Cutting device with synchronized calibration units.
The present invention relates to a cutting device as defined in the preamble of claim 1.
In prior art, cutting devices are known which cut an object by working its material. This type of devices include e.g. devices that use a high-energy jet for cutting, such as water jet cutting devices cutting by means of a high-pressure water jet, and plasma jet cutting devices cutting by means of a plasma jet.
The cutting device typically comprises a cutting table, upon which the object to be cut, which may be of sheet-like or other shape, can be set. Moreover, the cutting device comprises a cutting head for focus- ing the cutting tooling effect, such as a water jet. A portal robot or the like is arranged to operate above the cutting table to move the cutting head in accordance with predetermined instructions corresponding to a cutting pattern. The portal robot comprises a portal beam extending over the cutting table in a first horizontal direction. The portal beam is guidably movable relative to the cutting table in a second horizontal direction perpendicular to the first horizontal direction. Connected to the portal beam is a carriage guidably movable in the direction of the portal beam, i.e. in the first horizontal direction
Connected to the carriage is a vertical transfer device, on which the cutting head is mounted in a manner permitting vertical movement. The cutting head is connected to the vertical transfer device via a turning device. The turning device is provided with setting actuators, by means of which the cutting head can be tilted in any direction to an angle relative to the object to be cut so as to form a corresponding splay in the object. In the present description, 'setting actuator' refers to a CNC controlled actuator having a high setting accuracy.
The cutting device further comprises a main control unit, which is provided with program means containing predetermined control data for controlling the movements of the portal robot. This control data comprises instructions regarding the movements of the cutting head corresponding to the cutting pattern in the first horizontal direction, in the second horizontal direction and in a vertical direction as well as instructions regarding the cutting head tilt angle thus corresponding to the desired cutting pattern and splay tilt angle in different parts of the cutting pattern.
A problem with prior-art cutting devices is that both the entire control of all robot movements and the entire control of the turning device are taken care of by the main control unit, which controls all functions of the device in a centralized manner, including transfers and control of the operation of the cutting head. This means that the turning device and the cutting head are connected to the main control unit via a large number of different conductors. The main control unit also contains calibration data needed for the compensation of inaccuracies of the mechanisms of the device. Therefore, many equipment manufacturers provide different cutting machine models sold completely separately for normal perpendicular cutting without any formation of splays and, on the other hand, for splay cutting. A machine model designed for normal perpendicular cutting can not be easily applied for splay cutting without major modifications, which results in high expenses to the users. In prior-art devices, the turning device is fixedly mounted on the vertical transfer device and is not designed to be detachable from it. The object of the present invention is to eliminate the above-mentioned drawbacks.
A specific object of the invention is to disclose a cutting device that allows the user to easily convert the cutting device from a perpendicular cutting device into a splay cutting device and vice versa .
As for the features characteristic of the cutting device of the invention, reference is made to the claims below.
According to the invention, the turning de- vice comprises a turning device frame, which is de- tachably connected to the vertical transfer device. The cutting head setting actuators are mounted on this detachable turning device frame. Further, the turning device comprises an auxiliary control device mounted in the turning device frame. The auxiliary control device is connected via a data bus to the main control unit to function on the principle of decentralized data processing in synchronized cooperation with the main control unit. The auxiliary control device con- tains predetermined and stored turning device-specific calibration data for eliminating errors caused by inaccuracies of the transfer mechanism of the entire cutting device by using compensating corrections corresponding to the errors, the auxiliary control device being arranged to adjust the setting actuators on the basis of the calibration data and control data obtained from the main control unit to accurately adjust the angle of inclination of the cutting head.
The invention has the advantage that the turning device forms a compact, detachable and replaceable module which contains the necessary individual calibration data required in the auxiliary control device for the operation of the cutting head. Thus, this individual turning device-specific information is stored in the turning device and always remains together with it regardless of whether the turning device is detached from the cutting device or mounted on
it. Via the data bus, the auxiliary control device and the main control unit can communicate, exchange information and cooperate with each other. A further advantage of the invention is that the number of conductors leading to the turning device is substantially reduced.
In an embodiment of the cutting device, the cutting device comprises two or more carriages placed side by side. Connected to each carriage is a turning device, whose auxiliary control device contains control means for individual control of the movement of the carriage in a first horizontal direction and/or for individual control of the vertical motion of the vertical transfer device. This arrangement further in- creases the control functions of the auxiliary control device and decentralizes them away from the main control unit.
In an embodiment of the cutting device, the setting actuators are linear servo motors, such as ball screw motors.
In an embodiment of the cutting device, the cutting head of the cutting device has been arranged to cut an object by focusing a high-energy jet onto the object. In an embodiment of the cutting device, the cutting device is a water jet cutting device, in which the cutting head has been arranged to focus onto the object a high-pressure water jet, preferably with abrasive material, such as sand, added to it. In an embodiment of the cutting device, the auxiliary control device contains control means for controlling the supply of abrasive material.
In an embodiment of the cutting device, the cutting device is a plasma cutting device, in which the cutting head has been arranged to focus a plasma jet onto the object.
In an embodiment of the cutting device, the cutting device comprises means for controlling the feed of the cutting jet. The auxiliary control device may comprise control means for controlling the means controlling the jet feed.
In an embodiment of the cutting device, the means for controlling the jet feed comprise a magnetic valve or the like, in which case the auxiliary control device controls the operation of the magnetic valve. In an embodiment of the cutting device, the cutting head is a milling device provided with a rotary milling cutter.
In the following, the invention will be described in detail by the aid of embodiment examples with reference to the attached drawing, which presents a perspective view of a first embodiment of the cutting device of the invention.
The figure presents a cutting device. The cutting device comprises a cutting table 1, which sup- ports the object to be cut so that the object, which usually is in the form of a board, lies upon the support in a horizontal position (xy-plane) .
The cutting device presented in Fig. 1 has three cutting heads 2, which accomplish the cutting tooling. The device may be provided with one or more cutting heads 2. The cutting tooling may consist of focusing onto the object a high-pressure narrow water jet, which may contain abrasive material. In this case, the cutting head 2 is a water jet cutting noz- zle. The cutting tooling may also consist of focusing a high-energy plasma jet onto the object, in which case the cutting head 2 is arranged to direct a plasma jet against the object. The cutting head may also be a laser cutting head, which applies a cutting laser beam to the object. The cutting of the object may also take place by a metal-cutting technique, in which case the
cutting head 2 is provided with a milling cutter rotating about its longitudinal axis.
The cutting heads 2 are arranged side by side. The required movements of the cutting heads 2 are produced by a portal robot 3 arranged to operate above the cutting table 1 to move the cutting heads 2 according to a computer program corresponding to the desired cutting patterns .
The portal robot 3 comprises a portal beam 4 extending in a first horizontal direction y over the cutting table 1, which has been arranged to be guidably movable relative to the cutting table 1 in a second horizontal direction x perpendicular to the first horizontal direction y. Supported on the portal beam 4 are three carriages 5, which have been arranged to be movable in the first horizontal direction y, i.e. in the direction of the portal beam, along a guide track. The carriages 5 are moved relative to the portal beam 4 by means of an accurate setting actuator provided inside the portal beam 4, said actuator being based on a ball screw/nut mechanism. Each cutting head
2 is supported by a carriage 5. The portal beam 4 is moved in the x-direction relative to the cutting table 1 along a guide track mounted in the frame of the cut- ting table by means of an accurate setting actuator based on a ball screw/nut mechanism. The portal robot
3 has been arranged to operate above the cutting table 1 to move the cutting heads 2 according to a predetermined cutting program corresponding to the cutting patterns.
Connected to each carriage 5 is a vertical transfer device 6, which is provided with a linear servo motor producing a linear vertical motion, e.g. a ball screw motor. The vertical transfer device 6 serves to move the cutting head 2 in a vertical direction z. For each cutting head 2 there is a turning device 7, to which the cutting head is connected. The
turning device 7 comprises setting actuators 8, 9, by means of which the cutting head 2 is tilted to an angle relative to the surface of the object to be cut to form in the object a splay corresponding to the said angle.
The main control unit 10 of the cutting device contains a computer, such as a PC or the like, which is provided with software means containing predetermined control data for controlling the movements of the portal robot 3. The control data comprise instructions regarding transfers in the first horizontal direction y, in the second horizontal direction x and in the vertical direction z and instructions regarding the angle of inclination of the cutting head. The turning device 7 comprises a box-like turning device frame 11, which is detachably connected to the vertical transfer device 6 e.g. by a bolted joint. The setting actuators 8, 9 turning the cutting head 2 are mounted in the turning device frame 11. The setting actuators 8, 9 in the turning device frame box 11 are e.g. linear servo motors, such as ball screw motors .
Each turning device 7 has its own auxiliary control device 12, which is placed inside the turning device frame box 11. The auxiliary control device 12 is connected via a standard industrial data bus 13 to the main control unit 10, in other words, the control system functions on the principle of decentralized data processing, with the auxiliary control device 12 cooperating with the main control unit 10.
The auxiliary control device 12 of each turning device 7 contains predetermined and stored calibration data for the respective turning device for the correction of errors resulting from inaccuracies of the transfer mechanism of entire the cutting device by using compensating corrections corresponding to the errors . Using the calibration data and the control
data obtained from the main control unit, the auxiliary control device 12 controls the setting actuators 8, 9 to accurately adjust the setting of the angle of inclination of the cutting head 2. In each turning device 7, the auxiliary control device 12 also contains control means for individual control of the movement of the carriage 5 in the first horizontal direction x and additionally control means for individual control of the vertical movement z of the vertical transfer device 6. When the cutting principle is that of focusing a high-energy jet onto the object by the cutting head 2, the auxiliary control device 12 may also comprise control means for controlling the means controlling the jet feed, such as a valve, e.g. a magnetic valve. In the case of water jet cutting, the auxiliary control device 12 may also contain means for feeding an abrasive material together with water in the nozzle.
The invention is not limited to the embodi- ment examples described above; instead, many variations are possible within the scope of the inventive concept defined in the claims.