SE543824C2 - A method and an apparatus for material forming and/or cutting - Google Patents

Abstract

The invention provides a method for material forming and/or cutting, by means of a tool (4) and a drive unit (1), the method comprising moving the drive unit (1) to provide kinetic energy to the tool (4), for the tool (4) to strike a work material (W), so as to form and/or cut the work material (W), wherein the tool (4) is operatively disassociated from the drive unit (1) before the tool (4) strikes the work material (W).

Description

1 A method and an apparatus for material forming and/or cutting TECHNICAL FIELD The invention relates to a method for material forming and/or cutting. The invention alsorelates to a computer program, a computer readable medium, a control unit, and anapparatus for material forming and/or cutting.

BACKGROUND The invention is advantageously used for High velocity forming (HVF) and/or cutting, butmay according to other embodiments of the invention be used for material forming and/orcutting involving other velocities than used for HVF. -HVF is herein also referred to asHigh velocity material forming. HVF of metals is also known as High velocity metalforming. High velocity cutting or high-speed cutting may also be called high-speedcrosscutting or high velocity crosscutting. ln conventional metal forming operations, a force is applied to the metal to be workedupon, by using simple hammer blow or a power press; the heavy tools used are moved ata relatively low velocity. Conventional techniques include methods such as Forging,Extrusion, Drawing, and Punching, etc. ln conventional metal cutting operations, theremany technologies available to cut metal, including machine technologies such as turning,milling, drilling, grinding, sawing. Among other technologies, there are alsowelding/burning technologies, such as burning by laser, oxy-fuel burning, and plasma.

HVF involves imparting a high kinetic energy to a tool, by giving it to a highly velocity,before it is made to hit a work piece. HVF includes methods such as hydraulic forming,eXplosive forming, electro hydraulic forming, and electromagnetic forming, for example bymeans of an electric motor. ln these forming processes a large amount of energy isapplied to the work piece during a very short interval of time. The velocities of HVF maytypically be at least 1 m/s, preferably at least 3 m/s, preferably at least 5 m/s. Forexample, the velocities of HVF may be 1-20 m/s, preferably, 3-15 m/s, preferably 5-15m/s. HVF may be regarded as a process in which the material shaping forces areobtained from kinetic energy, whereas, in conventional material forming, the materialforming forces are obtained from pressure, e.g. hydraulic pressure.

Similarly, as in HVF, high velocity cutting involves ímparting a high kinetic energy to acutting tool, by giving it a highly velocity, before it is made to hit and cut a work piece. Thevelocities of high velocity cutting may typically be at least 1 m/s, preferably at least 3 m/s,preferably at least 5 m/s. For example, the velocities of high velocity cutting may be 1-20m/s, preferably, 3-15 m/s, preferably 5-15 m/s.

An advantage of HVF is provided by the fact that many metals tend to deform morereadily under a very fast application oi a load. The strain distribution is much more uniformin a single operation of HVF as compared to conventional forming techniques. This resultsin making it easy to produce complex shapes without inducing unnecessary strains in thematerial. This allows forming of complex parts with close tolerances, and forming of alloysthat might not be formable by conventional metal forming. For example, HVF may be usedin the manufacturing of metal flow plates used in fuel cells. Such manufacturing requiressmall tolerances.

An advantage with high velocity cutting is that more efficient and simple methods inproduction-engineering terms can be used to obtain high measuring accuracy. Further,the time between strokes of the cutting tool can be made extremely short, resulting in ahigh production rate.

Another advantage with HVF and high velocity cutting is that, while the kinetic energy atool is linearly proportional to the mass of the tool, it is squarely proportional to the velocityof the tool, and therefore, compared to conventional metal forming, considerably lightertools may be used in HVF. lt is known, in HVF and high velocity cutting, to allow a plunger to be driven from a startposition by a hydraulic pressure in a first chamber, in order to transfer, by a stroke, a highkinetic energy to a tool, which in turn processes a work material, e.g. a workpiece. Toavoid excessive deformation in the tool at the strike from the plunger, the tool has topossess a relatively high stiffness, and thereby a relatively high mass. As a result, thesystem for driving the plunger needs to present a high capacity. Further, due to highkinetic energy, the plunger may strike the tool more than one time. This may happen if thework material rebound because of deformation at the strike by the tool and asconsequence, the work material strikes in turn the tool thereby pushing the tool towards 3 and in contact again with the plunger. This is an undesirable action. The plunger shouldonly hit the tool once, otherwise the forming and/or cutting of the workpiece may result inimpaired properties of the end product, such as weakening and unevenness, or evenfailure in the production.

There is also a desire to improve the control of the energy provided to a work material inHVF and high velocity cutting. An improved energy control may improve the nature of theprocess in the work material. Doing this may expand the applicability of HVF and highvelocity cutting further, e.g. to tasks with even smaller tolerances that those achieved by present HVF and high velocity cutting processes. if :1ï::°: f: ~:i:::;?~". t' \**~“^ :w f=*-:;1:“:'::.:ï=:.~“. E:':;;ï:f::f1~í ;:;t:~;'; i: ::E;.':"j.2<_::^ :.:;; f: wïfïï. A further desire is to eliminate the risk for that plunger hits/strikes the tool more than one time for each forming and/or cutting ofa product.

SUMMARY An object of the invention is to improve the control of the energy provided to a workmaterial in material forming and/or cutting, preferably in high velocity forming and highvelocity cutting. Another object of the invention is to reduce the plunger driving systemcapacity need in material forming and/or cutting, preferably in high velocity forming andhigh velocity cutting. A further object is to be able to provide a work material with smallertolerances that those achieved by present material forming and/or cutting processes, andpreferably in present high velocity and/or cutting processes. Yet a further object is toprevent the plunger to hit/strike the tool more than one time for each forming and/orcutting of a product.

The objects are achieved by a method according to claim 1. Thus, the objects areachieved by a method for material forming and/or cutting, by means of a tool and a driveunit, the method comprising accelerating the drive unit to provide kinetic energy to thetool, for the tool to strike a work material, so as to form and/or cut the work material,wherein the tool is operatively disassociated from the drive unit before the tool strikes thework material. The risk for rebound is decreased or prevented since the tool is operativelydisassociated from the drive unit. This improves properties of the end product, avoidingproblems with weakening and unevenness, as well as decreasing the risk for failure in the 4 production. The method is advantageously used for high velocity forming and/or cutting.The method may however also be used for other types of material forming and/or cutting.

That the tool is operatively disassociated from the drive unit may comprise that the tool isseparated from the drive unit.

When moving the drive unit comprises accelerating the drive unit, the tool may be incontact with the drive unit during at least a major part of the acceleration of the drive unitand kinetic energy may be provided to the tool. The tool and the drive unit may startaccelerating simultaneously. ln some embodiments however, the tool may not be incontact with the drive unit during an initial phase of the drive unit acceleration. instead, thedrive unit may come into contact with the tool after the initial phase, the tool remaining incontact with the drive unit during the remainder of the acceleration. For example, the toolmay start its acceleration before the drive unit has reached 50%, preferably 20%, morepreferably 10% of its maximum velocity. ln embodiments where the drive unit contacts thetool after the start of the drive unit acceleration, the drive unit and/or the tool, may beprovided with a damper for the contacting of the drive unit to the tool. ln some embodiments, wherein moving the drive unit comprises accelerating the driveunit, the drive unit is a plunger arranged to be driven by a hydraulic system. The plungermay be movably arranged in a cylinder housing. The cylinder housing may be mounted toa frame. The hydraulic system may comprise a first chamber for biasing the plungertowards the workpiece. The hydraulic system may comprise a second chamber for biasingthe plunger away from the workpiece. The first and second chambers may be formed bythe cylinder housing and the plunger. As detailed below, the second chamber may beprovided with system pressure of the hydraulic system during an entire striking process. lnalternative embodiments, the plunger may be arranged to be driven in some alternativemanner, for example by explosives, by electromagnetism, or by pneumatics.

The energy of the tool may be adjusted by adjusting the velocity and/or mass of the tool. ltis understood that a second tool may be present on the opposite side of the work material.The work material may be a workpiece, such as a solid piece of material, e.g. in the formof a sheet, for example in metal. The work material may alternatively be a material in some other form, e.g. on powder form.

The acceleration and velocity of the drive unit can be controlled with a high degree of « §L.-\~\ -\.>\'._ . ._ .M ut. . ._ ._._.\_. n . .._.\_.\,,,__..\ _ .:;.t\ __. Nu-:Lw _ 4' :;'.\.-\ =.-\.-\i IM.- c-i - .»ê.-h~~~>, .l .~.\..t ß .\...\-\\..~\~\.\ w o. ..~..\..~.\-\-.~- t U- ~l -..^\t v* <~'~\:\ *Ami -\~\.-= ä*k.. ,.. om. »e-W; «. . . . the tool being in contact with the drive unit during at least a major part of theacceleration of the drive unit, the invention allows for an improved control of theacceleration and the velocity of the tool. Thereby, the invention provides an improvedcontrol of the kinetic energy of the tool, and hence the energy provided to the workmaterial.

Embodiments of the invention provides for the drive unit and the tool to be accelerated with the same simultaneous acceleration. Thus, the invention involve-:s- a considerably slower acceleration of the tool, compared to the movement obtained byprocesses with a drive unit to tool strike as mentioned above. Thereby, there is no need toconsider the risk of excessive deformation of the tool caused by a strike from the driveunit. Therefore, the tool may possess a reduced stiffness, and thereby a reduced mass. lnaddition, where the drive unit is a plunger it may present a reduced mass, compared to aplunger in a process with a plunger to tool strike. As a result, the capacity of the systemfor driving the plunger may be reduced.

The tool is operatively disassociated from the drive unit. The tool is arranged tooperatively disassociate from the drive unit during a work material striking processinvolving the movement of the drive unit. The tool is arranged to operatively disassociatefrom the drive unit, before the tool strikes the work material. For example, where themoving the drive unit comprises accelerating the drive unit, the drive unit may be aplunger that accelerates upwards. The tool may be arranged to rest on top of the plunger,without any fastening elements fixing the tool to the plunger. Thereby, advantageousembodiments exemplified below, are enabled.

Preferably, the drive unit is decelerated, before the tool strikes the work material, so as forthe tool to separate from the drive unit before the tool strikes the work material. Thereby,the drive unit may continue towards the work material by means of inertia.

Preferably, the method comprises guiding the tool towards the work material, after the toolhas separated from the drive unit. ln some embodiments, the path of the tool may becontrolled by a guiding arrangement. ln some examples, the guiding arrangement 6 comprises a plurality of pins, which are fixed to the tool. However, alternatives arepossible. For example, a frame, surrounding the tool, or the path of the tool, may bearranged to guide the tool. Thereby, one or more guiding devices, which are fixed to thetool, may be arranged to engage with the frame while the tool moves along the frame. Theguiding of the tool allows an accurate positioning of the tool onto the work material.

The tool may be positioned, before providing kinetic energy to the tool by the movementof the drive unit, at a distance of at least 3 mm from the work material. Preferably the toolis at a distance of at least 5 mm from the work material. Most preferably the tool is at adistance of at least 8 mm from the work material. The preferred positioning of the toolrelative the work material can be provided in embodiments where the tool is in contactwith the plunger during at least a major part of the acceleration of the plunger as well as inembodiments, exemplified below, where the tool is stationary before providing kineticenergy to the tool by the movement of the drive unit, and moving the drive unit to providekinetic energy to the tool comprises striking the stationary tool with the drive unit.

The drive unit__is * * ggdecelerated so that the tool does not come into contact with the plunger again, until after the tool has stricken the work material. " “ drive unitvdoes not reach a position in which it will be in contact with the tool, when thetool is in contact with the work material. Thereby, the energy imparted to the workmaterial, for forming the work material, is provided by the tool, without any participation ofthe drive unit. Thus, the operatively disassociation or the separation may provide for thedrive unit being absent at the strike of the work material by the tool. Thereby, problems ofknown system, such as the risk of one or more repeated strokes by the drive unit, are eliminated.

As suggested, the plunger may be arranged to be driven by a hydraulic systemcomprising a first chamber for hydraulically biasing the plunger towards the work material.The method may comprise, for the acceleration of the plunger, the hydraulic system beingcontrolled so that hydraulic fluid is moved to the first chamber, wherein, for the plungerdeceleration, the hydraulic system is controlled so that the transport of hydraulic fluidtowards the first chamber is reduced, but high enough to avoid cavitation of the hydraulicfluid. Thereby, fluid cavitation, which may be harmful to the process, may be effectivelyavoided. 7 Preferably, where the plunger is arranged to be driven by a hydraulic system, the methodcomprising, for the deceleration, allowing a part of the plunger to enter a braking chamber,and allowing thereby hydraulic fluid to be trapped in the braking chamber, whereby anincreased pressure in the trapped fluid decelerates the plunger. For example, said part ofthe plunger may be a waist. Thus, where the plunger is arranged to be driven by ahydraulic system, the plunger may be provided with a waist, the method comprising, forthe deceleration, allowing the waist to enter a braking chamber, and allowing therebyhydraulic fluid to be trapped in the braking chamber, whereby an increased pressure inthe trapped fluid decelerates the plunger. Where a second chamber for biasing theplunger away from the work material is provided, as suggested above, the brakingchamber may be formed at an end of second chamber, in the direction towards the workmaterial. “the drive unit Preferably, moving the drive unit comprises accelerating the drive unit,is a plunger that is accelerated upwards. Hence, the tool is also accelerated upwards.Thereby, said contact of the tool with the plunger, during at least a major part oi theacceleration, may be provided by the tool resting on the plunger. Thereby, the tool may beheld by the plunger by gravity, and the acceleration. This simplifies the arrangement forthe striking process. lt should be noted however, that alternatively the plunger and the toolmay be accelerated in another direction, for example downwards, or sideways. ln some embodiments the tool is stationary, and moving the drive unit to provide kineticenergy to the tool comprises striking the stationary tool with the drive unit. The tool maybe stationary at distance above the plunger before the plunger strikes the tool.

Where the plunger is accelerated upwards, the method may comprise allowing the tool tofall back onto the plunger after the strike of the work material by the tool. Preferably, thefall of the tool is damped as it approaches the plunger. For this, a damping arrangementmay be provided, as exemplified below. This softens the impact when the tool comes intocontact with the plunger, which may reduce wear.

The method steps described above may form parts of a work material striking process.Where the plunger is arranged to be driven by a hydraulic system comprising a firstchamber for hydraulically biasing the plunger towards the work material, and a valvearrangement for controlling the pressure in the first chamber, the method may comprise 8 receiving signals indicative of one or more of the plunger position, the plunger velocity, theplunger acceleration, the tool position, the tool velocity, the tool acceleration, the pressurein the first chamber, one or more response times of the valve arrangement, the ambienttemperature, and a temperature of the hydraulic system oil. The method may furthercomprise storing at least some of the signals received during at least one work materialstriking process, and/or storing data provided as a result of processing of at least some ofthe signals received during at least one work material striking process, and adjusting, for afurther striking process, the control of the valve arrangement, based at least partly on thestored signals and/or the stored data. The control of the valve arrangement may also beadjusted based partly on current sensor signals during the further striking process.Thereby the timing of valve actuations during the striking process may be accurate, inview of circumstances such as the temperature and the aging of the apparatus.

According to an embodiment of the invention, the drive unit is a rotating unit comprising aprotrusion fixed to a rotor, the protrusion is rotated by rotation of the rotor to provide kinetic energy to the tool.

The objects are also reached with a computer program according to claim or a control unit according to claim computer readable medium according to claim The control unit may be provided as a single physical unit, or as a plurality of units,arranged to communicate with each other. lt should be noted that, although, in some embodiments, the method may be controlled bya control unit, in other embodiments, the method may be controlled mechanically. Forexample, the method may comprise hydraulically pressurizing a first chamber so as tobias the plunger towards the work material. The method may further comprise, for adeceleration of the plunger before the tool strikes the work material, allowing a part of theplunger to enter a braking chamber, and allowing thereby hydraulic fluid to be trapped inthe braking chamber, whereby an increased pressure in the trapped fluid decelerates theplunger. ln such embodiments, the step of controlling the hydraulic system so that thetransport of hydraulic fluid towards the first chamber is reduced, may be omitted.

The objects are also reached with an apparatus according to any one of claims Thus, the invention also provides an apparatus for material forming and/or cutting, bymeans of a tool and a drive unit, the apparatus being arranged to move the drive unit to 9 provide kinetic energy to the tool, for the tool to strike a work material, so as to form or cutthe work material, wherein the apparatus is arranged so as for the tool to be operativelydisassociated from the drive unit before the tool strikes the work material. Where movingthe drive unit comprises accelerating the drive unit, the apparatus may be arranged so asfor the tool to be in contact with the drive unit during at least a major part of theacceleration of the drive unit. Advantages with such an apparatus is understood from thedescription above of the method according to the invention. ln some embodiments, thetool is operatively disassociated or separable from the drive unit. The tool may bearranged to be operatively disassociated or separate from the drive unit during a workmaterial striking process involving the acceleration of the drive unit. The tool is arrangedto be operatively disassociated or separate from the drive unit, before the tool strikes thework material.

Preferably, the apparatus is arranged to decelerate the drive unit, before the tool strikesthe work material, so as for the tool to separate from the drive unit. Preferably, a guidingarrangement is arranged to guide the tool towards the work material, after the tool hasseparated from the drive unit. Preferably, the tool is arranged fixed, before providingkinetic energy to the tool by the movement of the drive unit, and the apparatus is arrangedto move the drive unit to provide kinetic energy to the tool and strike the fixed tool with thedrive unit. Preferably, when moving the drive unit comprises accelerating the drive unit,the drive unit is a plunger arranged to be driven by a hydraulic system, the apparatusbeing arranged to allow, for the deceleration, a part of the plunger to enter a brakingchamber, and to thereby allow hydraulic fluid to be trapped in the braking chamber. Saidpart of the plunger may be a waist. Thus, the plunger may be arranged to be driven by ahydraulic system, wherein the plunger is provided with a waist, the apparatus beingarranged to allow, for the deceleration, the waist to enter a braking chamber, and tothereby allow hydraulic fluid to be trapped in the braking chamber.

The invention also provides a method for material forming and/or cutting, by means of atool and a plunger, the method comprising accelerating the plunger to provide kineticenergy to the tool, for the tool to strike a work material, so as to form or cut the workmaterial, wherein said method steps form parts of a work material striking process,wherein the plunger is arranged to be driven by a hydraulic system comprising a firstchamber for hydraulically biasing the plunger towards the work material, and a valvearrangement for controlling the pressure in the first chamber, the method comprising receiving signals indicative of one or more of the plunger position, the plunger velocity, theplunger acceleration, the tool position, the tool velocity, the tool acceleration, the pressurein the first chamber, one or more response times of the valve arrangement, the ambienttemperature, and a temperature of the hydraulic system oil, the method further comprisingstoring at least some of the signals received during at least one work material strikingprocess, and/or storing data provided as a result of processing of at least some of thesignals received during at least one work material striking process, and adjusting, for afurther striking process, the control of the valve arrangement, based at least partly on thestored signals and/or the stored data.

An aspect of the invention provides a method for material forming and/or cutting, bymeans of a tool and a drive unit, the method comprising operating the drive unit to providekinetic energy to the tool, for the tool to strike a work material, so as to form and/or cut thework material, wherein that the tool is operatively dis-associated from the drive unit beforethe tool strikes the work material. The drive unit could be arranged to drive the toolelectromagnetically. The drive unit could comprise an electromagnetic spool arranged toprovide a magnetic field to drive the tool. Operatively dis-associating the tool from thedrive unit could comprise controlling, e.g. disengaging, the electromagnetic spool so as toeliminate the electromagnetic field. ln other embodiments, operating the drive unit couldcomprise moving the drive unit, as exemplified above.

A further aspect of the invention provides a method for material forming, by means of atool and a plunger, the method comprising accelerating the plunger to provide kineticenergy to the tool, for the tool to strike a work material, so as to form the work material,wherein the tool is in contact with the plunger during at least a major part of theacceleration of the plunger. The aspect may be embodied with any suitable exampledescribed or claimed herein. For example, the plunger may be decelerated, before thetool strikes the work material, so as for the tool to separate from the plunger. However, insome embodiments, the tool may be fixed to the plunger during the work material strikingprocess. Thereby, the tool may be fixed to the plunger by one or more releasablefastening elements, for example comprising bolts or similar. ln such embodiments, thetool may be fixed to the plunger when the tool strikes the work material.

Further advantages and advantageous features of the invention are disclosed in thefollowing description and in the dependent claims. which: 11 BRIEF DESCRIPTION OF THE DRAWINGS Below, embodiments ot the invention will be described with reference to the drawings, in tig. 1 shows an apparatus tor high velocity material torming and/or cuttingaccording to an embodiment ot the invention, tig. 2 is a flow diagram, depicting steps in a striking process ot the apparatus in tig. 1 tig. 3 shows an apparatus tor high velocity material torming and/or cuttingaccording to another embodiment ot the invention, and tig. 4 shows an apparatus tor high velocity material torming and/or cuttingaccording to yet another embodiment ot the invention.

DETAILED DESCRIPTION OF EIVIBODIIVIENTS OF THE INVENTION Fig. 1 shows an apparatus tor high velocity material torming and/or cutting according to anembodiment ot the invention. The apparatus comprises a trame 7. The trame is supported by a plurality ot support devices 10. An anvil 6 is tixed to the trame. ln this embodiment, the anvil 6 is tixed at the top ot the trame 7.

A tool, herein reterred to as a tixed tool 5, is mounted to the anvil. The tixed tool 5 is mounted to a lower side ot the anvil 6. A movable tool 4, described closer below, is located below the tixed tool 5. The tools 4, 5 present complementary surtaces tacing each other. A workpiece W is removably mounted to the tixed tool 5. The workpiece W may be mounted to the tixed tool 5 in any suitable manner, e.g. by clamping, orwith vacuum. The workpiece W could be ot a variety ot types, tor example a piece ot sheet metal. The movable tool 4 is herein also reterred to as a tirst tool. The tixed tool 5 is herein also reterred to as a second tool. lt should be noted that in some embodiments, also the second tool 5 could be movable. ln the embodiment shown in tig. 1, a drive assembly comprising a cylinder housing 2 is mounted to the frame 7. Further, the drive assembly comprises a drive unit, hereinatter called plunger 1 that is arranged in the cylinder housing 2. The plunger 1 is elongated, and has, as understood from the description below, a varying width along its longitudinal 12 axis. Preferably, any cross-section of the plunger is circular. The plunger 1 is arranged tomove towards and away from the fixed tool 5, as described closer below.

Before providing kinetic energy to the tool 4 by moving or accelerating the drive unit to ïthe tool, the tool may be positioned at a distance of at least 5 mm fromthe work material W. Preferably the tool is at a distance of at least 8 mm from the workmaterial W. Most preferably the tool is at a distance of at least 12 mm from the work material W.

The plunger 1 is arranged to be driven by a hydraulic system. The hydraulic systemcomprises a first chamber 17 for biasing the plunger towards the workpiece, and a secondchamber 18 for biasing the plunger away from the workpiece. The first and secondchambers are formed by the cylinder housing 2 and the plunger 1. ln this example, theworkpiece is above the plunger. Thus, in this example, the first chamber 17 is locatedbelow the second chamber 18.

The hydraulic system comprises a hydraulic pump 16, for increasing the pressure of ahydraulic fluid in the system, to what is herein referred to as a system pressure pS. Thehydraulic system further comprises a non-return valve 161 downstream of the hydraulicpump 16. The second chamber 18 is permanently connected to the system pressure pS.A hydraulic accumulator 13 is arranged to store hydraulic fluid at the system pressure. Asunderstood from the description below, the accumulator 13 is provided to achieve a rapidpressure increase in the first chamber at a plunger acceleration.

The hydraulic system further comprises a valve arrangement. The valve arrangementcomprises a first valve 11, and a second valve 12. The first valve 11 is connected to thefirst chamber 17 as well as to the second chamber 18. Also, the second valve 12 isconnected to the first chamber 17 as well as to the second chamber 18. The valvearrangement is controllable by an electronic control unit CU. The valves 11 , 12 arearranged to assume positions, so as to provide the steps described below. lt is noted herethat the valve arrangement 11, 12 can assume a position in which there is nocommunication between the first and second chambers 17, 18. The valves may beprovided with draining devices for end bushing leaks. 13 At opposite ends, the cylinder housing and the plunger form axial slide bearings 21, 22.Thereby one of said bearings 21 delimits the first chamber 17, and is herein referred to asa first chamber bearing 21. The other of said bearings 22 delimits the second chamber 18,and is herein referred to as a second chamber bearing 22. At each of the first and secondbearings 21, 22, draining conduits 9 are provided. An intermediate axial slide bearing 23is formed, by the cylinder housing and the plunger, between the first and secondchambers 17, 18. The bearings 21, 22, 23 allow an axial movement of the plunger 1 inrelation to the cylinder housing 2.

The three bearings 21, 22, 23 are circular, as seen in a direction which is parallel to themovement direction of the plunger. Also, the bearings have mutually different diameters.More generally, the bearings have mutually different areas. ln other words, circles formedby the circular shape of the bearings have mutually different areas. As a result, theeffective areas of the plunger 1 in the first and second chambers differ. ln this example,the area A23 of the intermediate bearing 23 is larger than the area A22 of the secondbearing 22. ln turn, the area A22 of the second bearing 22 is larger than the area A21 ofthe first bearing 21. Thereby, for balancing the plunger 1 in a static position, with thesystem pressure pS in the second chamber and an adjusted pressure pA in the firstchamber, the adjusted pressure pA has to be such that pA*(A23-A21) = pS*(A23-A22) + mp*g where mp is the mass of the plunger and g is the acceleration of gravity.

Reference is made also to fig. 2, depicting steps in a striking process of the apparatus infig. 1, involving a strike by the movable tool 4 against the workpiece W and the fixed tool Before the strike, the movable tool 4 rests S1 on top of the plunger 1. ln addition, beforethe strike, the movable tool 4 is at a distance from the fixed tool 5. Thereby, the plunger 1and the movable tool 4 are S1 in, what is herein referred to as, respective startingpositions.

The first valve 11 is in this example, a 4 way, 3 position valve. Before the strike, the firstvalve 11 is closed. Also, before the strike, the second chamber 18 is subjected to the 14 system pressure pS. Simultaneously, the second valve 12 is used to control the adjustedpressure pA in the first chamber 17, so as to keep the plunger 1 is a fixed position, asdetailed above. The second valve 12 is preferably a proportional valve. lt is understoodthat, to keep the plunger 1 stationary, the adjusted pressure pA of the first chamber 17may be lower than the system pressure pS. Thereby, the plunger may be kept in itsstarting position.

The acceleration of the plunger 1 is affected by adjusting the starting position of theplunger 1 and the system pressure pS.

Before the strike by the movable tool 4 is effected, the workpiece W is fixed S2 at thefixed tool 5. lt is understood that in the starting position, the movable tool 4 is at a distancefrom the workpiece W.

When the strike is to commence, the first valve 11 and the second valve 12 are moved toa respective position, in which the respective ports P, with the system pressure pS, isconnected with respective ports A, connected to the first chamber 17. Also, in the firstvalve 11, in said position, port B, with the system pressure pS, is connected to port T,connected to the first chamber 17. As a result, the plunger 1 will accelerate S3, with themovable tool 4, towards the workpiece W. Thereby, hydraulic fluid will flow to the firstchamber 17, from the second chamber 18, and from the accumulator 13. Meanwhile, thesecond chamber 18 is provided with the system pressure pS. A force F moving theplunger can be expressed as F = pS*(A22-A21) - mp*g where A21 and A22 are the areas of the first and second bearings 21, 22, respectively, asexplained above.

During the acceleration, the movable tool 4 remains resting on the plunger 1. Thereby, theplunger and the movable tool are accelerated with the same, simultaneous acceleration.

Subsequently, the plunger 1 is decelerated S4, or braked. The plunger deceleration iscommenced before the movable tool 4 has reached the workpiece W. For the plungerdeceleration the first valve 11 is moved to a closed position. Further, for the plunger deceleration, the second valve 12 is controlled so that the transport of hydraulic fluidtowards the first chamber 17 is reduced. Thereby, the second valve 12 is controlled sothat the transport of hydraulic fluid towards the first chamber 17 is relatively low. However,said control of the second valve 12 is such that transport of hydraulic fluid towards the firstchamber 17 is high enough to avoid cavitation of the hydraulic fluid.

During the deceleration, the second chamber 18 remains connected to the systempressure pS. The plunger 1 is provided with a waist 14, which is arranged to enter abraking chamber 15 at an end of the second chamber 18. ln this example, the brakingchamber 15 is formed at the upper end of the second chamber 18. Thereby, for theplunger deceleration, the waist 14 enters to braking chamber 15. This will trap hydraulicfluid in the braking chamber, and the increased pressure in the trapped fluid will serve tobrake the plunger 1. Thereby, the plunger velocity may be reduced to zero.

When the plunger deceleration commences, the movable tool 4 is separated S5 from theplunger 1. The movable tool continues S5, by its inertia, towards the workpiece W. lnembodiments of the invention, the velocity of the movable tool 4 at this stage may be forexample between 1-20 m/s. The velocity of the movable tool 4 at this stage may forexample be above 10 m/s, or even above 12 m/s. The velocity of the movable tool 4 maybe selected. The velocity of the movable tool 4 may be selected to optimize the strikingprocess.

The path of the movable tool 4 is controlled S5 by a guiding arrangement 3. ln thisexample, the guiding arrangement comprises a plurality of pins, which are fixed to themovable tool 4. The pins extend from the movable tool and through respective opening inthe frame 7.

Subsequently, the movable tool hits S6 the workpiece, and the kinetic energy of themovable tool 4 shapes the workpiece W between the movable tool 4 and the fixed tool 5.

When the shaping of the workpiece is finished, the movable tool 4 will bounce back. lt isunderstood that when the shaping of the workpiece is finished, the movable tool 4 will fallS7 towards the plunger 1. Thereby, the movable tool will be guided by the guidingarrangement 3. 16 To brake the return movement of the movable tool 4, as it approaches the plunger 1, adamping arrangement 8 is provided. ln this example, the damping arrangement comprisesa damper mounted to the plunger 1. The damper is mounted at the top end of the plunger.The damper may be of any suitable kind, e.g. hydraulic or pneumatic. Alternatively, or inaddition, the damper may comprise an elastic element, such as a plate spring. ln someembodiments, the damping arrangement may comprise a damper mounted to themovable tool. ln further embodiments, the damping arrangement may comprise a dampermounted to the frame 7. The damping arrangement will effectively brake S8 the returnmovement of the movable tool. The damping arrangement may also prevent bouncing ofthe movable tool at the end of its return movement. Thereby, the movable tool 4 may bebrought back to rest on the plunger in a controlled manner.

When the plunger 1 has been stopped, the first valve 11 is closed. Thereby, the secondchamber is still subjected to the system pressure pS. Simultaneously, the second valve 12is used to control the adjusted pressure pA in the first chamber 17, so as to move S9 theplunger 1 back to its starting position, from which a subsequent plunger acceleration canbe initiated. ln some embodiments, the tool contacts the plunger, after the shaping of the workpiece,and before the plunger is moved S9 back towards its starting position. However, in otherembodiments, the plunger 1 may be moved S9 back to its starting position, before the toolcontacts the plunger after the shaping of the workpiece. ln further embodiments, theplunger 1 may be moved a part of the way towards its starting position, before the toolcontacts the plunger after the shaping of the workpiece.

The control unit CU is arranged to receive signals from one or more sensors (not shown).Thereby, the signals received by the control unit CU may be indicative of one or more ofthe plunger position, the plunger velocity, the plunger acceleration, the movable toolposition, the movable tool velocity, the movable tool acceleration, the adjusted pressurepA, the response time(s) of the valve arrangement 11, 12, and the ambient temperature.

The control unit CU is arranged to register and/or process the signals received during atleast one striking process, preferably the signals received during a plurality of strikingprocesses, more preferably the signals received during every striking process. Theprocessed, or un-processed signals are stored to form historic striking process data. 17 The control unit CU is also arranged to adjust for, or during, a striking process, the controlof the valve arrangement 11, 12, based on the historic data, and current sensor signals.Thereby the timing of valve actuations during the striking process may be accurate, inview of circumstances such as the temperature and the aging of the apparatus. lt is to be understood that the present invention is not limited to the embodimentsdescribed above and illustrated in the drawings; rather, the skilled person will recognizethat many changes and modifications may be made within the scope of the appendedclaims.

Fig. 3 shows an apparatus for high velocity material forming and/or cutting according toanother embodiment of the invention. The same reference numerals are used for thecorresponding features as shown and described with reference to fig. 1.

A tool, herein referred to as a fixed tool (not shown), can be mounted to the anvil 6. Thefixed tool can be mounted to a lower side of the anvil 6. A movable tool 4, describedcloser below, is located below the fixed tool. The tools present complementary surfacesfacing each other. A workpiece W is removably mounted to the fixed tool. The workpieceW may be mounted to the fixed tool in any suitable manner, e.g. by clamping, or withvacuum. The workpiece W could be of a variety of types, for example a piece of sheetmetal. The movable tool 4 is herein also referred to as a first tool. The fixed tool is hereinalso referred to as a second tool. lt should be noted that in some embodiments, also thesecond tool could be movable.

A drive assembly comprising a cylinder housing 2 is mounted to a frame (not shown).Further, the drive assembly comprises a drive unit, hereinafter called plunger 1, that isarranged in the cylinder housing 2. The plunger 1 is elongated, and has, as understoodfrom the description below, a varying width along its longitudinal axis. Preferably, anycross-section of the plunger is circular. The plunger 1 is arranged to move towards andaway from the fixed tool, as described closer below.

Before providing kinetic energy to the tool 4 by moving or accelerating the drive unit tostrike the tool, the tool may be positioned at a distance of at least 3 mm from the work 18 material W. Preferably the tool is at a distance of at least 5 mm from the work material W.Most preferably the tool is at a distance of at least 8 mm from the work material W.

The plunger 1 is arranged to be driven by a hydraulic system. Similarly to the embodimentdescribed with reference to fig. 1, the hydraulic system comprises a first chamber forbiasing the plunger towards the workpiece, and a second chamber for biasing the plungeraway from the workpiece. The first and second chambers are formed by the cylinderhousing 2 and the plunger 1.

The hydraulic system as described above with reference to the embodiment shown in fig.1 may be applied for the drive unit shown in Fig._3.

As the movable plunger is driven towards the workpiece W, the plunger strikes the tool 4--.

Similarly to the embodiment in fig. 1, during the deceleration, the second chamberremains connected to the system pressure. The plunger 1 is provided with a waist 14,which is arranged to enter a braking chamber 15 at an end of the second chamber.Thereby, for the plunger deceleration, the waist 14 enters to braking chamber 15. This willtrap hydraulic fluid in the braking chamber, and the increased pressure in the trapped fluidwill serve to brake the plunger 1. Thereby, the plunger velocity may be reduced to zero.

The tool 4 may be separated from the plunger 1, when the latter strikes the former. Thestrike may serve to decelerate the plunger 1. When the plunger deceleration commences,the movable tool 4 is separated from the plunger 1. The movable tool continues, by itsinertia, towards the workpiece W.

Similarly to the embodiment in fig. 1, the path of the movable tool 4 is controlled by aguiding arrangement. The guiding arrangement may comprise a plurality of pins, whichare fixed to the movable tool 4. The pins extend from the movable tool and throughrespective opening in the frame.

The guiding arrangement for controlling the path of the movable tool 4 is not shown in theembodiment shown in fig. 3. ln the embodiment shown in fig. 3, the tool 4 is arrangedstationary, preferably controlled by the mentioned guiding arrangement, before providingkinetic energy to the tool 4 by the movement of the drive unit 1. The apparatus is arranged 19 to move the drive unit 1 to provide kinetic energy to the tool 4 by striking the stationarytool 4 with the drive unit 1.

Fig. 4 shows an apparatus for high velocity material forming and/or cutting according toyet another embodiment of the invention. The same reference numerals are used for thecorresponding features as shown and described with reference to figs. 1 and 3.

A tool, herein referred to as a fixed tool (not shown), can be mounted to the anvil 6. Thefixed tool can be mounted to a lower side of the anvil 6. A movable tool 4, describedcloser below, is located below the fixed tool. The tools present complementary surfacesfacing each other. A workpiece W is removably mounted to the fixed tool. The workpieceW may be mounted to the fixed tool in any suitable manner, e.g. by clamping, or withvacuum. The workpiece W could be of a variety of types, for example a piece of sheetmetal. The movable tool 4 is herein also referred to as a first tool. The fixed tool is hereinalso referred to as a second tool. lt should be noted that in some embodiments, also thesecond tool could be movable. ln the embodiment in Fig. 4, the drive unit is a rotating unit 1 comprising a protrusion 101fixed to a rotor 102. The protrusion 101 is rotated by rotation of the rotor to provide kineticenergy to the tool 4. ln this way the protrusion will strike the tool 4 repeatedly, for each revolution.

A guiding arrangement for controlling the path of the movable tool 4 is not shown in theembodiment shown in fig. 4, but a similar guiding arrangement as in fig. 1 can be used. lnthe embodiment shown in fig. 4, the tool 4 is arranged stationary, preferably controlled bythe mentioned guiding arrangement, before providing kinetic energy to the tool 4 by themovement of the rotating unit 1. The apparatus is arranged to move the rotating unit 1 toprovide kinetic energy to the tool 4 by striking the tool 4 with the protrusion projecting fromthe periphery of the rotating unit 1. When the rotating unit, comprising the protrusion fixedto the rotor, continues its rotation, the movable tool 4 is separated from the protrusion ofthe rotor. The movable tool 4 continues, by its inertia, towards the workpiece W. Hence,the tool 4 will be operatively disassociated from the rotating unit 1 before the tool 4 strikesthe work material W. The tool 4 is brought back to the fixed position, preferably controlledby the mentioned guiding arrangement, when the protrusion is in the position ready tostrike the tool again for the next revolution of the rotor. The protrusion will strike the tool 4repeatedly, for each revolution, until the rotating unit is stopped in a controlled manner.

Claims (13)

1.A method for material forming and/or cutting, by means of a tool (4) and a driveunit (1), the method comprising operating the drive unit (1) to provide kineticenergy to the tool (4), for the tool (4) to strike a work material (W), so as to formand/or cut the work material (W), wherein the tool (4) is operatively disassociatedfrom the drive unit (1) before the tool (4) strikes the work material (W),characterized in that operating the drive unit comprises moving the drive unit (1 ),wherein moving the drive unit comprises accelerating the drive unit, and the tool(4) is in contact with the drive unit (1) during at least a major part of theacceleration of the drive unit (1). or vvftterelra the tool let ts statloharv beforetärovidiattt kinetic enorm' to the tool (43 hv the movement ot the :drive unit ft t. andhtovtatct the drive unit lll to oroa/ide kiltetlc eherotf to the tool titt contorâees strâkth-:tthe stetšoharv tool l-t-t twith the drive uhit (t).

2. A method .aocordërtg to ctašrr: l, ' '

3. nn \ -\ '-\'

4. ,...f.r..; t ..-,\..«...».

5. talent-ide-hähetta-ettetoy-tothetoa-l--(4)-,-tot-the-teel-(4)--to--s-tttk-e-a--wo-tfh-tt-tate-tiat--tïitftt

6. (tåewherein the drive unit (1) is decelerated, before the tool (4) strikes the workmaterial (W), so as for the tool (4) to separate from the drive unit (1).

7. A method according to claim 2, comprising guiding the tool (4) towards the workmaterial (W), after the tool (4) has separated from the drive unit (1).

8. A method according to any one of claims 2-3, wherein the drive unit (1) isdecelerated so that the tool (4) does not come into contact with the drive unit (1)again, until after the tool (4) has struck the work material (W).

9. A method according to any one of claims 2-4, wherein moving the drive unitcomprises accelerating the drive unit, and the drive unit is a plunger (1) arrangedto be driven by a hydraulic system (11, 12, 13, 16, 17, 18) comprising a firstchamber (17) for hydraulically biasing the plunger (1) towards the work material

10. A method according to anv one of the nrecedšefo claims 84% 2 (W), wherein, for the acceleration of the plunger (1), the hydraulic system iscontrolled so that hydraulic fluid is moved to the first chamber (17), wherein, forthe plunger (1) deceleration, the hydraulic system is controlled so that thetransport of hydraulic fluid towards the first chamber (17) is reduced, but highenough to avoid cavitation of the hydraulic fluid. A method according to any one of claims 2-5, wherein moving the drive unitcomprises accelerating the drive unit, and the drive unit is a plunger (1) arrangedto be driven by a hydraulic system (11, 12, 13, 16, 17, 18), the method comprising,for the deceleration, allowing a part (14) of the plunger to enter a braking chamber(15), and allowing thereby hydraulic fluid to be trapped in the braking chamber,whereby an increased pressure in the trapped fluid decelerates the plunger (1). A method argcordšno to any one of tite preceding claims fer--r-naterial-fetrrrfirfçg- feel-å4)-et-r-šfæee-ffie-vveffk-frtateffâaf--í-šfäi),-e-št-ar=ae§et=feed»irf--that-eperatšffgr--fffe-drive' 2 1 t; ' g . ' f , f wherein the tool (4) is positioned, beforeproviding kinetic energy to the tool (4) by the movement of the drive unit (1 ), at adistance of at least 3 mm from the work material (W), preferably at a distance of atleast 5 mm from the work material (W), and most preferably a distance of at least 8 mm from the work material (W). A method according to any one of the preceding claims, wherein moving the driveunit comprises accelerating the drive unit, and the drive unit is a plunger (1) that isaccelerated upwards. A method according to claim 8, wherein the tool (4) is in contact with the plunger(1 ), during at least a major part of the acceleration, said contact is provided by thetool (4) resting on the plunger (1).

11.

12.

13. . \ .f \ , feel-å4;~-et-r-šlæee-fffe-vveffk-tï-æaterâai--í-W),-e-šf-aafaeêermed»in-thaf-eperatšafgg-fåfe-á-rive aceelerat-š-rtg--the-drive-urf-itï-arid-the-drive--erfit--is-a-plur-fger-(f-)--that--is-aeeelera-ted comprising allowing the tool (4) to fall back onto the plunger(1) after the strike of the work material (W) by the tool (4). A method according to claim 10, comprising damping the fall of the tool (4) as itapproaches the plunger (1 ). A method according to any one of claims 1-7, wherein moving the drive unitcomprises accelerating the drive unit, and the drive unit is a plunger (1) that is moved downwards. A method for material forming and/or cutting, by means of a tool (4) and a driveunit (1), the method comprising operating the drive unit (1) to provide kineticenergy to the tool (4), for the tool (4) to strike a work material (W), so as to formand/or cut the work material (W), wherein the tool (4) is operatively disassociatedfrom the drive unit (1) before the tool (4) strikes the work material (W),characterized in that operating the drive unit comprises moving the drive unit (1 ),wherein said method steps form parts of a work material striking process, whereinthe drive unit is a plunger (1) arranged to be driven by a hydraulic system (11, 12,13, 16, 17, 18) comprising a first chamber (17) for hydraulically biasing the plunger(1) towards the work material (W), and a valve arrangement (11 , 12) for controllingthe pressure in the first chamber, the method comprising receiving signalsindicative of one or more of the plunger position, the plunger velocity, the plungeracceleration, the tool position, the tool velocity, the tool acceleration, the pressure(pA) in the first chamber (17), one or more response times of the valvearrangement, the ambient temperature, and a temperature of the hydraulic systemoil, the method further comprising storing at least some of the signals receivedduring at least one work material (W) striking process, and/or storing data providedas a result of processing of at least some of the signals received during at leastone work material (W) striking process, and adjusting, for a further striking 4 process, the control of the valve arrangement (11, 12), based at least partly on thestored signals and/or the stored data. 44-.--A-n-s-etffstå-fier--rrfaterfai-ferrï-firig-arielier-etsttârfg3--ley-rf-fear-fs-af--a-teze:å--ieti--aræd-a-dr-š-v-e .'5“ \ ar-feifer--e-ut--tlze-werk--sf-fateršal--tillfä-;--fsfllft-erei-rr-the-feel-424-;~-is-eperetâveEy-räêeasseeiated ' s 44-).- . __________ __A computer program comprising program code means for performing thesteps of any one of claims f-áflåšflënwhen said program is run on a computer. f;3:2: .......... _ . A computer readable medium carrying a computer program comprisingprogram code means for performing the steps of any one of claims f-ifälß-mwhensaid program product is run on a computer. A control unit configured to perform the steps of the method according to any one of claims 5 \\\\\\\\\\ “An apparatus for material forming and/or cutting, by means of a tool (4)and a drive unit (1), the apparatus being arranged to operate the drive unit (1) toprovide kinetic energy to the tool (4), for the tool (4) to strike a work material (W),so as to form or cut the work material (W), wherein the apparatus is arranged soas for the tool (4) to be operatively disassociated from the drive unit (1) before thetool (4) strikes the work material (W), characterized in that the apparatus isarranged to operate the drive unit (1) by moving the drive unit (1) to provide thekinetic energy to the tool (4), wherein moving the drive unit comprises acceleratingthe drive unit, the apparatus being arranged so as for the tool (4) to be in contactwith the drive unit (1) during at least a major part of the acceleration of the driveunit (1 ), or vvfiereiri the tool (4) is arranged statioriarv. before brovitiâaiti kirietâr:energy' to the tool (rii hv the nioifemeiit ot the flrive isnit ft i. and the apparatusbeing arranoeci to incive the cirive unit (1) to provide kinetât: ener-:iv to the tooi (4)arid strike the statlonary' tool (43 with the drive ianit li i. ^\.'u . An apparatus aocordšn. to claim tïf. 'g ' »- (1-)--to-provide-tiwe--k-inetie-oriergy-te-êiie-êeeiâ--(- to decelerate the drive unit (1 ), before the tool (4) strikes the work material (W), soas for the tool (4) to separate from the drive unit (1 ). J f \\\\\\\\\\ “An apparatus according to claim wherein a guiding arrangement (3) is arranged to guide the tool (4) towards the work material (W), after the tool (4)has separated from the drive unit (1 ). \\\\\\\\\\ “An apparatus according to any one of claims wherein movingthe drive unit comprises accelerating the drive unit, and the drive unit (1) is a plunger, arranged to be driven by a hydraulic system (11, 12, 13, 16, 17, 18), theapparatus being arranged to allow, for the deceleration, a part (14) of the plunger 6 (1) to enter a braking chamber (15), and to thereby allow hydraulic iluid to betrapped in the braking chamber. . ________ __An apparatus afgcordino to anv one of ciairns 1720 tex--rriateršaå--tferflrn-š-rrg I arrar-:gefä--tfa-egsfereêe--ëha-drive--ur-iit--(-fr-}--teprev-ide-Kir-:et-ie--ar-s-er-gi-y--tfa--tiae--teei--afßfåï-šezr -» nn '\ ' \ . « .~ âay-rri-av-š-rig»the-aa=äve-urtit--š-i-i»te-provide-fri:e--kifietiffi-energy-ta.iï-ie--åeaâ--íßiëit--whereinmoving the drive unit comprises accelerating the drive unit, and the drive unit (1) isa plunger, the apparatus is arranged to provide said plunger (1) accelerationupwards. _______ __An apparatus according to claim , comprising a damping arrangement (8), arranged to dampen the fall of the tool (4) as it approaches the plunger (1). and--strike-the-statiaræary--teei--t43~-va=âth--tri-e-eirâve-tarwit(ii:- An apparatus paçggfjç;iggg"tggiajgg__:Ä_fia:I-materiai-í-arrrsing»aridvfer-euttšizgg--åaff -. ..J \ - ..- . f. . 1 .J >f-tatt-re-test-Q;ï-fer--tiie--teei»ifià-te-strii-ee-e i _: _) mg'\ _ , in which apparatus the drive unit isa rotating unit comprising a protrusion fixed to a rotor, which protrusion is arrangedto be rotated by rotation of the rotor to provide kinetic energy to the tool (4). _______ “An apparatus according to any one of claims -t-âë-»íïš-êt 12-23, the apparatuscomprising a control unit according to claim