| WO/2005/023475 | TOOL FOR CUTTING CABLES |
| JP57178611 | FRAME BALANCING DEVICE OF DIE SET SHEAR |
| JP2008229733 | SHEAR PRESS MACHINE CAPABLE OF SHEARING IN HIGH SPEED |
Dahlberg, Kurt (Selkroksvägen 22 Karlskoga, S-691 42, SE)
Gustafsson, Olle (Näckrosvägen 3 Karlskoga, S-691 51, SE)
Dahlberg, Kurt (Selkroksvägen 22 Karlskoga, S-691 42, SE)
| 1. | A method for impact influence on a moving object (16), characterized in that an impact tool (1) is moved essentially in parallel with the object (16) in the moving direction (x) of the object at the same time as it is caused to perform an impact motion across said moving direction (x) in order to transfer an impact to the object (16) and thereby generate said impact influ ence. |
| 2. | A method according to claim 1, characterized in that the im pact tool (1) has essentially the same velocity as the object in its moving direction (x) at the impact moment. |
| 3. | A method according to claim 1 or 2, characterized in that the impact motion of the impact tool (1) is generated by a stroke against it by means of a striking tool (17), which is kept essen tially stationary in the moving direction (x) of the object (16). |
| 4. | A method according to any of claims 13, characterized in that the object (16) is supported by means of a supporting de vice (21) in an area adjacent the section thereof which is hit by the impact tool (1) at least at the impact moment. |
| 5. | A method according to claim 4, characterized in that the supporting device (21) is moved in the same direction and with essentially the same velocity as the object (16) at the impact moment. |
| 6. | A method according to any of claims 4 or 5, characterized in that the impact tool (1) before the impact moment, from a start ing position is accelerated in the moving direction of the object to the velocity of the impact tool (1) at the impact moment, and subsequently is slowed down and returned to the starting posi tion. |
| 7. | A method according to any of claims 16, characterized in that a flow of a pressurized medium is controlled for influencing the motions of the impact tool (1) in parallel with the moving di rection (x) of the object (16). |
| 8. | A method according to claim 7, characterized in that the im pact tool (1) is connected to a movable part (4), comprising a first surface (10) and a second surface (11) with different areas, the pressurized medium when operating against the first surface (10), gerrerating a force on the movable part (4) in the accelera tion direction of the impact tool, and generating a force in the opposite direction when operating against the second surface (11), and in that the flow of the pressurized medium is directed to at least one of said surfaces (10,11). |
| 9. | A method according to any of claims 18, characterized in that the object (16) is elongated and that it is moved continu ously in its longitudinal direction, while the impact tool (1) recur rently is activated to perform impact influence at given positions along the object. |
| 10. | A method according to any of claims 19, characterized in that the impact has such an impulse that a cutting of the object (16) across its moving direction is achieved without the impact tool (1) passing through the object (16). |
| 11. | A device for impact influence on a moving object (16), characterized in that it comprises means (2,3,4) for moving an impact tool (1) essentially in parallel with the object (16) in the moving direction (x) of the object, and means (17) for at the same time causing the impact tool (1) to perform an impact mo tion across said moving direction (x) in order to transfer an im pact to the object (16) and thereby generate said impact influ ence. |
| 12. | A device according to claim 11, characterized in that the means (2,3,4) for moving the impact tool (1) in the moving di rection of the object (16) are arranged to move the impact tool (1) with essentially the same velocity as the object (16) at the impact moment. |
| 13. | A device according to claim 11 or 12, characterized in that the means (17) comprise a striking tool being essentially sta tionary in the moving direction (x) of the object (16). |
| 14. | A device according to any of claims 1113, characterized in that it comprises a supporting device (21), at the impact moment supporting the object (16) in an area of this adjacent to the sec tion which is hit by the impact tool (1). |
| 15. | A device according to claim 14, characterized in that the supporting device (21) is arranged to be moved in the same di rection (x) and with essentially the same velocity as the object (16) at the impact moment. |
| 16. | A device according to any of claims 1115, characterized in that the means (2,3,4) for moving the impact tool (1) essen tially in parallel with the object (16) in the moving direction (x) of the object are arranged to before the impact moment, from a starting position, accelerate the impact tool (1) to the velocity it has in the moving direction of the object (16) at the impact mo ment, and to slow down and return it to the starting position af ter the impact moment. |
| 17. | A device according to any of claims 1116, characterized in that the supporting device (21) is connected to the impact tool and follows its motion in the moving direction of the object and back. |
| 18. | A device according to any of claims 1117, characterized in that the means (2,3,4) comprise a valve device (2) arranged to control a flow of a pressurized medium for influencing the mo tions of the impact tool (1) in the moving direction (x) of the ob ject (16). |
| 19. | A device according to claim 18, characterized in that the valve device (2) is arranged to be displaced from a first position, in which it controls the flow of the pressurized medium so that said acceleration of the impact tool (1) is achieved by the means (2,3,4) in the moving direction of the object (16), to a second position, in which it controls the flow of the pressurized medium so that said slowing down and returning of the impact tool is achieved by the means (2,3,4), depending on the position of the object (16) relative to the impact tool (1). |
| 20. | A device according to claim 18 or 19, characterized in that the means (2,3,4) comprise a movable part (4) connected to the impact tool and a stationary part (3), the movable part de fining a first surface (10) and a second surface (11) with differ ent areas, the pressurized medium, when operating against the first surface (10), generating a force on the movable part (4) in the acceleration direction of the impact tool, and, when operat ing against the second surface (11), generating a force on the movable part in a direction opposite said acceleration direction, and that the valve device (2) is arranged to direct the flow of the pressurized medium to at least one of said first and second surfaces (10,11). |
| 21. | A device according to claim 20, characterized in that the stationary part (3) comprises a section (7) provided in a space (6) in the movable part (4), the section (7) having an outer di mension essentially corresponding to the inner dimension of the space and separating the space into a first and a second cham ber (8,9) in which the first and second surface (10,11) respec tively are provided. |
| 22. | A device according to any of claims 1121, characterized in that the object (16) is elongated and that it is moved continu ously in its longitudinal direction, the device being arranged to periodically perform a reciprocating motion which is parallel with said direction while at each such reciprocating motion perform ing at least one impact against the object (16) for impact influ ence on this. |
| 23. | A device according to any of claims 1122, characterized in that the impact from the impact tool (1) against the object+16) has such an impulse that a cutting of the object (16) across its moving direction is achieved without the impact tool (1) passing through the object (16). |
| 24. | A device according any of claims 1123, characterized in that it comprises a damping arrangement (20), damping the mo tion of the impact tool (1) across the moving direction of the ob ject (16) and counteracting an impact motion of the impact tool right through the object (16). |
It is previously known, see for instance the patent application No. WO 97/00751 of the applicant, to provide a striking machine using hydraulics to achieve a fast impact influence on objects, such as bars and wire, to cut these. The strike of the impact thereby being applied against the object has such an impulse and results in such a transfer of energy to the object that the impact tool being used to perform said impact does not need to penetrate the object to achieve the cutting. At metal objects, the concentrated transfer of kinetic energy, achieves so called adia- batic coalescence, which in its turn results in that a very even and fine surface of fracture is obtained on the object. It is sug- gested that the transferred kinetic energy should have a value in the order of 100 to 200 Nm/cm2 cutting area. The striking tool should in connection with that have a velocity between 3 and 10 m/sec at the striking moment. The hydraulically activated strik- ing machine is a further development of striking machines of prior art, which have been pneumatically activated or spring ac- tivated. By using hydraulics to control the striking machine, it has been possible to increase the striking velocity from 200-400 strokes per minute to about 3000 strokes per minute.
Striking machines of this kind is with advantage used for cutting long objects, such as bars and wire, to a plurality of shorter units. Thereby the object is fed forward a given distance be- tween every activation of the striking tool of the striking ma- chine. Of course such an intermittent forward feeding requires a sophisticated and advanced forward feeding device with such performance that it can match the high striking velocity that the striking machine can work with. The forward feeding arrange- ment therefore easily becomes relative expensive and compli- cated.
To get away from the problem with intermittent forward feeding of the object to be cut, it is possible to perform said impact in- fluence on the object while this is fed continuously through the cutting machine and is hit by the impact tool or striking tool while being in motion. An increased velocity of the object will however result in an inexact impact influence on the object. The higher velocity, the higher the inexactness. This in its turn leads to an obtaining of more defect cutting surfaces than in the case where the striking tool directs its stroke towards an essentially stationary object.
SUMMARY OF THE INVENTION An object with the present invention is to enable to perform im- pact influence with precision on a moving object without mo- mentarily needing to stop its motion. In the case with cutting of the object, this means that cutting surfaces as free of defects as possible of the object are aimed at. The method should also be able to be implemented without unnecessarily complicated and expensive constructions or measures being required.
This object is achieved by means of a method of the initially de- fined kind, being characterized in that an impact tool is moved essentially in parallel with the object in the moving direction of the object at the same time as it is caused to perform an impact
motion across said moving direction in order to transfer an im- pact to the object and thereby generate said impact influence.
Thanks to the moving of the impact tool in the moving direction of the object, the velocity, with which the object passes the im- pact tool at the impact moment is reduced to such a degree that a correct and precise impact influence is achieved. The object can consequently be moved with high velocity without any unfa- vourably large sliding between the impact tool and the object occurring at the impact moment. In the case with cutting of the object by said impact influence, the emergence of cuttirrg--sur- faces with defects generated because of mutual displacement of the impact tool and the object at the impact moment can be re- duced or completely eliminated.
According to a preferred embodiment the impact tool has essen- tially the same velocity as the object in its moving direction at the impact moment. Thereby very high velocities of the object can be achieved with maintained precision of the impact tool, i. e. almost no mutual sliding between the impact tool and the object at the contact surfaces thereof at the impact moment.
According to a further preferred embodiment, the impact motion of the impact tool is generated by a strike against it by means of a striking tool, which is kept essentially stationary in the moving direction of the object. Because of this characteristic, in par- ticular a more simple and less complicated construction of a striking machine comprising an impact tool movable in the mov- ing direction of the object can be obtained. If also the striking tool should be provided movable together with the impact tool, or replace the impact tool, the unit being formed thereof will have a substantially larger weight than what would otherwise be the case. In certain cases, when one desires a fast acceleration and retardation of the impact tool in the moving direction of the object, a reduced weight of the unit to be accelerated and re- tarded is of substantial importance for the size of the forces re- quired to be applied to the unit, and consequently for the size of
the device implementing said force application. A smaller and faster device can thus be obtained.
According to another preferred embodiment, the impact tool is accelerated before the impact moment from a starting position in the moving direction of the object to the velocity of the impact tool at the impact moment, after which it is slowed down and returned to the starting position. The impact tool is in this way caused to perform a reciprocating motion in parallel with the moving-direction of the object. In this manner a continoous feeding of the object can be allowed, while a periodical applica- tion of an impact influence is performed. The ability to acceler- ate and retard the impact tool in parallel with the moving direc- tion of the object thus becomes crucial for the forward feeding velocity of the object or the distance between the sections of the object being subjected to said impact influence. The method, however, allows a very exact control of the application of impact influence with reference to the forward feeding velocity of the object and the distance between the sections of it to be sub- jected to impact influence.
According to a further preferred embodiment, a flow of a pres- surized medium is controlled for influencing the motions of the impact tool in parallel with the moving direction of the object. In connection with that the impact tool is connected to a movable part, comprising a first surface and a second surface with differ- ent areas, the pressurized medium generating a force on the movable part in the acceleration direction of the impact tool when it operates against the first surface and generating a force in the opposite direction when it operates against the second surface, and the flow of the pressurized medium is directed to at least one of said surfaces. Thanks to the method using the above defined principe to achieve velocity variations, possibly a reciprocating motion, of the impact tool in parallel with the mov- ing direction of the object, a relative uncomplicated and reli- able striking machine performing the method according to the
invention can be constructed and manufactured. By the control of the pressurized medium, a very exact adjustment of the mo- tions of the impact tool to the moving velocity of the object and the distance between the sections of the object to be subjected to said impact influence can be achieved. The medium is pref- erably a fluid, for instance an oil. By the use of a fluid, a sub- stantially higher velocity and in addition a higher accuracy can be achieved than when a gas or gas mixture, such as air, is used.
According to another preferred embodiment, the impact has such an impulse that a cutting of the object across its moving direction is achieved without the impact tool passing through the object. This requires transfer of a proportionally large kinetic energy to the object via the impact tool. To achieve cutting sur- faces free of defects on the object at this type of cutting, the im- pact against the object is required to be performed with high precision. Any substantial mutual sliding between the impact tool and the object at the impact moment can therefore not be accepted. The method according to the invention is thus par- ticularly advantageous in this type of impact influence.
A further object of the invention is to provide a device enabling to perform impact influence with precision on a moving object without needing to momentarily stop the moving thereof. In the case that said impact influence results in a cutting of the object, one desires to obtain cutting surfaces as free of defects as pos- sible. The device should furthermore be uncomplicated, simple to produce and control and be reliable.
This object is achieved by means of a device of the kind defined initially, being characterized in that it comprises means for moving an impact tool essentially in parallel with the object in the moving direction of the object, and means for at the same time causing the impact toot to perform an impact motion across said moving direction in order to transfer an impact to the object
and thereby generate said impact influence. Thanks to the im- pact tool being moved in parallel with the object when transfer- ring the impact to this, a mutual sliding between the surfaces of the impact tool and the object being in contact with each other during the impact moment can be reduced or completely elimi- nated. A continuous moving of the object with high velocity while it is being subjected to said impact influence could consequently be achieved at the same time as said impact influence is per- formed with high precision and with a minimum of possible slid- ing between contact surfaces of the impact tool and the object at the impact moment.
According to a preferred embodiment, the means for moving the impact tool in the moving direction of the object are arranged to move the impact tool with essentially the same velocity as the object at the impact moment. Thereby a minimum of mutual sliding between the impact tool and the object at the impact moment is achieved, resulting in a very exact impact influence on the object. In the case when said impact influence comprises a cutting of the object and the cutting is done by that a powerful impact is directed against the object without the impact tool passing through the object, a more even and finer cutting sur- face is obtained than if a mutual sliding between the impact tool and the object at the impact moment had occurred.
According to a further preferred embodiment, the means for bringing the impact tool to perform an impact motion across the moving direction of the object comprise a striking tool, being es- sentially stationary in the moving direction of the object. For ac- tivation of the striking tool at the right moment, when the impact tool is essentially right in front of this, the device should com- prise a sensor which based on the position of the impact tool gives an activation signal to the striking tool. Thanks to the striking tool being stationary, a substantially reduced weight of a movable unit that the impact tool is being part of can be ob- tained. Thereby faster velocity changes and higher velocities
can be achieved of the impact tool at the same time as smaller forces are required for said moving of the impact tool and the unit that this is being part of.
According to a further preferred embodiment, the device com- prises means to before the starting moment, from a starting po- sition, accelerate the impact tool to the velocity it has in the moving direction of the object at the impact moment, and to after the impact moment slow down and return it to the starting posi- tion. Thereby a reciprocating motion, which can be synchronized to the velocity of the object and the distance between the sec- tions of the object, where impact influence shall be performed, is achieved. The impact is performed when the impact tool has its highest velocity in the moving direction of the object, when this velocity is essentially as high as the velocity of the object at this moment.
According to a further preferred embodiment, the means for moving the impact tool in parallel with the object in the moving direction of the latter comprise a valve device arranged to con- trol a flow of a pressurized medium for influence of the motions of the impact tool in the moving direction of the object. Said means comprise a movable part, connected with the impact tool, and a-stationary part, the movable part defining a first surface and a second surface with different areas, and the pressurized medium, when operating against the first surface, generating a force on the movable part in the acceleration direction of the im- pact tool, and, when operating against the second surface, gen- erating a force on the movable part in a direction opposite said acceleration direction, and the valve device being arranged to direct the flow of the pressurized medium to at least one of said first and second surfaces. The valve device can easily be caused to control the flow with reference to the position of the object relative to the impact tool. For instance, a control of the flow generating an acceleration of the impact tool in the moving direction of the object can be initiated as soon as a certain
length of the object has passed by the impact tool or any part connected thereto. The slowing down and returning can be initi- ated essentially at the moment when a striking impulse is sent to the striking tool. Thanks to this technique, a very exact distance between the sections being subjected to impact influence can be achieved even when the moving velocity of the object is rela- tively high. The medium is preferably a fluid. Thereby especially fast and precise reciprocating motions of the impact tool in par- autel with the moving direction of the object can be achieved.
According to a further preferred embodiment, the impact from the impact tool against the object has such an impact that a cut- ting of the object across its moving direction is achieved without the impact tool passing through the object. The device com- prises in that connection with advantage a damping arrange- ment, damping the motion of the impact tool across the moving direction of the object and counteracting an impact motion of the impact tool right through the object. In this type of cutting a very even and faultless cutting surface of the object is obtained, pro- vided that no mutual sliding occurs between the impact tool and the object at the impact moment. The device according to the invention is consequently especially advantageous, when this type of impact influence shall be carried out on a moving object and when the velocity of the object is substantial, for instance higher than 1 m/sec.
Further advantages and characteristics of the invention will be apparent from the following description and from the other claims.
BRIEF DESCRIPTION OF THE DRAWINGS Hereinafter the invention will be described for exemplifying pur- poses with reference to the enclosed drawings, in which
Fig 1 is a schematic cross-sectional view from the side showing an embodiment of the device according to the invention in a first position and Fig 2 is a view corresponding to that of Fig 1, but with the de- vice in a second position.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT In--Figs 1-and 2 a preferred embodiment of the device according to the invention is shown in two different positions. The device comprises an impact tool 1, means 2,3,4 for moving the impact tool 1 essentially linearly forth and back, in parallel with a direc- tion x shown with an arrow in the Figures. The moving means 2, 3,4 comprise a stationary part 3, being fixedly connected with a frame 5, only roughly indicated. The moving means 2,3,4 fur- thermore comprise a movable part 4, being connected with the impact tool 1. The movable part 4 defines a casing with an inner space 6. The stationary part 3 defines a piston extending into the movable part 4 and relative to which the movable part 4 can be displaced forth and back in the direction x. The stationary part 3 comprises a section 7 having an outer dimension essen- tially corresponding to the inner dimension of the space 6 and which-essentially sealingly abuts against this. This section 7 separates the space 6 into two separate chambers 8,9. The op- posite end walls of the chambers 8,9 are penetrated by the sta- tionary part, i. e. the piston 3. The end wall of the first chamber 8 thereby defines a ring shaped first surface 10, while the end wall of the chamber 9 defines a ring shaped second surface 11. The first surface 10 and the second surface 11 have different areas.
The area of the first surface 10 is smaller than the area of the second surface 11.
The moving means 2,3,4 further comprise a valve device 2, which is connected to the movable part, i. e. the casing 4. From the valve device 2 a channel 12 leads to one of the chambers 8,
9, in this case the second chamber 9. Via the channel 12 and the valve device 2, the second chamber 9 can be connected to a source 13 for supply of a pressurized medium. This medium is here a fluid, preferably oil with a pressure in the order of 160 bar. The first chamber 8 is constantly connected via a further channel 14 to the source 13. The second chamber 9 can, via the cannel 12 and the valve device 2 alternatively be disengaged from the source 13 and be connected to a system or a container 15 with lower pressure than of the source 13. In this case, the system/container 15 consists of a discharge tank without'pres- sure for pressurized medium which via the channel 12 and the valve device 2 is led from the second chamber 9 to said tank 15.
By connection of the second chamber. 9 to the tank 15, an ac- celeration is achieved, by the influence of the pressurized me- dium on the first surface 10, of the movable part 4 in the direc- tion x, see Fig 1. By connection of the second chamber 9 to the source 13, a displacement is achieved, by the influence of the pressure medium on the second surface 11 and because of the area difference between the first and second surface, of the movable part 4 in opposite direction, see Fig 2. By means of the valve device 2, consequently the motions of the movable part 4 in parallel with the direction x can be controlled.
The device is penetrated by an object 16, which is fed continu- ously in the direction x by means of a not shown feeding device. The velocity thereof could be in the order of 1-3 m/sec. The object 16 is elongated and is moved continuously in its longitu- dinal direction. It is preferably made of metal and can be a bar or a wire. In this specific case, the object 16 defines a wire, which is moved continuously with a velocity of 2,5 m/sec and shall be cut into 20 cm long units, which shall be used as weld- ing wires. To allow the object 16 to penetrate the device, a hole is provided in the direction x in the stationary part 3 and in the mova- ble part 4. The path of the object 16 through the device passes by the impact tool 1. The impact tool 1 is arranged to periodically per- form an impact motion against the object 16, which is moved continu-
ously in the direction x. The impact being transferred by the im- pact tool to the object 16 has such an impulse and comprises transfer of such a large kinetic energy that a cutting of the ob- ject across its moving direction x is achieved without the impact tool 1 passing through the object 16. The impact being trans- ferred by the impact tool 1 originates from a striking tool 17, which can be a hydraulically or pneumatically activated striking piston and which is essentially stationary arranged in the direc- tion x and separated from the movable part 4. For transferring the impact, the impact tool 1 comprises a striking cap*18, against which the striking tool 17 hits. A sensor device 19 is ar- ranged to transmit an impulse for activation of the striking tool 17 based on the position in the direction x of the movable part 4, and thereby of the impact tool 1.
The device also comprises a schematically shown damping ar- rangement 20, damping the motion of the impact tool 1 across the moving direction x of the object 16, counteracting an impact motion of the impact tool 1 right through the object 16 and sub- sequently immediately returning the impact tool 1 to its initial position. The damping arrangement 20 is stationary and does not follow the movable part 4 and the impact tool 1 in their mo- tions in parallel with the moving direction x of the object 16.
Thereby the weight is kept as low as possible of the movable unit. The device further comprises a supporting device 21, in the impact moment supporting the object 16 in an area of this adja- cent the section which is hit by the impact tool 1. The supporting device 21 is connected with the movable part 4 and is arranged to be moved in the same direction and with essentially the same velocity as the object 16 at the impact moment.
The means 2,3,4 for moving the impact tool 1 in parallel with the object 16 in the moving direction x of the object, have the purpose of before the impact moment, from a starting position, accelerating the impact tool 1 to the velocity it has in the moving direction x of the object 16 at the impact moment, and after the
impact moment to slow down and return the impact tool 1 to the starting position. The impact tool 1 is in this connection moved together with the movable part 4 forth and back in parallel with the direction x. To synchronize the motions of the movable part 4 to the velocity of the object 16 and the length of the units to be cut, the valve device 2, via which the motions of the movable part 4 are controlled, is connected to a device 22 for sensing the position of the object 16. The sensing device 22 senses when the end of the object 16 which has passed the impact tool has reached a certain distance from the impact tool 1. The sensing device 22 is in this connection arranged to activate the valve device 2 to take a first position, in which it connects the second chamber 9 to the tank 15 and in which an acceleration of the movable part 4, including the impact tool 1 in the moving direc- tion x of the object 16 is achieved.
At or just after the impact moment, the valve device 2 is allowed or activated to be displaced from the first position to a second position, in which it controls the flow of the pressurized medium so that a slowing down and returning of the movable part 4 and the impact tool 1 is achieved. The activation of the valve device 2 could be associated either to the impulse of the sensor device 19 to the striking tool 17 or be associated to the sensing of the device-22 of a further displacement of the object 16 in its mov- ing direction x relative to the impact tool 1. In this embodiment the sensing device 22 is formed of an arm or a rocker, which via a wire or similar is connected to the valve device 2. When one end of the arm is hit by the end of the object 16 and is conveyed by this in the moving direction x, there is a mechanical influence on the valve device 2 via the wire 23, so that it is displaced to the first position, i. e. the acceleration position, see Fig 1. At a further forward conveying of the wire relative to the arm/rocker 22 the cutting of the object 16 is performed and the end of the object 16 ceases to influence the arm/rocker 22, which can go back to its initial position, see Fig 2. When the mechanical force displacing the valve device 2 to the first position no longer acts
on this, it will in this case automatically return to the second po- sition, in which the second chamber 9 is connected to the source 13. The automatic returning of the valve device 2 is here achieved by that a force seeking to put the valve device 2 to the second position is constantly applied to the valve device 2. Here this is achieved by that the valve device 2 comprises a chamber 24, which is constantly connected to the source 13 and exhibits a surface 25, against which the pressurized medium can operate to-displace the valve device 2 to the second position.
Thanks to the device according to the invention it is possible to achieve very fast reciprocating motions of the impact tool 1 and the movable part 4 in parallel with the moving direction x of the object 16. The maximum velocity of the impact tool in the direc- tion x can easily be controlled so that it is the highest, and es- sentially as high as the velocity of the object 16, at the impact moment. In connection with cutting of objects in the way de- scribed above, very even and fine cutting surfaces can be ob- tained at the same time as the cutting is done with very high velocity and a large number of cut units per time unit can be achieved.
Of course a range of alternative embodiments of the device ac- cording to the invention and the method according to the inven- tion will be apparent to a man skilled in the art. The invention should however be considered in its widest sense and be pro- tected according to what is defined in the enclosed claims with support from the description and the drawings.
It is for instance apparent that the sensing device 22 and its connection to the valve device 2 for the control of the latter can be varied in a plurality of ways within the scope of the invention.
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