Patent Application
20250128312
The invention relates to a process for the fine blanking of workpieces from a starting material in a fine blanking press in which the starting material is clamped between a punch guiding plate and a blanking plate and also between a punch guided in the punch guiding plate and a counter holder guided in the blanking plate and the unit comprising the punch and the counter holder is moved relative to the unit comprising the punch guiding plate and the blanking plate, whereby the workpiece is displaced with respect to the starting material along the blanking gap formed between the blanking plate and the counter holder, in particular is cut out from the starting material, while lubricant is applied into the active zone between the blanking plate and the workpiece.
The invention also relates to a fine blanking press for the fine blanking of workpieces from a starting material, comprising a punch guiding plate and a blanking plate and also a punch guided in the punch guiding plate and a counter holder guided in the blanking plate, with which a starting material can be clamped between the punch guiding plate and the blanking plate and also between the punch guided in the punch guiding plate and the counter holder guided in the blanking plate and the unit comprising the punch and the counter holder can be moved relative to the unit comprising the punch guiding plate and the blanking plate, whereby the workpiece can be displaced with respect to the starting material along the blanking gap formed between the blanking plate and the counter holder, in particular can be cut out from the starting material, while lubricant can be applied into the active zone between the blanking plate and the workpiece.
Fine blanking presses and processes for fine blanking are generally known in the prior art.
In the prior art, as well as in the invention, the starting material may for example take the form of a strip, for example be formed as a steel sheet. In this case, the workpiece is usually completely cut out from the starting material.
In the prior art, as in the invention, the starting material may however also already be a workpiece previously cut out from a metal sheet, from which a partial region is again cut out or which undergoes forming according to the steps mentioned above. Such a process step may be carried out for example in a progressive die of a fine blanking press.
The said relative movement in this case takes place in the clamped state, in particular in which an existing clamping force is therefore applied to the starting material between the elements of the two respective units during the movement and the relative movement between the units is carried out with a cutting force or forming force.
The said workpiece is a partial region of the starting material which is either cut out from a remaining part of the starting material or is at least displaced with respect to a remaining part of the starting material. In the latter case, the workpiece remains connected to the remaining part of the starting material.
The said active zone is the blanking gap, in particular a region of the blanking gap adjacent to the surface of the blanking plate on which the starting material rests, and/or the blanking plate surface which is facing into the blanking gap, preferably the region of the blanking plate surface near the starting material which is facing into the blanking gap, in particular therefore is arranged opposite the counter holder, and along which the workpiece is moved during the relative movement. The active zone is thus the blanking gap and/or a partial region of the surface of the blanking plate which extends in the direction of movement and which, lying opposite the counter holder, borders the blanking gap. When viewed in the direction of the stroke (the direction of relative movement), the active zone may be smaller than the entire length of the blanking gap considered in the direction of the stroke. In particular, the length of the active zone considered in the direction of the stroke may be less than the distance of the stroke or equal to the distance of the stroke of the two aforementioned units relative to one another or may be limited to the material thickness of the starting material considered in the direction of the stroke.
Lubricant is applied into this active zone to reduce friction and improve the quality on those regions of the surface of the workpiece or the starting material that arise during the fine blanking operation with the blanking plate and come into contact with the blanking plate.
According to the prior art up to now, the application takes place by the lubricant being applied to the starting material before the fine blanking operation, so that the lubricant is transferred into the active zone by the starting material. For this purpose, up to now the lubricant has to be applied over a large area, for example by spraying, at least to that side of the starting material which is facing the blanking plate and the counter holder. This produces high lubricant consumption because regions of the starting material that do not lie in or enter the active zone during the fine blanking process are also covered with lubricant.
Against this background, the object of the invention is to improve the feeding of lubricant into the active zone, in particular to save lubricant and to restrict the distribution of lubricant on the workpiece.
According to the invention, this object is achieved in that, in a process of the type mentioned at the beginning, the lubricant is fed to the active zone through the blanking gap between the blanking plate and the counter holder. The lubricant is thus fed through the blanking gap parallel to or in the direction of the direction of movement of the counter holder.
In a fine blanking press of the said type, the object is achieved in that the fine blanking press comprises a device with which lubricant can be fed to the active zone through the blanking gap between the blanking plate and the counter holder.
According to the invention, this achieves the effect that lubricant is only applied where it is required during the fine blanking operation, to be specific in the blanking gap and/or on the regions of the surface of the workpiece which during the said relative movement come into increasing contact with the regions of the surface of the blanking plate which border the blanking gap. Distribution of lubricant to other surface regions can thus be effectively prevented and accordingly the amount of lubricant required can be reduced.
Preferably, the invention may provide here that the lubricant is fed into the active zone through grooves or slots, preferably grooves or slots extending at least in some regions in the direction of the relative movement which are arranged in the surface of the blanking plate that is facing the opposite surface of the counter holder and/or arranged in the surface of the counter holder that is facing the opposite surface of the blanking plate. Thus channels which are bordered by the slot or groove and the surface of the opposite element can be formed.
The opposing surfaces are preferably meant to be those which form the blanking gap between them. Grooves/slots which are formed in both surfaces may preferably be arranged offset from one another.
It is particularly preferred if such grooves or slots are not formed in the surface of the blanking plate, but only in the surface of the counter holder which, considered in the direction of the stroke, is made to extend between its lower face and upper face and borders the blanking gap on the side of the counter holder. In this case, the grooves are prevented from impairing the surface quality at the cut edge/cut surface of the workpiece during the fine blanking.
Irrespective of whether the grooves or slots are arranged in the surface of the counter holder or in the surface of the blanking plate, in a first preferred embodiment it is provided that the grooves/slots each extend over the substantially entire length of the surface considered in the direction of the stroke.
In a second preferred embodiment it is provided that the set of all the grooves/slots extending in the direction of the stroke is divided into at least two groups of grooves/slots, with the grooves/slots of a respective group each extending only over a (in particular in each case another) partial region of the entire length of the surface considered in the direction of the stroke.
The grooves/slots in two adjacent groups that follow one another in the direction of the stroke are in this case each connected by a circumferential groove/slot running in the circumferential direction around the direction of the stroke in the surface. It is also preferred that the slots/grooves of different groups that run in the direction of the stroke may have an offset in relation to one another in this circumferential direction.
Preferably, in the first or second embodiment the invention provides that the grooves/slots running in the direction of the stroke, in particular the last group in the direction of the stroke located in the direction of the workpiece, open into a circumferential slot/circumferential groove which has been introduced into the surface at the end of the surface which, considered in the direction of the stroke, is facing the workpiece, in the circumferential direction around the direction of the stroke, and is open in the direction of the workpiece. This circumferential groove thus lies at the end of the blanking gap which is facing the workpiece and ensures that the lubricant can distribute itself very easily along the blanking gap. The invention preferably provides that the lubricant is conveyed through the blanking gap, in particular in the direction of the starting material, by pressurizing the lubricant, for which purpose arranged in the fine blanking press, in particular in the lower die part thereof, which comprises the blanking plate and the counter holder movably mounted therein, there is a spatial region which is filled with lubricant and can be subjected to pressure or is subjected to pressure during the blanking operation and into which the blanking gap opens, in particular into which the grooves/slots open, or which is connected to the active zone via the blanking gap, in particular via the slots/grooves that are preferably made to extend therein.
Pressurization for conveying the lubricant through the blanking gap while the said relative movement of the units is being carried out can be performed by any device which is suitable for increasing the pressure in the spatial region temporarily during the relative movement, in particular only during the time phase in which the counter holder enters the blanking plate, in particular away from the starting material.
Such a device may be formed for example by a cyclically operated pump, which during this entering movement causes the necessary pressure for conveying the lubricant through the blanking gap into the active zone.
It is particularly preferably provided in the invention that at least part of the pressure required for the feeding, or the required pressure completely or at least predominantly, is generated by the movement of the counter holder into a spatial region having/guiding the lubricant, in particular the aforementioned spatial region which is arranged on the side of the counter holder facing away from the starting material, in particular is arranged directly behind it. Preferably, the counter holder may form such a piston which is movable in this spatial region and thereby changes the volume of the spatial region.
For example, the lubricant in this spatial region may initially be at a first pressure level, in particular which is not yet sufficient to convey the lubricant into the active zone, while the commencing movement of the counter holder causes it to be moved in the direction of the spatial region, in particular therefore in a direction in which the volume of the spatial region is reduced, and thereby produces an increase in the pressure of the lubricant as a result of its compression in the spatial region for the period of time of its movement directed into the spatial region, so that the pressure level is raised, in particular to a level which is sufficient to convey lubricant, in particular in sufficient quantity, through the blanking gap into the active zone.
Preferably, it is provided that the pressure is generated during and/or by displacement of the lubricant out of the spatial region in the direction of a lubricant reservoir against the effect of the line resistance in at least one line formed between the lubricant reservoir and the spatial region, with the spatial region being supplied with lubricant from the lubricant reservoir.
Thus, although the pressure increase is caused by the compression of the lubricant, this does not inhibitively counter the movement of the counter holder, but only has a pressure-increasing effect, since the further movement of the counter holder by the displacement of the lubricant in the direction of the lubricant reservoir remains possible.
The supplying of lubricant to the spatial region may be performed for example by a pump or else by the lubricant reservoir being designed as a pressure accumulator, the pressurization of which feeds lubricant to the spatial region.
By displacing the lubricant in the direction of a lubricant reservoir, it can be taken into account that in conventional design configurations the volume of lubricant displaced in the spatial region by the movement of the counter holder is greater than the volume required in the active zone.
Thus, by the movement of the counter holder in the direction of the spatial region, in particular therefore in a direction reducing the volume of the spatial region, a part, in particular a predominant part, of the displaced lubricant volume is displaced in the direction of the lubricant reservoir and another part, in particular a smaller part, of the lubricant is displaced into the active zone.
The invention may preferably provide here that the displacement of the lubricant out of the spatial region in the direction of the lubricant reservoir takes place by at least one throttle valve, in particular by means of which the level of the pressure generated can be adjusted. Such a throttle valve is in this case preferably arranged in at least one line which runs between the lubricant reservoir and the spatial region and connects the two.
The invention may in this case preferably provide that the throttle valve only comes into effect, preferably is only flowed through, when lubricant is displaced out of the spatial region in the direction of the lubricant reservoir, thus for the purpose of the required pressure build-up, but the throttle valve preferably does not come into effect, in particular is flowed around in the bypass, when lubricant is conveyed from the lubricant reservoir in the direction of the spatial region. For this purpose, a combination of a throttle valve and a check valve connected in parallel may be used for example.
The invention preferably provides that the lubricant is circulated between the lubricant reservoir and the spatial region by means of at least one pump.
In such an embodiment it may preferably be provided that the lubricant is passed through the blanking plate by means of the at least one line, in particular by means of the supply line and return line of the circuit.
A device for conveying the lubricant through the blanking gap to the active zone is preferred to be at least partially formed in a lower die part, which comprises the blanking plate and the counter holder, and also the spatial region which is filled, or at least can be filled, with lubricant, into which the counter holder is displaced, in particular which is connected in the circulatory system with the lubricant reservoir.
The invention may also preferably that provide that, when there is a movement of the counter holder into the spatial region, the lubricant is displaced into the lubricant reservoir by a throttle valve in the return line between the spatial region and the lubricant reservoir, while a check valve arranged in the supply line closes as a result of the pressure or flow generated in the lubricant by the counter holder.
This ensures that the lubricant is not forced back with the full line cross section in the direction of the pump during the movement of the counter holder into the spatial region, but that the lubricant flow takes place at least also, or solely, via the throttle valve in the return line.
It may also be provided that, when there is a movement of the counter holder into the spatial region, the lubricant is also displaced into the lubricant reservoir by a throttle valve which is in the supply line between the spatial region and the pump and lies parallel to the closing/closed check valve in the supply line.
This has the effect that a return flow of lubricant to the lubricant reservoir with the required pressure generation can also be produced in the supply line, while however the lubricant can flow through the opened check valve to the spatial region while bypassing the throttle valve in the supply line, for example caused by the pump or in the return stroke of the counter holder out of the spatial region.
In the return stroke of the counter holder away from the spatial region in the direction of the initial position, in particular causing an increase in the volume of the spatial region, lubricant may flow through the at least one open check valve out of the lubricant reservoir into the spatial region, in particular with the return stroke taking place by pressure bolts which pass through the spatial region and act on the counter holder.
The return stroke can thus take place as usual in a fine blanking press. It may also be provided to perform, or at least assist, the return stroke by the pressurized lubricant.
In a preferred development it may be provided that, also on the punch side, wear of the punch is reduced, in particular in the regions of the punch which contact the remaining part of the starting material during a stroke.
For this purpose, it is preferably provided that the fine blanking press comprises a device with which lubricant can be guided into the gap present between the punch guiding plate and the punch, in particular can be guided through this gap in the direction of the starting material.
It is also preferred that the gap between the punch and the punch guiding plate is subjected to lubricant, in particular only by the effect of gravity on the lubricant, which is stored in a lubricant reservoir, which surrounds the part of the punch protruding from the punch guiding plate, in particular on the side of the punch guiding plate facing away from the starting material/the blanking plate. Preferably, the reservoir is open to the atmospheric surroundings, in particular so that there is no driving pressure potential that acts on the lubricant.
The lubricant reservoir is preferably arranged around the punch in the form of a frame/ring, with the radially outward facing punch outer surface forming a wall of the reservoir which can move with the stroke, by which means, in addition to the effect of gravity, lubricant is also entrained into the said gap. Through the gap, the lubricant thus reaches the radial outer surface of the punch close to its axial end face with which the starting material is contacted, and has a friction-reducing effect there.
The invention may then provide that the reservoir is replenished with lubricant, for example depending on consumption or continuously.
Exemplary embodiments of the invention are explained with reference to the following figures.
The partial region of a fine blanking press essential for the invention can be seen in the figures, without the drive units being shown. The figures here show a die 1, 2, which is divided into an upper die part 1 and a lower die part 2.
Between these two die parts 1, 2, a starting material 3, here in the form of a strip, is introduced, for example a steel strip, from which workpieces 3a are cut out.
For the blanking process, in the usual known manner in fine blanking presses, the starting material 3 is on the one hand clamped between the punch guiding plate 5 and the blanking plate 6. These two elements clamp for example the region of the starting material that remains in the starting material during the blanking operation. The starting material is on the other hand clamped between the punch 4 and the counter holder 7. The region clamped by these elements 4, 7 is for example the one which is cut out from the starting material 3 during the blanking operation, or is displaced with respect to it, and forms the workpiece 3a.
The blanking operation itself is produced by the fact that the unit comprising the punch 4 and the counter holder 7 is moved relative to the unit comprising the punch guiding plate 5 and the blanking plate 6, according to
Along the blanking gap 6a formed between the blanking plate 6 and the counter holder 7 movable downward therein, the workpiece 3a is displaced out of the plane of the starting material 3 and, provided that the movement of the counter holder 7 is longer than the thickness of the starting material 3, is cut out from it, otherwise only undergoes forming.
The invention provides here that in this embodiment a spatial region 13a filled with lubricant 13 is provided under the counter holder 7. During the movement of the clamped unit comprising the punch 4 and the counter holder 7 away from the plane of the starting material 3, the counter holder 7 is moved into this spatial region 13a and compresses the lubricant 13 there, so that, as a result of the pressure increase caused by this, the lubricant 13 is at least partially displaced counter to the current movement of the counter holder 7 through the blanking gap 6a into the active zone 18. In this way, the application of the lubricant 13 can be achieved precisely in the active zone 18, because the active zone 18 is formed in effect by the upper end of the blanking gap 6a, in particular on the side of the blanking plate 6 and/or by the surface thereof facing into the blanking gap. The workpiece 3a increasingly comes into contact with this region of the blanking plate 6 during the displacement.
The displacement of the lubricant 13 out of the spatial region 13a through the blanking gap 6a can be facilitated by channels through which the lubricant 13 can be conveyed by the pressure being formed in the blanking gap 6a. Such channels are preferably formed by grooves/slots in the surface of the counter holder 7 which is facing into the blanking gap 6a, in particular therefore lies parallel to the direction of movement. Such grooves/slots thus also open out into the spatial region 13a.
Here, the embodiment shown is such that, with a pump 16, the lubricant 13 is pumped out of a lubricant reservoir 17 into the spatial region 13a via the supply line 14 and out of the spatial region back into the lubricant reservoir 17 through the return line 15. There is therefore a lubricant circuit, in particular with the lubricant 13 being pumped in a circuit independently of a stroke movement of the fine blanking press.
By the movement of the counter holder 7, lubricant 13 can then also be displaced back out of the spatial region 13a into the lubricant reservoir 17 when the counter holder 7 moves into the spatial region 13a. Furthermore, during the reverse movement out of the spatial region 13a, the lubricant 13 can be drawn out of the lubricant reservoir 17, in particular with the filling of the spatial region 13a with the lubricant 13 also being assisted by the pump 16.
In order to achieve a sufficiently high pressure required for the displacement of the lubricant 13 into the active zone 18, it is provided that the displacement of the lubricant 13 out of the spatial region 13a in the direction of the lubricant reservoir 17 both in the supply line 14 and in the return line 15 takes place by a preferably adjustable throttle valve 11, 12.
Connected in parallel here with the respective throttle valve there is in each case a check valve, which closes during the stroke movement of the counter holder 7 into the spatial region 13a and thus ensures that the lubricant 13 can only flow through the throttle valves 11, 12. During the return stroke of the counter holder 7, therefore out of the spatial region 13a, in particular for the purpose of ejecting the workpiece 3a, however, the check valves open and allow a return flow of the lubricant in the spatial region 13a which is unaffected by the throttle valves 11, 12. The throttle valves thus only have a throttling effect on the lubricant 13 during the here downwardly directed stroke of the counter holder 7, but not during the time of the upwardly directed return stroke of the counter holder 7.
The return stroke can be brought about here by a return stroke force which pushes the counter holder 7 out of the spatial region 13a being exerted via the pressure bolts 8 on the counter holder 7 by means of a drive not shown. This causes the volume of the spatial region 13a to increase again and lubricant 13 to be sucked into it, in particular assisted by the action of the pump 16.
The spatial region 13a is bounded here in the upward direction by the lower face of the counter holder 7, to the side by the wall of the blanking plate 6, which on its side borders the blanking gap 6a, and in the downward direction by a plate which is arranged in the lower die part 2 and led through which are the pressure bolts 8, in particular sealed with seals 10.
The blanking plate 6 may, in particular on the underside, be sealed with respect to the aforementioned plate with a seal 9, in order in this way to prevent the lubricant 13 from passing between the blanking plate 6 and the said plate as a result of the built-up pressure.
The device of the fine blanking press for feeding lubricant 13 through the blanking gap 6a into the active zone 18 is here partially formed in the lower die part 2, to be specific by the line regions in the blanking plate 6 and the spatial region 13a, and partially externally therefrom by the pump and the lubricant reservoir 17, and if applicable the throttle valves 11 and check valves.
By contrast with the prior art, the invention has the effect that, with each stroke of the counter holder 7 causing the cutting, here in the downward direction, the lubricant 13 is only applied into the active zone 18, therefore precisely into the region where the lubricant is required. Excess application can thus be avoided.
In order to realize this, arranged over the punch guiding plate 5, in particular also over a punch guiding pressure plate 19, which rests on the punch guiding plate 5, there is a lubricant reservoir 21, which surrounds the punch 4 in the form of a frame/ring, in particular its part protruding upward out of the punch guiding plate 5/punch guiding pressure plate 19, in particular radially outward around the punch 4.
Thus, the radially outwardly facing wall of the punch 4 is a movable wall region which bounds the said reservoir 21 in the radially inward direction and is wetted by the lubricant 13. The reservoir 21 may be bounded radially outwardly by a limiting ring 20. Alternatively, the reservoir may also be arranged as a ring-shaped/frame-shaped recess at the top of the punch guiding plate 5 or the punch guiding pressure plate 20.
The reservoir 21 is preferably open to the atmosphere, so that lubricant 13 is preferably only guided by the effect of gravity and/or by the movement of the punch 4 itself in the gap 5a between the punch 4 and the punch guiding plate 5, in particular is guided through this gap 5a down to the surface of the starting material. Thus, the lubricant 13 can get into the regions where the punch 4 and the remaining part of the starting material 3 contact one another and reduce the friction and wear of the punch 4 there.
| Number | Date | Country | Kind |
|---|---|---|---|
| 23204705.0 | Oct 2023 | EP | regional |
