Attaching device, attaching arrangement and method for attaching an object to be worked to a working base

The invention relates to an attaching device, an arrangement and a method for attaching an object to be worked to a working base. The attaching device comprises: a first holder in the first end of the attaching device for attaching the attaching device to the working base or to another attaching device or to the object to be worked; a second holder in the second end of the attaching device for attaching the attaching device to the working base or to another attaching device or to the object to be worked; and a controller for controlling the holding forces produced by the first and second holders.

TECHNICAL FIELD OF THE INVENTION

An object of the invention is an attaching device, an arrangement and a method for attaching an object to be worked to a working base according to the preambles of the independent claims presented further below. The invention especially relates to a new way for supporting a piece to be for example welded, milled, cut, painted or sandblasted to its base during working.

PRIOR ART

The pieces to be worked must generally in some way be attached in their place for the duration of for example the milling, welding, drilling or bevelling. In order to achieve a precise result, the attaching must usually also be made in a precise manner. Known methods are slow and laborious and do not make possible automatic attaching like the arrangement presented in the invention.

OBJECT AND BRIEF DESCRIPTION OF THE INVENTION

It is an object of the present invention, among other things, to reduce or even eliminate above-mentioned problems of the prior art.

It is especially an object of the present invention to provide a solution, which provides a quick, precise and easy manner of attaching differently-shaped pieces to be worked to their working base.

In order to achieve among others the objects mentioned above, the attaching device, arrangement and method and other objects of the invention are characterised by what is presented in the characterising parts of the enclosed independent claims.

The embodiments and advantages mentioned in this text apply, when applicable, both to the attaching device, arrangement, method and other objects according to the invention, even though it is not always specifically mentioned.

A typical attaching device according to the invention for attaching an object to be worked to a working base comprisesa first holding means, i.e. a first magnet, in the first end of the attaching device, which first magnet is arranged to produce a first holding force for attaching the attaching device to the working base, such as to a table, or to another attaching device or to the object to be worked;a second holding means, such as a second magnet, in the second end of the attaching device, which second holding means, such as the magnet is arranged to produce a second holding force for attaching the attaching device to the working base, such as to a table, or to another attaching device or to the object to be worked;control means for controlling the holding forces produced by the first and second holding means, such as the magnets.

There may be more than two controllable holding means, such as magnets, in one attaching device.

The attaching device may thus have two or more controllable magnets. But the attaching device may have only one controllable magnet and one or more other holding means. The other holding means may for example be some mechanical holding means, such as a clamp, a suction cup or tongs. Typically the attaching device has at least two such holding means, the holding force of which can be controlled. The other holding means are known as such, so their operation is not described further in this text.

A typical arrangement according to the invention for attaching an object to be worked to a working base utilizes one or more attaching devices according to the invention. The arrangement comprises a control unit, such as a programmable computer and its user interface for producing control signals to the first and second holding means, such as the magnets, of the attaching devices. The control unit may be separate from the attaching devices. The arrangement also comprises data transfer devices for transmitting the control signals to the control means of the attaching devices. The data transfer devices may be wireless and they may use some known data transfer method, such as radio, light, sound or the like.

Some embodiments of the arrangement comprise a robot or a corresponding NC-programmable device, which comprises means for placing the attaching devices in desired places for example on the working base or attached to other attaching devices.

A machined metal plate or other magnetic substance may for example function as the working base. The system may also itself function as its own working base, i.e. the system may assemble a working base from itself. The jig may also be assembled completely without a particular working base.

One method according to the invention for attaching an object to be worked to a working base by means of an attaching device comprises:attaching an attaching device by its first end to the working base, such as a table, or to another attaching device or to the object to be worked, with the aid of a first holding force produced by the first holding means, i.e. the first magnet;attaching the attaching device by its second end to the working base, such as the table, or to another attaching device or to the object to be worked, with the aid of a second holding force produced by the second holding means, such as the second magnet or other holding means.

The method may utilize one or more attaching devices according to the invention and/or arrangements according to the invention.

The different embodiments of the invention are suitable for use in connection with various kinds of substances and working methods. The invention may be used for example for bevelling, flame cutting, laser cutting, water cutting, plasma cutting, pipe cutting, welding, milling, machining, pressing, painting, sandblasting, burring, drilling and for temporarily attaching parts to each other.

The attaching device must when desired be able to firmly grab onto another attaching device, an object to be worked and the working base. On the other hand, when desired, the attaching device must be possible to detach from the other attaching device, the object to be worked and the working base. In the attaching device according to the invention the grabbing onto another attaching device, an object to be worked and the working base is done by means of the magnetic field produced with magnets, negative pressure or the like. The attaching device has control means, by means of which the holding forces, i.e. the holding manner, such as the magnetic fields produced by the first and second holding means, such as the magnets, may be controlled to enable grabbing and detaching.

The magnetic field produced by the holding force may be provided with an electric magnet or a magnetic material or both. The magnet generates a magnetic field which produces a holding force, and when electric current is fed through the electric magnet coil, the holding force cancels out the magnetic flux produced by the magnetic material or strengthens it, depending on in which direction current is fed into the coil.

By controlling the amount of current, the holding force can be selected as desired. By turning off the current, the holding force does not cease, but the magnet remains holding. When using magnetic material, the weakening of the holding force of the magnetic fastener may be realized either mechanically by changing the magnetic circuit inside the attaching device or by weakening the field created by the magnetic material with the electric magnet close to the magnetic material.

In one embodiment of the invention the holding force is controllable, so that in connection with attaching the piece, the holding force of the magnet of the attaching device is increased in steps or degrees, so that the object to be attached would not slam against the attaching device. In one embodiment of the invention the holding force is controllable, so that in connection with detaching the piece, the holding force of the magnet of the attaching device is decreased in steps or degrees. In one embodiment of the invention the holding force may be increased if it is detected that the magnet is detaching.

The controlling of the holding force of the magnets may be performed manually, for example by a switch or a lever in the attaching device. The connecting of electric current to the magnets may also be arranged to occur automatically, for example controlled by a computer program. It is possible to arrange one or more magnets to be used remotely. The remote drive may be wireless. In one embodiment the remote drive may be wired.

It has thus now been noted that the piece to be worked may simply and quickly be attached to its working base by means of magnets, the holding force of which may be controlled, or with another corresponding method. Magnets are reliable and simple devices.

By means of the invention, the attaching of the piece to be worked to its base can simply be automated. It is possible to program a robot to place the attaching devices in desired places on the working base. The programming and designing of the robots and automatism is not especially an object of this application, so it is not discussed further in this context.

In one embodiment of the invention the control means are arranged so that the first and second holding means, such as magnet, are separately controllable. In one embodiment of the invention the second holding means, such as the magnet, is controlled manually from a lever or switch in the attaching device or remotely. In one embodiment of the invention one of the holding means, such as the magnet, is controlled manually and one automatically. Thus the same attaching device is suitable for different use purposes and situations.

In one embodiment of the invention an insulation insulating from the magnetic flux is arranged between the first and the second magnet, such as a plate manufactured from fibreglass or another material insulating the magnetic flux. Other suitable materials may for example be aluminium, plastic, acid resistant steel, glass. Thus the operation of one magnet does not disturb the operation of the other magnet.

In one embodiment of the invention the magnets are insulated to be waterproof. In one embodiment the magnets are cast into a suitable hardening material, for example polyester resin. Waterproofness is sometimes important, because workings often use liquids, which may otherwise cause a short circuit in the electric devices.

In one embodiment of the invention, the attaching devices according to the invention are used under water. In one embodiment of the invention the entire attaching device is insulated to be waterproof. Attaching devices according to the invention, which are waterproof, especially those which are waterproof and can be used remotely, are especially well suited for working under water.

In one embodiment of the invention the control means in the attaching device comprise means for leading the electric current in a controlled manner from an electric power source to the first and/or second holding means, such as magnet, in order to control its function.

In one embodiment of the invention the control means comprise an electric power source, such as a battery, and means for steering the electric current from the power source to the first and/or second magnet. In other words the attaching device thus has its own electric power source, such as battery.

An arrangement according to the invention may have a charging device, whereto the attaching devices are connected when they are not doing attaching work. The attaching device thus has the necessary means, for example connectors and cables or means enabling wireless charging, by means of which the electric power source is connectable to the charging device and chargeable. When using wireless attaching devices, electric wires can be avoided.

The charging device according to the invention may also be arranged to function as a parking device for the attaching device.

In one embodiment of the invention the attaching device comprises a wireless receiver for receiving a control signal from the control means. The arrangement according to the invention thus comprises a wireless transmitter. When using wireless attaching devices, electric wires can be avoided. In one embodiment of the invention the attaching device comprises a wireless transmitter for transmitting information, such as operation data of the attaching device, temperature, detaching of the magnet etc. data from the attaching device for example to a control unit outside the attaching device.

In one embodiment of the invention the attaching device comprises at least in its one end a mechanical attaching means, such as a hook, spike, bolt or peg. The first or second magnet may thus be arranged to move said mechanical attaching means. The mechanical attaching means may also be moved by hand. Such an attaching device may be arranged to attach to a working base or object to be worked manufactured from any material, also a non-magnetic material.

The mechanical attaching means may also function as a movement limiter or a limit switch. The automatism controlling the arrangement may be arranged to place said limiters or limit switches precisely in the desired places of the piece to be worked. The mechanical limiters or limit switches may for example be placed in precise places on the edges of the piece to be worked. When such limiters or limit switches are in place, the piece to be worked is easy to place correctly according to them.

In one embodiment of the invention the attaching device comprises a frame, in the different ends of which the first and second holding means, such as the magnet, is attached. The frame may for example be tube-like or cubic.

In one embodiment of the invention the frame of the attaching device is manufactured from stainless steel and in another embodiment from fibreglass.

In one embodiment of the invention the frame of the attaching device comprises means for selecting its length as desired. The frame may for example be telescopic. The frame may have a locking device, such as a clamp, for locking the length of the attaching device as desired. The locking of the length may also be done with a permanent magnet. Thus the same attaching device is suitable for different use purposes and situations.

In one embodiment of the invention the frame of the attaching device comprises means for bending it into a desired position. The frame may for example consist of two parts, which are joined together with a hinge or joint, for example with a ball joint. The frame may have a locking device, such as a clamp, for locking the position as desired. The locking of the position may also be done with a permanent magnet. Thus the same attaching device is suitable for different use purposes and situations.

In one embodiment of the invention the frame of the attaching device comprises several hydraulic cylinders, for example one in each corner of the frame. A magnet valve or the like may be used to control the passage of hydraulic fluid into the cylinders. When the fluid can flow, the length of the hydraulic cylinders may be changed. If the length of all of the hydraulic cylinders is changed by the same amount, the length of the frame changes, but the ends of the attaching device, their holding devices, do not turn in relation to each other. If, on the other hand, the lengths of the hydraulic cylinders are changed differently, the attaching device bends. In other words, the ends of the attaching device, their holding means, turn in relation to each other. By closing the magnetic valve or corresponding, the valve can be locked into place.

In one embodiment of the invention the first and/or second magnet comprises a magnetic material part comprising magnetic material and an electric magnet part comprising an electric magnet, whereby the control means are arranged to control the magnetic field produced by the electric magnet. By controlling the strength of the magnetic field produced by the electric magnet the first and/or the second holding force may be controlled. Using magnetic material makes it possible that the attaching device does not during its normal operation continuously need an external power source as a source for the holding force. A relatively small power source, such as a battery, well suffices as the power source for an electric magnet functioning in a control purpose. It may be arranged as a fixed part of each separate attaching device. Such an attaching device may function completely wirelessly, and does thus not during normal operation need electric wires to its outside.

In one embodiment of the invention the magnetic material is permanent magnetic material. Thus the effect of the holding force produced by the magnetic material may, if necessary, be decreased or strengthened with the magnetic field of the electric magnet. The magnetic fields of the permanent magnet and the electric magnet may in a manner known as such be set to cancel out each other's effect or set to strengthen each other. In other words the magnetic field of the permanent magnetic material may be used to provide the holding force according to the invention, which, if necessary, is weakened or strengthened with the magnetic field of the electric magnet and/or mechanically. The detaching or attaching of the attaching device thus occurs by weakening or strengthening the magnetic flux created by the first or second permanent magnet with the aid of an electric magnet. Suitable dimensions of the magnets and required electric currents and materials may be selected separately for each situation. For example in some cases, one must be careful that the permanent magnet is not demagnetised, if this is not the purpose.

In one embodiment of the invention the magnetic material is a demagnetisable and re-magnetisable magnetic material, whereby the magnetic material may, when necessary, in a manner known as such be demagnetised and re-magnetised with the magnetic field of the electric magnet. In other words the holding force is provided by magnetising the magnetic material with the aid of the electric magnet. The holding force may be decreased or even removed by demagnetising the magnetic material with the aid of the electric magnet. Suitable dimensions of the magnets and required electric currents and materials may be selected separately for each situation.

In one embodiment of the invention the magnet is switched off and on partly mechanically by moving the parts of the magnet in relation to each other. The attaching device may for example have a centre comprising a permanent magnet part, which is arranged to be moveable in relation to the rest of the magnet. The centre remains attached to the other parts of the magnet with the aid of the power of the permanent magnet, maintaining the part of the closed circuit of the magnetic flux, which is inside the magnet. Typically the piece to be attached to the magnet, such as for example the object to be worked or the working base, forms the part of the closed circuit of the magnetic flux, which is outside the magnet. An electric magnet coil has typically been suitably arranged around the centre. When current is led to the coil in a certain direction, the magnetic field produced by the coil weakens the magnetic field of the permanent magnet. At a certain strength of the magnetic field the centre is detached from the other parts of the magnet, whereby the closed circuit of the magnetic flux is broken, the magnetic force weakens and the magnet is switched off, i.e. the hold of the magnet is off.

The hold of the magnet comprising a moving centre is switched on so that current is led to the coil in the opposite direction to when the hold was detached. The electric current is thus steered in the direction of the coil, which strengthens the magnetic field of the permanent magnet. Now the magnetic field of the coil starts to pull the centre towards it. Finally, when the force has increased enough, the closed circuit of the magnetic flux inside the magnet is again closed. The piece, which the magnet is used to grab, closes the circuit outside the magnet. If the electric current is still increased when the circuit of the magnetic flux is closed, the holding force may even be increased multifold. The permanent magnet part in connection with the moving centre may for example be neodymium magnetic material. Neodymium magnetic material is in this text often called the shorter name neodymium, according to its one ingredient.

In one embodiment of the invention one or more springs have been arranged between the moving centre and the other parts of the magnet. The springback factor of the springs is arranged to push the centre away from the rest of the magnet, i.e. to break the closed circuit of the magnetic flux. This springback factor is then resisted with the permanent magnetic force. When the magnetic field generated with the coil is used to weaken the permanent magnetic field, at a certain strength of the electric magnetic field, the springs have the strength to push the centre away from the other parts of the magnet. Thus the closed circuit is broken, the magnetic force is weakened and the magnet is switched off, i.e. the hold of the magnet is off. When switching on such a magnet, the centre and the thereto attached permanent magnet part start to move, when the magnetic field is stronger than the springback factor of the springs. By means of said springs, the relationship between the coil and the permanent magnet may be adjusted. The springback factor of the springs manages a part of the switching off of the magnet, whereby the coil can be made a bit smaller than what would be needed without the springs.

In one embodiment of the invention the first and/or second magnet of the attaching device comprisesA shell and a centre, which are arranged to steer the magnetic flux to the piece to be grabbed. The centre is arranged to be moveable in relation to the rest of the magnet between a holding position and an open position, in order to close and open the circuit of the magnetic flux.A permanent magnet for forming a magnetic field and thereby for keeping the centre in connection to the rest of the magnet, i.e. in the holding position;An electric magnet coil arranged around the centre for switching off the magnetic flux provided by the permanent magnet at least partly, when necessary, in order to detach the centre from the connection of the rest of the magnet, i.e. for moving it into the open position.

In one embodiment of the invention the attaching device comprisesOne or more springs, which help the centre of the magnet to detach from the other parts of the magnet when the magnetic flux is weakened sufficiently with the aid of the magnetic field produced with the coil. One or more springs is thus arranged between the moving centre and the other parts of the magnet.

In one embodiment of the invention the magnet, i.e. typically its moving centre, is controlled between the holding position and the open position with electric current pulses led into the coil. The duration of the pulse may for example be about half a second or 0.1-1 seconds.

In the holding position the electric current pulse switches off the magnetic flux to the extent, where the springs move the parts of the centre away from the rest of the magnet and thus open the closed circuit of the magnetic flux. The magnet thus moves to the open position. The open position is changed to the holding position with an opposite pulse, which increases the magnetic flux, so that the centre moves into contact with the rest of the magnet, whereby the circuit of the magnetic flux again closes.

The movement of the magnet parts may be controlled in a controlled manner for example with the aid of a processor by giving the coil for example a PWM signal (Pulse Width Modulation). The control may occur also by changing the level of the current. The PWM signal means that the active time of the signal may be selected in relation to the inactive time of the signal. For example a pulse with a 10 second total duration may consist of a 0.5 second part, when the signal is on, and a 0.1 second part, when the signal is off.

In one embodiment of the invention the centre of the magnet has a shape, which is constricted in one end, which shape allows for the use of a larger permanent magnet and coil. Simultaneously the hold of the magnet is improved.

In one embodiment of the invention the edge of the shell meant to be in contact with the piece to be grabbed is bevelled to be thinner in order to improve the hold of the magnet.

The magnetic material part of the magnet of the attaching device can be realized from different magnetic materials, such as AlNiCo, so-called rare-earth magnets such as neodymium magnets (i.e. a NdFeB, NIB or Neo magnet) or a ceramic magnetic material. For example the AlNiCo magnetic material is suitable as a demagnetisable and re-magnetisable magnetic material. AlNiCo is a metal alloy, which is manufactured from aluminium (Al), nickel (Ni) and cobalt (Co). There may additionally be iron, copper and titanium in the alloy. A typical alloy ratio is 8-12% Al, 15-26% Ni, 5-24% Co, max. 6% Cu and 1% Ti, the rest is Fe. For example NdFeB and/or a ceramic magnetic material may be used as the permanent magnetic material. A neodymium magnet is a rare-earth magnet, an alloy of neodymium, iron and boron. A ceramic magnet is a magnet manufactured with powder-metallurgic methods, which has large amounts of metal oxides. For example ceramic ferrite is a ferromagnetic ceramic material, which has iron oxide, boron and barium or strontium or molybdenum. Some examples of suitable magnetic materials are AlNiCo 5, NdFeB 40 MGOe and Ceramic 8.

Depending on the used magnetic material and the need at the time, the outer dimensions of the magnetic clamp vary. The magnetic material part may be formed for example to be cylindrical. The diameter of the cylindrical magnetic material part may for example be less than 200 mm, less than 100 mm, less than 50 mm, 25-200 mm, 25 or 50-100 mm. The height of the magnetic material part may for example be less than 100 mm or less than 50 mm or less than 10 mm or 25-100 mm or 1-25 mm or 0.5-3 mm. In order to improve the hold, the diameter of the magnetic material may for example be 10-30% larger than the centre.

In one embodiment according to the invention the control means of the attaching device comprise a wireless receiver and/or transmitter in order to transmit control data.

In one embodiment according to the invention the attaching device functions completely wirelessly in normal use. In other words the electricity needed by the attaching device is charged wirelessly and the data transfer to the attaching device and from it is performed wirelessly.

In one embodiment according to the invention the control means of the attaching device comprise control devices for the holding means, such as the electric magnet, of the attaching device.

Even though this text mainly discusses an attaching device and an arrangement for attaching an object to be worked to a working base, it is clear that another aspect of the present invention is a magnet with a controllable effect according to the invention as such and a magnet used in many other embodiments. All embodiment examples and alternatives mentioned in this text are, when applicable, suitable also in connection with a magnet according to the second aspect of the invention. The attaching device according to the invention may be seen as one embodiment of the magnet with controllable effect according to the invention. In an advantageous embodiment the magnet is switched off and on partly mechanically by moving the parts of the magnet in relation to each other. The magnet may for example have a centre comprising a permanent magnet part, which is arranged to be movable in relation to the rest of the magnet, which can be arranged at least partly inside the coil. One or more springs may in a manner described above have been arranged between the centre and the rest of the magnet.

In one embodiment of the invention the magnet is used as a so-called bistable magnet. A small amount of energy is sufficient to open and close a bistable magnet. Bistable magnets can be kept switched on and switched off without using energy. Thus the arrangement according to the invention can be used to decrease the amount of energy used in the process.

In one embodiment of the invention the magnet functions as an electrically controllable shock absorber, which can simultaneously also be used to produce energy. The magnetic field of the coil may be used to decelerate the movement of the centre moving inside the coil. If for example a centre comprising neodymium is moved inside the coil, electric current is generated in the coil. This is thus a generator, which produces electric energy.

The magnet according to the invention can be used in applications moving along metal surfaces. Examples of such applications are for example means for washing the bottom of ships, and various other robots, such as welding and painting robots. In these applications the apparatus is moved along the metal surface and thus they need a strong, firmly holding magnet. Such a magnet is advantageously also controllable with a low amount of energy.

The magnet according to the invention can also be used for controlling magnetic valves and magnetic locks at least between an open position and a closed position. Magnetic valves and magnetic locks according to existing technology require energy for keeping them switched on or off, while the embodiment according to the invention needs energy only for changing the state.

The magnet according to the invention can be used for controlling movement, because the centre is arranged to be moving. This moving centre can be moved with a small pulse, whereby the springs are released, and a movement is generated, which always remains in its extreme position to await a new pulse.

DETAILED DESCRIPTION OF THE EXAMPLES OF THE FIGURES

For the sake of clarity, the same reference numbers are used for at least some corresponding parts in different embodiments.

In the middle of the mainly cylindrically formed attaching device11shown inFIGS. 1 and 2there is a shell3manufactured from a suitable material, such as fibreglass or some other material, which lets through an RF signal. If the control signal of the attaching device is something other than an RF signal, for example light, the material of the shell may be some other material suitable for the purpose. The other parts of the attaching device are supported on the shell or they are arranged inside it or joined together with screws. In the lower edge of the device10there is a first magnet8, which is meant for attaching the device10to a working base. In the upper edge of the device10there is a second magnet1, which to its structure corresponds to the first magnet8, which second magnet is meant for attaching the device10to the object to be worked. The structure of the magnets is shown15in more detail inFIGS. 2,4and5.

An electric magnet part11, i.e. an electric magnet, has been arranged inside the magnetic material part9manufactured from a permanent magnetic material. The coil of the electric magnet11is drawn in the figure very schematically with dotted lines12. A battery6and two circuit boards2and7have been arranged inside the shell3, between the first and second magnet. The shell3has a service hatch5that can be opened, which leads though the shell, for example to enable the changing of the battery6. Led lights have also been arranged through the shell, which can be used to indicate for example the charge state of the battery6or if the battery is charging. The leds may also be used to indicate for example if the first or second magnet is switched on or off.

In the lower i.e. first circuit board7there is for example control electronics for the electric magnets11, a thermometer, and a charging device for the battery6. In the upper second circuit board2there is a radio transmitter/receiver for transmitting control information and operation information of the attaching device10between the attaching device10and the control unit outside it.

FIGS. 3 and 4show an attaching device10, which to its shape mainly is a cubic or rectangular prism. The upper magnet1is attached to the rest of the device with attaching screws13. The lower magnet8is attached to the rest of the device with attaching screws14. Between the upper magnet1and lower magnet8there is a shell3. Inside the shell3has been arranged connection pipes15supporting the structure, by means of which the upper magnet1is connected to the lower magnet8. Among others a circuit board2is placed between the connection pipes, in the so-called frame part. Electric components needed by the device, such as selection switches16, are attached to the circuit board2, by which switches the operation of the attaching device10may be controlled manually. From the selection switches16the magnets1and8may for example be switched on and off. They may additionally be used to give commands to switch off the attaching device10or to activate a switched-off attaching device10. The selection switches16may have one or more led indicators, from which different information about the magnet state may be seen, such as “open” or “closed” or “system failure”. Batteries7have also been attached to the circuit board2, and electric charging connectors17for bringing charging current for the batteries from the charging device. The charging connectors17may for example also be strip-like. Openings18have been formed in the shell3for using the selection switches16. There are also openings for the charging connectors17in the shell (not shown).

Among others components needed for communication, such as a RF transmitter and receiver, sensors monitoring the state of the magnet and a processor, the software in which manages among others the data communications, interruptions in the operation and alarms, are also attached to the circuit board2. The communication may for example be the direct two-way communication with a device controlling the attaching device10, i.e. a so-called Interface, or the forwarding of a message to another attaching device and/or Interface. An interruption of the operation may be caused for example by the state of the magnet1or8, the temperature or a weakening in the charging level of the battery or other anomaly. The interruptions in operation may for example be set as limit values of the program controlling the attaching device, the surpassing of which causes an interruption.

FIG. 5shows a magnet8according to the invention taken apart. For example the lower magnet8shown inFIGS. 3 and 4may have the structure shown inFIG. 5. The upper magnet1inFIGS. 3 and 4may have a corresponding structure. The centre30of the magnet comprises a back plate23, a neodymium magnet24and a slide25attached together. The attaching screws26of the pushing plates attach the pushing plates27to the back plate23. Stopper screws31hold the parts of the magnet8together. The centre is arranged to be moveable in relation to the rest of the magnet8. When the centre is in the lower position it settles partly inside the coil29of the electric magnet. The pushing springs32are arranged around the stopper screws31so that they strive to push the centre30upwards, i.e. away from the coil29and the bottom plate22of the centre. The pushing springs32thereby help the coil29to switch off the magnet8and to keep the magnet8switched off. For example if the coil29does not switch off the magnet8completely but the pushing springs32can already push the centre30away, the magnet is switched off by the co-operation between these. The pushing plates27centre the slide25into place and relay the pushing force of the springs32to the slide.

The piece, which the magnet8inFIG. 5grabs, is placed against the lower surface of the magnet8. Brass plates20and21have been arranged at the bottom inside the shell19of the magnet, and a lower ring22of the centre between them. The lower ring22of the centre is attached with the outermost brass plate20to the shell19, so that the magnet8does not have moving parts, which can be seen from the outside. The smaller brass plate21is attached to the lower ring22of the centre, whereby the lower surface of the magnet is even. In its lower position the centre30touches the lower ring22of the centre, whereby the magnetic flux can pass to the piece to be grabbed. When the centre30is lifted up, the passage of the magnetic flux to the piece to be grabbed is prevented. The shell19of the lower magnet functions as a part which leads the magnetic flux. Correspondingly the shell47of the upper magnet seen inFIGS. 3 and 4functions as a part which leads the magnetic flux in the upper magnet1. The brass plates20and21insulate the magnetic flux so that it cannot leak from the shell19to the centre30. In the lower edge of the shell19there is a bevelling28, which is meant to be in contact with the piece to be grabbed. The bevelling28steers the magnetic flux in order to achieve a greater holding force and increases the surface adhesion of the magnet. Thus due to the bevelling28, the magnet holds well also with a thin plate.

The slide25narrows towards the bottom. Thus the centre30is constricted, i.e. tapered. A larger coil29may be arranged around the constricted centre30. A larger coil29makes possible the use of a larger effect, whereby a larger permanent magnet may in turn be used, such as a neodymium magnet24. By means of the constricted centre a greater holding force is thus achieved than without the constriction.

FIG. 6ashows a partial cross-section of a detail of a third attaching device according to the invention.FIG. 6bshows a partial cross-section of a detail of a fourth attaching device according to the invention. A piece33, which the magnet is meant to grab, is drawn to be visible inFIGS. 6aand6b. A back plate23, a shell19, a neodymium magnet24, a slide25, an electric magnet coil29and a lower ring22of the centre are seen in the figures. The back plate23, neodymium magnet24, slide25attached together form a moving centre30. The difference betweenFIGS. 6aand6bis that the surfaces of the centre30and the rest of the magnet, i.e. the shell19in the figures, are vertical inFIG. 6bin the contact spot34, i.e. in the direction of the movement of the centre. InFIG. 6athe corresponding surfaces in the contact spot34are slanted in relation to the movement of the centre30. By means of the solution inFIG. 6bthe opening and closing of the circuit of the magnetic flux is more efficient in some situations.

FIGS. 7a,7band7cshow simulations of the magnetic flux in the magnet8of an attaching device according to the invention.FIG. 7ashows just a simulation model when the centre30is in the lower position, i.e. the magnet is in the holding position. InFIG. 7bthe situation is the same as inFIG. 7a, but the simulated passage of the magnetic flux is drawn in the figure with lines. InFIG. 7bthe centre30is lifted away from the rest of the magnet i.e. the shell19. The magnet is thus in the open position. From the figures can be seen how the passage of the magnetic flux breaks in the open position.

FIG. 8shows an arrangement according to the invention for attaching an object to be worked to the working base. The arrangement comprises a control unit i.e. an interface35, and three identical attaching devices10,10′ and10″ according to the invention. The control unit35transmits messages from the controlling system (not shown) to the attaching device. The control unit has a so-called I/O inlet and it may be controlled for example with a 5V, 12V or 24V voltage. The controlling system may be a robot (seeFIG. 12), a welding device, a cutting device or another corresponding programmable device. In the program, which may be run on the processor of the control unit35, it has in advance been defined what should be done when as certain I/O command arrives. The I/O may for example be 8, 16, 32 or 64-bit.

The robot for example gives a command [32] to the control unit. It may for example mean “Open the upper magnet of the attaching device”. The control unit reads the command [32] in its inlet ports. The information that the MAC address of the upper magnet of the attaching device10is 54321 has been programmed into the software in advance. Thus the control unit sends the command [32] to the address 54321. The software in the processor in the attaching device10knows that when the command [32] arrives, the upper magnet should be opened. The attaching devices in the system may be identical. Only their MAC addresses are individual. The MAC addresses of the attaching devices are programmable with the control unit, so any available attaching device10,10′ or10″ may receive the command, as long as the attaching device is programmed into the system. Thus the program in the robot does not need to be changed, even if one of the attaching devices were to be out of use. There may be several, even hundreds of cubes in the system at the same time.

Various tools, which assist in grabbing the pieces33to be worked, may be connected to the attaching device10according to the invention.FIG. 9shows an attaching device10, where two lever pliers39have been attached.

FIG. 10shows the charging mount40for attaching devices according to the invention, which has six places41for an attaching device. The attaching devices11are stored in the charging mount when they are not needed. The mount has a charging device (not shown), which has charging means suitable for the attaching devices10, such as connectors suiting the charging connectors17seen inFIGS. 3 and 4. The battery of an attaching device10in the mount may thus be charged. The edges42of the places for the attaching devices advantageously also position the cube when it is set in the mount.

FIG. 11shows the working place of a robot43, where an arrangement according to the invention is used. The working place has eighteen attaching devices10and a charging mount40for them, which is placed in a tool mount44. The metallic work surface45is empty. The robot has a magnetic tool46, with which it takes the attaching devices from the charging mount40and places them on the work surface45. When it has assembled a desired jig from the attaching devices10, it places the piece to be worked in the jig, changes the tool and starts the working.

The operation of an embodiment of the invention may for example be described as follows. An electric current of a desired magnitude is steered to the coil29based on the software executed with the processor on the circuit board2of the attaching device10. When current is led to the coil in a certain direction, the magnetic field produced by the coil weakens the magnetic field of the permanent magnet24. At a certain strength of the magnetic field the moving centre30moves away from the rest of the magnet. The detaching occurs for example when the strings32have the strength to push the centre30away from the frame, into the open position. Thus the magnetic flux cannot pass, the magnetic force is weakened and the magnet is switched off, i.e. the hold of the magnet is off. When the hold of the lower magnet8is off, it can be placed on the metal of the work surface45or on another attaching device. Thereafter a current is led into the coil29in the opposite direction to when the hold was detached. The electric current is thus steered in the direction of the coil, which strengthens the magnetic field of the permanent magnet24. Now the magnetic field of the coil starts to pull the permanent magnet part24towards it. In the end, for example when the magnetic field is stronger than the springback factor of the springs32, the centre30i.e. the slide and the thereto attached permanent magnet part24start to move toward the holding position. Finally, when the force has increased enough, the circuit of the magnetic flux is again closed. Thus the magnet receives more holding force. The permanent magnet part24may for example be neodymium magnet.

The operation of an embodiment of the invention, where a robot controls the arrangement, may be described as follows. The control unit35receives from the robot43the command “Open the upper magnet1of the attaching device10”. The control unit35transmits the message to the attaching device10. The attaching device10receives the message and opens its upper magnet1according to the command. When the upper magnet has opened the attaching device10in turn sends a message to the control unit35, observes it, and forwards it to be read by the robot43to the I/O port of the control unit: “The upper magnet1of the attaching device10is open”. The robot may thus verify that the message has been received and the command has been realized.

The operation of another embodiment of the invention, where a robot controls the arrangement, may be described as follows. The control unit35receives from the robot43the command “Open the upper magnet1of the attaching device10”. The control unit35transmits the message to the attaching device10. If the attaching device10does not respond to the message within a certain time frame, the control unit35tries again. If the attaching device10still does not answer, the control unit35gives a forwarding command. The control unit35has information in its memory regarding which attaching devices the system has in use and it requests the nearest other attaching device to forward the message. Now the attaching device10′ receives a request to forward a message and forwards the message to the attaching device10. The attaching device10opens its upper magnet and responds to the attaching device10′ “The upper magnet1of the attaching device10is open”. The attaching device10′ forwards the message to the control unit35and this forwards it to the robot43. Thus the message has been received and the command has been acknowledged. The system functions like this itself and the user does thus not need to separately observe that the message is received. Any attaching device of the system may function as the transmitter to any other attaching device in the system. It is also possible to program corresponding programs in the processor of the attaching device as into the control unit35, whereby the attaching device itself may function as a controller of others, without a separate control unit35.

A sensor, which gives information to the processor if the centre strives to move when the magnet should be in the holding position, may be placed in the moving centre, for example in the back plate. In the holding position the centre moving in relation to the rest of the magnet would mean that the magnet is detaching. Thus the processor may increase the holding force of the magnet by giving more current to the coil in the suitable direction, which strengthens the magnetic flux. Such an active monitoring of the hold and increase in strength as needed is important, in order for the system to be reliable. Real-time information about the hold is needed for example when welding, cutting and in corresponding situations. Thus real-time monitoring of the state of different fasteners, for example those used in laser welding, becomes possible.

By means of the invention a work machine, such as a robot, may assemble a lifting device of a required shape for itself for object handling from attaching devices according to the invention and possible additional pieces.

The figures show only a few preferred embodiments according to the invention. Facts of secondary importance with regards to the main idea of the invention, facts known as such or evident for a person skilled in the art, such as electric cables, data communication devices or support structures possibly required by the invention, are not separately shown in the figures. It is obvious to someone skilled in the art that the invention is not limited merely to the above-described examples, but the invention may vary within the scope of the claims presented below. The dependent claims present some possible embodiments of the invention, and they are as such not to be considered to restrict the scope of protection of the invention.