Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C11/00—Moulding machines characterised by the relative arrangement of the parts of same
  • B22C11/02—Machines in which the moulds are moved during a cycle of successive operations
  • B22C11/08—Machines in which the moulds are moved during a cycle of successive operations by non-rotary conveying means, e.g. by travelling platforms
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C17/00—Moulding machines characterised by the mechanism for separating the pattern from the mould or for turning over the flask or the pattern plate

Definitions

• the invention relates to a method and an apparatus for separating the model and the sand bale molded in a mold by means of the model, in which the model and shape - with horizontal alignment of their horizontal dividing surfaces - can be moved relatively apart in the direction of a normal to these dividing surfaces.
• a mechanical synchronizing device is provided, which is arranged below the model carrier. This requires a spacious basement room under the machine.
• the mechanically controlled synchronization takes place via a centrally guided common yoke, which raises the four guide rods that serve to lift off evenly.
• One problem is that the yoke has to be freed or uncoupled from these guide rods, for example during the pressing process. In practice, it can be seen that the resulting impurities can have a negative impact on synchronism.
• the control is a control of the lift height (displacement control), preferably via a PID controller, which does not generate a dynamic control error (synchronism error) in response to the ramp (steadily increasing lift heights).
• a particular advantage is that only a floor-level foundation is required for the four individually driven and controlled axes and a generously designed basement space under the machine is unnecessary. It has also been shown that contamination and its negative influence on synchronism can be reliably avoided.
• the arrangement has a high degree of accuracy because the lifting axes, which can be configured from individually driven vertical drives, lifting cylinders, spindle drives, servo drives or other electric drives with a spindle rod, are fixedly arranged with their lower end area and can only be extended upwards in the vertical direction, which is what is subsequently referred to as the instantaneous value of the lifting height over time with the lifting height y (t).
• the invention goes the way of using several individual lifting drives and having them attack at the edges at the same time, in order to either separate the molding box itself with the sand bale or the model relative to the molding box with the sand bale.
• the separating movement runs regularly in the axis that runs vertically to the normal box transport displacement direction and the individually driven lifting axes are aligned parallel to this vertical (normal).
• the gripping on the edge ensures an exact introduction of the force and avoids mechanical imbalances which occur when forces are applied centrally and the force is distributed to the edges via a mechanical, transverse yoke. So no mechanical drive means are required below the fixed cylinders or other drives of the individually driven lifting axes, rather these lifting axes only move vertically in and out and are fixedly arranged at their lower end.
• the fixed arrangement can be provided on a movable carriage, which not only allows the unit consisting of molding box, filling frame and model and model carrier to be moved, but is also a common support device which is precisely aligned with respect to the vertical (claim 3, claim 7).
• the entire device comprising molding boxes and lifting axles can be moved together and thus their position relative to one another can be maintained in the long term (claim 8).
• this carriage can be moved with a horizontally oriented cylinder rod which engages below the carriage (claim 9).
• This pull rod which takes the carriage out of the main box conveying direction and moves to the parallel station, is thus kept very short. It engages the outer, lower end of the carriage without being hindered by deeper mechanical devices that are no longer required according to the invention.
• the regulation of the individual drives can experience several configurations.
• a particularly gentle separation of the molded material bale and the model is possible if the separation speed is greatly reduced at the beginning of the separation process in order to allow ventilation.
• a low speed at the starting point of the mechanical start of the separation is also advantageous because minor vibrations are produced, which gives the advantageous results of the invention, which works at a low speed, a so-called creep speed at the moment and shortly before the separation, during after that, after the critical time of separation and ventilation is over, the speed of separation can be increased again.
• the separation no longer has an immediate effect on the surface of the sand bale, but only serves to widen the distance between the sand bale and the model.
• the low vibration and the synchronization error at the time of the start of the take-off can be further favored, even if a tolerance band with very small (narrow) tolerances is specified for this point in time, the sm actual system on the axes are determined by measuring devices. After the height for physically grasping the molding box is usually very precisely determined by measuring the actual hoof height of the individual lifting axes, it is possible to determine when this point in time is reached and until this point in time the speed of lifting the individual lifting axes can be reduced so much that a practically ideal synchronization is achieved, which is in any case within the first tolerance band. So is already grasping the
• Shaped box caused very precisely and very evenly, so that the separation that follows after the exact gripping assumes a horizontally very uniform state (claim 15).
• This corresponds to a target regulation of the synchronism error to a predetermined first tolerance band and the reduction of the setpoints before reaching the point of attack, which cannot be determined with a centrally guided mechanical lifting, since the individual points of attack are exposed and there is no possibility of measurement there, while according to the invention the measurement takes place exactly at the points that engage vertically aligned on the molding box (claim 16).
• the manipulated variables are those signals that are output variables of the controller and that are fed to the hydraulic or electrical actuators for controlling the axis. Too large setting strokes are a sign that high forces are acting, which the individual lifting axes try to regulate individually, but which can also be a signal that an error that leads to a strong asymmetry or that originates from such a strong asymmetry is recognized can be. A second tolerance band can be used to record these strongly differing adjustment strokes. If such a tolerance band is exceeded, then either the error can only be registered or the lifting speed of all axes can be reduced immediately in order to give the possibility of intervention (claim 17).
• a higher accuracy is achieved with an additional averager (claim 18).
• This averager not only monitors one axis, but all of the intended axes and forms a total average of all actual height values that are measured individually on each axis. A mean value is formed from these total height values, which is then used as an additional setpoint for each controller can be switched on, so that there is an additional equalization.
• This additional connection works in such a way that those controllers which are deflected more strongly in one direction or the other are either accelerated or braked, so that the lifting process is evened out.
• the additional control loop can be specifically provided with integral components, since this integral component does not cause any problems with a very slow control system and still ensures the lowest possible errors.
• the additional controllers then work like additional connections in the sense of a precontrol because the other controllers of the lifting axes are also still present, but are then preferably designed with a P control behavior.
• Figure 1 shows a device for single-axis controlled separation of model and sand bale as a first example.
• Figure 2 shows a similar representation of a conventional lifting device next to a press station and under a filling station and the associated basement
• FIGS. 3a to 3f show a further device for the single-axis-controlled separation of
• FIG. 4 is a top view of those shown in the previous figures
• FIG. 5 is a control loop with which the individual axes 15, 16, which are also on Figure
• FIG. 6 is a diagram which has been obtained in a practical test with a device according to FIG. 1 and a control according to FIG. 5.
• FIG. 2 shows a conventional press station 1 with a multi-die press head 1a and a press table 3, which can be raised in the direction of the press head 1a by a device 4.
• Model carrier 8 and model 8a is arranged between the pressing station 1 and a station 2 which is also used for filling the sand.
• the normal corridor level is indicated by 12.
• the model carrier is designated 8 with model 8a.
• the lifting machine has a filling frame 6 below a sand bunker 10, and four guide rods 13, on which the elements serving to lift the molding box 7 containing the sand bale are arranged.
• the guide rods 13 are raised together by a yoke 9, which can be raised and lowered with the aid of a lifting device 11 arranged in a basement 14.
• the separating device 2 is again shown next to a press station 1.
• 20 is the perpendicular to the separating surfaces of the mold and the ball of sand Denoted normal.
• four individually driven and controlled hydraulic lifting cylinders 15, 16 are provided for separation in the arrangement according to FIG. These are jointly supported a little above the foundation, which is on the corridor level 12. A large basement room is therefore not required. A little above the foundation, the carriage 30 defining the support is laterally displaceable.
• the carriage 30 can be shifted from left to right (and vice versa) in FIG. 1, via the shifting device 5.
• This direction ⁇ A is transverse to the transport direction K of the molded boxes, which is oriented perpendicular to the paper plane, cf. also Figure 4.
• hydraulic lifting cylinders 15, 16 electrically operated drives can also be provided. They are also displacement-controlled in their lifting height y, preferably via individual sensors on each “axis”, which provide the actual values y (t) for the displacement control of FIG. 5. Cross coupling from one axis to the other is avoided; each axis regulates to its own setpoints - which are given in the same way - and regulates its own disturbance variables that occur individually, cf. see FIG. 6.
• the arrangement 5 previously described as being displaceable in the direction ⁇ A is to be explained in more detail in FIG.
• It consists of a horizontally lying cylinder, the cylinder area of which comes to lie below the compression station 1 and the pull / push rod 5z when the carriage 30 is moved over below the filling station 2.
• This rod 5z is arranged with its front end at the outer end region on the underside of the carriage 30 and can, when the cylinder 5 is triggered, pull the carriage 30 together with the unit consisting of model carrier 8, molding box 7, filling frame 6 into the compression station 1 and after that Compress back into the main box conveying direction K, which can be seen in FIG. 4.
• the cylinder 5 does not protrude much laterally next to the compression station 1, which is caused by the fact that below the support rail 31, on which the carriage 30 can be moved by means of rollers 32a, 32b, no further mechanical Elements are provided which have to perform strokes in the vertical direction in the filling station, rather the area between the lower edge of the running rail 31 and the foundation 12 is practically free here.
• the direction in which the displacement device 5 performs the movement is designated ⁇ A, it is perpendicular to the box conveying direction K according to FIG. 4.
• FIG. 3f shows the same device that was explained in FIG. 1, only additional support feet 33 are arranged on the foundation 12, which support the guide rail 31 below the filling station 2 on which the carriage 30 with its pairs of rollers 32a, 32b is laterally displaceable, in direction A.
• the conveying direction K of the boxes, both the supplied empty boxes and the removed boxes provided with compressed sand bales, is perpendicular to the plane of the paper.
• the compressed molding box of FIG. 3a is pushed out (to the front), while an uncompressed, yet empty molding box in FIG. 3b moves into the filling station, held by roller conveyor sections 41, which are supported on downwardly extending support arms 40 at the upper region 16a of the respective lifting axes 16 are arranged, cf. see FIG. 1 in detail.
• the molded molding box 7 When the empty molding box 7 is pushed in, the molded molding box is transported out of the filling station 2 and at the same time - depending on the sequence - an upper box model or a lower box model with a carrier is moved into the lifting-filling station via roller conveyors by means of cylinders (not shown here). More details about this retraction of models will be given later in FIG. 4.
• FIG. 3b the compression station 1 with its multi-punch press head 1a is in the basic position.
• the lifting cylinder 4 is also retracted.
• the retracted (still empty) molding box 7 and then the filling frame 6 are placed on the model plate carrier 8 with the lifting axes 15, 16 in order to enclose the model 8a.
• FIG. 3c is reached, in which molding material is additionally filled into the unit consisting of molding box, filling frame and model.
• the pre-selected amount of sand can be specified using a trigger belt conveyor.
• the amount of sand can be set depending on the model, e.g. B. by entering the number of revolutions of a pulley of the trigger belt conveyor, which are specified in the associated control.
• the compression station is still in the basic position in FIG. 3c.
• the unit filled with sand is moved over to the compression station on the carriage 30, in direction A.
• the press cylinders 1a compress the molding sand above the model after the unit has been lifted off the carriage by means of the lifting cylinder 4 and pressed against the press head from below.
• the lifting cylinder 4 lowers the unit - now in the compressed state - back onto the carriage 30, which travels in the direction -A into the filling station, which achieves the state of FIG. 3e.
• the plungers 16 which have been retracted up to that point now begin to separate the compressed sand bale 7a from the model 8a.
• the lifting axes 15, 16 are electronically controlled with the highest accuracy and first lift off the filling frame, which can be seen from the transition from FIG. 3e to FIG. 3f.
• the downward-reaching carrier 41 is so long that the filling frame 6 is first raised at the upper end 16a of the lifting axis; no mechanical vibrations of the model are associated with it. Only after a short stroke, in which the molding box 7 has not yet been gripped, do the supports 40 with their lower end, a roller section, engage the corresponding counter-sections of the molding box 7 and raise it mechanically. This lifting process will become clearer later, with a view to FIG. 6, in which the three time periods of the separating stroke of the filling frame, the creep speed and the remaining stroke can be explained in more detail.
• the free lifting of the filling frame is the starting point and at the beginning of the lifting of the molding box, a low speed is set in order to take the molding box softly off the rollers and to give the mold time for the separation process for ventilation.
• the lifting axes then continue to lift, this time faster, until the molding box has reached the height of the runways which are in the main box transport direction K of FIG. 4.
• FIG. 4 illustrates the retracted retraction of a model or the change of a model for an alternate impression of the upper box and lower box.
• the arrangement of the four individually regulated lifting axes 15, 16 in the corner regions of the molding box 7 can be seen in FIG. 4 when it is retracted in the filling station.
• the compression station 1 is offset parallel to the main box transport direction K and the carriage 30 is moved into the filling station 2 in the position shown in FIG.
• 30 arrangements are provided transversely to the direction of displacement A of the first carriage, which enable the retraction of a model for the upper box or a model for the lower box or other models.
• roller conveyors (sections thereof) are located above and below the filling station 2 shown in FIG.
• FIG. 6 This course of the measured values and setpoints is to be explained in connection with FIG. 5, which shows the control with which the four lifting axes of FIG. 1 are individually controlled.
• the starting point for the control of FIG. 5 is the jointly specified setpoint y s (t), which is jointly specified for all four axes.
• Each controller has a setpoint / actual value comparison, which subtracts the actual stroke value y (t) of the respective individual axis from the setpoint y s (t) and specifies the difference as a control difference for a respective individual controller 81, 82, 83, 84.
• This controller controls the drive for the respective axis, designated in the figure 5 with axis 1, axis 2, axis 3 and axis 4, and results in the control equivalent circuit diagram an actual value of the lifting height y (t), each individually for each Depending on the disturbance variables, the stroke axis results in individual effects on each axis.
• the additional controllers 81a, 82a, 83a, 84a which have already been drawn in in FIG. 5 and which are synchronous controllers for the respective axis and are fed by an averager 90 will be explained later.
• the starting point was the specification of a common setpoint, which appears as the course of the lifting height over time in FIG. 6. At first a slight increase and then a steeper gradient up to time T0, the separation of the
• Vf (t) the respective synchronism deviations for the four axes used are shown with Vf (t) in FIG. They are not identical, but run in a common window between the Limit values y 0 and y u , which is important for creep speed, in which the mold box 7 with the bale of sand 7a is lifted off the model 8a. Relevant for this is the beginning of the take-off, the time TO, at which the lowest possible speed is specified by the setpoint y s (t), that is, sufficient time for ventilation and little susceptibility to faults.
• the tolerance band TB delimited by the limit values y 0 and y u is set to ⁇ 0.05 mm in the example shown, but in fact the synchronism fluctuations are even smaller, as can be seen from the measurement in the tolerance band TB.
• FIG. 6 shows a time span of approximately 2.4 seconds for a complete disconnection, the course of the setpoint value for the lifting height y s (t) illustrating a larger path difference than the greatly enlarged scale drawn in between -0.1 and +0. 5 mm to represent the synchronization deviations yf (t).
• controller 5 uses proportional controllers for the controllers 81, 82, 83, 84 in order to regulate the controlled systems of the axes, which can be represented with a PT2 component for the valve with hydraulic control and an IT2 component for the cylinder .
• the additionally shown synchronous controllers 81a can be P controllers, but they preferably have an integral component switched on in order to switch off control errors even when ramps are specified by the height setpoint y s (t).
• the mean value generator 90 detects the sum of all stroke values y (t) of all axes and calculates a mean value M (t) for respective comparator points 81c, which individually subtract the individual actual value y (t) of each axis and the additional regulators 81a, 82a, 83a , 84a.
• This synchronous controller which is designed as a proportional or PI controller, connects a pilot control to a summing point 81b in order to influence the controlled system 15, 16 of the respective axis.
• All used lifting axes should preferably have the same behavior and therefore the same control structure.
• An adapted displacement measuring system can be used as a measuring transducer for the measuring height, adapted to the type of the respective axis, such as a measuring rod for a lifting cylinder or a rotary encoder for driven spindle rods.
• the setpoints, actual values and manipulated variables can be monitored at any time.
• the manipulated variable of each controller of each axis can be monitored for a tolerance band with a maximum value, so that the manipulated variables are not too large during the separation process. If it is determined that one of the manipulated variables lies outside the previously defined limit value or leaves the specified tolerance band, an error can be concluded.
• the associated cylinder is then loaded with either too large or too small a force.
• a looming malfunction can be compensated preventively by e.g. B. the slope of the setpoint curve y s (t) is reduced in order to reduce the path difference and to bring the torn manipulated variable back into the tolerance band.
• FIG. 6 shows the high accuracy in the time range TO to T1, which corresponds to creep speed.
• the start of the time TO can also be influenced by a controller that works in such a way that the setpoint specification of the stroke is reduced until the shown synchronization deviations yf (t) lie within the tolerance band TB when the time TO is reached.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Casting Devices For Molds (AREA)
• Separation Of Solids By Using Liquids Or Pneumatic Power (AREA)
• Underground Or Underwater Handling Of Building Materials (AREA)
• Investigation Of Foundation Soil And Reinforcement Of Foundation Soil By Compacting Or Drainage (AREA)
• Farming Of Fish And Shellfish (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Analysing Materials By The Use Of Radiation (AREA)

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• 1997
  • 1997-08-04 DE DE19733703A patent/DE19733703B4/de not_active Expired - Lifetime
• 1998
  • 1998-08-04 BR BR9811077-2A patent/BR9811077A/pt not_active IP Right Cessation
  • 1998-08-04 DK DK98948721T patent/DK1007244T3/da active
  • 1998-08-04 WO PCT/DE1998/002237 patent/WO1999006165A2/fr not_active Ceased
  • 1998-08-04 AT AT98948721T patent/ATE265905T1/de not_active IP Right Cessation
  • 1998-08-04 EP EP98948721A patent/EP1007244B1/fr not_active Expired - Lifetime
  • 1998-08-04 DE DE59811340T patent/DE59811340D1/de not_active Expired - Lifetime
  • 1998-08-04 DE DE19882523T patent/DE19882523B4/de not_active Expired - Lifetime
  • 1998-08-04 ES ES98948721T patent/ES2219910T3/es not_active Expired - Lifetime
  • 1998-08-04 JP JP2000504965A patent/JP2001512048A/ja active Pending

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