Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B47/00—Drives or gearings; Equipment therefor
  • B24B47/26—Accessories, e.g. stops
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B23/00—Portable grinding machines, e.g. hand-guided; Accessories therefor
  • B24B23/02—Portable grinding machines, e.g. hand-guided; Accessories therefor with rotating grinding tools; Accessories therefor
  • B24B23/03—Portable grinding machines, e.g. hand-guided; Accessories therefor with rotating grinding tools; Accessories therefor the tool being driven in a combined movement
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B24—GRINDING; POLISHING
  • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
  • B24B27/00—Other grinding machines or devices
  • B24B27/0038—Other grinding machines or devices with the grinding tool mounted at the end of a set of bars

Definitions

• the present description relates to the field of machine tools, in particular an orbital grinding machine for automated, robot-assisted grinding.
• a machine tool such as e.g. A grinding or polishing machine (e.g. an electrically operated grinding machine with a rotating grinding wheel as a grinding tool) is guided by a manipulator, for example an industrial robot.
• the machine tool can be coupled in different ways with the so-called TCP (Tool Center Point) of the manipulator; the manipulator can usually set the position and orientation of the machine practically at will and the machine tool e.g. move on a trajectory parallel to the surface of the workpiece.
• Industrial robots are usually position-controlled, which enables precise movement of the TCP along the desired trajectory. With a separate actuator, the process force between the machine tool and the workpiece surface can be set and controlled independently of the manipulator.
• eccentric grinders orbital sanding machine
• a grinding wheel is attached to a mounting plate (backing pad)
• the grinding plate rotating about an eccentrically arranged first axis of rotation, which itself rotates about a central second axis of rotation rotates.
• Orbital grinding machines are known per se (see for example US 6257970B1) and their functional principle is therefore not discussed further here.
• devices are known which allow the grinding wheels to be changed automatically (see, for example, US Pat. No. 8517799B2).
• the problem is that the assembly plate comes to a standstill in an undefined position, whereas it may be desirable for the automated changing of the grinding wheels that the assembly plate is in a defined position at the start of the automated changing process. Furthermore it can happen that the assembly plate continues to rotate for a comparatively long time after the motor has been switched off, which delays the change process.
• the inventor has set himself the task of improving existing orbital grinding machines so that an automated process for changing the grinding wheels becomes faster and more reliable.
• the braking device has a frame which is attached to the machine tool, a spring (in particular a leaf spring) which is fixed with a first end to the frame, and a lever which is connected to a second end of the spring is.
• the braking device furthermore has an actuator which is designed to move the lever, wherein when the lever is moved, the spring is tensioned and part of the lever is pressed against the mounting plate of the machine tool.
• FIG. 1 illustrates an example of an orbital sander with a braking device according to an exemplary embodiment.
• FIG. 2 shows the example from FIG. 1 with the braking device activated.
• Figure 3 illustrates an example of the braking device (without a grinding machine) in more detail.
• FIG 1 illustrates an example of an orbital grinder with a braking device.
• the grinding machine 1 essentially comprises a motor 11 for driving an eccentrically mounted (in a housing) mounting plate 12 (backing pad) on which a grinding wheel 13 can be attached.
• the eccentric mounting of the mounting plate 12 causes it to rotate around an eccentric axis of rotation D ‘during operation, which in turn rotates around a central axis of rotation D.
• the grinding wheel 13 thereby performs a small elliptical movement while it rotates (the elliptical path also rotating).
• the grinding machine 1 has a braking device 2 which is designed to brake the Montagetel ler 12 (from the motor 11 switched off) and to press it into a defined angular position.
• FIG. 2 shows the same exemplary embodiment as FIG. 1 with the brake activated.
• the braking device 2 comprises a spring 21, in particular a leaf spring made of spring steel.
• One end of the Fe of 21 is clamped to a frame 25 of the braking device 2, for example by means a clamping element 24.
• the spring 21 is clamped between a part of the frame 25 and the clamping element, which can be fastened to the frame 25 by means of screws.
• a lever 22 is mounted (for example also by means of screws), which has the shape of an elongated bar, which is bent at its free end by about 90 °.
• the spring 21 and lever 22 are positioned so that the free end of the lever 22 moves towards the mounting plate 12 until the free end of the lever 22 touches a circumferential surface of the mounting plate 12. During this movement of the lever 22, the spring is bent. The movement is brought about by a linear actuator 23.
• the linear actuator can be a pneumatic actuator that can be implemented, for example, as a bellow cylinder. Alternatively, a magnetic actuator can be used, which can be designed as a solenoid actuator for example. Regardless of the specific implementation, the actuator 23 acts between the frame 25 and the lever 22
• the combination of the lever 22 mounted on the frame 25 via a leaf spring with a direct drive (without gears and other mechanisms) such as e.g. A bellows cylinder enables the braking mechanism (lever 22, spring 21) to do without swivel joints. This means that there is no need for a mechanism that contains parts that can move relative to one another.
• the braking device 2 is more robust and less prone to errors.
• the bellows cylinder also does not contain any parts that can move relative to one another, only the bellows is inflated by means of compressed air, whereby the end of the bellows cylinder presses the lever 22 against.
• the frame 25 consists of several parts and is designed to be mounted on a grinding machine (see FIGS. 1 and 2).
• the frame 25 comprises a base plate 25a (carrier), the outer surface of which can be adapted to the (for example cylindrical) surface of the grinding machine.
• the spring 21 is fastened to the base plate 25a by means of the clamping element 24 and screws 24a. That is, the spring 21 designed as a leaf spring is clamped between a surface of the base plate 25 a and a corresponding surface of the clamping element 24.
• the screws 24a provide the necessary contact pressure.
• the lever 22 is screwed ver to the spring 21, as has already been shown in FIG. The lever 22 can be seen, so to speak, as an “extension” of the leaf spring 21, the lever 22 being rigid compared to the spring 21.
• the frame 25 For fastening the actuator 23, the frame 25 comprises a bracket 25b (bracket) which is mounted on the base plate 25a (e.g. by means of screws 25c) and which at least partially surrounds the lever 22.
• the actuator 23 is mounted on the bracket 25b in such a way that it can press the lever 22 towards the base plate 25a (and thus towards the grinding machine during operation).
• the actuator 23 is fastened to the bracket 25b by means of the screws 25d in such a way that it can press the lever 22 towards the base plate 25a (and thus also towards the grinding machine).
• the frame 25 can be constructed in a variety of ways.
• the construction shown in FIG. 3 can be modified in many ways without changing the function of the braking device 2 described here.
• a frame is understood to mean any structural component or any assembly of structural components that is suitable and designed to fulfill the function described here, namely in particular to enable one end of the spring 21 to be fixed and also to allow assembly of the actuator 23 in such a way that it can move the lever 22 attached to the spring 21.
• the frame as such is designed for mounting on the grinding machine.
• the exemplary embodiments described here relate to a device with a machine tool (in particular orbital grinding machine) and a braking device, the machine tool having an eccentrically mounted, rotatable mounting plate for receiving a tool.
• the braking device has a frame (see, for example, FIG. 3, frame with base plate 25a and Mon day bracket 25b), which is attached to the machine tool, a spring (see, for example, FIGS. 1 and 2, leaf spring 21), which with a first end is fixed to the frame, and a lever (see, for example, Fig.
• lever 22 which is ver with a second end of the spring connected.
• the braking device also has an actuator (see, for example, FIGS. 1 to 3, pneumatic linear actuator 23) which is designed to move the lever, the spring being tensioned when the lever is moved and part of the lever against the Monta plate the machine tool is pressed.
• the spring in the examples described here is a leaf spring, which can be made, for example, of spring steel, and the lever is connected to the frame (eg to the base plate of the frame) exclusively via the leaf spring.
• the actuator can be a pneumatic or electrical direct drive and in particular does not include a transmission or other rotating parts.
• An example of a pneumatic direct drive is a bellows cylinder.
• the frame has a base plate to which the first end of the spring is clamped by means of a clamping element.
• the frame can have a bracket which is fastened to the base plate, the actuator being mounted on the bracket in this example (see FIG. 3, actuator 23 is mounted on the bracket 25b by means of screws 25d).
• the bracket at least partially encloses the lever. In this case, the lever is arranged between the actuator mounted on the bracket and the base plate in the assembled state.
• One end of the lever can be angled, the angled end of the lever being pressed against a circumferential surface of the mounting plate of the machine tool when the lever is moved by the actuator. Due to a movement of the lever it is pressed against the assembly plate of the machine tool (grinding machine), whereby the assembly plate is braked and pushed into a defined position.
• Another aspect relates to the natural frequency of the lever (see FIGS. 1 to 3, lever 22), which, depending on its geometric shape and the stiffness of the material from which it is made, has certain natural frequencies and associated vibration modes, in usually one (namely the lowest) natural frequency dominates.
• the lever is constructed in such a way that its dominant natural frequency is not excited during operation of the grinding machine. This means that the eigenfrequency of the lever is higher than a specified maximum rotational frequency (in revolutions per second) of the mounting plate of the grinding machine.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
• Constituent Portions Of Griding Lathes, Driving, Sensing And Control (AREA)
• Grinding Of Cylindrical And Plane Surfaces (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=70681794

Family Applications (1)

Country Status (7)

Families Citing this family (2)

Citations (6)

Family Cites Families (14)

• 2019
  • 2019-05-14 DE DE102019112556.1A patent/DE102019112556A1/de not_active Withdrawn
• 2020
  • 2020-05-06 CN CN202080035136.XA patent/CN113825592B/zh active Active
  • 2020-05-06 WO PCT/EP2020/062515 patent/WO2020229247A1/de not_active Ceased
  • 2020-05-06 EP EP20725457.4A patent/EP3969224B1/de active Active
  • 2020-05-06 US US17/610,563 patent/US12296429B2/en active Active
  • 2020-05-06 KR KR1020217040088A patent/KR102850902B1/ko active Active
  • 2020-05-06 JP JP2021567849A patent/JP7333830B2/ja active Active

Patent Citations (6)

Also Published As

Similar Documents

Legal Events