EP0048248B1 - Method and device for transport of a molding line comprised of frameless molds - Google Patents

Abstract

In order to transport with simple means frameless molds arranged on a molding line (15) passing through supply, molding and cooling stations of a molding plant, so as to obtain a high finishing precision of the parts obtained, the acceleration and breaking forces required for the molding line (15) engaged or not with the molding line are adjusted for each case; these forces as well the forces opposite to the thermal expansion of the molds (17) are transmitted by the molds along the molding line.

Description

According to a first idea of the invention, the invention relates to a method for transporting boxless casting molds over a supply, casting and cooling section of a casting installation having at least one rectilinear branch, the casting molds having face and side surfaces oriented perpendicular to the transport plane being put together to form a complete mold strand the casting molds are continuously placed in the area of its rear end and casting molds are removed in the area of its front end to the same extent, and the forces required to accelerate the mold strand to be transported are introduced into the mold strand at the rear end of the mold strand in the transport direction. Another inventive concept relates to a device for performing such a method.

A method and a device of the type mentioned in the opening paragraph are known from US-A 3800935. The known device consists of a stationary table arranged downstream of a forming station and a transport device arranged upstream of an unpacking station and having a drivable conveyor belt. The boxless molds completed in the molding station are pushed onto the stationary table by means of an ejection piston, the molds coming into contact with one another and being pushed by the ejection piston in the form of a strand over the stationary table and onto the conveyor belt, which is at a feed rate corresponding speed is driven. The conveyor belt is driven at such a speed that the molds coming from the table onto the conveyor belt remain in mutual engagement and at the same time the rear molds are not crushed by the push-out piston. However, this is very difficult to achieve in the known arrangement. The mold strand here comprises two sections, namely the section accommodated on the stationary table and the section accommodated on the driven conveyor belt, different transport conditions being present in both sections. In the area of the stationary table, there are frictional forces between the table support surface and the contact surface of the molds that come into contact with it. In order to bring about a forward movement of the mold strand, this friction must first be overcome by means of the ejection piston driving the section of the mold strand lying on the table, which friction counteracts the movement of the section of the mold strand lying on the table when the driving force ceases. It is therefore extremely difficult to hold the mold strand together in such a way that the adjacent molds support each other. In the area of the driven conveyor belt, the movable arrangement of the belt eliminates frictional forces of the type outlined above. Since the conveyor belt has its own drive, the casting molds accommodated on the conveyor belt do not have to transmit any acceleration forces introduced at the rear end of the mold strand. Rather, they are transferred by friction from the driven conveyor belt to each individual mold that is accommodated thereon. Even when using constant belt ratios, it is also very difficult to achieve reliable mutual reinforcement in the area of the strand section taken up on the conveyor belt. This is further complicated by the fact that the mutual abutment of the casting molds arranged next to one another additionally depends on the stretching or shrinking of the conveyor belt and, in addition, belt tracking is very difficult to avoid. In the case of a belt follow-up, however, the mold strand is inevitably torn off, since the friction which acts in the area of the stationary table and counteracts the movement practically prevents the mold strand lying on the stationary table from running on.

The stationary table downstream of the molding station makes it necessary to drive the section of the mold strand lying thereon by means of the ejection piston pushing out the new mold to be placed on the mold strand, and practically does not permit any other drive. This results in a combination of the positioning process for positioning a new casting mold on the mold strand and the acceleration of the mold strand. However, the push-out piston which accomplishes these two processes must be pulled back into its starting position in order to start a new casting mold. When the mold strand is at a standstill, therefore, no force acts on the rear end of the mold strand that counteracts thermal expansion of the mold strand, apart from the frictional forces. There is therefore a risk that the molds will enlarge or shift relative to one another due to unavoidable thermal expansion and that in the event of subsequent cooling, for example in the event of a break, the molds will lose mutual contact. This applies not only to the shapes lying on the stationary table, but also to the shapes picked up on the conveyor belt. Another disadvantage of the transport of the mold strand, which is dependent on the adjustment process, is that high forces can occur when the casting mold to be adjusted hits the mold strand, which can lead to damage if a very large control effort is not carried out.

Based on this, it is therefore the task the present invention, while avoiding the disadvantages of the known arrangements, to provide a method of the type mentioned at the outset and a device suitable for carrying out this method, which ensure compliance with a dimensional accuracy and accuracy previously not considered possible.

According to the invention, the solution to this problem relating to the method is that the acceleration of the mold strand takes place independently of the acceleration of the new casting mold to be placed in each case at the rear end of the mold strand, and that the acceleration or braking of the entire mold strand occurs between that the downstream mold and the front mold upstream of the mold to be removed, or the forces required to hold the entire mold strand together, counteracting the thermal expansion, into the rear end of the mold strand downstream of the mold to be adjusted or the front mold upstream of the mold to be removed Introduced at the end of the mold strand and along the entire length of the mold strand between the rearmost mold downstream of the mold to be positioned thereon and the front mold upstream of the mold to be removed therefrom The first mold can only be transferred uniformly from one mold to the next through the mold itself.

These measures ensure that there is a steady flow of force running exclusively over the molds over the entire length of the mold strand, from the last cast mold to the foremost mold that still belongs to the mold strand. This accordingly results in a uniform mutual reinforcement of the end faces of the casting molds which run transversely to the transport direction over the entire length of the mold strand. At the same time, this results in a reliable clamping of the mold strand counteracting the thermal expansion forces, so that even thermal expansion does not result in the molds being displaced relative to one another and thus possibly. can lead to an undesirable offset between the lower part and the assigned upper part. Another advantage of the measures according to the invention can be seen in the fact that the driving and braking forces can be adjusted easily and simply as a result of the constant conditions over the entire length of the mold strand and the independence from the starting process, so that in any case not only an undesirable expansion of the Mold strand and an undesirable mutual offset of the molds, but also damage to the moldings can be avoided. At the same time, however, the required energy requirement can also be reduced to a minimum, which in turn not only offers economic advantages but also ensures a very gentle movement of the mold strand.

In many cases, it can prove to be particularly expedient and therefore preferable if the mold strand is held together with an adjustable force that counteracts the thermal expansion force outside the acceleration phases and in particular during the breaks, so that the individual casting molds are reinforced. This measure can prove to be particularly advantageous if the mold strand is at rest due to a lack of replenishment of liquid metal. The noticeable thermal expansion occurring during such breaks is contained here by the force holding the strand together. The force holding the mold strand together can advantageously be selected such that it is greater than the force required to completely prevent thermal expansion within the strand. Thermal expansion of the strand is therefore not possible here. In a further development of this idea, the force holding the mold strand together can be dimensioned such that it is somewhat smaller than the force required to move the mold adjacent to the first cast mold or its parts on its respective base. This ensures that when excessive forces occur within the mold strand, a certain amount of expansion of the mold strand can take place. However, the clamping force acting on the mold strand is retained. The molds are expediently designed in such a way that the force required to move the mold adjacent to the first cast mold or its parts on its respective base is in any case greater than the force generated within the mold strand due to the thermal expansion, so that due to the normal thermal expansion no expansion of the mold strand is to be feared.

The solution directed to the device for carrying out the method outlined at the outset is characterized in that, in the case of a device of the generic type, with a roller conveyor, which is arranged between a molding station and an unpacking station and has at least one rectilinear branch and is formed by stationary rollers, on the respective one or more casting molds load-bearing transport units are movable, the length of the transport units in the transport direction is less than the length of the mold or casting molds that can be accommodated thereon, which are arranged projecting forward and backward on the respectively assigned transport unit in the transport direction and that within a branch of the mold strand in the transport direction each rearmost and frontmost transport unit with the interposition of at least one slip clutch, the transmission torque of which is adjustable, is in engagement with a drive or braking station. Ensure these measures Maintain compliance with a force flow running directly via the casting molds over the entire length of the mold strand and enable individual metering of the drive or braking forces or the forces counteracting the thermal expansion force. The measures according to the invention also ensure that the casting molds are in a resting position with respect to their respective base, despite the mutual support achieved here during transport. At the same time, the easy mobility of the transport units, which are mounted so as to be slidable or carriage-shaped, comes into play.

In an expedient further development of these measures, the drive station can consist of at least one drive roller connected with the interposition of the assigned slip clutch with a drive element that can be blocked at least against the direction of transport, and the brake station can consist of at least one brake roller connected with the interposition of the associated slip clutch with a brake element that can be blocked in the transport direction. The drive roller and the brake roller can expediently engage the associated transport units in a frictional manner in such a way that the force that can be transmitted thereon is greater than the maximum adjustable force on the respectively assigned slip clutch, which can have a very wear-reducing effect. The rollers arranged between the drive station and the brake station can simply be designed as non-driven support rollers, so that overall a very simple structure results.

A further advantageous measure can consist in that each branch of the roller conveyor is inclined in the transport direction in such a way that the resistance acting on its rollers is at least almost completely equalized by the downward slope. The equalization of the internal friction advantageously results in almost identical supporting forces between the individual molds in the area of the entire mold strand. In addition, the force required to move the mold strand can be relatively small, which enables smooth operation.

In many cases, errors such as part misalignment, part formation or part breakage already arise when a new casting mold is placed on the rear end of the mold strand in the direction of transport, which also has a negative effect on the achievable accuracy and dimensional accuracy. Casting molds coming from behind must catch up with the rear end of the mold strand in order to achieve this. In order to avoid a sudden stress on the mold parts, which can lead to the above-mentioned errors, according to a further advantageous development of the invention, the setting speed of the mold to be placed on the last mold of the mold strand is selected such that when the mold hits the mold strand released kinetic energy can be absorbed in the plastic area of the molding compound and is not sufficient in the case of horizontally divided casting molds to bring about molding offset. The excess speed of the mold to be connected should expediently not exceed 5 cm / s. To carry out this method step, a feed unit formed by at least one drive roller can expediently be used, which is coupled to a drive element via a slip clutch with an adjustable transmission torque and which frictionally interacts with a transport element receiving the assigned casting mold. The slip clutch can be set to a relatively small value, so that the associated drive element immediately rotates empty when the casting mold to be connected hits the rear end of the mold strand, so that molded part deformation and the like are avoided.

The slipping clutches with adjustable transmission torque used can advantageously be designed as contactless magnetic clutches, preferably magnetostatic hysteresis clutches, to ensure freedom from wear.

Further advantageous refinements and expedient further developments of the superordinate measures result from the following description of preferred exemplary embodiments with reference to the drawing in conjunction with the remaining subclaims.

• Fig. 1 eine Gesamtdraufsicht auf eine mit horizontal geteilten, auf Paletten transportierten Giessformen arbeitende Giessanlage mit einer zwei parallele Äste aufweisenden Vorrats-, Giess- und Kühlstrecke in schematischer Darstellung,
• Fig. 2 eine Seitenansicht eines Astes der Vorrats-, Giess- und Kühlstrecke gemäss Fig. 1,
• Fig. 3 eine Draufsicht auf die Anordnung nach Fig. 2 mit teilweise entfernten Paletten,
• Fig. 4 eine Frontansicht einer horizontal geteilten Giessform gemäss Fig. 1 mit seitlichen Armierungsplatten,
• Fig. 5 eine Seitenansicht eine Vorrats-, Giess-und Kühlstrecke für mit lotrechter Teilfuge aneinandergereihte auf einem Schrittförderrost transportierbare Monoblockformen in Transportstellung und
• Fig. 6 eine Seitenansicht der Anordnung nach Fig. 5 im Ruhezustand und mit lotrecht geteilten Doppelblockformen beschickt.

The drawing shows:

• 1 is an overall plan view of a casting plant working with horizontally divided casting molds transported on pallets, with a supply, casting and cooling section having two parallel branches, in a schematic representation,
• 2 shows a side view of a branch of the supply, pouring and cooling section according to FIG. 1,
• 3 shows a top view of the arrangement according to FIG. 2 with the pallets partially removed,
• 4 shows a front view of a horizontally divided casting mold according to FIG. 1 with lateral reinforcement plates,
• 5 shows a side view of a supply, pouring and cooling section for monoblock molds which are lined up with a vertical parting joint and are transportable in a transport position and on a step conveyor grate
• Fig. 6 is a side view of the arrangement of FIG. 5 at rest and loaded with vertically divided double block molds.

A casting plant of the type on which the figures are based consists, as can best be seen from FIG. 1, of a molding station 1 in which boxless casting molds are produced, an unpacking station 2 in which the finished castings are separated from the sand of the casting molds and one Storage, casting and cooling section 3, which pass through the molds on the way from the molding station 1 to the unpacking station 2. The area adjoining the molding station 1 is considered to be a supply section which serves to provide finished molds. This is followed by the casting section, which can be operated with a pan, indicated at 4, holding liquid metal for pouring the casting molds through it. The guidance of the pan 4 that leads past a melting furnace (not shown) is indicated at 5. The casting section, which can be operated by pan 4, is followed by the cooling section, in which the castings cool down to the unpacking temperature. In Fig. 1, the supply, pouring and cooling section consists of a forward load and a return load.

In order to form the supply, pouring and cooling lines or their forward load and return load, as can best be seen from FIG. 2, a roller conveyor 6 provided with stationary rollers is provided. To accommodate the casting molds designated as a whole as 7, which are designed here as horizontally divided double block molds with an upper part 11 and a lower part 12, transport units running on the rollers of the roller conveyor 6, here in the form of pallets 8 each holding a casting mold 7, are provided. At the end of the cooling section, the pallets 8 are cleared by means of a clearing blade indicated at 9 in FIG. 1 and then transferred to the rear end of the forward branch to accommodate a new casting mold leaving the molding station 1. At the front end of the forward branch, the pallets 8 together with the mold 7 located thereon are transferred onto the return branch. For this purpose, translation units are provided at the ends of forward load 3a and return load 3b, indicated in FIG. 1 by arrows 10. As can be seen from FIG. 3, these can each consist of a carriage which is provided with a lifting device and can be moved perpendicular to the normal transport direction. The upper parts 11 and lower parts 12 of the molds 7, which are horizontally divided here, should be exactly the same size in the exemplary embodiment shown and have end faces 13 and side faces 14 oriented perpendicular to the transport plane. The length of the casting molds 7, as can also be seen in FIG. 2, at least in the transport direction, is greater than the length of the respectively assigned pallet 8, so that the molds 7 placed in the center protrude forward and backward from the respectively assigned pallet 8 in the transport direction . The successive casting molds can therefore be supported directly against one another with their vertical end faces, so that in the region of the forward branch 3a and the return branch 3b of the supply, casting and cooling section, there is a gapless mold strand 15, as shown in FIG. 1. The force flow caused by the driving and braking forces and possibly by the thermal expansion forces within each mold strand 15 runs over the casting molds 7. The pallets 8 receiving the casting molds 7 remain unaffected by this. The direct mutual end support of the casting molds thus enables a reinforcing effect to be achieved and therefore high accuracy and dimensional accuracy can be expected.

As shown in FIGS. 2 and 3, each of the mold strands 15 is assigned a drive station 16 arranged in the region of its rear end, which is expediently integrated in the roller conveyor 6 here, and a brake station 17 arranged in the region of its front end and expediently integrated in the roller conveyor 6 . The drive station 16 and the brake station 17 are each assigned a drive element 18 or brake element 19 shown in FIG. 3, wherein a slip clutch 20 is provided in the kinematic drive chain hoist, the transmission torque of which is adjustable, so that the mold strand 15 to be introduced or the drive or braking force to be derived from this is also adjustable. This ensures that no uncontrolled forces act on the associated mold strand 15, so that very gentle handling of the casting molds 7 is ensured. The drive station 16 and the brake station 17, as can also be seen in FIG. 2, each consist of at least one drive roller 25 or brake roller 26, which frictionally engage the pallets going over them. In order to avoid wear, this frictional engagement is expediently designed to be stronger than the maximum transmission torque that can be set in the area of the associated slip clutch 20, so that in the event of slippage this occurs in the area of the slip clutch. The rollers of the roller conveyor 6 located between the drive station 16 and the braking station 17 are simply designed as freely rotatable, non-driven support rollers 27. The rollers 25, 26, 27 can be designed as rollers running across the width of the roller conveyor 6. In the illustrated embodiment, mutually opposite pairs of rollers are used. In the exemplary embodiment shown, the drive station 16 and the brake station 17 each extend approximately over the length of a pallet 8 and are each equipped with 3 pairs of rollers, so that the drive or braking forces can be transmitted safely and without slippage with each adjustment of the clutches 20. An electric geared motor can expediently be used as the drive element 18 or brake element 19. To switch off the internal friction of the roller conveyor 6, its branches, as can be seen in FIG. 2, are inclined with respect to the horizontal in such a way that the bearing frictional forces and the like acting on the rollers are equalized by the downward slope of the pallets 8 and molds 7 located thereon.

In the idle state, the drive element 18 is blocked at least in the opposite direction to the transport direction and the brake element 19 is blocked at least in the transport direction. The drive element 18 can for this purpose with a backstop 30 be provided. The brake element 19 is provided with a blocking brake 31 that engages automatically when the vehicle is at a standstill. If the mold strand held together in this way tries to expand under the action of internal thermal expansion forces, these thermal expansion forces are contained by the blocked drive element 18 or brake element 19 up to the level of the force which can be transmitted by the slip clutches 20 or are held completely in the strand. The slipping clutches 20 are therefore expediently to be set such that no slippage occurs due to thermal expansion forces, which prevents expansion of the mold strand 15. The thermal expansion forces are relatively easy to determine since, as tests have shown, these do not add up over the length of the strand.

With the above-mentioned setting of the slip clutches 20, the complete molds 7 could slide against the pallets 8 or the mold upper parts 11 against the associated mold lower parts 12. However, the force required to accomplish such a shift is also easy to determine by experiment and is usually known. The molds 7 are not displaced with respect to the pallets 8 or the upper mold parts 11 with respect to the lower mold parts 12 if the displacement force required for this is greater than the thermal expansion force. This is as far as the molds 7 support each other, which is the case in the illustrated embodiment due to the same size of the upper mold part and lower mold part both in the region of the upper parts 11 and in the region of the lower parts 12, as seen from behind in the direction of transport the first cast mold, which may be subject to thermal expansion, would have to move all the molds of the supply section located behind it, so that the displacement force determined for a mold is multiplied. In the case of casting molds in which the upper parts are somewhat smaller than the lower parts, so that there is no mutual support in the area of the upper parts, this can be achieved by appropriate weighting. In order to avoid a displacement of the upper parts relative to the associated lower parts of the casting molds 7 located in the area of the supply section in such cases, the force that can be transmitted by the slip clutches 20 can be set to a value that is slightly below the displacement force, so that there is a slight stretching of the mold strand 15 rather than a mutual offset of the upper parts relative to the lower parts of the casting molds located in the region of the supply section. However, this does not occur under normal operating conditions.

When the mold strand 15 accelerates from standstill to the normal operating speed, the drive station 16 is activated and the required acceleration force is introduced into the mold strand 15. The setting of the assigned slip clutch 20 represents the limitation of the acceleration force. Activation of the braking station 17 together with the braking element 19 is not necessary in this phase. Only the blocking brake 31 has to be released. In this case, the braking station 17 is simply carried empty by the pallets 8 passing over the braking rollers 26. The internal resistance, for example in the area of the gear motor forming the braking element 19, counteracts the feed force. The acceleration forces transmitted from one mold to the next mold 7 in the area of the abutting end faces 13 decrease from the back to the front. Adequate mutual clamping of the casting molds 7 is therefore ensured in the rear region of the mold strand, which is particularly at risk from thermal expansion. As soon as the transport speed has been reached, the braking element 19 is activated and the transport speed is thereby kept constant. This can be accomplished by operating the brake 31. The braking force acting on the mold strand corresponds to the force resulting from the transmission torque of the slip clutch 20. The slipping clutch assigned to the braking element 19 is expediently set to a somewhat lower value than the slipping clutch 20 assigned to the drive element 18, so that the driving force which takes effect slightly outweighs. In the exemplary embodiment shown, the drive motor 18 and the gear motor forming the braking element 19 are put into operation simultaneously. During the acceleration phase, the gear motor forming the braking element 19 runs idle. For this purpose, a freewheel 32 forming an overrunning clutch is provided in the kinematic drive chain hoist leading to the brake rollers 26. As soon as the brake rollers 26 carried by the pallets 8 become faster than the gear motor forming the brake element 19 or the assigned gear output, the freewheel 32 acts as a transmission element, whereby the brake element 19 is itself carried by the brake rollers 26. The electric motor forming the braking element 19 is operated as a generator. The braking force acting on the mold strand 15 corresponds to the generator force. The electric motor forming the braking element 19 is connected in terms of control to the electric motor forming the drive element 18 and, as soon as it is operated as a generator, takes the lead in terms of speed. With the aid of the braking element 19, which runs idle via the freewheel 32 and works as a generator after being overhauled by the strand, the end of the acceleration phase can advantageously be detected automatically, so that a very uniform strand movement results. The translation of the gear assigned to the braking element is expediently somewhat less than the translation of the transmission assigned to the drive element 18, so that the same engine speed results in a somewhat lower transmission output speed in the area of the braking station than in the area of the drive station. This ensures that a defined generator force is available as a braking force in the last area of the acceleration phase and during normal feed operation, as a result of which the mold strand is held together cleanly.

The gear assigned to the drive element 18 and the brake element 19 can be combined with the respective electric motor to form a structural unit or, as indicated in the exemplary embodiment shown at 33, can be designed as a separate additional gear. To terminate the movement of the mold strand, the drive station 16 is passivated by switching off the associated electric motor. At the same time, the brake 31 of the brake element 19 is actuated, thereby blocking the motor forming the brake element 19. The braking force acting on the mold strand corresponds to the force resulting from the torque that can be transmitted in the area of the associated slip clutch 20. The blocked brake 31, together with the automatically acting backstop 30 in the area of the drive station 16, results in the clamping of the mold strand 15 between the drive station 16 and the brake station 17, which is particularly desired at a standstill, which results in the desired end-face reinforcement of the casting molds 7.

In addition to the end reinforcement of the casting molds 7, the side surfaces 14 can also be reinforced. For this purpose, as can best be seen from FIG. 4, clamping plates 21 resting on the side surfaces 14 of the casting molds 7 can be used. In the illustrated embodiment, the clamping plates 21 are pivotally supported by two-armed angle levers 22 on a load iron 23 placed on the upper part 11 for weighting. The angle levers 22, with their arms projecting from the associated load iron 23, form an opening pair of scissors into which a stick 24 can be inserted in order to achieve a self-locking lock and further weighting. Together with the end support of the casting molds and simultaneous clamping of the mold strand, this results in a reinforcement of the casting molds 7 on all four circumferential surfaces, which is equivalent to box reinforcement, which can be expected from a manufacturing accuracy previously not considered possible with boxless molds.

In order to place new casting molds ejected from the molding station 1 at the rear end of the mold strand 15, a feed device 127 arranged upstream of the drive station 16 is provided. A pull-off device 28 is arranged downstream of the braking station 17 of each mold strand 15, by means of which the foremost casting mold of the associated mold strand can be pulled off the front end of the strand. The feed device 127 and the take-off device 28 here, as can be seen from FIG., Also consist of three pairs of drive rollers 25, which are coupled to an assigned drive element 29 via slip clutches 20 which can be set with regard to the transmissible torque. Since only one casting mold and pallet can be accelerated in the area of the feed device 127 and the take-off device 28, the respectively assigned slip clutches 20 can be set to a relatively small transmission torque, so that the associated drive elements 29 spin empty when a slight resistance occurs, with which a load on the assigned mold is counteracted. A feed force of 100 N that is effective in the area of the feed device 127 has proven to be particularly expedient. The feed device 127 and the take-off device 28 run to achieve an effective infeed or an effective take-off, each with a speed slightly exceeding the transport speed of the assigned mold strand, and the speed difference in the area of the feed device 127 is preferably selected such that the resulting kinetic energy during Casserole of the casting mold to be started on the rear end of the mold strand in the plastic region of the molding sand is receivable and is not sufficient to offset the upper mold part relative to the associated lower mold part. A speed difference of the order of 5 cm / s has proven to be particularly useful. In the exemplary embodiment shown, the translation units 10 are integrated in the feed device 127 or the take-off device 28. If, as in the illustrated exemplary embodiment, a plurality of rollers or pairs of rollers are driven via a drive element and a respective slip clutch 20, these are of course connected to one another in a rotationally locking manner by chains, gearwheels or the like.

5 and 6 are based on a transport device for a mold strand, likewise designated 15, which consists of casting molds 7 lined up with a vertical parting joint. This can be the same monoblock shape as in the case of FIG. 5, or so-called double block shapes, each consisting of an upper part and a lower part and tilted by 90 ° after completion, according to FIG. 6. The transport of the mold strand 15 takes place step by step in accordance with the replenishment of new molds from the molding station, not shown here. During the movement phase, the entire strand 15, consisting of casting molds 7 which are gently lined up, rests on a plurality of transport units arranged one behind the other. The transport units are designed as conveyor grates 34 that can be moved back and forth in steps formed, which consist of a plurality of rails arranged next to one another at a distance and mesh with a standing grate 35 which extends over the entire length of the associated mold strand 15 and which also consists of a plurality of rails arranged next to one another at a distance, between the rails of the conveyor grates 34 forming the transport units intervene with sufficient running play. The standing grate 35 is arranged stationary. The conveyor grates 34 are received on a roller conveyor, also designated 6, the structure and mode of operation of which corresponds essentially to the roller conveyor 6 according to FIGS. 2 and 3. The same reference numerals are therefore used for the same parts. Accordingly, in the present exemplary embodiment, the roller conveyor 6 also consists of drive rollers 25 arranged in the region of its rear end to form a drive station, brake rollers 26 arranged in the region of its front end to form a brake station and non-driven support rollers 27 arranged between drive and brake station. The drive rollers 25 and brake rollers 26 are also to be connected in the present exemplary embodiment with the interposition of a respectively assigned slip clutch, the transmission torque of which is adjustable, to an electric gear motor as a drive element, the electric gear motor assigned to the brake rollers 26 as in the example above according to FIGS. 2 and 3 a blocking brake of the type indicated at 31 in FIG. 3 and a free-wheeling of the type indicated at 32 in FIG. 3 should also be provided in the kinematic drive chain hoist. The operating sequence during the acceleration, movement and braking phase is the same as described above with reference to FIGS. 2 and 3. In the exemplary embodiment shown, the conveyor grates 34 each hold a plurality of casting molds 7 arranged one behind the other. However, the length of the conveyor grates 34 is dimensioned such that the molds 7 accommodated thereon together have a somewhat greater overall length. With a central arrangement, there is a corresponding cantilever to the front and rear, so that the force flow during the movement of the conveyor grates 34 runs within the mold strand 15, whereby the mold strand 15 is held together during the movement phases and the internal thermal expansion forces are contained. The torque which can be transmitted with the slip clutch assigned to the drive rollers 25 is set to such a value that the feed force required to accelerate the mold strand 15 can just be transmitted. The slip clutch assigned to the brake rollers 26 can expediently be set to a somewhat smaller value.

In the rest periods caused by a lack of replenishment of liquid metal, the mold strand 15 can be accommodated on the conveyor grates 34, the associated drive rollers 25 and brake rollers 26 being blocked to counter thermal expansion of the mold strand 15 against or in the direction of conveyance, likewise as in FIG 2 and 3. For this purpose, a backstop or a blocking brake can also be provided. The force counteracting the thermal expansion force corresponds to the force resulting from the transmission torque set on the couplings 20, which is expediently above the thermal expansion force in order to completely prevent thermal expansion. If the mold strand 15 rests on the stand grate 35 during the breaks, the thermal expansion is contained by the frictional force in the area of the strand support.

The standing grate 35 and the conveyor grates 34 serving as transport units are alternatively adjustable relative to one another in the vertical direction so that the mold strand 15 either rests on the conveyor grates 34, as indicated in FIG. 5, or on the stand grating 35, as indicated in FIG. 6 . The mold strand 15 placed on the conveyor grates 34 is thereby moved forward by the length of a casting mold and placed on the grate 35 at the end of the assigned movement path. The released conveyor grates 34 are then returned to their starting position. This can be accomplished, for example, by reversing the drive rollers 25. The distance between the individual conveyor grates is fixed to a constant dimension by suitable drivers. This fixation is released as soon as the conveyor grates are brought into engagement with the strand.

A feed device 127 is provided between the rearmost conveyor grate 34 in the transport direction and the molding station (not shown). This consists of a push-on carriage 36 placed on drive rollers 25, which, to the same extent as the conveyor grates 34, has rails which are spaced apart from one another and which can engage between the rails of the standing grate 35. The push-on carriage 36 is connected to the adjacent conveyor grate 34 via guide pins 37, which ensure exact centering. To position the mold which can be pushed onto the push-on carriage 36 with the aid of a stamp 38, adjustable shields 39 are provided, one of which can be locked against an adjustable stop on the carriage frame and the other is adjustable by means of a cylinder-piston unit. The mold inserted between the shields 39 is hereby pressed onto the lockable shield and thus precisely aligned. For double-block molds, which consist of an upper part 11 and a lower part 12, a trolley with an angular grate is used, which, as shown in FIG. 6, can be tilted by 90 ° about an axis of rotation 40, so that parts that are subsequently aligned perpendicular to the transport plane are subsequently used eyes 41 result.

The drive rollers 25 assigned to the feed device 127 are also via a force adjustable slip clutch connected to an associated drive motor. The torque that can be transmitted by this slip clutch must be set so that the resulting feed force is approximately 100 N. As soon as the resistance when the casting mold to be set hits the rear end of the mold strand 15 reaches this force, the coupling rotates, so that deformation or damage to the casting mold is avoided with certainty. The speed of the drive rollers 25 assigned to the feed device 127 is set in such a way that there is an excess of speed of the casting mold to be set in relation to the moving mold strand 15 by approximately 5 cm / s. The kinetic energy released when the casting mold hits the rear end of the mold strand is absorbed in the plastic area of the molding material, so that shock-like loads and thus deformations and damage are also avoided from this side. The connection of a new casting mold to the rear end of the mold strand 15 in the direction of transport expediently takes place during the forward movement brought about by the conveyor grates 34 with the standing grate 35 lowered. During the backward movement, the last casting mold 7 in each case is pushed off a transport device 42 leading to an unpacking station, not shown in any more detail . The backward movement of the push-on carriage 36 into its starting position can also be expediently accomplished by reversing the assigned drive rollers 25. However, it would also be conceivable to leave the conveyor grates without their own drive and to attach them to the push-on carriage, for example by means of a transport chain engaging with the conveying gratings 34 and the push-on carriage 36.

The slip clutches 20 used according to the invention are expediently designed as contactless electrostatic hysteresis clutches, which ensures complete freedom from wear.

Claims (16)

1. A process for the transport of flaskless molds (7) along a storing, teeming and cooling conveyor (3) in a foundry plant and having at least one straight conveyor run, the molds (7) having end and side faces (13 and 14 respectively) aligned to be perpendicular to the transport plane being put together in the form of an unbroken train (15), at whose back end new molds are continuously added to the train and at whose front end molds are continuously taken from the train at the same rate, and the forces needed for accelerating the mold train to be transported are caused to take effect to the desired adjustable degree at the end of the train, which is to the back in the direction of transport, characterized in that the acceleration of the train (15) of molds takes place in each case independently of the new mold (7) to be added to the back end of the said train (15) of molds and in that the forces needed for the acceleration or the slowing down of the full train (15) of molds between the rearmost mold (7) coming after the new mold (7) to be added thereat, and the foremost mold (7) coming before and to the taken off, or the forces opposing thermal expansion and needed for keeping the overall mold train (15) together, is caused to take effect at the back end, coming after the mold (7) to be added, to the mold train (15) or at the front end, coming in front of the mold to be added, and such forces are equally transmitted along the full length of the mold train (15) between the re armost mold (7) coming after the mold (7) to be added to the train, and the foremost mold (7) placed in front of the mold (7) to be taken from the train, exclusively by way of the mold (7) themselves from one mold (7) to the next one thereof.

2. A process as claimed in claim 1, caracter- ized in that the mold train (15) out of the speeding up stage, more specially in the resting stages, is kept together by an adjustable force acting oppositely to the thermal expansion forces of the molds.

3. A process as claimed in claim 2, characterized in that the force keeping the mold train (15) together is greater than the force needed to completely overcome thermal expansion of the mold train (15).

4. A process as claimed in claim 2 or claim 3, characterized in that the force keeping the mold train (15) together is smaller than the force needed for causing slipping of a given mold (7) or parts thereof (11, 12) waiting its turn to be filled, next to the mold, which was last to be teemed up, on supports of said given mold.

5. A process as claimed in at least one of claim 1 to 4, characterized in that the force necessary for causing slipping of that mold (7) or parts thereof (11, 12) next to the last-filled mold and waiting its turn to be filled, on its support is in any case greater than the force produced by thermal expansion within the mold train (15).

6. An apparatus for the transport of a train (15) of flaskless casting molds (7) with a roller conveyor (6) placed between the mold station (1) and an unpacking station (2) and having at least one straight run and formed by stationary rollers (25, 26 and 27), on which conveyor transport units (pa- lets 8 and conveying grids 34) may be moved, characterized in that the length of the transport units (8 and 34) in the transporting direction is smaller that the length of the mold (7) or molds (7) to be accommondated thereon, said mold or molds (7) being placed on the respective transport unit (8 and 34) thereof so as to be project to the front and the back in the direction of transport, and in that the transport units (8 and 34) furthest to the back and furthest to the front in a run of the mold train (15) are joined by way of at least one slipping clutch (20), whose transmitted torque may be adjusted, with the a driving station (16) and a braking station (17).

7. An apparatus as claimed in claim 6, characterized in that the driving unit (16) is made up to at least one driving turning support (25) joined up with a driving machine (18) by way of a slip clutch (20), the driving machine being able to be locked at least in the direction opposite to the transport direction, and the brake unit (17) is made up of at least one braking turning support (26) which is joined up by way of the slip clutch (20) with at least one brake machine (19, 31) which may be locked at least in the transport direction, in that the driving respectively the braking turning supports (25 and 26) make friction contact with the transport structures (8 and 34) resting thereon, and the force which is able to be transmitted by the driving and braking turning supports (25 and 26) is greater than the greatest force which may be transmitted my the driving and braking unit (17) are free running turning supports (27).

8. An apparatus as claimed in claim 6 or claim 7, characterized in that each run of the turning support conveyor (6) is designed running downhill in the transport direction to such a degree that the resistance taking effect on this turning supports (25, 26 and 27) is equaled by the downhill driving effect of the train (15), at least nearly completely.

9. An apparatus as claimed in at least one of claims 6 to 8, characterized in that the driving machine (18) of the driving unit (16) and the braking machine (19) of the braking unit (17) are powered at least in the speeding up stages and forward motion of the mold train (15) coming thereafter in the transport direction together, and the starting up speed of turning at the braking unit is lower than at the driving unit and in that the torque which may be transmitted by the slip clutch (20) of the braking unit (17) is smaller than the torque which may be transmitted by the slip clutch (20) of the driving unit (16).

10. An apparatus as claimed in claim 9, characterized in that the driving machine (18) and the braking machine (19) are in each case made up of an electric motor, and the electric motor of the braking machine (19) for braking the mold train (15) may be run as a generator, which is joined up for feedback control with the electric motor used as the driving machine (18) and in that between the electric motor used as the braking machine (19) and the braking turning support or supports (26) of the braking unit (17) there is a freewheel to let overtaking take place once the braking turning support (26), moved by the mold train (15) has overtaken the electric motor used as the braking machine (19).

11. An apparatus as claimed in at least one of claims 6 to 10, characterized in that the conveyor run (6) with turning supports has a supply unit (127) placed upstream from the driving unit (16) and a supply unit has at least one driving turning support (25) joined up by way of an adjustable slip clutch (20) with its driving machine (29) so that the driving turning support (25) may be turned at a somewhat higher speed than the driving turning support (25) of the driving unit (16).

12. An apparatus as claimed in at least one of claims 6 to 11 more specially for transport of molds with upright parting planes, characterized in that the transport structures take the form of walking beams (34) able to be moved backwards and forwards on the turning supports (6) of the conveyor by a distance equal to at least the length of one mold (7) and the walking beams (34) are placed singly between supporting beams (35) which are not moved in the transport direction and are designed running for the full length of the bold train (15), the support beams being able to be moved upwards for taking over the mold train (15) so as to be higher than the top of the walking beams (34), and for handing over the mold train (15) back to the walking beams (34) may be lowered to a lower level than the same, in that the walking beams (34), after being moved forwards may be moved backwards with the mold train (15) resting on the support beams (35) and in that the supply unit (127) has a pusher carriage (36) able to be moved between the mold producing station and the transport structure furthest to the back, the pusher carriage (36) being moved by at least one turning driving part (25), and in that a mold (7) coming from the mold producing station may be pushed on to the carriage, the carriage having positioning parts (plate 39) for truly positioning the mold placed thereon and being connected by guide parts (guide pins 37) with the transport structure next thereto.

13. An apparatus as claimed in claim 12, characterized in that the pusher carriage (36) has rails able to be turned about a horizontal axis (40), which is normal to the direction of transport, through 90° for righting molds (7) produced in the mold producing station with a horizontal parting line.

14. An apparatus as claimed in at least one of claims 6 to 12, more specially for transporting molds with a horizontal parting line, characterized in that the transport structures take the form of palettes (8) running along at least one forward run and then back on a back run of a conveyor (6) with turning supports and the palettes (8) may be moved over at the front end (in the transport direction) of each run using a moving over unit (10) to the next run of the conveyor (6) with turning supports and in that the palettes (8) may be supplied to the moving over unit (10) to the next run of the conveyor (6) with turning supports and in that the palettes (8) may be supplied to the moving over unit (10) by way of change-over part (28), coming after the braking unit (17) and the part (28) has at least one driving turning support (25) joined up by way of an adjustable slip clutch (20) with its driving machine (29) and the driving turning support (25) may be run at a speed which is a little higher than the speed of the driving turning support or supports (25) of the driving unit (16).

15. An apparatus as claimed in at least one of claims 6 to 14, characterized in that the adjustable slip clutches (20) take the form of contactless magnetic clutches and more specially mag- netostatic hysteresis clutches.

16. An apparatus as claimed in at least one of claims 6 to 15, characterized in that the side faces (14), stretching in the transport direction, of the molds forming the mold train (15) may be reinforced by gripping plates (21) which are supported by way of self-locking leves (22) on a weighting iron (23) designed to be placed on the molds and which at the end of the conveyor run with turning support may be taken from the mold (7) supplied to the shake-out station (2).

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