Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J15/00—Gripping heads and other end effectors
  • B25J15/04—Gripping heads and other end effectors with provision for the remote detachment or exchange of the head or parts thereof
  • B25J15/0408—Connections means
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J11/00—Manipulators not otherwise provided for
  • B25J11/005—Manipulators for mechanical processing tasks
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
  • B25J—MANIPULATORS; CHAMBERS PROVIDED WITH MANIPULATION DEVICES
  • B25J15/00—Gripping heads and other end effectors
  • B25J15/0019—End effectors other than grippers

Definitions

• the present invention relates to a quick-clamping system for connecting machine tools to a robot.
• a machine tool e.g. a grinding machine, a drilling machine, a milling machine, a polishing machine and the like
• a manipulator such as an industrial robot.
• the machine tool can be coupled to the so-called TCP (Tool Center Point) of the manipulator in different ways;
• the manipulator can usually set the position and orientation of the TCP practically at will in order to move a machine tool on a trajectory, e.g. parallel to a surface of a workpiece.
• Industrial robots are usually position-controlled, which enables precise movement of the TCP along the desired trajectory.
• a regulation of the process force is necessary in many applications, which is often difficult to achieve with sufficient accuracy with conventional industrial robots.
• the large and heavy arm segments of an industrial robot have too great a mass inertia for a closed-loop controller to react quickly enough to fluctuations in the process force.
• a smaller (and lighter) linear actuator can be arranged between the TCP of the manipulator and the machine tool compared to the industrial robot, which couples the TCP of the manipulator with the machine tool.
• the linear actuator only regulates the process force (i.e.
• the force control enables the linear actuator to compensate for inaccuracies in the position and shape of the workpiece to be machined, as well as inaccuracies in the trajectory of the manipulator (within certain limits). Nevertheless, there are robots that are able to adjust the process force by means of force / torque control even without the aforementioned linear actuator.
• the inventor has set himself the task of creating a comparatively simple and for many applications sufficiently precise quick release system for connecting machine tools,
• the quick release system comprises the following: a chuck with a base plate which is designed to be mounted on a flange that can be positioned by a manipulator; a tool holder, which is currentlybil det for mounting on a machine tool, the tool holder having a mounting plate which was in locked position on the base plate of the chuck; two or more pins that are formed to align the mounting plate on the base plate in the assembled state and to prevent movement of the mounting plate relative to the base plate in a plane parallel to the base plate; at least one elastic element; and a clamping Conclusion, which is designed to lock the tool holder on the base plate of the chuck age, the elastic element being deformed in the locked state and causing a pretensioning force between the base plate and the mounting plate.
• FIG. 1 is an exemplary schematic representation of a robot-assisted grinding device with a grinding machine which is coupled to an industrial robot by means of a force-controlled linear actuator; the linear actuator causes a partial mechanical decoupling of the industrial robot and the grinding machine.
• Figure 2 is an exploded perspective view of an example of a quick release system for connecting a machine tool to a robot.
• FIG. 3 is a side view of the example from FIG. 2.
• Figure 4 is a perspective view of the quick release system in ge clamped state.
• FIG. 5 illustrates the system from FIG. 4 including the machine tool.
• a robot-assisted grinding device comprises a manipulator 80, for example an industrial robot and a grinding machine 50 with a rotating grinding tool 51, these being coupled to the so-called tool center point (TCP) of the manipulator 1 via a linear actuator 20 can is.
• TCP tool center point
• the TCP is not a point, but a vector and can be described, for example, by three spatial coordinates (position) and three angles (orientation).
• position position
• orientation orientation
• generalized coordinates usually six joint angles of the robot
• the position and orientation of the TCP are sometimes referred to as a "pose”.
• the position (including orientation) of the TCP as a function of time defines the movement of the grinding tool, which is referred to as the trajectory.
• the center of the end effector flange of the robot is often defined as the TCP, but this does not necessarily have to be the case.
• the TCP can be any point (and theoretically also outside the robot), the position and orientation of which can be set by the robot.
• the TCP can also define the origin of the tool coordinate system.
• the manipulator In the case of an industrial robot with six degrees of freedom, the manipulator
• the 80 can be constructed from four segments 82, 83, 84 and 85, which are each connected via joints Gn, G12 and G13.
• the first segment 82 is usually rigid with a foundation
• the joint G11 connects the segments 82 and 83.
• the joint G11 can be 2-axis and enable a rotation of the segment 83 about a horizontal axis of rotation (elevation angle) and a vertical axis of rotation (azimuth angle).
• the joint G12 connects the segments 83 and 84 and enables a pivoting movement of the segment 84 relative to the position of the segment 83.
• the joint G13 connects the segments 84 and 85.
• the joint G1 3 can be 2-axis and therefore (similar to the joint G11 ) a swivel movement in two directions is possible.
• the TCP has a fixed position relative to segment 85, this usually also including a swivel joint (not shown), which enables a rotary movement of the end effector flange 86 arranged on segment 85 about a longitudinal axis A of segment 85 (in FIG. 1 as a dash-dotted line in the example shown also corresponds to the axis of rotation of the grinding tool).
• a swivel joint (not shown), which enables a rotary movement of the end effector flange 86 arranged on segment 85 about a longitudinal axis A of segment 85 (in FIG. 1 as a dash-dotted line in the example shown also corresponds to the axis of rotation of the grinding tool).
• Each axis of a Ge joint is assigned an actuator (eg an electric motor) that can cause a rotary movement around the respective joint axis.
• the actuators in the joints are driven by a rotor Robot controller 70 controlled according to a robot program.
• Various industrial robots / manipulators and associated controls
• the manipulator 80 is usually position-controlled, i.e. the robot controller can determine the pose (location and orientation) of the TCP and move it along a predefined trajectory.
• the longitudinal axis of segment 85 on which the TCP lies is denoted by A.
• the pose of the TCP also defines the pose of the grinding machine 50 (and also of the grinding wheel 51).
• the actuator 90 is used to set the contact force (process force) between the tool and the workpiece 60 to a desired value during the grinding process.
• a direct force control by the manipulator 80 is usually too imprecise for grinding applications, since the high inertia of the segments 83 to 85 of the manipulator 80 enables rapid compensation of force peaks (e.g. when the grinding tool is placed on the workpiece 60) with conventional manipulators is practically impossible.
• the robot controller 70 is designed to regulate the pose (position and orientation) of the TCP of the manipulator 80, while the force regulation is carried out exclusively with the aid of the actuator 90.
• the contact force FK between the grinding tool (grinding machine 50 with grinding wheel 51) and workpiece 60 with the aid of the linear actuator 90 and a force control can be set during the grinding process be that the contact force FK (in the direction of the longitudinal axis A) between grinding wheel 51 and workpiece 60 corresponds to a predeterminable target value.
• the contact force FK is a reaction to the actuator force FA with which the linear actuator 90 presses on the workpiece surface. If there is no contact between workpiece 60 and tool 51, due to the lack of contact force on workpiece 60, actuator 90 moves against an end stop (not shown because it is integrated in actuator 2) and presses against it with a defined force.
• the force control is continuously active.
• the actuator deflection is therefore maximum and the actuator 90 is in an end position.
• the defined force with which the actuator 90 presses against the end stop can be very small or (theoretically) even regulated to zero in order to enable the workpiece surface to be contacted as gently as possible.
• the position control of the manipulator 80 (which can also be implemented in the controller 70) can work completely independently of the force control of the actuator 90.
• the actuator 90 is not responsible for the positioning of the grinding machine 50, but only for setting and maintaining the desired contact force FK during the grinding process and for detecting contact between tool 51 and workpiece 60. A contact can be detected in a simple manner, for example that the actuator has moved out of the end position (actuator deflection a is smaller than the maximum deflection aMAx at the end stop).
• the actuator 90 can be a pneumatic actuator such as a double acting pneumatic cylinder. However, other pneumatic actuators can also be used, such as bellows cylinders and air muscles. As an alternative, electrical direct drives (gearless) can also be considered. It goes without saying that the effective direction of the actuator 90 and the axis of rotation of the grinding machine 50 do not necessarily have to coincide with the longitudinal axis A of the segment 85 of the manipulator 80.
• the force control can be implemented in a manner known per se with the aid of a control valve, a regulator (e.g. implemented in the controller 70) and a compressed air reservoir or compressor. Since the inclination to the perpendicular is relevant for taking into account the force of gravity (i.e.
• the actuator 2 can contain an inclination sensor or this information can be determined based on the joint angles of the manipulator 80. The inclination determined is taken into account by the force regulator.
• the specific implementation of the force control is known per se and is not important for the further explanation and is therefore not described in more detail.
• the actuator 90 not only enables a certain mechanical decoupling between the manipulator 80 and the workpiece 60, but is also able to compensate for inaccuracies in the positioning of the TCP.
• Fig. 2 illustrates an exemplary implementation of a quick release system that makes it possible to relatively easily connect a machine tool such as a grinding machine, a polishing machine or a milling machine to a robot and detach it again.
• Fig. 2 shows part of the above-mentioned linear actuator 90, which is coupled at one end to the end effector flange 85 (on the distal arm segment 85 of the robot, see Fig. 1) and at the other end itself has a flange 91 for mounting a machine tool.
• the actuator 90 is therefore often referred to as an "active flange", because he can actively set a force between the end effector flange and the machine tool.
• FIG. 3 is a side view corresponding to FIG. 2.
• Fig. 4 is a perspective view of the assembled quick release system in a locked position.
• the quick release system essentially comprises a chuck 10 (chuck, clamping chuck), which can be mechanically coupled to the flange 91 (for example by means of screws) an elastic element, which in the present example is designed as a rubber washer 20, and a tool holder 30, which can be mechanically rigidly coupled to a machine tool.
• an elastic element which in the present example is designed as a rubber washer 20, and a tool holder 30, which can be mechanically rigidly coupled to a machine tool.
• plastics, in particular elastomers are also suitable materials for the disk 20.
• the flange 91 has several threaded bores 210. In the example shown, the flange 91 has six threaded bores 210, with cylinder pins 11 being screwed into three of the threaded bores 210.
• the cylinder pins have a cylindrical shape in an upper section and have a thread 110 in a lower section which can be screwed into the threaded bores 210.
• Dowel pins are often referred to as dowel pins. Instead of a screw connection, cylinder pins (without thread) can also be glued or pressed into corresponding holes.
• the screwed-in cylinder pins 11 serve as guides for the tool holder 30, in particular to avoid tilting of the tool holder 30 in relation to the z-axis (axis at right angles to the plane of the base plate 15, see FIG. 2).
• the pins 11 are used to prevent movement of the mounting plate 31 of the tool holder 30 relative to the base plate 15 of the chuck 10 in a plane (xy plane) paral lel to the plane of the plate, while a certain movement is permitted normal to this plane.
• the chuck 10 essentially has a base plate 15 and two or more clamping brackets 13 mounted laterally thereon.
• the base plate 15 has several holes 12 (usually bores).
• the base plate 15 has six holes, the cylindrical pins 11 screwed into the flange 91 being inserted through three of the holes 12 and thus defining the position of the chuck.
• the other three holes 12 are used to introduce screws 14, which can be screwed into corresponding threaded holes 21 in the flange 91 to the base plate 15 on the flange 91 to fix.
• the six threaded bores 210 are each offset by 60 °, and consequently the three cylinder pins 11 and the three screws 14 can each be arranged offset by 120 ° (with respect to the z-axis).
• the base plate 15 has laterally two brackets 16 protruding towards the flange 91, which form an angle of essentially 90 ° with the base plate 15 (see FIG. 3).
• the clamps 13 are mounted on these brackets (e.g. by means of screws).
• the cylinder pins 11 can alternatively also be mounted on the base plate 15 (e.g. screwed into it) (instead of in the flange 91).
• the variant shown in FIG. 2, in which the cylinder pins 11 are screwed into the flange 91 may be better (depending on the specific application).
• the cylinder pins 11 In order to fulfill their function, the cylinder pins 11 must protrude from the base plate 15 at a right angle.
• the tool holder 30 is rigidly connected to a machine tool (not shown in FIGS. 2-4).
• the specific construction of the tool holder 30 depends on the machine tool. In particular, those parts of the tool holder 30 which are used to fix the tool holder on the machine tool are variable and adapted to the respective machine tool.
• the tool holder 30 represents, so to speak, an interface which allows the machine tool to be clamped in the chuck 10.
• the tool holder 30 has a mounting plate 31 with bores 33 and 32 hooks.
• the mounting plate 32 fits the base plate 15 of the chuck 10. In the mounted state, the mounting plate 32 of the tool holder 30 is slipped onto the cylinder pins 11 so that the cylinder pins 11 run through the bores 33.
• the cylinder pins 11 thus define the position of the tool holder 30 (and therewith also the position of the machine tool) in the x and y directions (ie transversely to the z axis in the xy plane).
• the mounting plate 32 of the tool holder 30 rests against the base plate 15 of the chuck 10 and the clamps 13 (brackets) are hooked into the associated hooks 32 and tensioned (the hook is sometimes also referred to as a keeper).
• Clamping bracket 13 and hook therefore form a draw latch.
• An elastic element - in the example shown a rubber washer 20 arranged between the base plate 15 and mounting plate 32 - allows a small elastic displacement of the tool holder 30 relative to the chuck 10 in the z-direction.
• the elastic element for example rubber washer 20
• the elastic element can deform when locking the toggle fastener (the rubber washer 20 is squeezed) and Locked state for pre-tensioning the toggle fastener. That is, in the locked state, pull the clamps 13 on the respective hooks 32 (and vice versa). At the same time, the elastic element / rubber washer 20 is in a deformed, pre-tensioned state.
• Clamping brackets 13 and associated hooks 32 are known per se and are commercially available and are therefore not discussed further here.
• the draw latches which are each required from a clamping bracket 13 and a hook 31 in combination with the elastic element, are also referred to as dead center locking (over center latch), since the clamping bracket 13 when locking after hanging in the associated hook 32 is pivoted around the joint 131 to the dead center of the pivoting movement and beyond the dead center.
• the clamping lock / dead center lock is thus secure against unintentional loosening, since the clamping bracket 13 cannot move back beyond the dead center without the action of an external force. This external force must be applied manually by a worker when locking and unlocking the tension lock.
• the rubber plate 20 is only an example of an elastic element.
• any elastic element is suitable which is arranged (somewhere in the quick-release system) in such a way that it is elastically deformed when locking the Spannver (clamping bracket 13 and hook 32) and a pretensioning force between the chuck 10 and tool holder 30 in the locked state exerts z-direction, which is taken up by the latches.
• the elastic de formation enables a small movement of the tool holder 30 in the z-direction relative to the chuck 10, while a relative movement in the x-direction and y-direction is blocked by the cylinder pins 11, which serve as a linear guide.
• one or more elastic elements can also be integrated into the clamping brackets 13 or the hooks 32.
• the rubber washer 20 can be omitted.
• the hooks 32 and / or a part of the clamping brackets 13 themselves can be formed (at least partially) from an elastic or flexible material. In this case, one also speaks of flexible draw latches or strap closures.
• the clamping bracket 13 can be elastically displaceable Gela Gert by means of a spring in the z-direction on the arms 16 of the base plate 15.
• the hooks 32 can be mounted elastically displaceably on the mounting plate 31 by means of a spring element or another elastic element.
• the bearing bushes of the joints 131 the clamping bracket 13 can be formed from an elastic material and allow the elastic deformation mentioned when the clamping locks are locked.
• FIG. 5 illustrates a linear actuator 90 mounted on a robot (not shown in FIG. 5, see FIG. 1) with a locked quick release system according to the examples from FIGS is attached.
• the tool holder 30 serves, as mentioned, as an interface for clamping the machine tool to the chuck 10 of the quick release system.
• the quick release system described here can be used primarily in robots that are able to regulate the contact force between the tool and the workpiece surface. As mentioned, this force control can either be done with the aid of the actuator
• the actuator 90 can also be omitted and the chuck 10 can be mounted directly on the end effector flange 86 (see FIG. 1) instead of on the flange
• the contact force (process force) is controlled during the surface machining process.
• the z-direction shown in FIGS z-direction is also the effective direction of the controlled contact force. Any inaccuracies in the positioning of the machine tool in the z-direction are compensated for by the force control, since the machine tool is always pressed against the workpiece with a defined, controlled force. Therefore, inaccuracies in the position of the machine tool, which are a result of the deformation of the elastic element (e.g. rubber washer 20), do not play a role in practice. These inaccuracies are also practically automatically compensated for by the force control.
• the position of the hook 32 and the clamping bracket 13 can be interchanged, although it is probably more useful in practice to attach the clamping bracket the base plate of the chuck 10 (and not on the mounting plate 13 of the tool holder 30).
• the cylinder pins are immobile relative to the base plate 15 of the chuck 10 as shown in FIG. 2 and are passed through holes 33 in the mounting plate 31, or whether the cylinder pins are fixed to the mounting plate 31 (e.g. screwed into it) and are passed through corresponding holes in the chuck 10.
• the pins (11) are not necessarily independent parts and can theoretically also be manufactured in one piece with the base plate 15 or the mounting plate 31 (even if that would be more complicated to manufacture).
• the base (or mounting plate) and pins would be an integral part.
• the pins do not have to be cylindrical either. Any shape is possible that can engage in a corresponding opening in the opposite part in order to block movement in a plane parallel to the base plate and to allow a small movement at right angles thereto.
• the linear actuator 90 together with the quick-release system and machine tool is not attached to a manipulator (industrial robot), but rather to an immovable (stationary) base.
• the workpiece is held by the robot and positioned in such a way that the machine tool touches and can process the workpiece held by the robot.
• the robot works in a position-controlled manner and moves the workpiece during the machining process along a predetermined trajectory, while the linear actuator 90 mounted on a fixed base carries out the force control and presses the machine tool against the workpiece held by the robot. Examples of such systems - but without a quick release system - are described in the publication US 2018/0126512 A1.

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• 2020
  • 2020-04-24 DE DE102020111292.0A patent/DE102020111292A1/de active Pending
• 2021
  • 2021-04-22 CN CN202180037744.9A patent/CN115666875B/zh active Active
  • 2021-04-22 EP EP21721895.7A patent/EP3934862B1/de active Active
  • 2021-04-22 JP JP2022564631A patent/JP7726912B2/ja active Active
  • 2021-04-22 KR KR1020227040392A patent/KR20230006512A/ko active Pending
  • 2021-04-22 WO PCT/EP2021/060529 patent/WO2021214217A1/de not_active Ceased
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