The present invention relates to a device, comprising a support, preferably mobile, for grinding of plane surfaces by grinding means in the form of one or more grinding rounds or an endless grinding band, which grinding means are driven by one or more electric motors.

State of the technical art

Since a long time a number of devices, i e machines of the art mentioned introductorily are known, from hand tools with a rotating grinding disc or an endless grinding band driven between two drums. More developed machines, e g with a free or driven rotating planet disc, carrying rotating grinding rounds are also known. Said machines show certain drawbacks, as they demand a high degree of skill in order to achieve a satisfying result of the grinding. The reason for this is in many cases, that the grinding rounds and grinding bands are not clearly defined in relationship to the rotation speed of the machines resp the properties of the surface to be grinded.

The invention

There is thus a great demand for a device of the art mentioned introductorily, that admits an adaption of present devices for grinding of plane surfaces by grinding means.

According to the invention such a device is primarily characterized in that the device comprises a control system with a control program for controlling the rotation speed of the grinding rounds resp. the speed of the grinding band in the direction of the band, whereas the device also comprises an identifying system for identifying of the characteristic data of the grinding means and transferring of these to the control system .

Other characteristics of the invention are obvious from the attached depending claims.

The device according to the invention shall in the following be disclosed more closely, reference being made to the enclosed figures, which show, schematically some embodiments. Thus, there shows:

figure 1 a view towards a section through a device according to the invention with a planet disc and an number of grinding rounds, figure 2 a view in perspective of a planet disc with one grinding round, figure 3 a view in perspective of a planet disc with two grinding rounds,

figures 4A to 4D a principal view of a planet disc with 2 to 5 grinding rounds, figures 5a to 5c a principal view of a planet disc with 3 different operational constellations,

figure 6 view towards a section through a device with a grinding band,

figure 7 a view in perspective of a device with a planet disc and a grinding round with identifying device in the form of a RFDI-transmitter/receiver, and

figure 8 schemes of identifying systems.

In the figures there is shown in principle a number of variants of the device according to the invention as to the design of a support with a rotating planet disc and a varying number of rotating grinding rounds. Thus figure 1 schematically shows a view of a device according to the invention with a support 11 , wherein a planet disc 12 is freely rotatable. In the planet disc there are shown two electric motors 13, each for driving of its grinding round 14. As is obvious from the figures 4A- 4D the planet disc 12 may carry 2,3,4 or 5 grinding rounds. As is obvious from figure 5a the grinding rounds 14 are driven alternatively by its own electric motor 13, or according to figures 5b and 5, where two or three grinding rounds 14 are driven each by its own electric motor 13, whilst a grinding round 14 is driven together with another grinding round by a driving belt 15.

From figure 2 is obvious how the rotation direction A of the grinding round 14 by the friction created against the base causes the planet disc to rotate in the direction B. The relationship between the rotation speeds A and B depends on the friction against the surface to be ground and the moment of inertia of the planet disc.

A special embodiment of the device according to the invention is obvious from figures 3 and 4a. Here a planet disc 12 carries two grinding rounds 14a and 14b, rotating around axes at different distances from the rotation axis of the planet disc 12. From figure 3 is obvious, that the rotation direction A of the grinding round 14a creates an opposite rotation force B at the planet disc 12. In order to control the rotation of the planet disc 12, the same carries a second grinding round 14b, which rotates with a second rotation direction D in relationship to the rotation direction A, which rotation direction D creates a rotation force C, in opposition to the rotation force B. Figure 6 shows a band grinding machine with a support 26, in which two drums 27,28 are provided with bearings, carrying a grinding band 29. The drums are driven by an electric motor 30 via a driving belt 31.

In figure 7 there is shown for an embodiment of the device according to the invention with a planet disc 12 and a grinding round 14 parts of the identifying system, that is to say an RFID-transmitter/receiver 17 at the planet disc 12 and corresponding transponder, RFID-tag 16 at the grinding round. In a corresponding way in figure 6 there is shown at a band grinding machine an RFID-transmitter/receiver 17 at the support 16 and an RFID-tag at the grinding band 29.

Reference is made to figure 8, that schematically shows the control of the device 10 whereas the planet disc 12 and resp. grinding round 14 is connected to a control system 19 for the control of the rotation direction and speed of the grinding rounds 14 and for indirect control of the rotation speed and direction by control of the grinding rounds 14. The control system 19 comprises rotation sensor 21 or corresponding means for control of the rotation speed and rotation direction of the planet disc 12 and the grinding round 14 in question. The control system 19 creates a feed-back of the positions of the movable parts, that is to say the positions of the planet disc 12 and the grinding rounds 14. Via feed- back of the positions of the movable parts the rotation speed and rotation direction of the planet disc 12 are controlled by choice of different rotation speed and rotation direction of the grinding rounds 14. The device 10 in accordance with the invention gives great flexibility as to rotation speed and rotation direction of the grinding rounds 14 in relationship to the rotation speed and rotation direction of the planet disc.

A motor 13 may also be considered for driving of several grinding rounds 14. The motors 13 are for example arranged in the planet disc 12. The grinding rounds 14 are directly or indirectly driven by the motors 13.

The control system 19 comprises a control program 24, suitable for the floor in question, in order to give the operator full control of the process via a data interface 20, which may be formed like a number of knobs, or a data panel. The control system 19 of the device 10 must obtain different control programs 24 via e g a computer 18, which defines the relationship between the rotation speeds and rotation directions of the planet disc 12 and the grinding rounds 14. There shall also be possible to program different control programs 24, defining the sequence to obtain the desired relationship and keep it in operation. The communication of the device may be carried out by Ethernet, wireless Ethernet or other suitable bus system, by wire or wireless. The feed voltage, or communication by wire to and from the rotating planet 12 is carried out via rotation contacts 23. The communication between the control system 19 and the motors 13 is carried out via a suitable bus system. As a rule the motors 13 are provided with built- in rotation sensors 21 , but also external rotation sensors 21 may be used. Also the driving steps 22 of the motors may be included in the planet disc 12. All electric motors 13 may be used, like step motors 13, servo motors 13, DC-motors 13 or asyncronous motors 13. Other sensors and participants in the device 10, like rotation sensors 21 for the planet disc 12, RFID-transmitter/receiver 17 and RFID-tag 16 are either directly connected to the control system 19 or connected via a bus system. In some cases rotation contacts 23 may be needed.