The present invention concerns an arrangement for simultaneously pouring first and second mould cavities in a mould string, such as in a green sand metal foundry, and a method therefor.

Operators of metal foundries have always been interested in increasing the production rate of metal castings to improve cost efficiency. Accordingly manufacturers of equipment for metal foundries have devised improvements to the machines used in the metal foundries for increasing production rate. For green sand metal foundries these improvements have in- cluded improvements to the green sand moulding machines, which machines form the green sand moulds by compressing green sand between pattern plates, as well as im- provement to the conveyors on which the green sand moulds are placed, one after the other in a mould string. Further improvements have been made to the pouring machines used to pour the molten metal into the mould cavities.

As the production rate of green sand moulding machines has increased, the time available in the machine cycle for pouring the moulds formed by the green sand moulding machines has decreased. There is a practical limit to how many kg of molten metal per second that can be poured without increasing the amount of scrap, i.e. discarded castings due to errors for instance caused by erosion of the mould during pouring. Thus, in practice the pouring of the moulds is often the limiting factor on production rate. The currently most promising solu- tion for circumventing this limiting factor is to advance the mould string the distance of two mould thicknesses each time the mould string is advanced. With this solution, the mould string is stationary for the time needed to produce two moulds, accordingly leaving a signifi- cantly longer time for pouring, and first when the two moulds have been produced is the mould string advanced. Accordingly there arises a need to be able to pour two moulds at the same time.

On example of a technique for pouring molten metal into more than one mould cavity at the same time is described in WO2005056214, in which green sand moulds are formed so as to include runners in the moulds, resulting in that every two mould cavities formed by the moulds in the mould line are fluidly connected, such that both mould cavities can be filled with molten metal simultaneously by pouring molten metal into only one of the mould cavi- ties. Another way of achieving pouring of metal into more than one mould cavity at the same time is described in WO2013003359, which discloses a pouring machine or pouring unit which has a molten metal holding and pouring box with dual pouring nozzles. Each of the pouring nozzles may be selectively opened or closed to pour the molten metal by its own stopper rod.

In the case of the technique disclosed in WO2005056214, it may be difficult to control the level of molten metal in both moulds, as there may be a delay when the metal flows from the mould cavity being directly filled with the molten metal to the mould cavity which is filled via the runner. The metal present in the runner connecting fluidly the two moulds will even- tually solidify together with the metal in the moulding cavities, thus necessitating removal from the cast object and remelting, which requires time and energy and lowers the yield. Furthermore, there is a risk of having different temperature profiles in the molten metal in the two moulds, possibly leading to different properties of the castings coming from the mould being directly poured and the mould being indirectly poured. All the liquid metal for two moulds has to flow through one pouring cup. This leads to a high load on the sand around this pouring cup and may lead to excessive erosion etc. On the other hand, the dual pouring nozzles of the molten metal holding and pouring box of WO2013003359, which allow the pouring of two mould cavities at the same times, are ex- posed to wear from the molten metal passing through them during pouring, and must therefore regularly be replaced, which increases costs of performing moulding operations. Further the dual stoppers, dual nozzles, and the machinery needed to move the respective stopper to control the pouring, render the technique complex and increases the mainte- nance need. Further rt is difficult and time consuming to change the distance between the nozzles, which is required when the mould thickness is changed. The mould thickness is often changed when pattern is changed, i.e. when changing from one part to another. This is important as foundries need to be flexible, i.e. be able to change pattern fast according to the just-in-time principle.

In light of the above there is still a need for devices and methods able to simultaneously pour two mould cavities without the above mentioned drawbacks and limitations. It is accordingly an object of the present invention to provide an arrangement for simultane- ously pouring two mould cavities which is simple. It is further an object of the present invention to provide an arrangement for simultaneously pouring two mould cavities which can be easily adjusted to pour moulds with other thick- nesses.

It is further an object of the present invention to provide an arrangement for simultaneously pouring two mould cavities which requires little maintenance.

It is further an object of the present invention to provide an arrangement for simultaneously pouring two mould cavities which can ensure equal filling of both mould cavities.

It is further an object of the present invention to provide a method for simultaneously pour- ing two mould cavities. At least one of the above objects, or at least one of any of the further objects which will be evident from the below description, are according to corresponding first and second aspects of the present invention achieved by the arrangement according to claim 1 and the method according to claim 13. By using the rocker body, a single primary stream of molten metal, such as supplied from a conventional pouring unit utilizing a single conventional stopper rod, is simply divided into two secondary streams and used to fill two mould cavities simultaneously. The rocker body divides the primary stream of molten metal into two secondary streams of molten metal without needing any additional stopper rods or pouring nozzles that will lead to extra main- tenance. Simple pivoting of the rocker body makes it possible to ensure an equal filling of both mould cavities and pivoting of the rocker body. i.e. adjusting the flow rate ratio (kg molten metal per second) of the first secondary stream to the second secondary stream, does not involve contact with the molten metal as compared to the prior art dual nozzle - dual stopper devices. Further the rocker body may be manufactured with less tolerance and of cheaper materials than pouring nozzles and stopper rods, as it is a simple part.

By dividing the primary stream of molten metal into a flow for each mould cavity using the rocker body, both mould cavities can be filled at the same time. The rocker body is supplied with molten metal in a single stream. Thus a standard molten metal holding box or tundish, equipped with a single pouring nozzle and a single stopper, may be used to supply the molten metal for pouring both mould cavities. This makes the arrangement simple when compared to the prior art solution.

In the context of the present invention, the term "mould cavity" refers to a shaped cavity which gives a definite shape to molten metal introduced into it. Once the molten metal has solidified, its solidified shape is determined by the mould cavity.

The first and second mould cavities may be formed in first and second moulds in the mould string, however it is preferred that the first and second mould cavities are defined between adjacent moulds in the mould string, such as in a mould string produced by a vertical flask- less green sand moulding machine. However, the moulds poured may alternatively be a number of moulds away from each other.

The first and second mould cavities to be poured may comprise, or be fluidly connected to, corresponding first and second pouring cups and further downsprues or channels, into or through which molten metal is introduced or flows, in the moulds or defined between moulds in the mould string.

In the context of the present invention 'simultaneously" is to be understood as encompass- ing at the same time, and in a single operation.

In the context of the present invention 'pouring first and second mould cavities" is to be un- derstood as encompassing pouring molten metal into first and second cavities. The mould string may be an array of adjacent moulds, each mould comprising a mould cav- ity, an array of moulds, each mould comprising two mould parts defining a mould cavity, or alternatively an array of adjacent moulds, each two adjacent moulds defining a mould cavity between them. The source of molten metal may be any device capable of delivering a controlled flow of molten metal, such as a molten metal holding and pouring box of a pouring unit. Alterna- tively the source of molten metal may be a tundish or a ladle.

The rocker body is preferably shaped as a semicylinder of a refractory material. The semi cylinder is preferably right cylindrical, i.e. having a constant radius and an axis orthogonal to the radius; however, the semi cylinder may be elliptically cylindrical, i.e. with a radius that varies along the arc.

Preferably the curved surface is devoid of sharp edges which can disturb the flow of molten metal on the curved surface.

The rocker body is preferably made from known refractory materials. The choice of refrac- tory material depends on the type of metal, the temperature of the molten metal in the pri- mary stream of molten metal, and the desired lifetime.

In the context of the present invention 'arranged so as to receive ^* is to be understood as encompassing positioned for. The rocker body is preferably arranged below the source of molten metal so that the primary stream of metal pours down onto the rocker body. In the context of the present invention "curved surface" is to be understood as encompass- ing convex upper surface.

The curved surface is preferably as described above a semicylindrical surface having its highest point along a centreline and curving down towards the first and second end por- tions. The curved surface is preferably rectangular. The curved surface may however also be the inner surface of a cylinder or channel. In this case, the rocker body may be shaped like a prism.

In the context of the present invention "curved" is not to be limited to the meaning of smoothly or continuously curved. Rather curved is to be understood as encompassing sur- faces which change orientation in discrete steps, such as the surface of a prism or a halved polygonal cylinder.

The primary stream of molten metal is preferably received in the centre of the curved sur- face between the first and second end portions. The primary stream of molten metal is pref- erably received on the highest point of the curved surface or above said pivot axis.

The primary stream of molten metal is divided into the first and second secondary stream by the force of gravity and by the inertia of the molten metal in combination with the shape of the curved surface. The opposite first and second end portions can be straight edges, but may alternatively be curved so as to concentrate or funnel the first and second secondary streams of molten metal, i.e. by decreasing the width of the first and second secondary streams of molten metal in relation to the length of the first and second end portions. This may be advanta- geous where the opening of the mould cavity, i.e. the pouring cup into which the first and second secondary stream of molten metal is to be poured, is narrow. This is typically the case in order to reduce the size of the pouring cup and thereby the amount of metal need- ing to be remelted. The first and second secondary streams of molten metal preferably pour down into the first and second mould cavities from the first and second end portions. Accordingly, the rocker body is preferably arranged above the mould string and adapted so that the first end portion is positioned above the first mould cavity, and the second end portion is positioned above the second mould cavity.

The rocker body may be pivotable, for example by being mounted or arranged on a rocker body axle, by being attached to a rotating surface, by being attached or positioned on a tiltable surface, etc. If used with a rocker body axle, the rocker body should comprise a bore.

The position of the pivot axis in relation to the curved surface and/or the shape of the curved surface may be adapted such that pivoting of said rocker body affects the flow rate ratio of the first secondary stream of molten metal to the second secondary stream of mol- ten metal by positioning the pivot axle in relation to the curved surface, and/or by shaping the curved surface, such that pivoting of the rocker body changes the impact angle between the primary stream of molten metal and the curved surface at the point of impact of the pri- mary stream of molten metal on the upper curved surface.

If the impact angle is equal on both sides of the primary stream of molten metal, i.e. if the impact angle is 90 ^* , then equal amounts of the primary stream of molten metal are diverted to each of the secondary streams of molten metal. On the other hand, if the impact angle between the primary stream of molten metal and the curved surface is larger on the side of the primary stream on which the first end portion of the curved surface is positioned, then more of the primary stream of molten metal will be diverted to the first secondary stream of molten metal than the second secondary stream of molten metal, and vice versa. The flow rate (kg/s) ratio of the first and second secondary streams of molten metal is the ratio between the flow rate (kg/s) of the two secondary streams of molten metal.

The primary stream of molten metal is preferably delivered in a metered portion. The pivoting of the rocker body is preferably performed concurrent with the delivering of the primary stream of molten metal, but may alternatively be performed after the delivering of the primary stream of molten metal. Alternatively, the primary stream of molten metal may be delivered as discrete portions of molten metal, whereby the pivoting of the rocker body may be performed in the pauses between delivering such discrete portions.

The pivoting of the rocker body may be performed manually, or as advantageously embod- ied by the arrangement and the method according to the corresponding first and second aspects of the present invention defined in claims 2 and 12. by a control system. By using the control system, it is ensured that the levels of molten metal in the mould cavi- ties, in particular the pouring cups, are kept at the same predetermined level during pouring, such that pouring of both mould cavities can be completed at the same time, thus keeping the time for pouring of the mould cavities at a minimum. The need for changing the flow rate ratio of the first and second secondary streams of mol- ten metal arises because the flow rate may vary due to presence of slags in the molten metal or other phenomena resulting in the first and second secondary streams of molten metal having non-balanced, i.e. different, flow rates. Techniques for configuring the control system are known to, and can be selected and im- plemented by, the skilled person.

The first and second sensors are preferably laser distance sensors using a laser beam to measure a distance. The first and second sensors may be carried by the source of molten metal. The first and second levels of molten metal may be determined by measuring the distance from the respective one of the first and second sensors to the surface of the mol- ten metal, or by measuring the distance from the top of the mould to the first and second levels of molten metal. Alternatively, the first and second sensors may comprise video cameras, ultra sound trans- ceivers, or other types of distance sensors. In the context of the present invention "determining a level of molten metal " is to be under- stood as encompassing determining an amount of molten metal or determining a fill per- centage of molten metal.

The pivoting device may for example comprise a rocker body axle, onto which the rocker body is mounted along the pivoting axis, and a motor, such as a step motor, for rotating the rocker body axle, optionally via one or more gears. Furthermore, a pneumatic or hydraulic actuator, or any other actuator device, may be used to pivot the rocker body axle.

The control device may comprise a computer or comparator circuit. The control device may be connected to, or comprise, a relay circuit for energising the motor, or a valve for control- ling the hydraulic or pneumatic cylinder, or a device for activating any other actuator device. The control device may be set up with the direction of pivoting being correlated to the differ- ence, or the sign positive/negative, of the difference, between the first and second levels of molten metal and the predetermined level.

In the context of the present invention "pivoting the rocker body so as to keep the first and second levels at the predetermined level' is to be understood as encompassing pivoting the rocker body so as to equalize the first and second levels, and pivoting the rocker body so as to increase the flow rate of the one of the first and second secondary stream of molten metal pouring into the one of the first and second mould cavities having the lowest level of molten metal in the mould cavity or in the pouring cup fluid ly connected to that mould cavity.

Determining the first and second levels is preferably performed continuously during pouring. However, determining the first and second levels may also be performed at discrete times during the pouring, such as at the beginning, midpoint, and end of pouring. The preferred embodiments of the arrangement and method according to the corresponding first and second aspects of the present invention as defined in claims 3 and 15 are advan- tageous as they provide the fastest filling, i.e. pouring, of the mould cavities.

Alternatively the predetermined level may be below the level of the top surface of the moulds, such as for example 1 -20 mm, more preferably 1-10 mm, below the level of the top surface of the moulds. The embodiments of the anrangement and the method according to the corresponding first and second aspects of the present invention defined in claims 4 and 16 are advantageous in that they utilize the first and second sensors to also provide measurements for the control of the primary stream of molten metal. Thus, there is no need for additional sensors to con- trol the primary stream of molten metal.

The flow device may for example comprise a stopper rod or a gate valve and an actuator for moving, such as to open or close the stopper rod and the gate valve. Typically, the flow de- vice comprises a hydraulic cylinder and a stopper rod connected to the hydraulic cylinder for movement in relation to a pouring nozzle.

The control device may be adapted by comprising a comparator circuit or program module for comparing the first and second levels to the predetermined level. The predetermined level is preferably set by an operator, but may alternatively be set by measuring the appar- ent level of the upper surface of the moulds in the mould string using one or both first and second sensors.

It is further contemplated within the context of the present invention to position the first and second sensors such that each sensor projects a beam parallel to the first and second sec- ondary streams of molten metal as the secondary streams of molten metal pour from rocker body down into the moulds. Thus, where the volume of molten metal in the first and second secondary streams of molten metal increases, these streams will eventually intersect the beams from the first and second sensors for interfering with the determining of the first and second levels. This can be used by the control device to determine that the amount of mol- ten metal on the rocker body is too high, thus requiring that the primary stream of molten metal is decreased.

The embodiments of the arrangement and the method according to the corresponding first and second aspects of the present invention as defined in claims 5 and 15 are advanta- geous as they allow increased yield by lowering the amount of metal that has to be remelted. As the molten metal solidifies in the mould, a portion of the molten metal solidifies in the pouring cup. Generally the pouring cup should be filled up to the level of the upper surface of the moulds to ensure the highest fill rate of the moulds. This however leads to a bigger amount of metal solidifying in the pouring cups, which metal must subsequently be remelted, a process which requires energy. By keeping the first and second levels at the predetermined level, preferably at the level of the upper surface of the moulds during the initial major period of time of the pouring of the first and second moulds, a high fill rate is achieved for the major part of the pouring. Then, by ending the pouring by keeping the first and second levels at the lower predetermined level, it is ensured that the amount of metal needing to be remelted is minimized.

For example the first and second levels may be kept at the predetermined level until about 80% of the molten metal is delivered, whereafter the first and second levels are allowed to fall to the further predetermined level for delivering the last 20% of the molten metal.

The further predetermined level may for example be at the lower third or half of the pouring cup or lower. This method can be used when the castings/feeders are not too close to the top of the mould.

Alternatively the further predetermined level can be higher than the predetermined level. This is advantageous when the castings/feeders are too close to the top of the mould be- cause it may ensure that the feeders/risers are sufficiently filled with molten metal so that sufficient molten metal may be provided to the casting as the casting cools down and solidi- fies, and thereby shrink.

The embodiments of the arrangement and the method according to the corresponding first and second aspects of the present invention defined in claims 6 and 18 are advantageous in that they more directly prevent overflow of the rocker body.

The supply sensor may comprise a distance sensor or a camera for measuring the amount, such as the thickness and/or width of the primary stream of molten metal at the point where it is received by the curved surface of the rocker body, or for measuring the thickness and/or width of the first and second secondary streams of molten metal on the curved sur- face or at the first and second end portions.

The amount corresponding to an overflow may be determined empirically by performing tests at different flow rates, noting which amount results in an overflow, this amount being the maximum amount. If the amount is above the maximum amount, the amount is too much and indicates an overflow If the amount is too far below the maximum amount, such as below 50% of the maximum amount, the amount is less than the rocker body can handle. An overflow of the curved surface may comprise molten metal pouring from other parts of the curved surface than the first and second end portions.

The embodiment of the arrangement according to the first aspect of the present invention defined in claims 7 is advantageous in that it increases the capacity of the rocker body and reduces spilling of molten metal from the rocker body.

The first and second ridges are preferably straight. The first and second ridges prevent or limit any flow of molten metal not directed towards the first or second end portions.

The embodiment of the arrangement according to the first aspect of the present invention defined in claims 8 is advantageous as it provides a more direct division of the primary flow of molten metal. As the central ridge extends above the curved surface, it moves primarily horizontally, by being further away from the pivot axis, during limited pivoting of the rocker body. Instead of relying on the impact angel between the primary stream of molten metal and the curved surface, the central ridge moves at a right angle to the transversal cross section of the primary stream of molten metal. Accordingly, for a given angle that the rocker body is pivoted, the central ridge causes a larger difference in volume ratio between the first and second secondary streams of molten metal.

The embodiment of the arrangement according to the first aspect of the present invention defined in claims 9 is advantageous in that it increases the capacity of the rocker body as well as directs the first and second secondary streams of molten metal to the first and sec- ond end portions and into the first and second mould cavities. The depth and width of the groove determine the maximum flow rate that can be handled by the groove.

The at least one groove preferably runs in a straight line along the curved surface. Prefera- bly the curved surface comprises several parallel grooves. The embodiment of the arrangement according to the first aspect of the present invention defined in claims 10 is advantageous to use when pouring moulds capable of handling dif- ferent flow rates in kg molten metal per second. Simply moving the rocker body allows the selection of the groove which is to receive the primary stream of molten metal and which is suitable for handling the flow rate of the primary stream of molten metal. The first groove imparts a first cross section to the first and second secondary streams of molten metal where the first and second secondary streams of molten metal leave the rocker body. Likewise the second groove imparts a second, larger cross section to the first and second secondary streams of molten metal where the first and second secondary streams of molten metal leave the rocker body. Preferably the first and second grooves are configured so that the distance between the centres of these cross sections are the same for both grooves. This corresponds to the mould thickness being the same for both grooves.

The embodiment of the arrangement according to the first aspect of the present invention defined in claim 11 is advantageous as it allows quick changes of mould thickness by sim- ply moving the rocker body axially along the pivot axis and thereby selecting which of the first and second grooves is to receive the primary stream of molten metal.

The first groove imparts a first cross section to the first and second secondary streams of molten metal where the first and second secondary streams of molten metal leave the rocker body.

Likewise the second groove imparts a second cross section to the first and second secon- dary streams of molten metal where the first and second secondary streams of molten metal leave the rocker body. Preferably the first and second grooves are configured so that the first and second cross sections are the same, the first and second groves further being configured such that the distance between the centres of these cross sections differs be- tween the grooves. This corresponds to the mould thickness being different for the grooves.

The embodiment of the arrangement according to the first aspect of the present invention as defined in claim 12 is advantageous as it gives better control over the molten metal and as it prevents splashing off of molten metal from the rocker body.

The inlet aperture is preferably round and the first and second outlets are also preferably round. The invention and its many advantages will be described in more detail below with refer- ence to the accompanying schematic drawings, which for the purpose of illustration show some non-limiting embodiments, and in which: Fig. 1 shows, in perspective view, an overview of parts of a metal foundry including a vertical green sand moulding machine, a mould conveyor carrying a mould string, and a pouring unit comprising a first embodiment of an arrangement for simultaneously pouring two moulds according to the first aspect of the present invention, Fig. 2 shows, in cross section, a first embodiment of the arrangement for simultane- ously pouring two moulds according to the first aspect of the present invention, the first em- bodiment comprising a molten metal holding and pouring box and a first embodiment of a rocker body, and, Fig. 3 shows, in perspective view, the first, a second, a third, a fourth, and a fifth em- bodiment of a rocker body.

In the below description, one or more 'signs added to a reference number indicates that the element referred to has the same or similar function as the element designated the refer- ence number without the 'sign, however, differing in structure.

Additionally, where useful for discussing two or more identical elements, a subscript Arabic numeral is used to designate such further identical elements. When further embodiments of the invention are shown in the figures, the elements which are new, in relation to earlier shown embodiments, have new reference numbers, while elements previously shown are referenced as stated above. Elements which are identical in the different embodiments have been given the same reference numerals, and no further explanations of these elements will be given.

Fig. 1 shows, in perspective view, a highly schematic overview of parts of a metal foundry 2 in which casting of molten metal 4 is performed. The metal foundry 2 comprises a vertical green sand moulding machine 10 which is connected to a mould conveyor 12 which carries and conveys a mould string 14 made up from the individual moulds, one of which is desig- nated the reference numeral 20. which are produced by the vertical green sand moulding machine 10. The metal foundry 2 further comprises a pouring unit 16 for pouring the molten metal 4. The pouring unit 16 further comprises a first embodiment 30 of an arrangement according to the first aspect of the present invention, shown in detail in fig. 2.

In operation the vertical green sand moulding machine 10 compresses green sand between two pattern plates to form moulds 20. which moulds 20 are then each ejected from the verti- cal green sand moulding machine 10 and added to the mould string 14 on the moulding conveyor 12. The moulds 20 are subsequently conveyed to the pouring unit 16. which pours the molten metal 4 into the mould cavities of the moulds 20. The metal foundry 2 operates using the principle described in EP1326726, or a similar principle, according to which prin- ciple the mould string 14 is transported two moulds at a time in order to provide a longer continuous pouring time. This however requires that two moulds 20 must be poured at the same time while the mould string 14 is stationary. The pouring of the moulds 20 is shown in further details in fig. 2. Fig. 2 shows, in cross section, a first embodiment 30 of the arrangement according to the first aspect of the present invention, the first embodiment 30 comprising a molten metal holding and pouring box 40 positioned above the mould string 14 and forming a part of the pouring unit 16 in fig. 1 , and a first embodiment of a rocker body 60. The molten metal holding and pouring box 40 comprises a sidewall 42 and a bottom 44 defining a reservoir 46 for holding the molten metal 4. Part of the bottom 44 defines a pouring nozzle 48. through which the molten metal 4 may be selectively poured. A stopper rod 50 is disposed within the reservoir 46 and is displaceable up and down by a stopper actuator such as a hydraulic cylinder 114 or a electric gear mechanism (not shown) as is known in the art, for selectively causing the tip 52 of the stopper rod 50 to enter the pouring nozzle 48 for closing and opening the pouring nozzle 48.

Referring briefly back to fig. 1 , it can be seen that the molten metal holding and pouring box 40 is supplied with molten metal from the main body of the pouring unit 16, which pouring unit is regularly filled up with molten metal from a ladle (not shown).

The rocker body 60 is arranged beneath the pouring nozzle 48. The rocker body 60 com- prises a curved surface 62 for receiving a primary stream of molten metal 4' pouring from the pouring nozzle 48 of the molten metal holding and pouring box 40. The rocker body 60 further comprises first and second opposite end portions 64 and 66. As the primary stream of molten metal 4' is poured down onto the curved surface 62, it is divided into first and sec- ond secondary streams 4" and 4"'. Referring briefly to fig. 3A, which shows the rocker body 60 in more detail, the rocker body 60 has a generally semi-circular cross section with opposite semi-circular end faces, one of which is designated the reference numeral 68. To prevent the primary stream of molten metal 4' from splashing off the rocker body 60 and down on the mould string 14 or the mould conveyor 12, the rocker body 60 advantageously, as shown in fig. 3A, comprises opposite ridges 70 and 72 above the semicircular end surfaces 68, the ridges 70 and 72 being orthogonal to the first and second end portions 64 and 66. Further advantageously, the rocker body 60 comprises a groove 74 formed in the curved surface 62, the groove 74 running parallel to the ridges 70 and 72 and orthogonally to the first and second end portions 64 and 66 for receiving the primary stream of molten metal 4' and directing the first and second secondary stream of molten metal 4" and 4"' towards the first and second end portions 64 and 66.

Furthermore the rocker body 60 comprises a bore 76 for allowing the rocker body 60 to be suspended on an axle as described below with renewed reference to fig. 2.

As shown in fig. 2, the rocker body 60 is pivotably arranged on a rocker body axle 80. The rocker body axle 80 is preferably attached to the molten metal holding and pouring box 40, or may alternatively be attached to its own support structure, or to another part of the pour- ing unit 16, and positioned between the molten metal holding and pouring box 40 and the mould string 14. Although the rocker body 60, once arranged on the rocker body axle 80, may be pivoted manually in order to affect the volume ratio of the first secondary stream of molten metal 4" to the second secondary stream of molten metal 4"', the arrangement 30 advantageously further comprises a control system 90. The control system 90 comprises an electric step motor 92 which is connected to the rocker body axle 80 via drive gear 94 and rocker body axle gear 96. The control system further comprises first and second laser distance sensors 98 and 100, emitting first and second laser beams 102 and 104, and third and fourth laser distance sensors 106 and 108, emitting third and fourth laser beams 1 10 and 112. A com- puter 120 receives the distance information from the first and second laser distance sensors 98 and 100 and for actuating the step motor 92 for pivoting the rocker body 60 as will be described further below. The computer 120 further receives the distance information from the third and fourth laser distance sensors 106 and 108, the distance information corresponding to the amount of molten metal on the rocker body 60. Although an electric step motor 92 is shown in fig. 2. a hydraulic or other type of actuator could also be used.

The first embodiment 30 of the arrangement according to the first aspect of the present in- vention is arranged above the mould string 14. The mould string is made up from moulds 20 as shown in fig. 1. Fig. 2 in particular refers to the individual moulds 20, 20,, 20 ₂ ,20 ₃ . 20„, and 20 ₅ . Each of the moulds 20, 20,, 20 ₂ , 20 ₃ , 20 ₄ , and 20 ₅ defines, together with the one of the moulds 20, 20-,. 20 _? ,20 ₃ . 20 _4l and 20 ₅ that is adjacent to it, a mould cavity 22, 22,, 22 ₂ , 22 ₃ , 22 ₄ , by the space created between each pair of moulds of the moulds 20,, 20 _{2 >} 20 ₃ , 20 ₄ , and 20 ₉ due to the impressions created by the pattern plates of the vertical green sand moulding machine 10 in the green sand during the making of each of the moulds 20, 20, , 20 ₂ ,20 ₃ , 20 ₄ , and 20 ₅ . Accordingly, the moulds 20 are poured by providing the mould cavi- ties with the molten metal 4.

Each mould cavity 22, 22,, 22 ₂ , 22 ₃ , 22 ₄ defines the shape of the object that is to be cast of the molten metal 4 and the mould 20.

Each mould 20, 20,, 20 _? . 20 ₃ , 20 ₄ . and 20 ₆ further, together with the adjacent one of the moulds 20, 20,, 20 ₂ . 20 ₃ , 20 ₄ , and 20 ₅ , defines a pouring cup 24, 24,, 24 _? , 24 ₃ , 24 ₄ which is open to the top surface of the moulds 20 and into which the molten metal 4 is poured as the secondary streams of molten metal 4" and 4"'. Downsprues 26. 26,, 26 ₂ , 26 ₃ , 26 ₄ defined by the moulds 20. 20,, 20 ₂ , 20s, 20 ₄ . and 20 _s fluidly connect the pouring cups 24. 24,, 24 ₂ . 24 ₃ , 24 ₄ to the moulding cavities 22, 22,, 22 ₂ , 22 ₃ , 22 ₄ . The positioning of the rocker body 60 along the mould string 14 and the distance between the first and second end portions 64 and 66 are chosen such that the first and second secondary streams 4" and 4"' simultane- ously pour down into the pouring cups 24, and 24 ₂ for simultaneously filling the moulding cavities 22, and 22 ₂ via the downsprues 26, and 262.

In fig. 2 the pouring of the moulds forming the mould cavities 22, and 22 _? has just begun. The mould cavity 22 formed by the moulds 20 and 20, has already been filled with molten metal 4"". while the mould cavities 22 ₃ and 22 ₄ formed by the moulds 20 ₃ , 20 ₄ and 20 ₅ are still unfilled. After the mould cavities 22, and 22 ₂ have been filled, the mould string 14 will move the dis- tance of two mould thicknesses to the left, by being conveyed by the mould conveyor 12, and thereby position the pouring cups 24 ₃ and 24 ₄ beneath the first and second end por- tions 64 and 66 of the rocker body 60.

As can be seen from fig. 2, the first embodiment 30 of the arrangement according to the first aspect of the present invention allows two mould cavities, i.e. 22, and 22 ₂ , to be filled at the same time, yet it requires only a single stopper rod 50. The rocker body 60 may be pro- duced from any readily available refractory material and can easily and inexpensively be replaced as needed when worn out from the contact with the molten metal 4'. If needed, the rocker body 60 may be replaced by a rocker body 60 having other dimensions if the thick- ness of the moulds 20 or the flow rate kg/s of molten metal needed in the two secondary streams of molten metal 4" and 4'" is changed at a pattern change.

The control system 90 controls the pouring of the molten metal into the pouring cups 24i and 24 _∑ and thereby controls the pouring of the mould cavities 22i and 22 ₂ by measuring first and second levels of molten metal in the pouring cups 24, and 24 ₂ using the first and second laser distance sensors 98 and 100. The measurements are then relayed to the computer 120, which is programmed to compare the first and second levels and energize the step motor 92 for pivoting the rocker body 60 so as to keep the first and second levels at a predetermined level during the pouring. This ensures that both moulds, i.e. mould cavities 22, and 22 ₂ , are filled simultaneously and at the same rate. Further it ensures that the same filling profile is achieved for each mould 20 poured, thereby providing a stable and repro- ducible quality of the castings produced.

Preferably this predetermined level is defined by the top surface of the moulds 20, i.e. the highest possible level without the pouring cups 24, and 24 ₂ overflowing, for achieving the maximum filling rate of the mould cavities 22, and 22 ₂ , the filling rate being influenced of the height of molten metal in the pouring cups 24, and 24 ₇ .

The computer 120 is further programmed to compare the first and second levels of molten metal in the pouring cups 24, and 24? to the predetermined value, and if the levels of molten metal exceeds the predetermined value, control the hydraulic cylinder 114 to decrease or stop the primary stream of molten metal 4', or if the levels of molten metal fall below the predetermined value, control the hydraulic cylinder 114 to increase the primary stream of molten metal 4'.

The computer 120 further uses the distance information from the third and further laser dis- tance sensors 106 and 108 to determined the amount of molten metal on the curved sur- face 62 of the rocker body 60. If this amount becomes too high, which indicates an overflow of the curved surface 62 and the rocker body 60, the computer 120 is programmed to con- trol the hydraulic cylinder 1 14 to decrease or stop the primary stream of molten metal 4'. Although fig. 3A has already been discussed above, it may further be mentioned that the inner walls of the bore 76 may advantageously comprise axial splines, ridges or grooves (not shown) for interacting with mating splines, grooves or ridges provided on the rocker body axle 80 for providing a rotation fast connection of rocker body 60 to the rocker body axle 80 with rocker body axle gear 96. Alternatively, the bore 76 may be smooth and a modified rocker body axle gear (not shown), which is pivotable around the rocker body axle 80 and which carries pins (not shown) for engaging holes (not shown) on the end face 68 of the rocker body 60, may be used to pivot the rocker body 60.

Fig. 3B shows a second embodiment of the rocker body 60' which differs from the first em- bodiment of the rocker body 60 shown in figs 2 and 3A by having a modified curved surface

62' and a central ridge 78 extending parallel to the first and second end portions 64 and 66.

The central ridge 78 defines a central end portion 82 and assists in dividing the primary stream of molten metal 4' into the first and second secondary streams 4" and 4 " and further increases the effect that pivoting the rocker body 60' has on the flow rate ratio of the first secondary stream of molten metal 4" to the second secondary stream of molten metal 4"".

The ridges 70 and 72 may comprise first and second central ridge portions 71 and 73 flanking the central ridge 78.

Referring briefly to fig. 3A, it can be appreciated that the bore 76, corresponding to the axis around which the rocker body 60 pivots, is placed close to or at the centre of gravity of the rocker body 60. The position of the bore 76 in relation to the radius of the curved surface 62 at the centre of the curved surface 62, i.e. where the primary stream of molten metal 4' im- pacts the curved surface 62, should be chosen such that the impact angle between the pri- mary stream of molten metal 4' and the centre of the curved surface 62 changes when the rocker body 62 is pivoted. This may for example be achieved as shown in fig. 2 and 3A by ensuring that the distance between the bore 76 and the centre of the curved surface 62 is smaller than the radius of at least the centre of the curved surface.

If this is the case, then, as may be appreciated from fig. 2 and fig 3A, if the rocker body 60 pivots clockwise, the impact angle between the primary stream of molten metal 4' and the centre of the curved surface 62 changes such that the volume flow of the first secondary stream of molten metal 4", which is directed towards the first end portion 64, which is now raised, lessens while the volume flow of the second secondary stream of molten metal 4 ", which is directed towards the second end portion 66, which is now lowered, increases, and vice versa.

With reference to fig. 3B and in contrast to the above, the pivoting of the rocker body 60 ^' clockwise instead increases the first secondary stream of molten metal 4" and decreases the second secondary stream of molten metal 4"'. This is because pivoting of the rocker body 60' causes the central end portion 80 to move to the right in relation to the cross sec- tion of the primary stream of molten metal 4', thereby dividing the primary stream of molten metal 4' such that more of the molten metal falls on the left side of the central ridge to thereby form the first secondary stream of molten metal 4". Fig. 3C shows a third embodiment of the rocker body 60" which differs from the rocker body 60 in that a modified curved surface 62" forms a branching channel 74", which is a modifi- cation of the groove 74, within the rocker body 60". The branching channel 74' has an inlet aperture 84 for receiving the primary stream of molten metal 4' and directs the first and sec- ond secondary streams 4" and 4"' of molten metal to first and second end portions 64' and 66', which are modifications of the first and second end portions 64 and 66 of the rocker body 60.

The rocker body 60" is advantageous as it gives good control over the molten metal. Fur- ther it prevents splashing of the molten metal, and it insulates and prevents contamination of the first and second secondary streams 4" and 4"' of molten metal.

Fig. 3D and 3E show a fourth embodiment of the rocker body 60"' which differs from the first embodiment 60 in that a modified curved surface 62"' comprises three grooves 74, 74" and 74'" having different widths and depths for receiving a primary stream of molten metal 4' having different flow rates (kg molten metal per second). The three grooves 74. 74" and 74"' extend from modified first and second edge portions 64" and 66" and shape first and second secondary streams of molten metal 4" and 4'" of different cross sectional areas where the first and secondary streams of molten metal 4" and 4'" leave the respective groove 74, 74" and 74"' of the rocker body 60'" to pour down into the pouring cups 24, and 24 ₂ . As seen in fig. 3E, the distance A between the centres of the cross sectional areas of the first and second secondary stream of molten metal 4" and 4"' is the same for all three grooves 74, 74" and 74"'. Accordingly the rocker body 60"' is to be used for pouring moulds having a single predetermined mould thickness corresponding to the distance A.

Rocker body 60"' is advantageous to use when pouring moulds 20 requiring different flow rates of molten metal. Each of the grooves 74, 74" and 74 " is dimensioned for being used with a specific maximum flow rate. Thus groove 74 is dimensioned for receiving a primary stream of molten metal 4' for instance containing 6 kg molten metal per second, while groove 74" and 74"' for instance are dimensioned for receiving primary streams of molten metal 4' containing 8 kg molten metal per second and 10 kg molten metal per second, re- spectively.

In use the rocker body 60'" is positioned axially on the rocker body axle 80 such that the primary stream of molten metal 4' is deposited into only one of the grooves 74. 74" and 74" and flows towards the modified end portions 64" and 66". These end portions differ from those of fig 3A and 3B merely due to the grooves 74" and 74'". By sliding the rocker body 60 " axially on the rocker body axle 80. any one of the groves 74, 74" and 74"' may be se- lected for receiving the primary stream of molten metal 4', thus allowing one and the same rocker body 60'" to be used to pour moulds 20 at different flow rates. Selecting the groove 74. 74" or 74 " to use is very fast by sliding the rocker body 60 " back and forth on the rocker body axle and can be performed by hand, by using an electric motor or hydraulic/pneumatic actuator. Preferably the rocker body axle 80 may be fashioned with axially directed splines, and the bore 76', which is modified from the bore 76 by being longer, is provided with corresponding axially directed grooves or ridges for ensuring a rota- tion-fast connection between rocker body and rocker body axle. To prevent overflow of the grooves 74, 74" and 74 " the stopper 50 must be controlled such that the flow of molten metal 4' is not larger than the grooves 74, 74" and 74'" can handle. The optional ridges 70' and 72 can reduce the consequences of overflow Fig. 3F and 3G show a fifth embodiment of the rocker body 60"" which differs from the first embodiment 60 in that a modified curved surface 62"" comprises three grooves 74, 74"" and 74" " having the same widths and depths for receiving a primary streams of molten metal 4' having the same flow rates.

The grooves 74, 74"" and 74 extend from modified first and second edge portions 64"' and 64 " and shapes first and second secondary streams of molten metal 4" and 4"' of identical cross sectional areas, where the first and secondary streams of molten metal 4" and 4"' leave the respective groove 74, 74"" and 74'"" of the rocker body 60"" to pour down into the pouring cups 24i and 24?. As seen in fig. 3E, the distances A, B and C between the centres of the cross sectional areas of the first and second secondary stream of molten metal 4" and 4 " differ for each groove 74, 74"" and 74 Accordingly the rocker body 60 " is to be used for pouring moulds 20 having varying mould thicknesses using a set flow rate.

In use the rocker body 60"" is positioned axially on the rocker body axle 80 such that the primary stream of molten metal 4' is deposited into only one of the grooves 74, 74"" and 74""' and flows towards the modified end portions 64'" and 66'". By sliding the rocker body 60"" axially on the rocker body axle 80, any one of the groves 74. 74"" and 74'"" may be selected for receiving the primary stream of moKen metal 4', thus allowing one and the same rocker body 60"' to be used to pour moulds 20 having different thicknesses. Selecting the groove 74, 74"" or 74""' to use is very fast by sliding the rocker body 60"" back and forth on the rocker body axle, and can be performed by hand by using an electric motor or hydraulic/pneumatic actuator. Being able to change the mould thickness fast is a very important feature as this makes it possible to change patterns without limitations on differences in mould thickness. Preferably the rocker body axle 80 may be fashioned with axially directed splines, and the bore 76", which is modified from the bore 76 by being longer, is provided with corresponding axially directed grooves or ridges for ensuring a rota- tion-fast connection between rocker body and rocker body axle. To prevent overflow of the grooves 74. 74"" and 74'"" the stopper 50 must be controlled such that the flow of molten metal 4' is not larger than the grooves 74 and 74"' and 74""' can handle. Optional ridges 70 and 72 can reduce the consequences of metal overflow.