Patent Publication Number: US-2022234240-A1

Title: Tool device and method

Description:
The invention relates to a tool device comprising a shaft. Preferably, the tool device comprises a drivable tool coupled to the shaft. Expediently, the tool is drivable via the shaft. 
     EP 1 234 285 B1 describes a table saw having a braking mechanism comprising at least one pawl which is brought into engagement with the saw blade to stop the rotating saw blade. 
     It is an objection of the invention to provide a tool device that can be operated with less effort. 
     The object is solved by a tool device according to claim  1 . The tool device comprises a braking device with at least one brake body, in particular designed as a brake disc, and a brake section. The tool device is adapted to set, within a braking operation, the braking device from a release state via a feed state into a braking state. In the release state, the at least one brake body is coupled to the shaft in a rotationally fixed manner, so that the at least one brake body rotates with the shaft in the release state. In the feed state, a relative rotational movement is provided between the at least one brake body and the shaft and the relative rotational movement is converted into an axial movement of the brake body towards the brake section. In the braking state, the at least one brake body is in contact with the brake section and exerts a braking force on the shaft so that the shaft is braked. Expediently, braking the shaft brakes the tool. 
     The term braking in this context refers to the reduction of a speed, in particular a rotational speed. Braking is expediently carried out to a standstill or not to a standstill. 
     In EP 1 234 285 B1 mentioned at the beginning, a pawl is brought into engagement with the saw blade in order to stop the saw blade. This usually results in damage to the saw blade and the pawl, so that both have to be replaced so that the table saw can continue to be operated. 
     In contrast, in the tool device described, the tool and/or the at least one brake body expediently remain undamaged and/or continue to be usable even after the tool has been braked, so that no replacement is required for further operation. 
     For this reason, the described tool device can be operated with less effort. 
     Advantageous further embodiments are the subject of the subclaims. 
     The invention further relates to a method for braking a shaft of a tool device, comprising the step of: putting a braking device, which comprises at least one brake body, in particular designed as a brake disc, and a brake section, from a release state, in which the at least one brake body is coupled to the shaft in a rotationally fixed manner, so that the at least one brake body rotates with the shaft, via a feed state, in which the at least one brake body performs an axial movement towards the brake section caused by a relative rotational movement between the at least one brake body and the shaft, to a braking state in which the at least one brake body is in contact with the brake section and exerts a braking force on the shaft so that the shaft is braked. 
     In a preferred embodiment, the method is carried out using a tool device described herein. 
    
    
     
       Further exemplary details as well as exemplary embodiments are explained below with reference to the figures. Thereby shows 
         FIG. 1  a schematic representation of a tool device, 
         FIG. 2  a braking device in a release state, 
         FIG. 3  a sectional view of the braking device, 
         FIG. 4  the braking device in a feed state, 
         FIG. 5  the braking device in a braking state, 
         FIG. 6  a reset mechanism in an inactive position, and 
         FIG. 7  the reset mechanism in an active position. 
     
    
    
     In the following explanation, reference is made to the directions “x”, “y” and “z” shown in the figures. The x-direction, y-direction and z-direction are orthogonal to each other. The x-direction and y-direction may also be referred to as horizontal direction, and the z-direction may be referred to as vertical direction. The directions “radial direction” and “axial direction” mentioned below are to be understood in particular with respect to the longitudinal axis of the shaft  2 . In an exemplary embodiment, the longitudinal axis or axial direction of the shaft  2  is parallel to the x-direction. The term “axial movement” means in particular a movement parallel to the longitudinal axis of the shaft  2 . 
       FIG. 1  shows a tool device  10  with a drivable tool  1 . The tool device  10  comprises a shaft  2  coupled to the tool  1 , by means of which shaft  2  the tool  1  is expediently drivable. 
     The tool device  10  comprises a braking device  12 , which is exemplarily shown in  FIGS. 2 to 5 . The braking device  12  comprises at least one brake body  3 . The at least one brake body  3  is expediently configured as a brake disc. Exemplarily, the braking device  12  comprises two brake bodies  3 —a first brake body  3 A and a second brake body  3 B. Alternatively, the braking device  12  may comprise only one brake body  3 . 
     The tool device  10  further comprises a brake section  14 . Exemplarily, the brake section  14  is located in the axial direction of the shaft  2  between the two brake bodies  3 A,  3 B. Preferably, the shaft  2  is rotatably mounted on the brake section  14 . 
     The tool device  10  is configured to put, as part of a braking operation, the braking device  12  from a release state to a braking state via a feed state. 
     The release state is exemplarily shown in  FIGS. 2 and 3 . In the release state, the at least one brake body  3  is coupled to the shaft  2  in a rotationally fixed manner, so that the at least one brake body  3  rotates with the shaft  2  (about the longitudinal axis of the shaft) in the release state. In particular, the rotationally fixed coupling is such that the at least one brake body  3 , preferably both brake bodies  3 A,  3 B, co-rotates with the shaft  2  (at the same rotational speed) in a state in which the shaft  2  rotates, and in a state in which the shaft does not rotate, the brake body  3 , preferably both brake bodies  3 A,  3 B, also does not rotate. Exemplarily, both brake bodies  3 A,  3 B are non-rotatably coupled to the shaft  2  and rotate with the shaft  2  when the shaft  2  rotates. In an exemplary embodiment, the tool device  10  comprises a coupling mechanism for providing the rotationally fixed coupling in the release mode. In an exemplary embodiment, the coupling mechanism is configured to provide the rotationally fixed coupling by frictional engagement. In an exemplary embodiment, the coupling mechanism comprises at least one coupling section  15 , exemplarily a nut, which is non-rotatably fixed to the shaft  2  and is pressed against the at least one brake body  3  in the release mode, so as to provide a frictional connection between the coupling section  15  and the at least one brake body  3 , so as to provide the non-rotatable coupling between the at least one brake body  3  and the shaft  2 . 
     In the release state, the shaft  2  can expediently rotate freely and is in particular not braked by the braking device  12 . For example, the braking device  12  assumes the release state during normal operation—that is, in particular during rotation of the shaft  2  and the tool  1  and, for example, during processing of the workpiece  11  with the tool  1 . 
     The tool device  10  is configured to move the braking device  12  from the release state to the feed state. 
       FIG. 4  shows the braking device  12  in the feed state. In the feed state, a relative rotational movement is provided between the at least one brake body  3 , preferably both brake bodies  3 A,  3 B, and the shaft  2 . Preferably, the shaft  2  has a higher rotational speed than the brake body  3  during the relative rotational movement. In particular, the relative rotational movement is provided by rotationally braking the at least one brake body  3 , preferably both brake bodies  3 A,  3 B, relative to the shaft  2 . This is exemplarily done by bringing an actuating section  16  into contact with the at least one brake body  3 . By braking the at least one brake body  3 , the rotational coupling between the at least one brake body  3  and the shaft  2  is released, so that the at least one brake body  3  is no longer rotationally coupled to the shaft  2  and rotates relative to the shaft  2 . Expediently, the shaft  2  rotates faster than the at least one brake body  3  in the feed state, in particular faster than both brake bodies  3 A,  3 B. 
     Alternatively, or in addition to the embodiment described above in which the tool device  10  brakes the brake body  3  to provide the relative rotational movement, the tool device  10  may also be configured to provide the relative rotational movement by a jerky change in rotational speed of the shaft  2 , in particular a rotational acceleration of the shaft  2 . 
     The relative rotational movement between the at least one brake body  3 , preferably the two brake bodies  3 A,  3 B, and the shaft  2  is converted into an axial movement  31  of the at least one brake body  3 , preferably the two brake bodies  3 A,  3 B, towards the brake section  14 . Suitably, the at least one brake body  3  performs the axial movement until the at least one brake body  3  is in contact with the brake section  14 . The axial movement  31  is parallel to the x-direction. Preferably, the axial movement  31  is a linear movement. 
     Exemplarily, the axial movement  31  is provided by a thread  4  arranged in particular on the shaft  2 , with which thread  4  the at least one brake body  3  is in engagement. Via the thread  4 , the relative rotational movement between the at least one brake body  3  and the shaft  2  is thus expediently converted into a relative axial movement between the at least one brake body  3  and the shaft  2 . 
       FIG. 5  shows the braking device  12  in the braking state. In the braking state, the at least one brake body  3 , preferably both brake bodies  3 A,  3 B, has reached the brake section  14 . The at least one brake body  3  is in contact with the brake section  14  and exerts a braking force on the shaft  2 , so that the shaft  2  and thereby also the tool  1  are braked. 
     The contact between the at least one brake body  3  and the brake section  14  prevents a (further) relative rotational movement between the at least one brake body  3  and the brake section  14 , in particular by frictional engagement between the at least one brake body  3  and the brake section  14 . Furthermore, the contact between the at least one brake body  3  and the brake section  14  prevents a further axial movement of the at least one brake body  3  towards the brake section  14 , in particular by positive engagement between the at least one brake body  3  and the brake section  14 . 
     Due to the motion coupling between the at least one brake body  3  and the shaft  2 —namely the coupling, provided for example by the thread  4 , between relative rotational movement and relative axial movement between the at least one brake body  3  and the shaft  2 —the shaft  2  can only continue to rotate relative to the brake body  3  if the axial movement of the brake body  3  continues. Consequently, by preventing the axial movement of the brake body  3 , the relative rotational movement between the brake body  3  and the shaft  2  is prevented. Thereby, due to the aforementioned stopping of the relative rotational movement between the brake body  3  and the brake section  14 , the rotational movement of the shaft  2  is also stopped relative to the brake section  14 . The brake section  14  is expediently a stationary part of the tool device  10 , and consequently the shaft  2  and expediently also the tool  1  are stopped relative to a stationary part of the tool device  10 . 
     In particular, the braking device  12  is self-locking and/or self-amplifying. As soon as a brake body  3 A,  3 B contacts the brake section  14 , each further rotation of the shaft  2  increases the braking effect on the shaft  2 . In particular, the brake bodies  3 A,  3 B are pressed more strongly against the brake section  14  by each further rotation of the shaft  2 , so that in particular the frictional connection between the brake bodies  3 A,  3 B and the shaft  2  and thus the braking effect is increased. 
     Suitably, the axial forces exerted by the first brake body  3 A and the second brake body  3 B on the shaft  2  in the braking state cancel each other out. Preferably, the first brake body  3 A and the second brake body  3 B simultaneously strike the brake section  14  after performing the axial movement. 
     Further exemplary details are explained below. 
     First of all, to tool device  10 : 
     In an exemplary embodiment, the tool device  10  is a saw. Suitably, the tool  1  is a rotating saw blade. Preferably, the tool device  10  is a circular table saw. Alternatively, the tool device  10  may be a different tool device. In particular, the tool device  10  may be formed as a stationary or semi-stationary machine. Furthermore, the tool device  10  may be configured as a hand-guided machine, in particular a hand-guided machine tool. Preferably, the tool device  10  is designed as a chop saw, plunge saw, pendulum hood saw, band saw, jigsaw, router and/or angle grinder. In particular, the tool device  10  is a power tool. 
     In an exemplary embodiment, the tool device  10  comprises the tool  1 , the shaft  2 , a drive unit  5 , an actuator unit  6 , and a control unit  7 . Further, the tool device  10  expediently comprises a support structure  8  and/or a support surface  9 . 
     The support structure  8  is exemplarily designed as a housing. The drive unit  5 , the actuator unit  6  and/or the control unit  7  are expediently accommodated in the support structure  8 . 
     Exemplarily, the support surface  9  is arranged on the upper side of the support structure  8 . The support surface  9  serves to support a workpiece  11  while the workpiece  11  is being processed by the tool  1 . Exemplarily, the support surface  9  represents an x-y plane. Exemplarily, the tool  1  protrudes from the support surface  9 , in particular in the z-direction. 
     The drive unit  5  is exemplarily designed as a rotary drive, in particular as an electric rotary drive. The drive unit  5  serves to drive the tool  1 , in particular to set the tool  1  in rotation, preferably in clockwise direction. The tool  1  is coupled to the drive unit  5  via the shaft  2 . The drive unit  5  is designed to drive the shaft  2 , in particular to set it in rotation, via which in turn the tool  1  is driven. Exemplarily, the tool  1  is connected to the shaft  2  in a rotationally fixed manner, so that the tool  1  rotates with the rotating shaft  2 . 
     In particular, the shaft  2  is a shaft of the drive train of the tool device  10 . The shaft  2  and the tool  1  are expediently rotatably mounted with respect to the support structure  8 . 
     The shaft  2  is aligned with its longitudinal axis parallel to the x-direction. Exemplarily, the shaft  2  has a circular-cylindrical basic shape. The axis of rotation of the tool  1  is expediently aligned parallel to the x-direction. Exemplarily, the shaft  2  and the tool  1  are aligned coaxially to each other. 
     Expediently, the actuator unit  6  serves to move the braking device  12  from the release state to the feed state, as will be further explained below. 
     The control unit  7  is expediently adapted to provide a drive unit control signal to the drive unit  5  to cause the drive unit  5  to drive the tool  1 . The control unit  7  is suitably further adapted to provide an actuator unit control signal to the actuator unit  6  to cause the actuator unit  6  to set the braking device  12  to the feed state. The control unit  7  is suitably further adapted to detect an operating state and to initiate the braking operation based on the detected operating state, in particular by providing the actuator unit control signal to the actuator unit  6  and/or a control signal to the drive unit  5 . The operating state is in particular an emergency state. The emergency state is in particular a potentially dangerous situation for a user, in which the user may be injured by the tool and/or the workpiece, for example. The control unit  7  is suitably configured to detect the emergency state on the basis of a detected contact between the tool  1  and the human body, for example a finger. 
     Preferably, the tool device  10 , in particular the control unit  7 , is configured to supply an electrical detection signal to the tool  1  and to detect the emergency state on the basis of a change in the detection signal. More expediently, the tool device  10 , in particular the control unit  7 , is configured to supply the electrical detection signal to the tool  1  by capacitive coupling. More expediently, the tool device  10 , in particular the control unit  7 , is adapted to detect the emergency state, in particular the contact between the tool  1  and the human body, on the basis of a capacitive change. Further details on how the detection of the emergency state can be implemented in an exemplary manner are described in EP 1 234 285 B1. 
     The control unit  7  is suitably further adapted to detect a kickback as the emergency state. The term “kickback” means in particular a state in which, during processing of the workpiece  11  by the tool device  10 , a sudden and unexpected force occurs between the tool device  10  and the workpiece  11 , causing the tool device  10  and/or the workpiece  11  to move. 
     The tool device  10  expediently comprises a sensor device, for example an acceleration sensor and/or a force sensor, in particular a strain gauge arrangement, for detecting the kickback. Such a sensor device is described, for example, in WO 2019/020307 A1. 
     The tool device  10  is expediently configured to bring the tool  1  to a standstill within 5 ms or less by performing the braking operation, expediently from a driven, in particular rotating, state of the tool  1  in which processing of the workpiece  11  is or can be performed. 
     With reference to  FIGS. 2 to 5 , the braking device  12  will be discussed in more detail below. 
     Expediently, the braking device  12  is integrated in the tool device  10 . The braking device  12  is in particular an actively switched brake (preferably via the control unit  7  and/or the actuator unit  6 ). The braking device  12  is in particular reversible, so that it can be moved from the braking state back to the release state (and from there, expediently, back to the braking state), preferably without having to replace a component of the braking device  12  for this purpose. 
     In an exemplary embodiment, the braking device  12  comprises the shaft  2 , the brake bodies  3 , the brake section  14 , the coupling sections  15  and the actuating section  16 . The shaft  2  is oriented with its longitudinal axis parallel to the x-direction. The shaft  2  extends through the brake bodies  3 , the coupling sections  15  and expediently also through the brake section  14 . The brake bodies  3  are arranged distributed in the x-direction. In particular, the brake bodies  3  are aligned coaxially with the shaft  2  and coaxially with each other. The brake section  14  is arranged in the x-direction between the brake bodies  3 . The brake section  14  and the brake bodies  3  are arranged together in the x-direction between the coupling sections  15 . The brake section  14 , the brake bodies  3  and the coupling sections  15  do not overlap each other in the x-direction. In particular, the actuating section  16  is arranged spaced apart from the shaft  2  in the radial direction. 
     In the release state (see  FIGS. 2 and 3 ), the shaft  2 , the coupling sections  15  and the brake bodies  3  are coupled to each other in a rotationally fixed manner. For example, the brake bodies  3  are frictionally and/or positively coupled to the shaft  2  in the release state. The shaft  2  is freely rotatable relative to the brake section  14  in the release state. The brake bodies  3  are not in contact with the brake section  14  in the release state. The actuating section  16  is not in contact with the brake bodies  3  in the release state. 
     In the feed state (see  FIG. 4 ), the shaft  2  and the brake bodies  3  are not coupled to each other in a rotationally fixed manner. The shaft  2  can rotate relative to the brake bodies  3 . Expediently, the shaft  2  and the one brake body  3 , in particular both brake bodies  3 A,  3 B, rotate in the same direction of rotation in the feed state. The shaft  2  continues to be freely rotatable relative to the brake section  14  in the feed state. The brake bodies  3  are not in contact with the brake section  14  in the feed state. The actuating section  16  is expediently in contact with the brake bodies  3  in the feed state. 
     In the braking state (see  FIG. 5 ), the brake bodies  3  and the shaft  2  are coupled to the brake section  14  in a rotationally fixed manner. Furthermore, in the braking state, the brake bodies  3  are in contact with the brake section  14 . 
     In the following, the brake bodies  3  will be discussed in more detail. 
     Exemplarily, two brake bodies  3  are present—a first brake body  3 A and a second brake body  3 B. According to an alternative embodiment, only one brake body  3  is present; that is, the first brake body  3 A or the second brake body  3 B is not present in the alternative embodiment. 
     The two brake bodies  3 A,  3 B are expediently formed in correspondence with each other. Explanations referring to a brake body  3  apply in particular to both brake bodies  3 A,  3 B. Furthermore, explanations relating to the first brake body  3 A expediently apply in correspondence also to the second brake body  3 B. 
     The brake bodies  3 A,  3 B are exemplary brake discs. The first brake body  3 A may also be referred to as the first brake disc and the second brake body  3 B may be referred to as the second brake disc. 
     The brake bodies  3  are expediently separate parts from each other. In particular, the two brake bodies  3 A,  3 B run separately from each other on the shaft  2 . 
     Each brake body  3 A,  3 B comprises, in an exemplary manner, a respective disc section  18  which is aligned coaxially with the shaft  2 . At the end face of each disc section  18  facing the brake section  14 , there is exemplarily a respective contact region  17 , in particular a flat contact region, for example a brake lining. The end face facing the brake section  14  is oriented perpendicular to the x-direction. In the braking state, the respective contact region  17  of each brake body  3 A,  3 B is in contact with the brake section  14 . The contact regions  17  of the two brake bodies  3 A,  3 B are exemplarily aligned facing each other. 
     In an exemplary embodiment, each brake body  3 A,  3 B further comprises a respective cylinder section  19  which is coaxially aligned with the shaft  2 . Each cylinder section  19  is arranged at the end face of the respective disc section  18  facing away from the brake section  14 . 
     Each brake body  3 A,  3 B is in contact with a respective coupling section  15  with its end face facing away from the brake section  14 , in particular with the end face of the respective cylinder section  19  facing away from the brake section  14 . This expediently provides the rotationally fixed coupling to the shaft  2 , in particular by frictional engagement. 
     Each brake body  3 A,  3 B expediently comprises a respective brake body thread  22 A,  22 B. Each brake body  3 A,  3 B is in engagement with the shaft  2  via its respective brake body thread  22 A,  22 B. The brake body threads  22 A,  22 B are expediently designed as internal threads. Each brake body thread  22 A,  22 B is expediently arranged in a through hole arranged centrally in the respective brake body  3 A,  3 B, in particular centrally in the respective disc section  18  and/or cylinder section  19 . 
     In the following, the shaft  2  will be discussed in more detail: 
     The shaft  2  is exemplarily designed as a drive spindle. Preferably, the shaft  2  is designed as a threaded shaft. The shaft  2  is expediently connected to a motor shaft and/or the tool  1  in a torque-resistant manner. 
     In an exemplary embodiment, the shaft  2  comprises the first thread  4 A. The first thread  4 A is in engagement with the first brake body  3 A, in particular with the first brake body thread  22 A. 
     Expediently, the shaft  2  further comprises a second thread  4 B. The second thread  4 B is offset in the x-direction from the first thread  4 A. The second thread  4 B is in engagement with the second brake body  3 B, in particular with the second brake body thread  22 B. 
     The first thread  4 A differs in its thread direction from the second thread  4 B. Preferably, the thread direction of the first thread  4 A is opposite to the thread direction of the second thread  4 B. Expediently, the first thread  4 A is a right-hand thread and the second thread  4 B is a left-hand thread. Alternatively, the first thread  4 A is a left-hand thread and the second thread  4 B is a right-hand thread. 
     In the embodiment shown, the braking device  12  comprises the two threads  4 A,  4 B. According to an alternative embodiment, in particular an embodiment with only one brake body  3 , the braking device comprises only one thread  4 A or  4 B. 
     The tool device  10  is adapted to convert the relative rotational movement  30  between each brake body  3 A,  3 B and the shaft  2  into the axial movement  31 A,  31 B of each brake body  3 A,  3 B towards the brake section  14 . In particular, the tool device  10  is adapted, in the feed state, to set the two brake bodies  3 A,  3 B in opposite axial movements  31 A,  31 B towards the brake section  14  by the relative rotational movement  30  between the two brake bodies  3 A,  3 B and the shaft  2 . Expediently, the brake bodies  3 A,  3 B move towards each other when performing the axial movements  31 A,  31 B. 
     To convert the relative rotational movement  30  into the axial movements  31 A,  31 B, the tool device  10  comprises a conversion mechanism, which is formed by the threads  4 A,  4 B and the brake body threads  22 A,  22 B, for example. The engagement of the first thread  4 A with the first brake body thread  22 A causes the first brake body  3 A to undergo the first axial movement  31 A towards the brake section  14  upon a relative rotational movement between the first brake body  3 A and the shaft  2 . In an exemplary embodiment, the first axial movement  31 A is antiparallel to the x-direction. The engagement of the second thread  4 B with the second brake body thread  22 B causes the second brake body  3 B to undergo a second axial movement  31 B towards the brake section  14  upon a relative rotational movement between the second brake body  3 B and the shaft  2 . In an exemplary embodiment, the second axial movement  33 B is parallel to the x-direction. 
     Next, the brake section  14  will be discussed. 
     Exemplarily, the brake section  14  is a part of the support structure  8  or is non-rotatably connected to the support structure  8 , in particular to the support structure  8  configured as a housing. In particular, the brake section  14  is a stationary section. More expediently, the brake section  14  does not rotate with the shaft  2 . The brake section  14  is configured to dissipate a force and/or a torque acting on the shaft  2  in the braking state. 
     In an exemplary embodiment, the brake section  14  has a basic plate-like shape. In particular, the brake section  14  is designed as a brake block and/or bearing block. In an exemplary embodiment, the largest side of the brake section  14  in terms of area is oriented normal to the x-direction. The brake section  14  has a first braking surface  21 A, which faces the first brake body  3 A and is in contact with the first brake body  3 A in the braking state. The brake section  14  further comprises a second braking surface  21 B facing the second brake body  3 B and in contact with the second brake body  3 B in the braking state. The first braking surface  21 A and the second braking surface  21 B are oriented in opposite directions. 
     Exemplarily, the brake section  14  comprises a through hole through which the shaft  2  is guided. Expediently, the brake section  14  comprises a pivot bearing  24 , in particular a rolling bearing, which mounts the shaft  2 . 
     The coupling sections  15  will be discussed in more detail below. 
     The coupling sections  15  serve to provide the rotationally fixed coupling between the brake bodies  3 A,  3 B and the shaft  2  in the release state. In particular, the coupling sections  15  are configured to provide the rotationally fixed coupling as a releasable rotationally fixed coupling. 
     Exemplarily, two coupling sections  15  are present. In an alternative embodiment, in particular an embodiment with only one brake body  3 , there is preferably only one coupling section  15 . 
     The coupling sections  15  are expediently arranged on the shaft  2 , in particular fastened thereto. Exemplarily, the coupling sections  15  are each designed as a nut and are screwed onto the shaft  2 . According to an alternative embodiment, the coupling sections  15  are part of the shaft  2 . 
     Each coupling section  15  is in contact with a respective brake body  3 A,  3 B, in particular with its respective end face. Suitably, each coupling section  15  is pressed against a respective brake body  3 A,  3 B, in particular in the axial direction. The contact between a respective coupling section  15  and a respective brake body  3 A,  3 B provides a frictional connection, which in turn provides the rotationally fixed coupling between the respective brake body  3 A,  3 B and the shaft  2 . 
     The actuating section  16  will be discussed in more detail below. 
     The actuating section  16  serves to actuate the brake bodies  3 A,  3 B to thereby provide the relative rotational movement between the brake bodies  3 A,  3 B and the shaft  2 . In particular, the actuating section  16  serves to rotationally brake the brake bodies  3 A,  3 B by contact (while the shaft  2  expediently continues to rotate). 
     In an exemplary embodiment, the actuating section  16  has two actuating portions  32 —a first actuating portion  32 A for actuating the first brake body  3 A and a second actuating portion  32 B for actuating the second brake body  3 B. In an exemplary embodiment, the actuating section  16  is U-shaped, the actuating portions  32  being formed by respective legs. 
     The actuating section  16  is expediently set into an actuating movement towards the brake bodies  3  by the actuator unit  6 , in order to actuate the brake bodies  3 . The actuating movement comprises in particular a linear movement of the actuating section  16 , in particular in the radial direction of the shaft  2 . The actuating movement is in particular a movement of the actuating section  16  relative to the brake bodies  3 . 
     Expediently, the actuator unit  6  comprises an electric actuator for imparting the actuating movement to the actuating section  16 . Expediently, the actuator unit  6  comprises a solenoid and/or a piezo unit for imparting the actuating movement to the actuating section  16 . Alternatively or additionally, the actuator unit  6  comprises a pneumatic cylinder for imparting the actuating movement to the actuating section  16 . 
     Furthermore, for setting the actuating section  16  in the actuating movement, the actuator unit  6  may comprise an actuator of a different design, in particular a piezoelectric actuator, an electromagnetic actuator, a shape memory alloy actuator (SMA actuator), an electroactive polymer actuator (EAP actuator), a magnetic shape memory actuator (MSM actuator), a pneumatic actuator, a hydraulic actuator, a pyroactuator, a mechanical actuator, an electrostrictive actuator and/or a thermal actuator. 
     Preferably, the tool device  10  is adapted to set the actuating section  16  in the actuating movement to bring the actuating section  16  into contact with the brake bodies  3  and thereby cause the braking device  12  to change from the release state to the feed state. 
     Expediently, the tool device  10  is adapted to set the actuating section  16  in the actuating movement on the basis of the detected operating state, in particular the emergency state. 
     Alternatively, or in addition to the described embodiment in which the braking device  12  is actively triggered by the actuator unit  6 , the tool device  10  can also be designed in such a way that the braking device  12  is triggered in a different way—i.e. not by an actuator unit. For example, the braking device  12  may be torque actuated. This can be achieved, for example, by changing the rotational speed of the drive unit  5 , in particular by means of a corresponding closed-loop control. Due to the coupling of the drive unit  5  to the shaft  2 , the rotational speed of the shaft  2  is thereby also changed. Due to a jerky change in rotational speed, in particular an acceleration, of the shaft  2  and the mass inertia of the brake body  3 , torque arises between the shaft  2  and the brake body  3  which leads to a release of the brake body  3  from the release state and, expediently, further to a relative speed change between the shaft  2  and the brake body  3 . 
     Exemplarily, the tool device  10  further comprises a bearing section  25  on which the shaft  2  is mounted, in particular radially and/or axially. Exemplarily, the shaft  2  is supported by one of its ends on the bearing section  25 . The bearing section  25  comprises a rotary bearing  26 , exemplarily a roller bearing. 
     An exemplary operation of the tool device  10  will be described below. 
     Expediently, the tool  1  is driven by the drive unit  5 . The workpiece  11  is processed by the driven tool  1 . During processing, contact occurs between the tool  1  and the user&#39;s body. The control unit  7  detects this contact as an emergency state and thereupon triggers the braking device  12 . The actuator unit  6  actuates the actuating section  16  to actuate the brake bodies  3 , thereby putting the braking device  12  from the release state to the feed state. A relative rotational movement between the brake bodies  3  and the shaft  2  results, which is translated into axial movements  31 A,  31 B of the brake bodies  3  up to the brake section  14 . Exemplarily, the brake bodies  3  move towards each other when performing the axial movements  31 A,  32 B. The braking device  12  is in the braking state when the brake bodies  3  contact the brake section  14 . As a result of the contact between the brake bodies  3  and the brake section  14 , the shaft  2  and the tool  1  are braked to a standstill. In particular, the braking occurs in less than 5 ms. 
     Expediently, the braking device  12  is returned to the release state, in particular automatically by the tool device  10  and/or by a manual actuation. The tool  1  is again driven by the drive unit  5 . The workpiece  11  or another workpiece is then processed by the tool  1 . Expediently, no replacement of the tool  1  and/or of the brake bodies  3  takes place between the braking of the tool  1  and/or of the shaft  2  and the renewed processing. 
     According to a preferred embodiment, the tool device  10  is configured to set the braking device  12  back into the release state, in particular by means of the actuator unit  6  and/or a further actuator unit. Preferably, the tool device  10  is configured to move the braking device  12  back to the release state in response to a reset command. The reset command is expediently entered into the tool device  10  by a user, for example via an input device, in particular a button. 
       FIGS. 6 and 7  show a reset mechanism  40 , which is expediently part of the tool device  10 . The reset mechanism  40  is used to return the braking device  12  to the release state. Exemplarily, the reset mechanism comprises a reset element  41 , for example a lever, having a reset element contact portion  42  which can be brought into contact with a brake body contact portion of the brake body  3 , for example the cylinder section  19 , in particular by a linear movement, and may be positively connected to the brake body contact portion. A rotational movement (in particular manually effected) of the reset element  41  then causes the brake body  3  to rotate, thus bringing it back into the release state. In  FIG. 6 , the reset mechanism  40  is in an inactive state in which the reset contact portion  42  does not contact the brake body contact portion. In  FIG. 7 , the reset mechanism  40  is in an active state in which the reset contact portion  42  contacts the brake body contact portion. 
     Alternatively or in addition thereto, the tool device  10  is configured such that the braking device can be returned to the release state via manual actuation of the tool  1  and/or of the shaft  2  and/or of an operating element, for example a lever, that is mechanically coupled to the shaft  2 . Alternatively or additionally, the tool device  10  is configured in such a way that the braking device can be returned to the release state via manual actuation of the brake body  3  and/or of an operating element, for example a lever, that is mechanically coupled to the brake body  3 . 
     The tool device can also be expediently designed as an angle device, for example as an angle grinder, angle screwdriver or angle drill. 
     Expediently, the tool device comprises a first shaft, for example an input shaft, and a second shaft, for example an output shaft. Preferably, the first shaft and the second shaft are coupled to each other by means of a redirecting joint. Expediently, the first shaft or the second shaft is the aforementioned shaft braked by means of the braking device.