Handheld grinding tool

Abstract

Handheld grinding tool The present invention relates to a handheld grinding tool, comprising a housing, an 5 electric motor, a main shaft, a control unit, an auxiliary handle and an auxiliary detection mechanism, wherein the housing accommodates the electric motor and extends in a front-rear direction; the main shaft projects from a front part of the housing and rotates under the driving action of the electric motor; the control unit controls the driving action of the electric motor; the auxiliary handle is mounted on a handle mounting part at the 0 front part of the housing; the detection mechanism performs electrical detection of whether the auxiliary handle is gripped, and the detection mechanism comprises a positive electrode terminal which extends inwards to an inner side of the handle mounting part, an insulating partition is provided in front of the electric motor in the housing, and an electrically conductive component for electrically connecting the 5 control unit to the detection mechanism is mounted on the insulating partition. Thus, the present invention provides a grinding tool in which an electrical connection between the detection mechanism of the auxiliary handle and the control unit can be achieved in a simple and reliable way.

Description

[0001] 2024P00034 CN

[0002] Hilti Aktiengesellschaft

[0003] Principality of Liechtenstein

[0004] Handheld grinding tool

[0005] TECHNICAL FIELD

[0006] The present invention relates to an electric tool, in particular to a handheld grinding tool.

[0007] BACKGROUND ART

[0008] Grinding tools capable of subjecting a workpiece being processed to abrasion, grinding, cutting and other processing are already widely used in the prior art. An angle grinder is an illustrative example of a grinding tool, in which a main shaft projects downwards from a front part of a housing that extends in a front-rear direction and accommodates an electric motor, with a top-end tool such as a disc-shaped abrasive wheel mounted on a lower end of the main shaft. Thus, jobs such as grinding and polishing of the workpiece being processed can be performed with the top-end tool that rotates together with the main shaft.

[0009] Handheld angle grinders equipped with detection mechanisms (such as sensors) are also known in practice. Detection mechanisms are for example arranged in gripping regions of an angle grinder, e.g. in a main handle of a machine body and an auxiliary handle on the front part of the housing, for the purpose of detecting a user's hands positioned in the gripping regions, so as to provide so-called unattended functionality. The detection mechanism needs to be electrically coupled to a control unit of the angle grinder via an electrically conductive component; existing electrically conductive components are generally electric wires. In the case of a handheld angle grinder with a detection mechanism arranged in the auxiliary handle, since the control unit is often positioned behind the electric motor in the housing, the electric wire that connects the detection mechanism of the auxiliary handle in the front part of the housing to the control unit in a rear part of the housing must be installed in a confined space between a gearbox and the electric motor, and in this situation it is very difficult to avoid the electric motor and a fan when laying out the wiring. Furthermore, since an angle grinder vibrates during operation, the contact reliability and transmission stability of the electric wire used to connect the detection mechanism to the control unit in the prior art are also threatened.

[0010] SUMMARY OF THE INVENTION

[0011] The technical problem to be solved in the present invention is to provide a grinding tool in which an electrical connection between a detection mechanism of an auxiliary handle and a control unit can be achieved in a simple and reliable way.

[0012] A handheld grinding tool comprises a housing, an electric motor, an output main shaft, a control unit, a handle mounting part, and an auxiliary handle equipped with a detection mechanism, wherein the housing accommodates the electric motor and the electric motor comprises a motor shaft extending in a front-rear direction; the output main shaft projects from a front part of the housing and rotates under the driving action of the electric motor; the control unit controls the driving action of the electric motor; the handle mounting part is disposed at the front part of the housing; and the auxiliary handle is detachably mounted on the handle mounting part, wherein an insulating partition is provided in front of the electric motor in the housing, and an electrically conductive component for electrically connecting the control unit to the detection mechanism is disposed on the insulating partition. The electrically conductive component is disposed on the insulating partition between the electric motor and a gear transmission mechanism of the grinding tool, thereby saving much installation space, making it possible to avoid complex electronic components of the electric motor, and facilitating electrical coupling between the detection mechanism and the control unit behind the electric motor.

[0013] According to an embodiment of the present invention, the electric motor comprises a fan mounted on the motor shaft, and the insulating partition is disposed in front of the fan and comprises a hollow annular part, with ventilation holes provided in the annular part. Here, the insulating partition is constructed as a fan cover, with the electrically conductive component disposed on the fan cover; this not only saves installation space but also improves the heat dissipating properties of a gearbox, as well as improving the contact reliability and transmission stability of the electrically conductive component. The electrically conductive component is formed of an electrically conductive material, and comprises a first portion which is at least partially continuous in a circumferential direction, a second portion extending towards the front from the first portion locally, a third portion extending radially outwards from the first portion locally, and a fourth portion extending towards the rear from the third portion, the second portion extending forwards until it at least partially coincides with the handle mounting part, the third portion extending radially beyond an outer periphery of the insulating partition, and the fourth portion being connected to the control unit via a wiring line. Since a main body of the electrically conductive component is made of a metal spring plate, the first portion can be firmly secured to the insulating partition, thus improving stability. The forwardextending second portion forms an electrically conductive terminal connected to the detection mechanism of the auxiliary handle, while the rearward-extending fourth portion forms another electrically conductive terminal connected to the control unit; in this way, the detection mechanism in the auxiliary handle and the control unit in the tool body are connected to form a closed-loop circuit, so that electrical signals are transmitted to the control unit.

[0014] Preferably, the second portion extends towards the front at an angle which deviates outwards from the motor shaft relative to an axial direction of the motor shaft. The second portion made of a metal spring plate has a certain degree of elasticity, so when a front edge thereof abuts a terminal of the detection mechanism, the fact that the second portion extends towards the front at an angle which deviates outwards from the motor shaft can ensure the reliability of contact between a front end of the second portion acting as an electrically conductive terminal, and a terminal of the detection mechanism that extends inwards to the handle mounting part.

[0015] Two or more said handle mounting parts are provided on the housing, the second portion comprises two or more second portions arranged to correspond to the handle mounting parts in number and position, and when the auxiliary handle is mounted on one of the handle mounting parts, a front edge of the corresponding second portion abuts a terminal of the detection mechanism arranged on the auxiliary handle, said terminal extending inwards to the handle mounting part. To suit different application scenarios of the handheld grinding tool as well as users' operating habits, the auxiliary handle is generally optionally mounted on a left side, right side or upper side of the front part of the housing of the grinding tool, and handle mounting parts will be correspondingly reserved on the left side, right side and / or upper side of the front part of the housing of the angle grinder. The second portions acting as electrically conductive terminals are also arranged to correspond to the handle mounting parts in number and position, so that when the auxiliary handle is at different mounting positions, the detection mechanism arranged on the auxiliary handle can always be electrically coupled to the control unit reliably.

[0016] Preferably, the wiring line is an electric wire with a quick-connect terminal, and is preembedded in the housing. Thus, the fourth portion acting as another electrically conductive terminal will be connected to the quick-connect terminal as a plug-pin or by touch, making installation extremely simple. The fact that the electric wire is preembedded in the housing further avoids complex wiring in the housing, and improves the reliability and stability of the electric coupling circuit.

[0017] According to a preferred embodiment of the present invention, the electrically conductive component is at least partially overmoulded within the insulating partition, the first portion being an annular metal plate overmoulded within the annular part, and the insulating partition further comprising an axial extension part for at least partially covering the second portion, and a radial extension part at least partially covering the third portion; a front edge of the second portion is at least partially exposed, so as to be able to be electrically coupled to an electrically conductive terminal of the detection mechanism, and a rear edge of the fourth portion is at least partially exposed. Having the electrically conductive component substantially overmoulded within the insulating partition avoids short circuits as much as possible and increases the service life of the electrically conductive component. Furthermore, the electrically conductive component overmoulded within the insulating partition will not be at risk of detaching from the insulating partition, so the stability of assembly is increased.

[0018] According to another preferred embodiment of the present invention, the electrically conductive component is mounted on the insulating partition, the first portion is an arcshaped metal plate attached to the annular part, and the second portion comprises two second portions respectively arranged at two ends of the arc shape of the first portion. The electrically conductive component can be conveniently removed thanks to the special way in which it is mounted; from the manufacturer's perspective, this enables sharing of components between a product version equipped with a detection mechanism and a product version not equipped with a detection mechanism.

[0019] The detection mechanism performs electrical detection of whether the auxiliary handle is gripped. Alternatively, the detection mechanism performs electrical detection of a mounting state of the auxiliary handle relative to the handle mounting part.

[0020] In the handheld grinding tool of the present invention, the electrically conductive component made of an electrically conductive metal spring plate is disposed on the insulating partition constructed as a fan cover, such that the sensor in the side handle and the control unit in the tool body are connected to form a closed-loop circuit, so that electrical signals are transmitted to the control unit; this configuration saves space and makes installation convenient. Furthermore, as a result of its special structural design, the electrically conductive component can ensure reliability of contact between the electrically conductive terminals and stability of transmission.

[0021] BRIEF DESCRIPTION OF THE DRAWINGS

[0022] A better understanding of the embodiments described can be gained from the following detailed description with reference to the drawings. It is emphasized that the various components are not necessarily drawn to scale. In fact, dimensions may be increased or decreased at will for the purposes of clear discussion. In the drawings, identical reference signs denote identical elements.

[0023] Fig. 1 is a sectional view of a handheld angle grinder of the present invention.

[0024] Fig. 2 is a partial exploded schematic drawing of a handheld angle grinder in an embodiment of the present invention.

[0025] Fig. 3 is a partial schematic drawing of a mounted state of the handheld angle grinder of the embodiment shown in Fig. 2.

[0026] Fig. 4 is a schematic drawing of an insulating partition in which an electrically conductive component is overmoulded, in a handheld angle grinder in another embodiment of the present invention. Fig. 5 is a sectional view along line A-A of the electrically conductive component and the insulating partition in the embodiment shown in Fig. 4.

[0027] Fig. 6 is a partial sectional view of the electrically conductive component fitted to the angle grinder in the embodiment shown in Fig. 4.

[0028] Fig. 7 is another partial sectional view of the electrically conductive component fitted to the angle grinder in the embodiment shown in Fig. 4.

[0029] DETAILED DESCRIPTION OF THE INVENTION

[0030] The handheld grinding tool of the present invention is described below with reference to Figs. 1 - 7. The following description is merely exemplary, and does not limit the disclosed content of the present application or the applications or uses of the present invention. The terms “front”, “rear”, “above...”, “below...”, “left” and “right” in the present invention are used throughout this Description to define various components of the handheld angle grinder of the present invention when arranged in an orientation in which it is to be used.

[0031] Referring to Fig. 1 , as an example, a grinding tool 1 of the present invention is a rechargeable handheld angle grinder. The angle grinder has a housing 2 extending in a front-rear direction, the housing comprising a gear housing 21 , a motor housing 22 and a gripping part 23, wherein the gear housing 21 is made of metal, and the motor housing 22 and gripping part 23 are made of plastic, in particular a resin material. The motor housing 22 is substantially in the form of an elongated tube, and contains an electric motor 4. The electric motor 4 comprises a motor shaft 5, and the electric motor 4 is held in the motor housing 22 in such a way that the motor shaft 5 lies in the frontrear direction; a fan 7 is mounted on the motor shaft 5 in front of a stator of the electric motor 4, and a front end of the motor shaft 5 extends into the gear housing 21. A gear mechanism 6 arranged in front of the electric motor 4 is provided in the gear housing 21. The gear mechanism 6 is connected to an output main shaft 3 projecting downwards from the gear housing 21 , and a front-end tool (not shown) such as a cutting disc or an abrasive wheel can be detachably connected to the output main shaft 3. Thus, torque generated by the electric motor 4 can be transmitted to the gear mechanism 6 and then to the output main shaft 3, and finally, the torque of the output main shaft 3 is transmitted to a top-end tool.

[0032] The gripping part 23 is positioned behind the motor housing 22. The gripping part acts as a main handle, allowing a user's hand to hold and guide the angle grinder. It will be understood that the motor housing 22 and the gripping part 23 may be a single piece, or independent components fitted and connected together. Preferably, the motor housing 22 is an integrally formed tube, and the gripping part is formed of a pair of opposed half-shells fastened by screw-threads in a left-right direction, with a front end of the gripping part connected to a rear end of the motor housing. In addition, the angle grinder is supplied with current by a battery (not shown) that can be connected to the gripping part 22. Alternatively, the angle grinder could be supplied with current from a network by means of a power cable.

[0033] In the exemplary angle grinder in the drawings, a control unit 8 is designed as a printed circuit board, and is electrically and electronically connected to a main control electronic device; in this case, the main control electronic device is arranged in a region of the battery. As shown in Fig. 1 , the control unit 8 is located at a rear side of the electric motor, and fixed in the gripping part 23.

[0034] In addition, referring to Figs. 2 and 6, the angle grinder 1 further comprises an auxiliary handle 10, at least one handle mounting part 24 is provided on the gear housing 21, and the auxiliary handle 10 may be detachably mounted on the handle mounting part 24. Preferably, handle mounting parts 24 are separately provided on left and right sides of the gear housing 21 , so that the auxiliary handle 10 can be optionally mounted on the left side or the right side of the gear housing, so as to suit the gripping habits of different users and different application scenarios of the grinding tool. More preferably, one handle mounting part 24 may also be provided on an upper side of the gear housing 21 , and the auxiliary handle 10 is mounted on the upper side of the gear housing, so that when the grinding tool 1 is performing a cutting job and might be tilted through a certain angle such as 90 degrees, the auxiliary handle mounted on the upper side of the gear housing is more easily gripped by the user of the tool. Referring to Fig. 6, according to an illustrative embodiment of the present invention, the handle mounting part 24 is a mounting hole with an internal thread. The auxiliary handle 10 has a handle part 11 and a threaded part 12 located at a front end of the handle part 11. The threaded part 12 is screwed into the mounting hole, and the auxiliary handle 10 is thus mounted on the handle mounting part 24. It will be understood that the handle mounting part is not limited to being the mounting hole with the internal thread as shown in the embodiment above, nor is the auxiliary handle 10 limited to being mounted by having the threaded part 12 screwed into the mounting hole. The auxiliary handle could employ a structure other than a threaded connection structure. Furthermore, the auxiliary handle is not limited to being a side handle as in the embodiment above, and the handle part's shape, etc. can be altered appropriately.

[0035] A detection mechanism 13 is arranged on the auxiliary handle 10, and the detection mechanism 13 performs electrical detection of whether the auxiliary handle is gripped. Alternatively, the detection mechanism 13 performs electrical detection of a mounting state of the auxiliary handle 10 relative to the handle mounting part. The configuration of the detection mechanism 13 is already well known; for example, the detection mechanism 13 comprises a sensor element, in particular a capacitive sensor element. The capacitive sensor element is designed as a line, wherein one electrode of the sensor is arranged on an inner side of a casing of the handle part 11 , and another electrode is arranged in a hollow core part of the handle part 11 , wherein this other electrode extends along the handle part and beyond the threaded part 12, forming a positive electrode terminal 14 of the detection mechanism 13. The control unit 8 has a signal generator, wherein a signal sender is used to define a voltage for charging the sensor element. Furthermore, the control unit 8 detects a change in charge in at least one sensor element, and for example detects the presence of a hand if the determined charge is greater than a defined threshold. When the auxiliary handle 10 is not gripped, the charge of the signal of the sensor element detected by the control unit 8 does not exceed the threshold, so the control unit 8 will not actuate the electric motor 4.

[0036] The detection mechanism 13 is not limited to the above embodiment which uses a linear capacitive sensor. For example, the sensor element could also be a touch sensor, an optical sensor, a pressure sensor, or a combination of multiple types of sensors. In this case, the control unit 8 is also not limited to detecting a change in charge exceeding the threshold to judge whether the auxiliary handle is gripped. Again referring to Figs. 1 and 2, an insulating partition 9 is provided in front of the electric motor 4 in the housing 2, and an electrically conductive component 30 for electrically connecting the control unit 8 to the detection mechanism is disposed on the insulating partition 9. Preferably, the insulating partition 9 is constructed as a fan cover, disposed in front of the fan 7. According to this embodiment, the insulating partition serving as the fan cover is constructed of plastic, and comprises a hollow annular part 90, with ventilation holes 91 provided in the annular part 90; the configuration of the ventilation holes depends on the type and structure of the fan 7, and enables better heat dissipation while ensuring insulation between the electric motor 4 and the gear transmission mechanism 6. Regarding the insulating partition, the fact that the electrically conductive component is disposed on the fan cover not only saves installation space but also improves the heat dissipating properties of the gearbox, as well as improving the contact reliability and transmission stability of the electrically conductive component. It should be noted that the fan 7 is not limited to being mounted in front of the electric motor 4; in certain grinding tools, the fan 7 may be arranged behind the electric motor 4, in which case the insulating partition 9 is an additional insulating component arranged between the electric motor 4 and the gear transmission mechanism 6.

[0037] Referring to Figs. 2 and 3, according to a preferred embodiment of the present invention, the electrically conductive component 30 is formed of an electrically conductive metal spring plate, wherein "metal spring plate" refers to a sheet material having a certain degree of flexibility as well as a certain strength and being able to deform appropriately in accordance with installation conditions, which is more stable and durable than wire material. The electrically conductive component 30 comprises an arc-shaped or annular first portion 31 , which is at least partially continuous in a circumferential direction and engaged with the annular part 90 of the insulating partition 9. At least one second portion 32 extends towards the front from the first portion locally, the second portion 32 extending forwards until it at least partially coincides with the handle mounting part 24; that is to say, when the auxiliary handle 10 is mounted on the handle mounting part 24 and the positive electrode terminal 14 of the detection mechanism 13 extends inwards to an inner side of the handle mounting part 24, a front edge of the second portion 32 is able to abut the positive electrode terminal 14. The electrically conductive component 30 further comprises at least one third portion 33 extending radially outwards from the first portion 31 locally, and a fourth portion 34 extending towards the rear from the third portion 33. The various portions of the electrically conductive component 30 may be integrally formed, or independent portions fitted and connected together, but a one-piece electrically conductive component will obviously be more advantageous in terms of manufacturing, cost and reliability.

[0038] Preferably, the second portion 32 extends towards the front at an angle which deviates outwards from the motor shaft 5 relative to the axial direction of the motor shaft 5. The second portion 32 made of a metal spring plate has a certain degree of flexibility, so by having the second portion 32 extend towards the front at an angle which deviates outwards from the motor shaft, it is possible to ensure the reliability of contact between a front end 36 of the second portion acting as an electrically conductive terminal, and the positive electrode terminal 14 of the detection mechanism that extends inwards to the handle mounting part. The value of the angle depends on the position of the handle mounting part 14 in the gear housing 21 , and the distance by which the positive electrode terminal 14 extends inwards to the inner side of the handle mounting part 14.

[0039] As stated above, two or more said handle mounting parts 14 are provided on the gear housing 21 , and correspondingly, the second portion 32 comprises two or more second portions, which are arranged to correspond to the handle mounting parts 14 in number and position, so as to ensure that when the auxiliary handle 10 is mounted on one of the handle mounting parts, the front end 36 of the corresponding second portion 32 is able to abut the positive electrode terminal 14 of the detection mechanism, so that when the auxiliary handle 10 is at different mounting positions, the electrically conductive component 30 is always able to electrically couple the detection mechanism 13 arranged on the auxiliary handle 10 to the control unit 8 reliably. Preferably, there are two said second portions 32, respectively arranged at two ends of the arc shape of the first portion 31. The electrically conductive component can be conveniently removed thanks to the special way in which it is mounted; from the manufacturer's perspective, this enables sharing of components between a product version equipped with a detection mechanism and a product version not equipped with a detection mechanism. Furthermore, the third portion 33 extends radially beyond an outer periphery of the insulating partition 9, and the fourth portion 34 is connected to the control unit 8 via a wiring line 35. Preferably, the wiring line 35 is an electric wire with a quick-connect terminal, and is pre-embedded in the housing 2. Thus, since a radial extremity of the third portion 33 extends beyond the outer periphery of the insulating partition 9, the fourth portion 34 extending rearwards from the radial extremity of the third portion 33 forms another electrically conductive terminal, which is connected to the quick-connect terminal as a plug-pin or by touch, and thereby connected to the control unit 8; and the fact that the electric wire is pre-embedded in the housing further avoids complex wiring in the housing, and improves the reliability and stability of the electric coupling circuit.

[0040] The fact that the first portion 31 of the electrically conductive component 30 can be firmly secured to the insulating partition improves the stability of the electrically conductive component. The forward-extending second portion 32 forms an electrically conductive terminal connected to the detection mechanism 13 of the auxiliary handle 10, while the rearward-extending fourth portion 34 forms another electrically conductive terminal connected to the control unit 8; in this way, the detection mechanism 13 of the auxiliary handle 10 and the control unit 8 of the tool body are connected to form a closed-loop circuit, so that electrical signals of the detection mechanism 13 are transmitted to the control unit 8.

[0041] Figs. 4 - 7 show another preferred embodiment of the present invention schematically. Unlike the previous embodiment, in this embodiment the electrically conductive component 30 is at least partially overmoulded within the insulating partition 9, thus avoiding short circuits as much as possible and increasing the service life of the electrically conductive component 30. Furthermore, the electrically conductive component 30 will not detach from the insulating partition 9, so the stability of assembly is improved.

[0042] Referring to Figs. 4 and 5, in this embodiment, the first portion 31 is an annular metal plate overmoulded within the annular part 90. Further, the insulating partition 9 further comprises an axial extension part 92 for at least partially covering the second portion 32, and a radial extension part 93 at least partially covering the third portion 33. Moreover, as shown in Fig. 6, the front end 36 of the second portion 32 is at least partially exposed, so as to be able to be electrically coupled to the positive electrode terminal 14 of the detection mechanism. In addition, as shown in Fig. 7, the fourth portion 34 may also be partially overmoulded with insulating material, but a rear edge thereof is at least partially exposed, so as to be able to be electrically connected to the wiring line 35.

[0043] In the handheld grinding tool of the present invention, the electrically conductive component with a main body made of an electrically conductive metal spring plate is disposed on the insulating partition constructed as the fan cover, such that the sensor in the side handle and the control unit in the tool body are connected to form a closed- loop circuit, so that electrical signals are transmitted to the control unit; this configuration saves space and makes installation convenient. Furthermore, as a result of its special structural design, the electrically conductive component can ensure reliability of contact between the electrically conductive terminals and stability of transmission.

[0044] The grinding tool of the present invention is not limited to being an angle grinder. For example, the present invention is also applicable to other grinding / polishing tools, etc., such as polishers and sanders.

[0045] As stated above, although exemplary embodiments of the present invention have been explained herein with reference to the drawings, the present invention is not limited to the specific embodiments above, and could have many other embodiments. The scope of the present invention shall be defined by the claims and their equivalent meaning.

Claims

PATENT CLAIMS1. Handheld grinding tool, comprising a housing, an electric motor, an output main shaft, a control unit, a handle mounting part, and an auxiliary handle equipped with a detection mechanism, wherein the housing accommodates the electric motor and the electric motor comprises a motor shaft extending in a front-rear direction; the output main shaft projects from a front part of the housing and rotates under the driving action of the electric motor; the control unit controls the driving action of the electric motor; the handle mounting part is disposed at the front part of the housing; and the auxiliary handle is detachably mounted on the handle mounting part, characterized in that an insulating partition is provided in front of the electric motor in the housing, and an electrically conductive component for electrically connecting the control unit to the detection mechanism is disposed on the insulating partition.

2. Grinding tool according to Claim 1 , characterized in that the electric motor comprises a fan mounted on the motor shaft, and the insulating partition is disposed in front of the fan and comprises a hollow annular part, with ventilation holes provided in the annular part.

3. Grinding tool according to Claim 2, characterized in that the electrically conductive component is formed of an electrically conductive material, and comprises a first portion which is at least partially continuous in a circumferential direction, a second portion extending towards the front from the first portion locally, a third portion extending radially outwards from the first portion locally, and a fourth portion extending towards the rear from the third portion, the second portion extending forwards until it at least partially coincides with the handle mounting part, the third portion extending radially beyond an outer periphery of the insulating partition, and the fourth portion being connected to the control unit via a wiring line.

4. Grinding tool according to Claim 3, characterized in that the second portion extends towards the front at an angle which deviates outwards from the motor shaft relative to an axial direction of the motor shaft.

5. Grinding tool according to Claim 3, characterized in that two or more said handle mounting parts are provided on the housing, the second portion comprises two or moresecond portions arranged to correspond to the handle mounting parts in number and position, and when the auxiliary handle is mounted on one of the handle mounting parts, a front edge of the corresponding second portion abuts a terminal of the detection mechanism arranged on the auxiliary handle, said terminal extending inwards to the handle mounting part.

6. Grinding tool according to Claim 3, characterized in that the wiring line is an electric wire with a quick-connect terminal, and is pre-embedded in the housing.

7. Grinding tool according to any one of Claims 3 - 6, characterized in that the electrically conductive component is at least partially overmoulded within the insulating partition, the first portion being an annular or arc-shaped metal plate overmoulded within the annular part, and the insulating partition further comprising an axial extension part for at least partially covering the second portion, and a radial extension part at least partially covering the third portion, and a front edge of the second portion is at least partially exposed, so as to be able to be electrically coupled to a terminal of the detection mechanism.

8. Grinding tool according to any one of Claims 3 - 6, characterized in that the electrically conductive component is mounted on the insulating partition, and the first portion is an arc-shaped or annular metal plate engaged with the annular part.

9. Grinding tool according to any one of Claims 1 - 8, characterized in that the detection mechanism performs electrical detection of whether the auxiliary handle is gripped.

10. Grinding tool according to any one of Claims 1 - 8, characterized in that the detection mechanism performs electrical detection of a mounting state of the auxiliary handle relative to the handle mounting part.

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