Abstract
The method for the stepwise production and advancing of sand mold parts in a mold-string foundry plant comprising a station (1) for making mold parts, a pouring station (3) and a conveyor (2) for stepwise advancing of mold parts (101-109) from said station (1) for making mold parts towards said pouring station (3), includes the step of double indexing the mold parts using a first, moveable, part (21) of the conveyor. By double indexing the mold string, the time during which pouring into the molds has to be interrupted can be reduced.
Claims
1. Method for the stepwise production and advancing of sand mould parts in a mould-string foundry plant comprising a station for making mould parts, a pouring station and a conveyor for stepwise advancing of mould parts from said station for making mould parts towards said pouring station, said conveyor comprising a first part that is movable to displace mould parts from the station for making mould parts towards the pouring station, the method comprising producing a plurality of moulds parts in the station for making mould parts and placing said mould parts on the conveyor in order to form a mould string on the conveyor, and forwarding the mould parts towards the pouring station using the conveyor, the method comprising the steps of, repetitively and sequentially, (a) producing a first mould part of a pair of two subsequent mould parts; (b) placing said mould part on the conveyor; (c) producing a second mould part of said pair of two subsequent mould parts; (d) placing also said second mould part on the conveyor; (e) optionally producing at least one further mould part and placing said further mould part on the conveyor; (f) displacing the mould string a distance corresponding to at least two mould part widths, so as to position at least two new moulds to be filled in correspondence with the pouring station, wherein step (f) is carried out by displacing said first part of the conveyor; wherein step (f) is carried out without using any squeeze plate or rear plate of the station for making mould parts to push the mould string in-sync with movement of said first part of the conveyor for displacing the mould string said distance corresponding to at least two mould part widths.
2. Method according to claim 1, comprising the step of, after step (f), retaining the mould string using first retaining means to prevent mould parts from being displaced towards the station for making mould parts during pouring at the pouring station.
3. Method according to claim 2, wherein said first retaining means are arranged so as not to be horizontally displaced with said first part of the conveyor, and to interact with the mould string at a position between the pouring station and the station for making mould parts.
4. Method according to claim 2, wherein said first retaining means are arranged to be displaced together with said first part of the conveyor.
5. Method according to claim 2, wherein said first retaining means are arranged to retain the mould string by applying pressure to opposite lateral surfaces of a mould part.
6. Method according as in claim 2, comprising the step of retaining mould parts when delivered from the station for making mould parts, using second retaining means arranged to retain a mould part to prevent it from being pulled back towards the station for making mould parts, when a press plate used for delivering the mould part to the conveyor is returning towards the station for making mould parts.
7. Method according as in claim 1, wherein the conveyor comprises said first part and a second part, both of said first part and second part being moveable in the vertical direction between an upper position in which the mould parts are in contact with the corresponding part of the conveyor so that said part of the conveyor supports the mould parts, and a lower position in which the mould parts are not supported by the respective part of the conveyor.
8. Method according to claim 7, wherein said first part and second part are coordinated so that while the method is carried out, at least one of said first part and second part are in the upper position, so as to maintain the mould string at a constant height.
9. Method according to claim 7, wherein said second part is in the lower position while said first part is being displaced in step (f).
10. Method for the stepwise production and advancing of sand mould parts in a mould-string foundry plant comprising a station for making mould parts, a pouring station and a conveyor for stepwise advancing of mould parts from said station for making mould parts towards said pouring station, said conveyor comprising a first part that is movable to displace mould parts from the station for making mould parts towards the pouring station, the method comprising producing a plurality of mould parts in the station for making mould parts and placing said mould parts on the conveyor in order to form a mould string on the conveyor, and forwarding the mould parts towards the pouring station using the conveyor, the method comprising the steps of, repetitively and sequentially, (a) producing a first mould part of a pair of two subsequent mould parts; (b) placing said mould part on the conveyor; (c) producing a second mould part of said pair of two subsequent mould parts; (d) placing also said second mould part on the conveyor; (e) optionally producing at least one further mould part and placing said further mould part on the conveyor; (f) displacing the mould string a distance corresponding to at least two mould part widths, so as to position at least two new moulds to be filled in correspondence with the pouring station, wherein step (f) is carried out by displacing said first part of the conveyor; wherein the station for making mould parts includes a mould part making apparatus comprising a moulding chamber in which mould parts are made by pressing sand between a front plate and a rear plate, said rear plate being horizontally displaceable with a stroke so as to push a finished mould part out of the moulding chamber and onto the conveyor, wherein during steps (a)-(e), the rear plate is repetitively displaced with the same stroke.
11. Method according to claim 10, comprising the step of, after step (f), retaining the mould string using first retaining means to prevent mould parts from being displaced towards the station for making mould parts during pouring at the pouring station.
12. Method according to claim 11, wherein said first retaining means are arranged so as not to be horizontally displaced with said first part of the conveyor, and to interact with the mould string at a position between the pouring station and the station for making mould parts.
13. Method according to claim 11, wherein said first retaining means are arranged to be displaced together with said first part of the conveyor.
14. Method according to claim 11, wherein said first retaining means are arranged to retain the mould string by applying pressure to opposite lateral surfaces of a mould part.
15. Method according as claim 11, comprising the step of retaining mould parts when delivered from the station for making mould parts, using second retaining means arranged to retain a mould part to prevent it from being pulled back towards the station for making mould parts, when a press plate used for delivering the mould part to the conveyor is returning towards the station for making mould parts.
16. Method according as in claim 10, wherein the conveyor comprises said first part and a second part, both of said first part and second part being moveable in the vertical direction between an upper position in which the mould parts are in contact with the corresponding part of the conveyor so that said part of the conveyor supports the mould parts, and a lower position in which the mould parts are not supported by the respective part of the conveyor.
17. Method according to claim 16, wherein said first part and second part are coordinated so that while the method is carried out, at least one of said first part and second part are in the upper position, so as to maintain the mould string at a constant height.
18. Method according to claim 16, wherein said second part is in the lower position while said first part is being displaced in step (f).
19. Method for the stepwise production and advancing of mould parts in a mould-string foundry plant, said plant comprising a station for making mould parts, a pouring station and a conveyor for stepwise advancing of mould parts from said station for making mould parts towards said pouring station, said conveyor comprising a first part that is movable to displace mould parts towards the pouring station, the method comprising producing a plurality of mould parts in the station for making mould parts, and placing said mould parts on the conveyor in order to form a mould string on the conveyor, and forwarding the mould parts towards the pouring station using the conveyor, said conveyor further being associated with first retaining means and second retaining means, wherein the method includes the steps of, repetitively and sequentially, (i)- producing a mould part, (ii)- placing said mould part on the conveyor in contact with a preceding mould part of a string of moulds parts, (iii)- displacing the string of mould parts a distance corresponding to one mould part width so as to position a first new mould to be filled in correspondence with the pouring station, by displacing the first part of the conveyor in a horizontal direction towards said pouring station, and optionally pushing the mould string with a rear plate of the station for making mould parts; (iv)- returning said first part of the conveyor towards the station for making mould parts a distance corresponding to one mould part width, while optionally retaining the mould string using said second retaining means; (v)- once again displacing the string of mould parts a distance corresponding to one mould part width so as to position a second new mould to be filled in correspondence with the pouring station, by once again displacing the first part of the conveyor in said horizontal direction towards said pouring station; (vi)- optionally, repeating steps (iv) and (v); (vii)- retaining the mould string using said first retaining means or said second retaining means so as to prevent mould parts from being displaced towards the station for making mould parts during pouring into the moulds, and beginning pouring into at least two moulds at the pouring station; (viii)- producing at least one mould part and placing said mould part on the conveyor in contact with the mould part produced in step (i), and optionally retaining said mould part produced in step (viii) by using said second retaining means.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) To complete the description and in order to provide for a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the description and illustrate embodiments of the invention, which should not be interpreted as restricting the scope of the invention, but just as examples of how the invention can be carried out. The drawings comprise the following figures:
(2) FIG. 1A-1H schematically illustrate a sequence of mould part production and mould string displacement in accordance with an embodiment of the invention.
(3) FIG. 2A-2H schematically illustrate a sequence of mould part production and mould string displacement in accordance with another embodiment of the invention.
(4) FIGS. 3A-3F illustrate some details of a system or installation operating according to the principles of the embodiment illustrated in FIGS. 2A-2H.
(5) FIGS. 4A-4F illustrate some details of a system or installation operating according to another embodiment of the invention.
DESCRIPTION OF WAYS OF CARRYING OUT THE INVENTION
(6) FIGS. 1A-1H illustrate how the production of mould parts can be synchronised with the pouring of metal and movement of the mould string, in accordance with an embodiment of the invention.
(7) In FIG. 1, a plurality of mould parts 101-106 are placed on a conveyor 2 comprising a first part 21 that is moveable in the horizontal direction to displace the mould string comprising mould parts 101-106 horizontally in the direction from the station for making moulds 1 towards a pouring station 3 comprising two pouring spouts 31 and 32 for filling two moulds, by pouring, for example, molten metal 33 into the moulds. The conveyor system can be of the type comprising a plurality of parallel beams extending in the horizontal direction, some of which form part of the horizontally moveable first part 21 and some of which are part of a second part 22 of the conveyor, shown in FIG. 1B. The first part 21 of the conveyor and the second part 22 of the conveyor are both moveable in the vertical direction, but in this embodiment of the invention, only the first part of the conveyor is moveable in the horizontal direction. Both the first part 21 and the second part 22 are moveable in the vertical direction between an upper position in which the mould parts are in contact with the beams of the respective part of the conveyor so that the beams support the mould parts, and a lower position in which the mould parts are not supported on that part of the conveyor. The first part 21 and the second part 22 are coordinated so that during operation of the system, at least one of said first part 21 and second part 22 are in the upper position. Thus, the mould string is preferably maintained at a constant height during operation, and is not moved up and down.
(8) In FIG. 1A, both the first part 21 and the second part 22 are in the upper position and thus arranged in parallel so that only the first part 21 can be observed in the figure. The beams of the two parts can be placed so that beams of the first part alternate with beams of the second part in the direction orthogonal to the paper in FIG. 1A. This kind of conveyor system is well known in the art and there is thus no need to describe the conveyor system as such more in detail. In FIG. 1A, the beams of the first part 21 and the second part 22 thus alternate in the direction orthogonal to the surface of the paper, and the mould parts 101-106 can be supported both by the first part 21 and the second part 22, that is, by the longitudinally extending beams of said first part 21 and second part 22.
(9) In FIG. 1A, the two spouts 31 and 32 are currently pouring molten metal 33 into the cavities of two moulds, more specifically, the first spout 31 is filling the cavity of the mould defined by mould parts 102 and 103, and the second spout 32 is currently filling the cavity of the mould defined by mould parts 103 and 104. In order to prevent for example mould parts 104-106 from being displaced towards the mould making station, for example, by the pressure created when pouring molten metal into the mould formed by the mould parts 103 and 104, first retaining means 41 are provided to interact with one or more of the mould parts, such as with the rearmost mould part 106 in the mould string, to prevent the mould parts from being displaced towards the station 1 for making mould parts. In FIG. 1A, the first retaining means 41 are schematically illustrated as applied onto the top of the mould part 106, but this is just for illustration purposes, and the retaining means may well interact with the mould part or mould parts in any suitable way, such as by applying pressure to the top surface or to the lateral surfaces of the mould parts, and/or by applying pressure to or gripping behind the rear surface of the mould part or mould parts, such as mould part 106. Thus, the first retaining means 41 serve to prevent movement of the mould parts of the mould string towards the station 1 for making mould parts.
(10) Also, in FIG. 1A, second retaining means are schematically illustrated. These second retaining means 42 can serve to retain a mould part when delivered from the mould making station, to prevent it to be drawn back by the press plate 12 when the press plate returns towards a moulding chamber after delivery of the mould part to the conveyor 2. Also in this case, the second retaining means are only illustrated schematically, and the fact that they appear to apply pressure from above does not mean that this option is necessarily preferred over other options, such as second retaining means 42 that apply pressure to the lateral sides of the mould part. In FIG. 1A, the second retaining means are not activated as no mould part has yet been delivered by the station for making mould parts, after the last indexing of the mould string; that is, no mould part is placed in correspondence with the second retaining means 42.
(11) On the right in the figure station 1 for making mould parts is schematically illustrated. Only the front plate 11 and the rear plate 12 of the mold part making apparatus are shown, as well as the piston 13 driving the rear plate. FIG. 1A shows the moment in which a sand mould part 107 is being formed by pressing sand between the front plate 11 and the rear plate 12. As this kind of machines for making mould parts are well known in the art, there is no need here to describe them more in detail. Any suitable machine can be used, such as, for example, the one known from EP-A-1219830 or the one known from EP-A-2357050, referred to above.
(12) In FIG. 1B, the mould part 107 has been produced and delivered to the conveyor 2 by the pushing action of the rear plate 12. At this stage, the second retaining means are activated and applied to retain this mould part 107, preventing it from being pulled backwards when the second press plate 12 returns into the apparatus for making mould parts. This is illustrated as a downward action of said second retaining means 42, but this is just an option, and other options are likewise valid, such as pressure applied to the sides of the mould part. In FIG. 1B, metal continues to be poured into the two moulds defined by mould parts 102, 103 and 104, and the first retaining means 41 continue to retain the mould string and preventing mould parts from moving towards the station for making mould parts. In FIG. 1B, the second part 22 of the conveyor has been displaced to its lower position, whereby the mould string is only supported by the first part 21 of the conveyor. However, this vertical displacement can likewise take place at a later stage of the process.
(13) In FIG. 1C, a further mould part 108 is being produced in the station 1 for making mould parts, while molten metal 33 continues to be poured into the moulds at the station for making mould parts.
(14) In FIG. 1D, the second mould part 108 of the pair of mould parts made up of mould parts 107 and 108 is delivered to the conveyor 2. Here, the second retaining means 42 have been deactivated so as to allow the previously produced mould part 107 to be indexed on step and to enter into contact with the mould string (namely, with the last mould part 106 of the mould string), and leave room for the recently produced mould part 108. At this stage, pouring of metal into the moulds can have been interrupted, or can be about to be interrupted, and the first retaining means can be about to be deactivated. On the other hand, the second retaining means 42 are about to be activated to prevent the newly produced mould part 108 from being dragged towards the mould making machine when the second press plate 12 returns towards the machine.
(15) In FIG. 1E, pouring has been interrupted at the pouring station 3, the first retaining means 41 and the second retaining means 42 have been deactivated, and the second part of the conveyor is being displaced horizontally, so as to displace the mould string in the direction from the station for making mould parts to the pouring station. In FIG. 1E the first part 21 of the conveyor has been displaced the distance corresponding to the width of one mould part, and the movement continues until the position illustrated in FIG. 1F, where the first part of the conveyor 21 has been displaced a distance corresponding to the width of two mould parts. In this position, the first retaining means 41 can be activated again, and the pouring of metal 33 can begin again, this time into the moulds defined by mould parts 104, 105 and 106, as illustrated in FIG. 1E. Next, the second part 22 of the conveyor can return to its upper position and thereafter the first part of the conveyor can be displaced to its lower position, whereafter the second part 22 of the conveyor can return towards the station 1 for making mould parts, as illustrated in FIG. 1G, and return to its upper position, as shown in FIG. 1H. Here, the system is in the same state as in FIG. 1A, with simultaneous pouring into two moulds taking place while a new mould part 109 is being produced.
(16) The advantages of this system are self-evident: it provides for a flexible approach allowing for multiple indexing (such as double, triple, quadruple, etc.) without requiring any special pushing action by the rear plate, apart from the pushing action that the rear plate conventionally performs for delivering mould parts to a conveyor, and pouring can take place uninterruptedly during the entire cycle, except for the time needed for indexing the mould string two steps or more.
(17) In the embodiment of FIGS. 1A-1H, the first retaining means 41 are not associated with the first part 21 of the conveyor, but remain in a fixed position in relation to the pouring station. This approach can sometimes be practical, as it can render the implementation of the first retaining means 41 independent of the design of the conveyor, which can contribute to increased flexibility. However, it may require additional adjustments when there is a change in the width of the mould parts, that is, when production is commenced of mould parts having a width differing from the width of the previously produced mould parts. In such cases, in addition to the adjustment of the displacement or stroke of the first part of the conveyor, also the position of the retaining means may sometimes need adaptation.
(18) FIGS. 2A-2H schematically illustrate another embodiment of the invention, in which this potential drawback is overcome by integrating the first retaining means with the first part 21 of the conveyor. In FIG. 2A it can be observed how the first part 21 and the second part 22 of the conveyor are both placed in their upper position, so that the mould parts 101-106 rest on both parts 21 and 22 of the conveyor, while molten metal 33 is being poured into the moulds defined by mould parts 102 and 103, and by mould parts 103 and 104, respectively. In this embodiment of the invention, the mould parts are prevented from moving back towards the station 1 for making mould parts by the first retaining means 41, which are associated with the first part 21 of the conveyor. In FIG. 2A, the first retaining means are schematically illustrated as retaining the rearmost mould part 106 of the mould string by applying pressure to the sides of said mould part 106, but any other suitable retaining means are within the scope of the invention, for example, retaining means applying pressure from above.
(19) In FIG. 2B, the rear plate 12 has pushed a newly produced mould part 107 out of the machine and delivered it to the conveyor 2, by placing it on the rearmost portion of the second part 22 of the conveyor, and in FIG. 2C the rear plate 12 has returned while the newly delivered mould part 107 is retained on the conveyor 2 by the second retaining means 42.
(20) In FIG. 2D the station 1 for making mould parts has delivered a further mould part 108 to the conveyor 2, by placing it on the second part of the conveyor, pushing the previously produced mould part 107 one step towards the mould string made up of the mould parts 101-106, so that it makes contact with said mould string. Subsequently, the second retaining means 42 are activated to retain the mould part 108 in its position.
(21) Thereafter, as illustrated in FIG. 2E, the first retaining means are deactivated so as to release the mould string; at this stage, the second retaining means 42, interacting with the latest produced mould part 108, prevent the mould parts from being displaced towards the mould part making machine. Next, the first portion 21 of the conveyor is lowered and displaced towards the station 1 for making mould parts, as schematically illustrated in FIG. 2E. This displacement amounts to a distance corresponding to the width of two mould parts. After this displacement, the first part 21 of the conveyor returns to its upper position so as to support the mould string including mould parts 107 and 108, whereas the second part 22 of the conveyor is lowered, so as to allow shifting of the mould string in the direction towards the pouring station 2, as schematically illustrated in FIG. 2F, by displacement of the first part 21 of the conveyor; during this displacement, pouring is interrupted at the pouring station.
(22) In FIG. 2G, the displacement of the first part 21 of the conveyor has concluded, and this first part 21 of the conveyor and the mould string have been displaced in the direction from the station 1 for making mould parts towards the pouring station, a distance corresponding to twice the width of a mould part, that is, the mould string has been double indexed, and pouring at the pouring station can begin again, this time into the moulds defined by mould parts 104-106. Also in this embodiment of the invention, pouring only has to be interrupted during the displacement of the mould string, that is, during the displacement of the first part 21 of the conveyor.
(23) Both of these embodiments are advantageous in that they minimize the time during which pouring has to be interrupted, while allowing for filling of more than one mould at a time, and while allowing for completing the filling of the moulds prior to indexing the mould string. These embodiments are also advantageous in that they achieve this objective without requiring any special adaptation of the mould making machine, especially, without requiring any special adaptation of the stroke of the rear plate, as the rear plate is not needed to displace the mould string, but just used to position the newly produced moulds on the conveyor. In these embodiments, each newly produced mould is positioned on the conveyor in substantially the same position, so that the mould making machine can be operated with a constant stroke of the rear plate. The embodiments of FIGS. 1A-1H are advantageous in that the first retaining means are not associated with the first part 21 of the conveyor, which sometimes can be advantageous from a constructional point of view or in what regards logistics in relation to machine components, whereas the embodiment of FIGS. 2A-2H have the first retaining means associated with the first part of the conveyor so that they move with the first part of the conveyor, so that they can be arranged to always interact with, for example, the rearmost mould part of the mould string without requiring any adaptation when there is a change in the width of the mould parts to be produced. That is, as the first retaining means 41 move with the first part 21 of the conveyor, they can be placed to interact with mould parts in a position close to the rear portion of the first part of the conveyor 21, that is, in a position that will always be occupied by the rearmost mould part of the mould string, such as mould part 106 in FIGS. 2A-2D or mould part 108 in FIGS. 2F to 2G. This can serve to facilitate adaptation of a system to different mould widths.
(24) FIGS. 3A-3F illustrate with more detail a system operating in line with some of the principles of the method of FIGS. 2A-2H. In FIG. 3A, it can be observed how a string of mould parts 100-106 has just been double indexed so that two new moulds to be filled have been placed under corresponding spouts 31 and 32 of a pouring station, in order to start simultaneous filling of the moulds defined by mould parts 101 and 102, and 102 and 103, respectively, by pouring the metal into the holes 100a and 100b formed between the mould parts 101 and 102 and between the mould parts 102 and 103, respectively.
(25) The mould parts 100-106 have been displaced a distance corresponding to two mould part widths, that is, the mould string has been double indexed, so as to place the two new moulds under the spouts. Two recently filled moulds, a rear one of which is formed between mould parts 100 and 101, have been shifted away from the pouring station in the same step of double indexing, towards a station (not shown) for extracting the moulded objects from the moulds.
(26) The mould parts have been shifted by horizontally displacing the first part 21 of the conveyor 2, which comprises a plurality of beams 21a, 21b, arranged in parallel and interlaced with beams 22a, 22b of the second part 22 of the conveyor. The first part 21 of the conveyor and the second part 22 of the conveyor are both displaceable in the vertical direction, so that the second part 22 of the conveyor can be displaced to a lower position so as not to interfere with the mould parts when shifted away from the station 1 for making mould parts by horizontal displacement of the first part 21 of the conveyor.
(27) In the illustrated embodiment, there is also a third part 23 of the conveyor, which can be substantially fixed in its vertical position, for example, as part of an output section of a mould making machine. Thus, the conveyor 2 can be made up of the first part 21, the second part 22 and the third part 23, the second part 22 being arranged to be lowered when the double indexing of the first part 21 for shifting of the mould parts is to take place, to avoid friction between the mould parts 104-106 and the beams of the second part 22 of the conveyor.
(28) First retaining means 41 are provided to apply pressure to the rearmost mould part 106 of the mould string. These first retaining means are arranged on pivotally arranged arms 411 than can pivot by rotation of vertical bars or shafts 412 actuated by an actuator 413. These shafts 412 and the actuator 413 are arranged in a frame structure 414, 415 connected to the first part 21 of the conveyor, so that the entire arrangement including the first retaining means moves horizontally with the first part 21 of the conveyor. In the position illustrated in FIG. 3A, the first retaining means 41 are applying pressure to lateral surfaces of the rearmost mould part 106, thus preventing the mould parts 103-106 from being displaced rearwards, that is, towards the station 1 for making mould parts, for example, when pressure is built up inside the moulds during pouring of metal into the moulds.
(29) On the other hand, second retaining means 42 are provided on a crossbeam 421 extending between two columns 423 associated with the mould part making machine of the station 1 for making mould parts, and these second retaining means are pivotally arranged on said crossbeam so as to be activated and deactivated by respective actuators 421 arranged to pivot said second retaining means so that they, when they are activated, apply pressure on a top surface of the last mould part delivered from the mould part making machine onto the conveyor 2. The second retaining means 42 can be part of the mould part making machine and arranged to apply the pressure onto the top surface of the mould part placed on the third part 23 of the conveyor, so as to prevent said mould part from being pulled rearwards when the rear plate 12 (shown in FIG. 3B) returns into the moulding chamber after delivering a mould part to the conveyor 2.
(30) In FIGS. 3A-3F, the front plate is not illustrated, for simplicity.
(31) As indicated above, FIG. 3A illustrates the system immediately after a double indexing of the mould string, whereby two new moulds to be filled have been placed under the respective spouts 31, 32. On the other hand, a most recently made mould part 107 is just coming out of the mould part making machine. The first retaining means 41 are activated, thus retaining the mould string and preventing rearward movement of the mould parts by firmly clamping the rearmost mould part 106 of the mould string, and the second retaining means are deactivated so as not to interact with the recently produced mould part 107 when delivered. In FIG. 3A, the pattern plate 12a associated with the rear plate 12 can be observed, just coming out of the moulding chamber of the mould part making machine.
(32) FIG. 3B illustrates the state of the system immediately after the state shown in FIG. 3A, that is, immediately after the double indexing of the mould string by the horizontal shifting of the first part 21 of the conveyor. In FIG. 3B, molten metal 33 is just beginning to pour into the moulds defined by mould parts 101-103. The mold string is being retained at its rear end by the first retaining means 41. At the station 1 for making mould parts, the latest produced mould part is being pushed out of the machine by the stroke of the rear plate 12 actuated by the piston 13, in the way in which extraction of mould parts is conventionally carried out in this kind of machines.
(33) In FIG. 3C and while metal 33 continues to pour into the moulds at the pouring station 3, the mould part 107 has been delivered to the conveyor and the second retaining means 42 have been activated to apply pressure onto the top surface of the mould part 107, thus preventing it from being pulled rearwards by the rear plate 12 when the rear plate 12 with its pattern plate 12a is returning into the moulding chamber of the machine, for carrying out a new cycle of mould part production. Thus, the second retaining means are retaining the recently produced mould part 107 on the third part 23 of the conveyor.
(34) In FIG. 3D, a new mould part 108 is being pushed out of the moulding chamber of the mould part making machine, arriving at the previously produced mould part 107 which is under the second retaining means. At this moment, the second retaining means 42 have been or are deactivated so as to allow the previously produced mould part 107 to be pushed forwards by the action of the rear plate 12, until the position shown in FIG. 3E, where the latest produced mould part 108 has occupied the position on the third part 23 of the conveyor previously occupied by the previously produced mould part 107, which has in turn been pushed onto the second part 22 of the conveyor until making contact with the rearmost mould part 106 of the mould string. At this stage, the second retaining means 42 are activated again so as to apply pressure onto the top surface of the rearmost mould part 108. At this stage, the second retaining means actually retain the entire mould string, as mould parts 100-106 are all in contact.
(35) At this stage, the first retaining means 41 can be released/deactivated so as to cease to apply pressure onto the lateral surfaces of the mould part, by pivoting the arms 411 outwards (only one of said arms being shown in FIG. 3E, the other one being on the other side of the mould string), whereafter the first part 21 of the conveyor can be lowered and subsequently displaced two mould widths in the horizontal direction, in the direction towards the station 1 for making mould parts, until the position shown in FIG. 3F, where the first part 21 of the conveyor can return to its upper position, engage the mould string by applying pressure onto the lateral surfaces of the rearmost mould part 108 and, after lowering of the second part 22 of the conveyor and stopping of the pouring at the pouring station 3, the mould string can be double indexed by displacing the first part 21 of the conveyor horizontally, a distance corresponding to the width of two mould parts, thereby placing two new moulds, defined by mould parts 103-105, under the spouts 31 and 32 of the pouring station 3, thereby returning to the state of the system shown in FIG. 3A.
(36) An alternative embodiment is illustrated in FIGS. 4A-4F. The components of the system are the same as those already described with reference to FIGS. 3A-3F, but the system is arranged to operate in accordance with a different sequence, basically, using two strokes of the first part 21 of the conveyor for completing the double indexing.
(37) FIG. 4A illustrates a state of the system in which two moulds have just been filled, namely, the moulds between mould parts 100 and 101, and 101 and 102, respectively. The pouring at the pouring station has stopped. At this stage, a new mould part 107 is being pushed out of the mould making machine 1 and pushed until it arrives at the mould string, which includes previously produced mould parts 100-106. Now, the mould string is indexed one step, that is, the mould string is displaced a distance corresponding to the width of one mould part, so that a new mould arrives at the pouring station, namely, the mould defined by mould parts 102 and 103. This first indexing is achieved by displacing the first part 21 of the conveyor horizontally, a distance corresponding to one mould part width, in synchronization with the pushing movement of the rear plate 12. Here, the second retaining means may be activated so as to allow the rear plate 12 to be withdrawn and returned into the mould part making machine without displacing the new mould part 107 rearwards.
(38) Next, the first part 21 of the conveyor returns towards the station 1 for making moulds, towards the position illustrated in FIG. 4C. Here, the second retaining means 42 can optionally continue to be activated and exerting pressure onto the top surface of the mould part 107. When the first part of the container arrives at its rearmost position, the first retaining means 41 are preferably activated to couple the mould string to the first part 21 of the conveyor, the second retaining means are deactivated to release the mould part 107, and the first part 21 of the conveyor is then indexed one step to towards the pouring station 3, thereby indexing the mould string so as to bring a new mould, the one defined by mould parts 103 and 104, into the pouring station. At this stage, as shown in FIG. 4D, compared to the situation in FIG. 4A, two new moulds have been brought into the pouring station and simultaneous pouring of molten metal 33 into the two moulds can now begin, as suggested in FIG. 4D. Thus, a difference when compared to the operation illustrated in FIGS. 3A-3F is that in the operation illustrated in FIGS. 4A-4F, the double indexing of the mould string is carried out in two steps, with a double stroke of the first part 21 of the conveyor, each stroke bringing the mould string one step forward, each step corresponding to the width of one mould part. In FIGS. 4E and 4F a new mould part 108 is produced by the mould making machine and pushed onto the third part 23 of the conveyor, and the second retaining means 43 are activated, applying pressure onto the top surface of the mould part 108 thus preventing it from being displaced backwards when the rear plate 12 is withdrawn into the moulding chamber to produce a further mould part.
(39) This approach can be practical from a constructional point of view and it requires a comparatively short stroke in the horizontal direction by the first part 21 of the conveyor, as each stroke of said first part 21 of the conveyor only corresponds to the width of one mould part. However, a potential disadvantage compared to the way of operation illustrated in FIGS. 3A-3F resides in the fact that for a given mould part production rate, the time available for pouring is reduced, as pouring generally has to be interrupted during the time from that the first part of the conveyor 21 starts to move the mould string from the position shown in FIG. 4A and until the first part 21 of the conveyor has completed its second stroke forward, arriving at the state of the system illustrated in FIG. 4C. Thus, if it is desired to reduce as far as possible the time during which pouring has to be interrupted, in many cases the way of operation illustrated in FIGS. 3A-3F may be preferred over the way of operation illustrated in FIGS. 4A-4F.
(40) On the other hand, whereas the embodiments described above correspond to a method and system for double indexing of the mould string, the invention also encompassed options such as triple indexing, quadruple indexing, etc. The same principles as those above can be applied, the only difference residing in the number of moulds that are produced between the subsequent shiftings of the mould string. For example, in the case of the method described in relation to FIGS. 4A-4F, triple indexing could imply repeating the stroke of the first part 21 three times while pouring is interrupted, and afterwards producing three new mould parts, the first one of which is pushed to make contact with the mould string when the second one comes out of the moulding chamber.
(41) Also, whereas the invention has been disclosed in relation to specific types of conveyors, the invention can also be embodied with other types of conveyors, for example, with conveyors using horizontally moveable lateral squeeze plates to shift the mould string. In such embodiments, the first part of the conveyor may comprise said horizontally moveable lateral squeeze plates, and the second part of the conveyor can comprise a stationary surface on which the mould parts can be placed and slide when moved by the horizontally moveable lateral squeeze plates. Such squeeze plates can extend along a portion of the mould string comprising several mould parts, or even along the entirety of the mould string.
(42) Obviously, the method and machine or system can include core setting by using core setters, for example, using prior art approaches such as those described in U.S. Pat. No. 7,806,161 or EP-B-1326726.
(43) In this text, the term comprises and its derivations (such as comprising, etc.) should not be understood in an excluding sense, that is, these terms should not be interpreted as excluding the possibility that what is described and defined may include further elements, steps, etc.
(44) On the other hand, the invention is obviously not limited to the specific embodiments described herein, but also encompasses any variations that may be considered by any person skilled in the art (for example, as regards the choice of materials, dimensions, components, configuration, etc.), within the general scope of the invention as defined in the claims.
