Patent Description:
Please refer to <FIG>, a main structure of a conventional grinding machine tool <NUM> comprises a motor <NUM>, a working shaft <NUM> that rotates with the motor <NUM>, a housing <NUM> for providing the motor <NUM> and the working shaft <NUM> to dispose therein, a pressing plate <NUM> disposed on the housing <NUM> for determining whether the motor <NUM> operates or not based on an operated state of the pressing plate <NUM>, and a grinding disc <NUM> disposed on the working shaft <NUM> and driven by the working shaft <NUM>. When a user intends to perform grinding, the user operates the pressing plate <NUM> to drive the motor <NUM> to drive the working shaft <NUM>, so that the grinding disc <NUM> rotates with the working shaft <NUM> for grinding. When the user wants to stop grinding, the user releases the pressing plate <NUM> to stop the motor <NUM> from driving the working shaft <NUM>. At this time, although the grinding disc <NUM> stops being driven, the grinding disc <NUM> will continue to rotate due to an inertia of the motor <NUM> and the working shaft <NUM> and its own inertia until an inertial kinetic energy is consumed. The aforementioned phenomenon means that although the user has stopped driving the motor <NUM>, the grinding disc <NUM> will continue to idle, as a result the user cannot replace consumables of the grinding machine tool <NUM> during this period, and also the safety of the user is easily affected.

In view of the above-mentioned problems in the prior art, the current technology has disclosed a structure of providing with a brake lining <NUM> in the grinding machine tool <NUM>, such as shown in <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT>, <CIT> and <FIG>. Please refer to <FIG> again for further illustration, the brake lining <NUM> is an elastic rubber ring, the brake lining <NUM> is disposed between the housing <NUM> and the grinding disc <NUM>, the brake lining <NUM> is in contact with the grinding disc <NUM> normally and provides a resistance to the grinding disc <NUM> at any time. When the grinding machine tool <NUM> is started, because a kinetic energy output by the motor <NUM> is greater than the resistance exerted on the grinding disc <NUM>, the grinding disc <NUM> can be rotated. When the motor <NUM> stops rotating, the resistance provided by the brake lining <NUM> is greater than an inertial force of the grinding disc <NUM>, so that the grinding disc <NUM> can stop rotating. However, although the aforementioned implementation mode can achieve an effect of braking the grinding disc <NUM>, it is easy to increase a load of the motor <NUM> due to the resistance provided by the brake lining <NUM> normally. In addition, the grinding disc <NUM> is also easily affected by the resistance of the brake lining <NUM> to cause a rotation speed to decrease, in turn reducing a grinding efficiency. Furthermore, since the brake lining <NUM> is in contact with the grinding disc <NUM> normally, the brake lining <NUM> wears out quickly.

<CIT> discloses a safety device for rotary grinding tool to solve the problem of stopping the rotation of a grinding machine in connection with the turning-off of a switch. Therefore, a safety device is disclosed which comprises (see Figs. ): a rotation suppressing rod <NUM> which is provided with a projecting part <NUM> on a trigger <NUM> of a switch <NUM> and a flange part <NUM> abutted on the projecting part <NUM>; two metals <NUM>, <NUM> which are slid on the rotation suppressing rod <NUM>, and a spring <NUM> to push back the rotation suppressing rod <NUM> through the flange part <NUM> of the rotation suppressing rod <NUM>. This construction generates the braking force on the grinding machine <NUM>.

A main object of the invention is to solve the problems of the conventional grinding machine tool that the brake lining keeps contacting with the grinding disc when the grinding disc is rotating.

In order to achieve the above object, the invention provides a grinding machine tool, the grinding machine tool a housing, a driving assembly disposed in the housing, a grinding disc driven by the driving assembly, a switch driving the driving assembly, and a pressing plate disposed on the housing, wherein the grinding disc comprises a grinding surface and a non-grinding surface, and when the pressing plate is operated, the pressing plate is in a first state that the switch is forced to drive the driving assembly to rotate the grinding disc, and when the pressing plate is not operated, the pressing plate in a second state that the switch is stopped to drive the driving assembly to rotate the grinding disc. Further, the grinding machine tool comprises a grinding disc braking structure, wherein when the pressing plate is in the first state, the grinding disc braking structure is detached from the non-grinding surface, and a spacing is remained between the grinding disc braking structure and the non-grinding surface, and when the pressing plate is in the second state, the grinding disc braking structure moves toward the non-grinding surface and contacts the grinding disc to stop the grinding disc from rotating. The grinding disc braking structure comprises at least one connecting rod forced by the pressing plate, and a brake block disposed on the at least one connecting rod, the brake block is provided to contact with the non-grinding surface. The at least one connecting rod comprises a first part forced by the pressing plate, and a second part provided for the brake block to be disposed thereon, wherein a number of the at least one connecting rod is plural, the connecting rods are pivotally connected with one another, one of the connecting rods is provided for the brake block to be disposed thereon, and another one of the connecting rods is in contact with the pressing plate to force the other connecting rods. Further embodiments are defined in the appended claims.

Accordingly, compared with the prior art, the invention has the following features: through disposition of the grinding disc braking structure in the invention, the grinding disc is capable of rotating without being affected by a resistance of the grinding disc braking structure, and at the same time the grinding disc braking structure is also capable of providing braking for the grinding disc when the grinding disc is intended to stop rotating.

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

Please refer to <FIG>, <FIG>, <FIG>, <FIG> and <FIG>, the invention provides a grinding machine tool <NUM>, the grinding machine tool <NUM> includes a housing <NUM>, a driving assembly <NUM>, a grinding disc <NUM>, a switch <NUM> and a pressing plate <NUM>. Specifically, the driving assembly <NUM> is disposed in the housing <NUM>, the driving assembly <NUM> comprises a motor <NUM> and a working shaft <NUM>, and the motor <NUM> is not limited to an electric type or a pneumatic type. The motor <NUM> outputs power after being started, the working shaft <NUM> is connected to the motor <NUM> and driven by the motor <NUM>. The grinding disc <NUM> is connected to the working shaft <NUM>, and the grinding disc <NUM> rotates with the working shaft <NUM> to grind an object. The switch <NUM> is used to determine on and off of the driving assembly <NUM>. The switch <NUM> drives the driving assembly <NUM> to work after being operated, and stops driving the driving assembly <NUM> after being operated again. The pressing plate <NUM> is disposed on the housing <NUM> and capable of being operated. The pressing plate <NUM> determines whether to drive the driving assembly <NUM> or not according to an operated state of the pressing plate <NUM>. In detail, the pressing plate <NUM> has a first state when the pressing plate <NUM> is operated, and a second state when the pressing plate <NUM> is not operated. When the pressing plate <NUM> is in the first state, the switch <NUM> is acted to drive the driving assembly <NUM>, so that the driving assembly <NUM> drives the grinding disc <NUM> to rotate. When the pressing plate <NUM> is in the second state, the switch <NUM> is no longer acted and stops driving the driving assembly <NUM>, so that the driving assembly <NUM> stops driving the grinding disc <NUM>.

When the switch <NUM> stops driving the driving assembly <NUM>, the grinding disc <NUM> no longer receives a kinetic energy output by the driving assembly <NUM>, but the grinding disc <NUM> will continue to rotate subject to an inertia effect of the driving assembly <NUM> and the grinding disc <NUM> itself. In this regard, in order to prevent the grinding disc <NUM> from idling, the grinding machine tool <NUM> of the invention is provided with a grinding disc braking structure <NUM> which is forced by the pressing plate <NUM> when the pressing plate <NUM> is operated to provide braking for the grinding disc <NUM>. In detail, please together refer to <FIG>, the grinding disc <NUM> has a grinding surface <NUM> and a non-grinding surface <NUM>. The grinding surface <NUM> is disposed on a side of the grinding disc <NUM> facing the object, and the grinding surface <NUM> is used for grinding the object to be ground. The non-grinding surface <NUM> can be a surface disposed on another side of the grinding disc <NUM> facing the housing <NUM>, or be disposed on an inclined side of the grinding disc <NUM> connected with the surface mentioned above, and the non-grinding surface <NUM> is not used for grinding. When the grinding disc braking structure <NUM> contacts the non-grinding surface <NUM> (the surface or the inclined side of the grinding disc <NUM>), the grinding disc braking structure <NUM> produces a resistance for the grinding disc <NUM> to stop the grinding disc <NUM> from rotating.

For a more detailed explanation of implementation of the grinding machine tool <NUM>, please refer to <FIG> and <FIG>. Assuming initially that the pressing plate <NUM> is not operated, the pressing plate <NUM> is in the second state and the grinding disc <NUM> is not driven. At this time, the grinding disc <NUM> is in contact with the grinding disc braking structure <NUM> and is completely stationary, as shown in <FIG>. When the pressing plate <NUM> is operated, the pressing plate <NUM> turns into the first state, and the switch <NUM> is acted to drive the driving assembly <NUM> so that the grinding disc <NUM> starts to rotate. At the same time, the grinding disc braking structure <NUM> is forced by the pressing plate <NUM> to move away from the non-grinding surface <NUM> of the non-grinding surface <NUM>, so that the grinding disc braking structure <NUM> is detached from the non-grinding surface <NUM>, and a spacing <NUM> is maintained between the grinding disc braking structure <NUM> and the non-grinding surface <NUM>. The grinding disc <NUM> is capable of rotating without the resistance of the grinding disc braking structure <NUM>, as shown in <FIG>. When the pressing plate <NUM> is no longer operated, the pressing plate <NUM> then turns into the second state. The switch <NUM> stops driving the driving assembly <NUM> so that the grinding disc <NUM> is no longer driven. At this time, the grinding disc braking structure <NUM> moves toward the non-grinding surface <NUM> and contacts the grinding disc <NUM>, so that the grinding disc <NUM> is braked by the grinding disc braking structure <NUM>, and then stops rotating.

Please refer to <FIG> and <FIG> again. It can be known from the above that in order for the invention to solve the problem that the conventional grinding disc <NUM> idles when the conventional grinding disc <NUM> stops being driven, the grinding disc braking structure <NUM> is provided on the grinding machine tool <NUM>, so that the grinding disc <NUM> can be braked by the grinding disc braking structure <NUM> when the grinding disc <NUM> stops being driven, and rotation of the grinding disc <NUM> can be stopped quickly. In addition, the grinding disc braking structure <NUM> of the invention provides braking only when the grinding disc <NUM> is not driven. When the grinding disc <NUM> is driven, the grinding disc braking structure <NUM> does not contact the grinding disc <NUM>, and the grinding disc braking structure <NUM> does not produce resistance force on the grinding disc <NUM> when the grinding disc <NUM> is rotating, thereby reducing a loss of kinetic energy output by the driving assembly <NUM>, and further improving the problem that the conventional brake lining <NUM> wears out quickly due to the conventional brake lining <NUM> rubbing the grinding disc <NUM> over a long period of time.

Please refer to <FIG>, <FIG>, <FIG> and <FIG>. According to the invention, the grinding disc braking structure <NUM> comprises at least one connecting rod <NUM> and a brake block <NUM> disposed on the connecting rod <NUM>. The least one connecting rod <NUM> faces the pressing plate <NUM>, and the brake block <NUM> is disposed on the connecting rod <NUM> and is moved along with the connecting rod <NUM>. When the pressing plate <NUM> turns into the second state, the least one connecting rod <NUM> is forced by the pressing plate <NUM> so that the brake block <NUM> is in contact with the non-grinding surface <NUM>.

Further, the housing <NUM> is formed with a first assembling portion <NUM>; the pressing plate <NUM> is formed with at least one hole <NUM>; and the grinding machine tool <NUM> includes a first shaft <NUM>, wherein the at least one hole <NUM> is disposed corresponding to the first assembling portion <NUM>, and the first shaft <NUM> is disposed in the first assembling portion <NUM> and the at least one hole <NUM>. When the pressing plate <NUM> is operated to turn into the first state from the second state, the pressing plate <NUM> is capable of displacing toward the housing <NUM> through the first shaft <NUM>. The least one connecting rod <NUM> and the switch <NUM> are located on a displacement path of the pressing plate <NUM>, so that the pressing plate <NUM> presses the least one connecting rod <NUM> and the switch <NUM> when the pressing plate <NUM> turns into the first state.

Please refer to <FIG>, <FIG>, <FIG>, and <FIG>. According to the invention, the number of the at least one connecting rod <NUM> is plural, and the connecting rods <NUM> are pivotally connected with one another, one of the connecting rods <NUM> is provided for disposing the brake block <NUM>, and another one of the connecting rods <NUM> is forced by the pressing plate <NUM>. In addition, for the convenience of description hereinafter, one of the connecting rods <NUM> provided with the brake block <NUM> is defined as a first connecting rod <NUM>, another one of the connecting rods <NUM> forced by the pressing plate <NUM> is defined as a second connecting rod <NUM>. In one embodiment, the second connecting rod <NUM> is pivotally connected with the first connecting rod <NUM> directly. In another embodiment, other connecting rods <NUM> are assembled between the second connecting rod <NUM> and the first connecting rod <NUM>. The first connecting rod <NUM> is forced by the second connecting rod <NUM> after the second connecting rod <NUM> is forced by the pressing plate <NUM>.

Further, the grinding disc braking structure <NUM> comprises a torsion spring <NUM>. The torsion spring <NUM> is disposed on the housing <NUM> and is in contact with the second connecting rod <NUM>. The torsion spring <NUM> includes a first arm <NUM> and a second arm <NUM>, the first arm <NUM> butts against the housing <NUM>, the second arm <NUM> butts against the second connecting rod <NUM>. When the second connecting rod <NUM> is forced by the pressing plate <NUM>, the torsion spring <NUM> is pressed by the second connecting rod <NUM> from the second arm <NUM>, and so that an elastic potential energy is stored in the torsion spring <NUM>. When the second connecting rod <NUM> is no longer forced by the pressing plate <NUM>, the elastic acting force is released, and the torsion spring <NUM> pushes the second connecting rod <NUM> via the second arm <NUM> to reset the second connecting rod <NUM>.

The housing <NUM> comprises a second assembling portion <NUM>; the second connecting rod <NUM> comprises at least one opening <NUM> corresponding to the second assembling portion <NUM>; the grinding disc braking structure <NUM> comprises a second shaft <NUM>. The second shaft <NUM> is assembled with the torsion spring <NUM> and is disposed in the second assembling portion <NUM> and the opening <NUM>. The second shaft <NUM> is provided as a fulcrum for movement of the second connecting rod <NUM>, and the fulcrum enables two ends of the second connecting rod <NUM> to swing relative to the housing <NUM> when the second connecting rod <NUM> are forced by the pressing plate <NUM> or are pushed against by the torsion spring <NUM>. In addition, one of the two ends of the second connecting rod <NUM> is a working end <NUM>, and another end of the second connecting rod <NUM> is a swinging end <NUM>. The working end <NUM> is forced by the pressing plate <NUM>, and the swinging end <NUM> is directly or indirectly connected to the first connecting rod <NUM>. Since the swinging end <NUM> is affected by a gravitational effect of the first connecting rod <NUM>, the second connecting rod <NUM> is assembled with the housing <NUM> in an inclined manner, that is to say, the second connecting rod <NUM> is assembled with the housing <NUM> in a position that a horizontal height of the working end <NUM> is greater than a horizontal height of the swinging end <NUM>. In one embodiment, when the second connecting rod <NUM> is directly pivotally connected to the first connecting rod <NUM>, the swinging end <NUM> is formed with at least one through hole <NUM>, and the first connecting rod <NUM> is formed with at least one perforation <NUM> aligning with the at least one through hole <NUM>. The grinding disc braking structure <NUM> includes a third shaft <NUM> disposed in the at least one through hole <NUM> and the at least one perforation <NUM>, so that the swinging end <NUM> is pivotally connected to the first connecting rod <NUM> through the third shaft <NUM>. When the working end <NUM> is pressed by the pressing plate <NUM>, the swinging end <NUM> lifts the first connecting rod <NUM> based on lever action. Further, in another embodiment, the second connecting rod <NUM> is formed with an auxiliary working block <NUM> extending from the working end <NUM> toward the pressing plate <NUM>, wherein an extension direction of the auxiliary working block <NUM> is different from an inclined direction of the second connecting rod <NUM>, thereby assisting the pressing plate <NUM> to press the working end <NUM>.

Please refer to <FIG>, <FIG>, <FIG> and <FIG>. In one embodiment, the housing <NUM> is formed with an assembly boss <NUM> facing the pressing plate <NUM>, and the assembly boss <NUM> is provided for the switch <NUM> to be disposed thereon. The assembly boss <NUM> is adjacent to the working end <NUM> and does not interfere with movement of the second connecting rod <NUM>. In detail, a center line <NUM> is defined on the pressing plate <NUM> as shown in <FIG>, the working end <NUM> is located on the center line <NUM>, and the assembly boss <NUM> is located on one side of the working end <NUM>, so that the switch <NUM> is disposed offsetly from the center line <NUM>. It should be noted that a disposing range of the switch <NUM> must be within an area where the pressing plate <NUM> is capable of contacting the switch <NUM> simultaneously when the pressing plate <NUM> presses the working end <NUM>, so that the pressing plate <NUM> is capable of forcing the working end <NUM> and forcing the switch <NUM> at the same time.

Further, the second connecting rod <NUM> comprises a rod body <NUM> and an extension arm <NUM>. The rod body <NUM> is provided with the working end <NUM> and the swinging end <NUM>, and the rod body <NUM> is disposed on the housing <NUM>. The rod body <NUM> is formed with a hollow area <NUM> which prevents the second connecting rod <NUM> from interfering with the second assembling portion <NUM> when the second connecting rod <NUM> swings. The extension arm <NUM> extends from one side of the rod body <NUM>, and the extension arm <NUM> provides the second arm <NUM> of the torsion spring <NUM> to butt thereon. In one embodiment, the extension arm <NUM> is formed with an assembly opening <NUM>, the assembly opening <NUM> and the opening <NUM> are located on a same extension line, and the opening <NUM> is provided for the second shaft <NUM> to insert therein.

On the other hand, please refer to <FIG>, <FIG>, <FIG> and <FIG>, in one embodiment that the grinding machine tool <NUM> of the invention is a pneumatic machine tool, the housing <NUM> comprises a set of gas passages <NUM> and a mounting hole <NUM>. The set of gas passages <NUM> comprises an air inlet passage <NUM> and an air outlet passage <NUM>, the air inlet passage <NUM> is controlled by the switch <NUM> to determine whether to allow the air to enter and drive the driving assembly <NUM>, and the air outlet passage <NUM> communicates with the air inlet passage <NUM> and is provided for discharging gas. The mounting hole <NUM> is provided for at least one of the connecting rods <NUM> to dispose therein, and the mounting hole <NUM> does not communicate with the set of gas passages <NUM>. In one embodiment, the mounting hole <NUM> is integrally formed with the housing <NUM>; in another embodiment, the mounting hole <NUM> is formed by communicating two ports respectively provided on the housing <NUM>, and one of the two ports of the mounting hole <NUM> is located within a projection area of the pressing plate <NUM>.

Claim 1:
A grinding machine tool (<NUM>), comprising a housing (<NUM>), a driving assembly (<NUM>) disposed in the housing (<NUM>), a grinding disc (<NUM>) driven by the driving assembly (<NUM>), a switch (<NUM>) driving the driving assembly (<NUM>), and a pressing plate (<NUM>) disposed on the housing (<NUM>), wherein the grinding disc (<NUM>) comprises a grinding surface (<NUM>) and a non-grinding surface (<NUM>), and when the pressing plate (<NUM>) is operated, the pressing plate (<NUM>) is in a first state that the switch (<NUM>) is forced to drive the driving assembly (<NUM>) to rotate the grinding disc (<NUM>), and when the pressing plate (<NUM>) is not operated, the pressing plate (<NUM>) in a second state that the switch (<NUM>) is stopped to drive the driving assembly (<NUM>) to rotate the grinding disc (<NUM>), the grinding machine tool (<NUM>) is characterized in that:
the grinding machine tool (<NUM>) comprises a grinding disc braking structure (<NUM>), wherein when the pressing plate (<NUM>) is in the first state, the grinding disc braking structure (<NUM>) is detached from the non-grinding surface (<NUM>), and a spacing (<NUM>) is remained between the grinding disc braking structure (<NUM>) and the non-grinding surface (<NUM>), and when the pressing plate (<NUM>) is in the second state, the grinding disc braking structure (<NUM>) moves toward the non-grinding surface (<NUM>) and contacts the grinding disc (<NUM>) to stop the grinding disc (<NUM>) from rotating,
wherein the grinding disc braking structure (<NUM>) comprises at least one connecting rod (<NUM>) forced by the pressing plate (<NUM>), and a brake block (<NUM>) disposed on the at least one connecting rod (<NUM>), the brake block (<NUM>) is provided to contact with the non-grinding surface (<NUM>);
wherein the at least one connecting rod (<NUM>) comprises a first part (<NUM>) forced by the pressing plate (<NUM>), and a second part (<NUM>) provided for the brake block (<NUM>) to be disposed thereon; and
wherein a number of the at least one connecting rod (<NUM>) is plural, the connecting rods (<NUM>) are pivotally connected with one another, one of the connecting rods (<NUM>) is provided for the brake block (<NUM>) to be disposed thereon, and another one of the connecting rods (<NUM>) is in contact with the pressing plate (<NUM>) to force the other connecting rods (<NUM>).