipated.

2. The invention provides a framework to meet requirements of static electricity dissipation under conditions of without substantially changing a structure of the electric tool grinding machine and without making the dust collecting element with metal.

3. Implementation of the electric tool grinding machine of the invention does not need to be equipped with the dust suction device with anti-static function and the anti-static dust suction pipe to realize static electricity dissipation.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The detailed description and technical content of the invention are described below with reference to the accompanying drawings.

Please refer toFIG.1.FIG.2,FIG.3,FIG.4andFIG.5, the invention provides an electric tool grinding machine20with static electricity dissipation, the electric tool grinding machine20includes a machine tool body21, a motor22disposed in the machine tool body21, a power supply unit23disposed in the machine tool body21and connected to the motor22, a grinding disc24that rotates with the motor22, and a dust collecting element25facing the grinding disc24and assembled with the machine tool body21. The power supply unit23comprises at least one power live wire231, a power ground wire232, a circuit board233connected to the at least one power live wire231and the power ground wire232, and a plurality of electronic components234disposed on the circuit board233. The power supply unit23generates functional circuits required for operation of the electric tool grinding machine20such as power conversion through the electronic components234and printed circuits on the circuit board233. The circuit board233includes a grounding part235connected to the power ground wire232. The at least one power live wire231and the power ground wire232extend to reach the machine tool body21. The at least one power live wire231and the power ground wire232are collectively disposed in a power wire236. On the other hand, the dust collecting element25is implemented with a dust collecting pipe26, one end of the dust collecting pipe26is connected to the dust collecting element25, and the other end of the dust collecting pipe26is connected to a dust suction device (not shown in the figures). When the dust suction device is activated, dust produced by the grinding disc24will be collected through the dust collecting element25.

Please refer toFIG.2,FIG.3andFIG.5, the dust collecting element25of the invention has static dissipative characteristics, without initial electric charge or only a small amount of initial electric charge, to prevent discharging when in contact with a human body. On the other hand, the machine tool body21includes a charge conducting element211contacting the dust collecting element25, and the charge conducting element211is electrically connected to the power ground wire232by one of the following: direct connection and indirect connection. No matter in which manner the charge conducting element211is being connected, the charge conducting element211will form an electrical connection relationship with the power ground wire232. By the aforementioned structure, an electrostatic charge generated by friction between the dust and an inner wall of the dust collecting element25during a suction process no longer accumulates on the dust collecting element25, the dust will move through a contact between the dust collecting element25and the charge conducting element211. Due to an electrical connection relationship between the charge conducting element211and the power ground wire232, the electrostatic charge is guided to the power ground wire232to achieve an object of static electricity dissipation.

The invention provides an implementation framework to meet requirements of static electricity dissipation under conditions of without substantially changing a structure of the electric tool grinding machine20and without making the dust collecting element25with metal. In addition to the above, the invention is capable of dissipating a static electricity when an operator touches the dust collecting element25and the operator has static electricity, avoiding a phenomenon of spark discharge, and greatly increasing a safety of the electric tool grinding machine20in terms of static electricity protection. Furthermore, an implementation of the electric tool grinding machine20of the invention does not need to be equipped with the dust suction device with anti-static function and an anti-static dust suction pipe to realize static electricity dissipation. In addition to adding product value, consumers can use the invention without spending a lot of money.

In one embodiment, a surface resistance value of the dust collecting element25of the electric tool grinding machine20is between 103ohms and 107ohms, preferably a surface resistance value of the dust collecting element25is between 103ohms and 105ohms. Further, materials of the dust collecting element25comprise a static dissipative material. The static dissipative material refers to a material containing carbon conductive elements, such as carbon powder or carbon fiber. Further, the static dissipative material is less than 30% of all materials used to make the dust collecting element25. It should be understood that the dust collecting element25of the invention uses plastic as a main material, and the static dissipative material is mixed with a material used for injection molding to make the dust collecting element25.

Please refer toFIG.2andFIG.3, the charge conducting element211of the invention is directly connected to the power ground wire232through a conductive wire212. Please refer toFIG.5as well, the aforementioned indirect connection of the invention means that the charge conducting element211is electrically connected to the power ground wire232through a third structure other than the conductive wire212. In one embodiment, the power supply unit23further comprises a heat sink237used for assisting the electronic components234to dissipate heat. The heat sink237is a metal component or a metal-containing component. In this embodiment, the heat sink237is electrically connected to the grounding part235of the circuit board233, and the charge conducting element211is electrically connected to the heat sink237. More specifically, a connection relationship is formed between the charge conducting element211with the heat sink237through the conductive wire212, so that the charge conducting element211is indirectly connected to the power ground wire232through the heat sink237.

Please refer toFIG.2andFIG.3, the machine tool body21includes a linking block213provided for assembling the dust collecting element25, and the dust collecting element25includes a connecting block251assembled with the linking block213. The charge conducting element211is disposed on the linking block213, and the dust collecting element25includes a contact surface252disposed on the connecting block251and facing the charge conducting element211. It should be understood that although the charge conducting element211is preferably in full contact with the contact surface252, the invention is not limited thereto, as long as the charge conducting element211does not contact with the contact surface252in points. Please refer toFIG.2andFIG.3again, one of the linking block213and the connecting block251is formed as a groove-like structure for snapping in, and the other one is formed to fit with the groove-like structure. In this way, in addition to stabilizing an assembly relationship between the machine tool body21and the dust collecting element25, the charge conducting element211always contacting the contact surface252is also ensured. Please refer toFIG.2andFIG.3again. In one embodiment, the linking block213is a groove-like structure, and the charge conducting element211is disposed in the groove-like structure. Further, the charge conducting element211is disposed on a terminal214of the groove-like structure. The machine tool body21is divided into a grasping part215and a gripping part216connected with the grasping part215based on a shape of the machine tool body21. Most part of the power supply unit23is located on the gripping part216, and the motor22is located on the grasping part215. Moreover, the linking block213is located on the gripping part216and faces the dust collecting element25.

Please refer toFIG.6, in one embodiment, the dust collecting element25is provided with an auxiliary conducting element253disposed on the contact surface252and contacted to the charge conducting element211. The auxiliary conducting element253is a metal terminal for strengthening an electrical connection between the dust collecting element25and the charge conducting element211.

Please refer toFIG.2andFIG.5, the dust collecting element25of the invention is a dust collecting hood254on the electric tool grinding machine20, a dust collection connecting pipe255for connecting the dust collecting pipe26, or a combination of the dust collecting hood254and the dust collection connecting pipe255, wherein the combination of the dust collecting hood254and the dust collection connecting pipe255is integrally formed, or the dust collecting hood254and the dust collection connecting pipe255are components that can be optionally assembled. To implement the dust collection connecting pipe255of the dust collecting element25of the invention, the charge conducting element211is disposed at a position where the dust collection connecting pipe255is connected with other structures, as disclosed inFIG.3andFIG.7. In an embodiment disclosed inFIG.7, the dust collecting element25refers to the combination of the dust collection connecting pipe255and the dust collecting hood254, and the charge conducting element211extends from the machine tool body21to reach a connection position between the dust collection connecting pipe255and the dust collecting hood254. Furthermore, a position of the auxiliary conducting element253is designed according to a position of the charge conducting element211.