EP3492196A1 - Pressure diecasting device - Google Patents

Abstract

The invention relates to a die casting device (10) for producing metallic die cast parts with a die casting mold which forms a mold cavity (16) and with a press piston (26) for pressing molten metal casting material into the mold cavity (16), the press piston (26) by means of an electric drive unit (28) which has at least one electric linear motor (30, 32), can be displaced linearly in a filling chamber (18) connected to the mold cavity (16) via a filler channel (20). In order to further develop the die casting device (10) in such a way that the press-in piston (26) can be driven with simpler and less expensive linear motors (30, 32) and nevertheless optimum casting results can be achieved, it is proposed that the flow cross-section of the filling channel (20) be in a channel section during the filling of the mold cavity (16) by means of a cross-section changing device (58).

Description

The invention relates to a Druckgießvorrichtung for producing metallic die castings with a die, which forms a mold cavity, and with a press-in piston for pressing molten metallic casting material into the mold cavity, wherein the press-in piston by means of an electric drive unit having at least one electric linear motor, in a via a filling channel with the mold cavity connected filling chamber is linearly displaceable, and with an electrical control device for controlling the electric drive unit.

Such die casting devices are used for the production of metal die-cast parts, in particular for the production of die-cast parts from an aluminum or magnesium alloy. Die casting devices of the type in question are also referred to as cold chamber Druckgießvorrichtungen.

To produce a die-cast part, the filling chamber of the die casting apparatus is filled with molten metallic casting material which is provided in a melting furnace. Subsequently, the casting material is pressed by means of a press-in piston in the mold cavity of the die, in particular at the end of Einpressvorganges high pressures are exerted on the casting material to compress the casting material by still liquid casting material is pressed into solidifying and the solidification shrinkage underlying material areas.

The drive of the press-fit piston is usually hydraulic, since very high pressures can be achieved by means of hydraulic drives. However, hydraulic drives have the disadvantage that the movement of the press-in piston when pressing the casting material are not controlled very accurately can. This makes it difficult to achieve optimal casting results. The repeatability of the press-fit process is often not satisfactory. Among other things, the movement of the hydraulically driven press-in piston depends on the temperature of the hydraulic oil, which may have non-negligible variations. Known Druckgießvorrichtungen with hydraulic drives therefore often have a considerable rejection rate.

In the DE 20 2014 000 916 U1 It is proposed to drive the press-in piston by means of a linear electric motor. This makes it possible to improve the repetition accuracy of the press-fitting operation and to control the movement of the press-in piston more accurately. However, in order to be able to provide the high pressures required for the press-fitting process, very expensive and expensive linear motors are often required.

Object of the present invention is therefore to develop a Druckgießvorrichtung of the type mentioned in such a way that the press-fit piston can be driven with simpler and less expensive linear motors and yet optimal casting results can be achieved.

This object is achieved in a die casting device of the generic type according to the invention in that the flow cross section of the filling channel is variable in a channel section during the filling of the mold cavity by means of a cross-sectional change device.

In the invention, the idea flows in that the thrust force that must be exerted by the electric drive unit on the press-in piston to accelerate the press-in piston from an initial rest position, can be reduced by the flow cross-section of the filling channel at least in a channel section as possible is chosen large. A larger flow cross-section results in a lower flow resistance, so that the casting material can be pressed with lower flow losses through the filling channel. To the flow resistance, especially during the initial acceleration phase of the press-in piston low To hold, by means of the cross-sectional change device, a large flow cross-section can be provided. After the press-fit piston has been set in motion by the drive unit, it has a high inertia, which facilitates the further pressing in of the casting material. This makes it possible to change the flow cross-section of the filling channel after an initial acceleration phase of the injection piston at least in a channel section by means of the cross-sectional change device in a predeterminable manner to optimally adapt the filling of the mold cavity to the structure of the mold cavity. It has been shown that each mold cavity has a specific "filling characteristic" which describes the per unit time to be injected in the mold cavity amount of casting material (filling rate). The filling characteristic is dependent on the flow cross section of the filling channel, a large flow cross section allows a large filling rate and thus the injection of a large amount of casting material within a predetermined time, and a small flow cross section allows a small filling rate and thus the injection of a smaller amount of casting material within a given Time. Thus, not only the thrust of the drive unit required for the initial acceleration of the press-fit piston can be reduced by changing the flow cross-section during the injection of casting material by means of the cross-sectional change device, so that structurally simpler and less expensive linear motors can be used, but it can also be the filling of the mold cavity be optimally adapted to its structure in order to achieve the best possible casting results.

Die casting machines with a cross-sectional modification device, with the aid of which the flow cross section of the filling channel can be changed, are in principle already known to the person skilled in the art WO 2007/107223 A1 known. In this die-casting device, the drive of the press-in piston takes place with the aid of a complex hydraulic drive unit. It has now been found that the use of a cross-sectional change device when using an electric drive unit for the press-in piston is of particular advantage, since thereby by the electric drive unit to the press-fit piston force to be exerted can be reduced, especially in the initial movement of the press-in piston from its rest position. The combination of an electric drive unit with at least one linear motor for the injection piston and a cross-sectional change device for the filling channel therefore makes it possible to use inexpensive linear motors for the electric drive unit, so that the movement of the press-in piston can be precisely controlled with very high repeat accuracy and high quality die castings low rejection rate can be generated.

It is advantageous if the at least one linear motor of the electric drive unit of the press-in piston has at least one stationary primary part and at least one movable secondary part, wherein the at least one movable secondary part cooperates magnetically with one or more primary parts and is mechanically connected to the press-in piston.

The at least one primary part may, for example, form a coil arrangement which can be supplied in a predeterminable manner with power to generate a variable magnetic field, and the at least one movable secondary part may, for example, comprise at least one permanent magnet which is set in motion by the variable magnetic field of the coil arrangement can be. Such primary parts and secondary parts are known to those skilled in the art and therefore require no further explanation in the present case.

The at least one secondary part is preferably mechanically connected to the press-in piston in such a way that a linear movement of the secondary part is transferred into a synchronous linear movement of the press-in piston.

It is particularly advantageous if the at least one secondary part is rigidly connected to the press-in piston via a mechanical pushing device. The use of the mechanical push device makes it possible to easily move the linear movement of the secondary parts towards the press-in piston transferred, without structurally complex and fault-prone transmission elements are required.

The mechanical thrust device preferably has a push rod, via which the at least one secondary part is rigidly connected to the press-in piston.

In a preferred embodiment of the invention, the at least one linear motor of the electric drive unit of the press-in piston has a plurality of stationary primary parts and a plurality of movable secondary parts, wherein each secondary part is arranged between two primary parts and rigidly connected to the press-in piston via the push device. In such an embodiment, a movable secondary part is in each case arranged between two stationary primary parts, which is rigidly connected via the mechanical pushing device with the press-in piston.

The primary parts and / or the secondary parts are preferably configured identically, so that they can be produced inexpensively in large quantities.

It is advantageous if the electric drive unit of the press-in piston has at least two linear motors which are arranged parallel to one another or aligned with respect to the direction of movement of the press-in piston. The arrangement of at least two linear motors in alignment with each other makes it possible in a cost effective manner to extend the thrust stroke of the press-in piston. The arrangement of at least two linear motors parallel to one another makes it possible to increase the force exerted by the electric drive unit on the press-in force in a cost-effective manner.

For the design of the cross-sectional change device, with the aid of which the flow cross-section of the filling channel can be changed at least in one channel section, no further details have been given so far. In an advantageous embodiment of the invention, the cross-sectional change device an immersed in the filling channel actuator which is linearly movable by means of an electric drive member, wherein the electric drive member in response to the position, the speed and / or the acceleration of the press-in piston is controllably connected and signal-conducting with the control device. With the aid of the actuator, the flow cross-section of the filling channel in a channel section can be changed in a predeterminable manner in a structurally simple manner. For this purpose, the actuator can be moved precisely by means of the electric drive member with very high repeatability. The movement of the actuator and thus also the change of the flow cross section of the filling channel takes place in particular in dependence on the position, the speed and / or the acceleration of the press-in piston. As mentioned above, it can be provided, for example, that at the beginning of the filling process the press-in piston is accelerated from a rest position in the direction of the filling channel. The assumption of the rest position and the initial acceleration of the press-fit piston can be detected by means of a sensor which provides the control device with a corresponding sensor signal. The control device controls the drive member such that the actuator first assumes a retracted position, so that it practically does not affect the flow cross section of the filling channel and molten casting material can be pressed with relatively little force in the mold cavity. During the further filling operation, the press-in piston moves within the filling chamber in the direction of the filling channel and the actuator can be caused by the controllable drive member to move, which has a change in the flow cross-section of the filling channel to result in filling the mold cavity in an optimal manner. Under the action of the casting material entering the mold cavity, the press-in piston may undergo abrupt changes in speed which may be sensed and which may cause the control device to change the position of the actuator, with appropriate positional changes being able to be made precisely by means of the electric actuator.

Conveniently, the electric drive member comprises at least one electric linear motor which has at least one stationary primary part and at least one movable secondary part which is rigidly connected mechanically to the actuator. Preferably, the at least one secondary part is connected via a push rod to the actuator.

The die casting mold of the die casting apparatus according to the invention preferably has a first mold half and a second mold half which form the mold cavity between them, wherein at least one mold half can be moved back and forth between a closed position closing the mold cavity and an open position releasing the mold cavity.

In a particularly preferred embodiment of the invention, the die casting device has a temperature detection device, wherein by means of the temperature detecting device in the open position of the at least one mold half, the temperature of the mold cavity defining surfaces of the two mold halves at a plurality of mutually spaced, programmable predetermined measurement points is separately detected, and wherein the temperature detection device is signal-connected to the control unit. With the aid of the temperature detection device, the temperature of the mold cavities defining surfaces of the two mold halves at a plurality of measuring points, the position of which can be specified programmatically, are detected. The measured surface temperatures of the measuring points can be stored for a fault diagnosis. In addition, the measured surface temperatures also allow precise control of a heating and cooling device of the die casting device, with the help of which the temperature of the mold halves can be controlled. The temperature of the measuring points is detected when at least one mold half assumes its open position. For example, it may be provided that after each completion of a casting process, that is to say after ejection of the diecast part from the mold cavity, the surfaces of the two mold halves are detected at measurement points which can be predetermined by the program. In particular, the temperature at depressions and / or elevations of the the mold cavity limiting surfaces of the two mold halves are detected.

It is advantageous if the surface temperature of the mold halves can be detected without contact by means of the temperature detection device.

In an advantageous embodiment of the invention, the temperature detection device has at least one infrared sensor.

It is advantageous if the temperature of the press-in piston can be detected by means of the temperature detection device prior to pressing in or during the pressing of casting material into the mold cavity. In such an embodiment, the temperature of a plurality of programmable predetermined measurement points of the mold cavity defining surfaces of the two mold halves can be detected by means of the temperature detection means, but by means of the same temperature detection means, the temperature of the press-in piston can be detected preferably without contact, especially at the beginning of a casting process. The detection of the temperature of the press-in piston can serve to monitor the casting processes and facilitates fault diagnosis.

Alternatively or additionally, it can be provided that the temperature of the casting material can be detected by means of the temperature detection device before or during the introduction of casting material into the filling chamber. As already mentioned, the filling chamber is filled with molten metallic casting material, which is then pressed into the mold cavity by means of the press-in piston. It is advantageous if the temperature of the casting material is detected by means of the temperature detection device before or during the introduction of the casting material into the filling chamber. This also serves to monitor the casting processes and facilitates fault diagnosis.

In an advantageous embodiment of the invention, the temperature detection device has a measuring head which is connected to a positioning device held and movable by means of the positioning in at least one measuring position. By means of the positioning device, the measuring head can be positioned between the two mold halves, for example, if at least one mold half assumes its open position and thus a distance from the other mold half. After detecting the temperature of the programmatically predetermined measuring points of the mold cavity defining surfaces of the mold halves, the measuring head can be moved out of the area between the two mold halves by means of the positioning, in order subsequently to assume, for example, a rest position or a further measuring position.

It is particularly advantageous if the measuring head is rotatably mounted on the positioning device. This makes it possible to rotate the measuring head relative to the positioning device, in order thereby to detect the temperature of a multiplicity of measuring points predetermined by the method.

Conveniently, the measuring head is rotatably mounted on the positioning device about two axes of rotation aligned perpendicular to each other. This allows a structurally simple way to change the orientation of the measuring head relative to the positioning both in a horizontal plane and in a vertical plane in order to detect the temperature of different measuring points can.

In a particularly advantageous embodiment of the invention, the die casting device has a suction device for sucking gas from the mold cavity, wherein the suction device is coupled to the press-fit piston for sucking the mold cavity in response to the movement of the press-fit piston. The suction device makes it possible to pressurize the mold cavity before and / or during filling with negative pressure. This makes it easier to press the casting material into the mold cavity, since the casting material is sucked into the mold cavity under the effect of the negative pressure prevailing in the mold cavity. In combination with the use of the aforementioned cross-sectional change device, the Use of the suction device proved to be particularly advantageous in driving the press-in piston by means of the electric drive unit.

The suction device is conveniently mechanically coupled to the press-in piston.

It can be provided that the suction device has a suction piston, which is held linearly displaceable in a suction cylinder and mechanically coupled to the press-in piston, wherein the suction cylinder is connected via a suction line with the mold cavity. A movement of the press-in piston is mechanically transferred to the suction piston in such a configuration, which carries out a movement within the suction cylinder, which corresponds to the movement of the press-in piston in the filling chamber. As a result, the mold cavity can be acted upon in a structurally simple manner in response to the movement of the press-in piston with negative pressure.

In a particularly advantageous embodiment of the invention, the die casting device has a signal sensor connected to the control device motion sensor, wherein by means of the motion sensor, the movement of the press-fit piston can be detected. The motion sensor allows monitoring of the casting processes and facilitates fault diagnosis. In addition, the output signal of the motion sensor can be incorporated into the above-explained control of the drive member of the cross-sectional change device.

In a preferred embodiment of the invention, the acceleration of the press-in piston can be detected by means of the motion sensor.

Alternatively or additionally, the position of the press-fit piston and / or the speed of the press-fit piston can be detected by means of the motion sensor.

Figur 1:

eine schematische Darstellung einer Druckgießvorrichtung während des Einbringens von Gießmaterial in eine Füllkammer;

Figur 2:

eine schematische Darstellung der Druckgießvorrichtung aus Figur 1 während des Einpressens des Gießmaterials in einen Formhohlraum;

Figur 3:

eine schematische Darstellung der Druckgießvorrichtung aus Figur 1 am Ende des Einpressvorgangs;

Figur 4:

eine schematische Darstellung der Druckgießvorrichtung aus Figur 1 während der Erfassung der Temperatur der den Formhohlraum definierenden Oberflächen von zwei Formhälften an vorgegebenen Messpunkten;

Figur 5:

eine schematische Darstellung der Druckgießvorrichtung aus Figur 1, wobei der Einpresskolben in seine Anfangsstellung zurückgefahren wird;

Figur 6:

eine Schnittansicht einer elektrischen Antriebseinheit der Druckgießvorrichtung längs der Linie 6-6 in Figur 1.

The following description of an advantageous embodiment of the invention is used in conjunction with the drawings for further explanation. Show it:

FIG. 1:

a schematic representation of a die casting device during the introduction of casting material in a filling chamber;

FIG. 2:

a schematic representation of the die casting from FIG. 1 during the injection of the casting material in a mold cavity;

FIG. 3:

a schematic representation of the die casting from FIG. 1 at the end of the press-fitting process;

FIG. 4:

a schematic representation of the die casting from FIG. 1 during the detection of the temperature of the mold cavities defining surfaces of two mold halves at predetermined measuring points;

FIG. 5:

a schematic representation of the die casting from FIG. 1 , wherein the press-in piston is returned to its initial position;

FIG. 6:

a sectional view of an electric drive unit of the die casting device along the line 6-6 in FIG. 1 ,

In the drawing, an advantageous embodiment of a die-casting device according to the invention is shown schematically and overall occupied by the reference numeral 10. The die casting apparatus 10 comprises a die 11 having a first, stationary mold half 12 and a second, movable mold half 14 forming therebetween a mold cavity 16 having the shape of a die cast part to be cast. The two mold halves 12, 14 act in a conventional manner with a known per se and therefore not shown in the drawing to achieve a better overview Mold closing unit together. The mold clamping unit has a fixed and a movable platen, on which the two mold halves 12, 14 are held in a known manner. By means of the mold clamping unit, a predetermined closing force can be exerted on the two mold halves 12, 14. To remove a finished diecast part, the movable mold half 14 by means of the mold clamping unit from a in the FIGS. 1 . 2 . 3 and 5 shown closed position in a in FIG. 4 shown open position to be moved.

Molten metallic casting material may be injected into the mold cavity 16. For this purpose, the die casting device 10 has a filling chamber 18, which can be filled with the liquid casting material and which is connected via a filling channel 20 with the mold cavity 16. The filling of the filling chamber 18 with liquid casting material takes place via a filling opening 22 of the filling chamber 18, wherein the molten casting material is provided in a melting furnace 24. With the help of a known and therefore to achieve a better overview in the drawing also not shown controllable heating and cooling device of the die casting device 10, the two mold halves 12, 14 are heated to a predetermined temperature.

In the filling chamber 18, a press-in piston 26 is slidably mounted, with the aid of which the molten casting material can be pressed into the mold cavity 16.

To drive the press-in piston 26, the die casting device 10 has an electric drive unit 28. The electric drive unit 28 comprises a first linear motor 30 and a second linear motor 32. The two linear motors 30, 32 are arranged in alignment with each other with respect to the direction of movement of the press-fit piston 26. The two linear motors 30, 32 are identical. In the illustrated embodiment, the two linear motors 30, 32 each have four identically configured movable secondary parts 34, 36, 38, 40, each comprising permanent magnets and rigidly connected to a mechanical pusher 42 having a push rod 44. This is especially true FIG. 6 clear. Via the push rod 44, the secondary parts 34, 36, 38, 40 are rigidly connected to the press-in piston 26, so that a linear movement of the secondary parts has a synchronous linear movement of the press-in piston 26 result.

The secondary parts 34, 36, 38, 40 are arranged distributed uniformly in the circumferential direction of the push rod 44 and each positioned between a first primary part 46 and a second primary part 48, each forming a coil assembly. Overall, the two linear motors 30, 32 four secondary parts and eight primary parts. Such primary and secondary parts are known to those skilled in the art and therefore require no further explanation in the present case.

As an alternative to the use of four circumferentially evenly distributed over the circumference of the push rod 44 arranged secondary parts, the linear motors 30 and 32 also have a larger or a smaller number of secondary parts, which are preferably positioned in each case between two primary parts. For example, it may be provided that the two linear motors 30, 32 each have only two secondary parts, which are aligned at an angle of 180 ° to each other.

To guide the secondary parts 34, 36, 38, 40, the two linear motors 30, 32 each have a guide carriage 50, which is held linearly movable on parallel to each other guide rails 52, 54.

The control of the linear motors 30, 32 by means of an electrical control device 56 of the die casting device 10. The electrical control device 56 is connected via not shown in the drawing to achieve a better overview electrical lines with the linear motors 30, 32.

The flow cross section of the filling channel 20 can be changed in a channel section by means of a cross-sectional change device 58 in a predeterminable manner. The cross-sectional change device 58 has an actuator, which in the illustrated embodiment designed as a control piston 60 it. The adjusting piston 60 is rigidly connected to an electric drive member 62 via a piston rod 61. The electric drive member 62 also has a linear motor with at least one stationary primary part and at least one movable secondary part, wherein the at least one secondary part is connected via the piston rod 61 to the actuating piston 60. The control of the electric drive member 62 by means of the electric control device 56 in dependence on the position, the speed and / or the acceleration of the Einpresskolbens 26. To detect the movement of the Einpresskolbens 26, the Druckgießvorrichtung 10 has a motion sensor 64, the electrical control device 56 provides a dependent of the movement of the injection piston 26 sensor signal. In the illustrated embodiment, the motion sensor 64 is formed as an acceleration sensor, which detects the acceleration of the rigidly connected to the press-in piston 26 push rod 44.

For sucking off the mold cavity 16, the die casting device 10 has a suction device 66, which is coupled to the press-in piston 26. This allows the mold cavity 16 to be sucked off in response to the movement of the press-fit piston 26. The suction device 66 has a suction cylinder 68, which is arranged on the rear side of the electric drive unit 28 facing away from the press-in piston 26. In the suction cylinder 68, a suction piston 70 is slidably mounted. The push rod 44 extends from the press-fit piston 26 through the two linear motors 30, 32 and dips into the suction cylinder 68, wherein it carries the suction piston 70 at its end facing away from the press-in piston 26. A movement of the press-in piston 26 is thus transmitted via the push rod 44 to the suction piston 70.

The suction cylinder 68 is in fluid communication with an outlet 74 of the mold cavity 16 via a suction line 72, wherein the suction line 72 branches at its end facing the suction cylinder 68 via a T-piece 76 into a first branch line 78 and a second branch line 80. The first branch line 78 opens into the suction cylinder 68 at a front cylinder end 82 facing the electric drive unit 28, and the second branch line 80 opens at a rear cylinder end 84 facing away from the electric drive unit 28 into the suction cylinder 68. The first branch line 78 has a first directional control valve 86, and in the second branch line 80, a second directional control valve 88 is connected. The two-way valves 86, 88 are designed as solenoid valves and communicate with the electrical control device 56 via control lines not shown in the drawing. The directional valves 86, 88 can each take two switching positions. In a first switching position, the directional control valves 86, 88 each release a flow path from the suction cylinder 68 to the suction line 72 and simultaneously block a flow path from the suction cylinder 68 to the atmosphere (environment), and in a second switching position, the directional control valves 86, 88 each provide a flow path from the suction cylinder the atmosphere (environment) free and simultaneously block the flow path from the suction cylinder 68 to the suction 72nd

To the suction line 72, the T-piece 76 adjacent to a pressure accumulator 90 is connected. Adjacent to the outlet 74, a filter 92, a check valve 94, and an air flow meter 96 are connected in the suction line 72. The check valve 94 is also designed as a solenoid valve and is connected via a control line, not shown in the drawing with the electrical control device 56 in connection.

The air amount measuring unit 96 makes it possible to measure the amount of air sucked from the mold cavity 16. About a only partially shown in the drawing measuring line 98 is the air flow measuring unit 96 with the electrical control device 56 in electrical connection. About the air flow measuring unit 96, a measurement signal corresponding to the extracted air quantity can be transmitted to the electrical control device 56.

The two mold halves 12, 14 have facing surfaces 100, 102 which define the mold cavity 16. With the aid of a temperature detection device 104 of the die casting device 10, the temperature of the surfaces 100, 102 of the two mold halves 12, 14 can be detected at a plurality of programmable predetermined measurement points, when the second mold half 14 their in FIG. 4 shown open position occupies. For this purpose, the temperature detection device 104 has a measuring head 106 with an infrared sensor 108. The measuring head 106 is rotatably supported on a positioning device 110 of the temperature detection device 104 about a vertical axis of rotation 112 and about a horizontal axis of rotation 114. This makes it possible to align the infrared sensor 108 to program predetermined measurement points to detect their temperature without contact.

In the illustrated embodiment, the positioning device 110 has a first pivot arm 116 which is rotatably mounted on the first mold half 12, and a second pivot arm 118 which is articulated to the first pivot arm 116 and carries at its free end the measuring head 106.

With the aid of the temperature detection device 104, not only the surface temperature of a plurality of measuring points of the two mold halves 12, 14 can be detected without contact, but also the temperature of the casting material can be detected, which is introduced into the filling chamber 18 via the filling opening 22. In addition, with the aid of the temperature detection device 104, the temperature of the press-fit piston 26 can be detected when the press-in piston 26 its in FIG. 1 shown withdrawn rest position occupies. For this purpose, the measuring head 106 can be moved by means of the positioning device 110 into respectively suitable measuring positions. About a measuring line, not shown in the drawing, the infrared sensor 108 of Temperature detection device 104 is connected to the electrical control device 56.

At the beginning of a casting process, the press-in piston 26 takes its in FIG. 1 shown retracted rest position and molten metallic casting material is introduced via the filling opening 22 in the filling chamber 18, wherein by means of the temperature detecting means 104, both the temperature of the casting material and the temperature of the press-fit piston 26 is detected. The check valve 94 is closed at this time. The first directional control valve 86 assumes its second switching position, so that the front cylinder chamber 120 of the suction cylinder 68 arranged between the suction piston 70 and the front cylinder end 82 is in fluid communication with the outside environment. The second directional control valve 88 assumes its first switching position, so that the rear cylinder chamber 122 of the suction cylinder 68 arranged between the suction piston 70 and the rear cylinder end 84 is in fluid communication with the suction line 72.

The injection piston 26 is subsequently displaced by means of the electric drive unit 28 within the filling chamber 18 in the direction of the filling channel 20, so that the casting material located in the filling chamber 18 is pressed into the mold cavity 16 via the filling channel 20. This is going out FIG. 2 clear. The shut-off valve 94 is open in this phase of the casting process. The movement of the press-fit piston 26 is transmitted via the push rod 44 to the suction piston 70, so that it is moved starting from a position adjacent to the rear cylinder end 84 in the direction of the front cylinder end 82. This has the consequence that the volume of the rear cylinder chamber 122 is increased and thereby the mold cavity 16 is sucked off via the suction line 72. At the same time, the volume of the front cylinder space decreases and air is discharged via the first directional control valve 86 to the outside environment. The movement of the press-in piston 26 thus not only results in that molten casting material is pressed into the mold cavity 16, but that at the same time the mold cavity 16 is sucked off becomes. This facilitates the pressing in of the casting material with the aid of the electric drive unit 28.

The pressing of the molten casting material into the mold cavity 16 is further facilitated by the fact that at the beginning of the press-fitting operation of the adjusting piston 60 of the cross-sectional modification device 58 is an in FIG. 1 shown retracted position occupies, so that the flow cross-section of the filling channel 20 assumes a maximum value and thereby the filling channel 20 exerts the lowest possible flow resistance to the molten casting material. The use of the suction device 66 and the cross-sectional modification device 58 makes it possible for the press-in piston 26, starting from its in FIG. 1 shown rest position by applying force by means of the electric drive unit 28 in a predeterminable manner.

During the further Einpressvorganges the actuating piston 60 of the cross-sectional change means 58 by means of the electric drive member 62 in a predetermined manner moved back and forth to optimize the filling of the mold cavity 16, and at the same time the mold cavity 16 is sucked by means of the suction device 66, wherein the extracted air quantity means the air amount measuring unit 96 is detected.

At the conclusion of the press-fitting process, the actuating piston 60 is again moved to its maximum retracted position, so that it releases the flow cross-section of the filling channel 20 as far as possible. This is in FIG. 3 shown. The flow cross section of the filling channel 20 assumes its maximum value. This makes it easier to compact the casting material in the mold cavity 16, wherein liquid casting material is still pressed into the solidifying casting areas. Of the electric drive unit 28 can be exercised in this case due to the large inertial mass of the press-in piston 26, the push rod 44 and a considerable weight having secondaries 34, 36, 38, 40, a high pressing force.

After completion of the casting process, the mold cavity 16 is opened by the second mold half 14 in their in FIG. 4 shown open position is moved. The shut-off valve 94 is closed and the two-way valves 86, 88 take their second switching position, in which they interrupt the flow connections from the front and rear cylinder chambers 120, 122 to the suction line 72 and instead the flow connections from the front and rear cylinder chambers 120, 122 to Release the outside environment. By means of the temperature detection device 104, the temperature of the mutually facing surfaces 100, 102 of the two mold halves 12, 14 is then selectively detected at a plurality of measurement points which can be predetermined by the program. In particular, the temperature is detected at individual measuring points which are positioned in the region of elevations and depressions of the two surfaces 100, 102.

To detect the surface temperatures of individual measuring points, the measuring head 106 is positioned by means of the positioning device 110 between the two mold halves 12, 14 and then rotated about the vertical axis of rotation 112 and about the horizontal axis of rotation 114.

After the temperature of the individual measuring points has been detected, the measuring head 106 is moved out of the intermediate region between the two mold halves 12, 14 again and the second mold half 14 is moved back into its closed position. This is in FIG. 5 shown. The injection piston 26 is moved back to its initial position, whereby the volume of the front cylinder chamber 120 increases and the volume of the rear cylinder chamber 122 decreases. The second directional control valve 88 assumes its second switching position so that air can be released to the outside environment from the decreasing rear cylinder space 122. The first directional control valve 86 assumes its first switching position and thus releases the flow connection from the front cylinder chamber 120 to the suction line 72, so that a negative pressure is provided in the suction line 72 and in the pressure accumulator 90. This allows the mold cavity 16 and the filling chamber 18 at the beginning a subsequent Einpressvorgangs by opening the shut-off valve 94 to apply negative pressure.

The use of the electric drive unit 28 allows a fast and precise control of the movement of the press-in piston 26, wherein a high repeatability can be achieved. By changing the flow cross-section of the filling channel 20 by means of the cross-sectional change means 58 and by the suction of the mold cavity 16 by means of the suction device 66 which is coupled to the press-in piston 26, the force to be provided by the electrical pressing unit 28 can be kept relatively low , so that inexpensive linear motors can be used.

Claims (20)

Die casting apparatus for producing metal die cast parts with a die casting mold forming a mold cavity (16) and with a press-in piston (26) for injecting molten metallic casting material into the mold cavity (16), the press-in piston (26) being driven by an electric drive unit (28) , which has at least one electric linear motor (30, 32), is linearly displaceable in a filling chamber (18) connected to the mold cavity (16) via a filling channel (20), and an electric control device (56) for controlling the electric drive unit (56). 28), characterized in that the flow cross section of the filling channel (20) during the filling of the mold cavity (16) in a channel section by means of a cross-sectional change means (58) is variable. Die casting apparatus according to claim 1, characterized in that the at least one linear motor (30, 32) has at least one stationary primary part (46, 48) and at least one movable secondary part (34, 36, 38, 40), wherein the at least one movable secondary part ( 34, 36, 38, 40) cooperates magnetically with one or more primary parts (46, 48) and is mechanically connected to the press-fit piston (26). Die casting apparatus according to claim 2, characterized in that the at least one secondary part (34, 36, 38, 40) via a mechanical thruster (42) with the press-in piston (26) is rigidly connected. Die casting apparatus according to claim 3, characterized in that the at least one linear motor (30, 32) has a plurality of stationary primary parts (46, 48) and a plurality of movable secondary parts (34, 36, 38, 40), wherein each secondary part (34, 36, 38, 40) between two primary parts (46, 48) is arranged and rigidly connected via the mechanical thrust device (42) with the press-in piston (26). Die casting apparatus according to claim 3 or 4, characterized in that the mechanical pushing device (42) has a push rod (44) via which the at least one secondary part (34, 36, 38, 40) is rigidly connected to the press-fit piston (26). Die casting apparatus according to one of the preceding claims, characterized in that the electric drive unit (28) has at least two linear motors (30, 32), which are arranged with respect to the direction of movement of the press-in piston (26) parallel to each other or in alignment with each other. Die casting apparatus according to one of the preceding claims, characterized in that the cross-sectional change means (58) in the filling channel (20) dipping actuator (60) which is linearly movable by means of an electric drive member (62), wherein the electric drive member (62) in Dependent on the position, the speed and / or the acceleration of the press-in piston (26) controllable and signal-connected to the control device (56). Die casting apparatus according to claim 7, characterized in that the electrical drive member (62) comprises at least one electric linear motor having at least one stationary primary part and at least one mechanically with the actuator (60) rigidly connected to the movable secondary part. Die casting apparatus according to one of the preceding claims, characterized in that the die has a first mold half (12) and a second mold half (14) which form between them the mold cavity (16), at least one mold half (14). between a closing position closing the mold cavity (16) and an open position releasing the mold cavity (16), and that the pressure casting device (10) has a temperature detection device (104), wherein by means of the temperature detection device (104) in the open position the at least a mold half (14) the temperature of the mold cavity (16) defining surfaces (100, 102) of the two mold halves (12, 14) at a plurality of mutually spaced, programmable predetermined measurement points is separately detected, and wherein the temperature detecting means (104) is connected to the electrical control device (56) signal-conducting. Die casting apparatus according to claim 9, characterized in that the surface temperature of the mold halves (12, 14) by means of the temperature detecting means (104) is detected without contact. Die casting apparatus according to claim 9 or 10, characterized in that the temperature detecting means (104) comprises at least one infrared sensor (108). Die casting apparatus according to claim 9, 10 or 11, characterized in that prior to the pressing of casting material or during the pressing of casting material into the mold cavity (16), the temperature of the press-in piston (26) by means of the temperature detecting means (104) is detectable. Die casting device according to one of claims 9 to 12, characterized in that prior to introduction or during the introduction of the casting material into the filling chamber (18), the temperature of the casting material by means of the temperature detecting means (104) is detectable. Die casting device according to one of claims 9 to 13, characterized in that the temperature detecting means (104) has a Measuring head (106) which is held on a positioning device (110) and by means of the positioning device (110) in at least one measuring position is movable. Die casting apparatus according to claim 14, characterized in that the measuring head (106) is rotatably mounted on the positioning device (110). Die casting apparatus according to one of the preceding claims, characterized in that the die casting device (10) has a suction device (66) for sucking gas from the mold cavity (16), wherein the suction device (66) is coupled to the press-fit piston (26) for sucking off the Mold cavity (16) in response to the movement of the press-in piston (26). Die casting apparatus according to claim 16, characterized in that the suction device (66) is mechanically coupled to the press-in piston (26). Die casting apparatus according to claim 16 or 17, characterized in that the suction device (66) has a suction piston (70) which is held linearly displaceably in a suction cylinder (68) and is mechanically coupled to the injection piston (26), the suction cylinder (68). is connected via a suction line (72) with the mold cavity (16). Die casting apparatus according to one of the preceding claims, characterized in that the die casting device (10) has a signal conductively connected to the control device motion sensor (64), by means of the motion sensor (64), the movement of the press-fit piston (26) can be detected. Die casting apparatus according to claim 19, characterized in that by means of the motion sensor (64) the acceleration of the press-fit piston (26) can be detected.

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