KR20010101651A - Method and device for the production of castings - Google Patents

Abstract

The present invention relates to a method and apparatus for producing a casting made of a dispersible flowable preliminary material that is at least heated and at least partially flexible. According to the method the at least partially pliable material is pressurized in the chamber and then transported out of the chamber and finally injected into the mold. The material is pressurized in a chamber having a moving wall, and the volume inside the chamber is changed by the movement of the wall so that the volume of the chamber is increased and reduced during the casting process as the material is fed into the chamber through the inlet. The volume corresponds as accurately as possible to the volume of material contained in the chamber such that the contents of the chamber are almost zero when there is no melt in the chamber, such as before filling or after the injection process of the chamber. Also in accordance with the apparatus, the injector has a chamber having an inlet opening for material supply and a outlet opening guided to the mold and a moving wall, the wall being mobile such that the interior of the chamber is variable with respect to volume. The chamber of the injection device has two moving walls which are moved together in one direction or in opposite directions with respect to each other, by which the inside of the chamber can be variable and / or moved in volume. The interior of the chamber can be reduced to near zero.

Description

Method and apparatus for manufacturing castings {METHOD AND DEVICE FOR THE PRODUCTION OF CASTINGS}

German Patent Application Publications DE 43 10 755 A1 and DE 198 29 336 A1 are known in the scope of the present invention. Each chamber has one plunger in which material is injected into the mold. The chamber according to DE 43 10 755 A1 is evacuated in a relatively complex process to prevent the ingress of unexpected air before it is filled with the material.

In WO 98/33610, methods and apparatus are known, respectively, which do not fall within the scope of the present invention, wherein bar solids partially solidified in accordance with the methods and apparatus are forged into the mold by means of devices which are not forged or described in detail. Sprayed.

It is known from DE 35 00 561 A1 that the material to be sprayed is conveyed to the mold by means of a screw conveyor instead of the plunger device and a predetermined spray pressure can be produced by the screw conveyor.

It is also known to cast a metal, for example magnesium, in a manner similar to the injection molding method. Because magnesium is a highly reactive material, the apparatus used to cast magnesium requires complex treatment to prevent ambient air from accessing the magnesium melt. Thus, for example, it is known that the casting device, for example in the area of the injection device, is operated by a protective gas to prevent the penetration of ambient air and oxygen when the mold is opened to allow air to enter the system.

The present invention relates to a method and an apparatus for producing a casting according to the preamble of claim 1 or 4.

1-4 are cross-sectional views of adjacent assemblies of the spraying device and the molding machine in different stages of the casting process.

It is an object of the present invention to improve a method which falls within the scope of the invention, which is adapted to process the material by simple means by blocking the ambient air. It is also an object of the present invention to provide a device suitable for the method.

This object is achieved by a method having the features of claim 1 and an apparatus having the features of claim 4.

In other words, a morphological chamber is provided by the present invention, wherein the pliable material from the chamber can be sprayed directly into the mold, or first indirectly continued to be transported, then ejected from a separate spray device into the mold. Can be. Due to such shape variability of the chamber and thus variable internal, in particular variable internal volume, the chamber volume can be minimized during the injection process. More specifically, after the material from the chamber has been transported or injected into the mold, the filling volume of the chamber is reduced.

Empty chamber volumes into which air can be introduced by not being filled with material in this way are always kept to a minimum or completely avoided, thereby preventing or nearly minimizing the ingress of outside air into the chamber. It is possible in this way to prevent the chamber or the entire injection device from being surrounded by a protective gas or being evacuated. In addition, the need for encapsulation of the chamber or injection device is significantly reduced, so that the device can be simplified or inexpensively formed throughout the structure despite the moving chamber walls.

Here, in particular, the injection pressure can be generated due to the variability of the chamber walls, whereby the combination of these functions makes the device relatively simple and inexpensive.

Method Technically, the advantage is that an injection pressure can be generated in the chamber when the chamber finishes supplying the material by movement of the chamber wall. Complex check valves are not used and the pressure build up that appears in the chamber can be controlled much more accurately than when using the check valves. That is, for example, when the mobility of the chamber wall is used for opening and closing the inlet opening at the same time, the inlet opening and the material supply zone in front of the inlet opening are separated from the inherent injection process, so that no backflow is formed in the material supply region. Pressure build up that occurs within the chamber may be achieved. Therefore, the change in the injection pressure can be precisely controlled.

Difficult to calculate backflow flowing through the check valve until it is fully closed is excluded. The conveying device in the material supply zone is not involved in the pressure build up of the spraying process, which is therefore structurally simpler and more simply controlled. This is because the conveying device must only convey material into the chamber and correspondingly monitor the delivery pressure and in some cases the temperature.

Switchable axial mobility, for example in a conveying device known to form a particularly high pressure or rapid spraying process on a rotary drive conveying screw, can thus be implemented simply in structure or method.

The method according to the invention and the device suitably formed therefor are suitable, for example, for processing magnesium. However, the present invention is also preferably applied for the processing of other materials, especially when the materials have to be processed to be shielded from the outside air. Here, metal, plastic or other materials can be used, which materials can be fed into an already liquefied or partially liquefied mold of the device, or the device is connected to the top of the injection device, eg granules formed of solid It may have its own melting apparatus introduced into the mold input material.

Simplifying the structure and method by providing a movable chamber wall for controlling the inlet and outlet of the chamber, that is to say the opening and closing times of the opening, is to be understood, for example, in the inlet of the chamber and in the direction of movement of the moving chamber wall. The outlets can be achieved by spaced apart from each other. Thus, by moving the chamber wall, it can be controlled as to which opening of the inlet or outlet should be closed, and in some cases both openings should be opened or closed at the same time. Such closure also further reduces the possibility of ambient air entering the chamber. This is because the chamber capacity available to the air is not only minimized, but the chamber can be completely closed.

The device may have a tubular chamber in a relatively simple manner, in which two opposite walls of the tube, for example two front walls, are formed as moving walls, the moving walls being driven in the same one direction or in opposite directions to each other. Can be. More specifically, they may be driven at the same speed or at different speeds to adjust the ratios appearing inside the chamber.

The tube can be preferably formed as a cylinder with a round cross section, so that the moving wall can be reliably sealed against the tube wall relatively simply.

Preferably, in the conveying device, a plurality of screw conveyors can be used that engage each other, which can be driven in the same direction or in opposite directions to each other. Thus, a more uniform and defined pressure is generated and self-purification or forced transportation can be achieved.

Screw conveyors can have different outer structures over the entire length to enable processing of the material in different ways during material transport, such as to homogenize, mix, feed additional materials, cut or knead.

The chamber may optionally be connected to the top of an additional conveying device, which may be formed as a mixing, conveying and heating device, similar to a heated screw conveyor. By such multiple conveying devices different materials, ie different materials with different temperatures or the same materials can be fed into the chamber. By distributing different materials inside the chamber, a workpiece can be produced with points having different properties, such as points reinforced by fibers or particles provided in the threaded region or loaded by grinding, so that the workpieces at these points This sandwich can be formed.

Preferably the desired dosing can be flexibly modified by the control of an individual conveying device or of a conveying and heating device. However, by the formation of inlets or outlets leading into the chamber and by the closing and opening of the openings being controlled as the moving wall is moved, the fixed dosing ratio can basically be adjusted or influenced by the control of the wall movement, or The opening can be changed, for example by a bar.

Preferably multiple chambers can be connected to the same mold. In this way, workpieces having points of different properties can be produced particularly well with differently sprayed materials. Here, each chamber may be formed for the supply of one material or a plurality of different materials.

In particular, additional feeders can be provided, for example for mixing grainy or powdery particles or for mixing fibers. As granular or powdered particles, for example SiC—, Al ₂ O ₃ − or carbon particles may be provided. The addition of particles or fibers can be made by providing them directly into the chamber without mixing. Preferably, however, this addition is achieved by accumulating and supplying the material-base material, such as plastic or light metal, of course into particles or fibers into an additional supply device, whereby the desired partitioning of the particles or fibers can be achieved while at the same time the workpiece from which the base material is to be produced. The desired material combination can be achieved at. Particularly the particles or fibers at the outer points can be mixed uniformly, for example by inductive or mechanical stirring, just before entering the chamber and optionally before entering the conveying device.

In the context of the present invention, for example with respect to the number of screw conveyors used, "multiple" conveying devices or chambers always represent "at least two" conveying devices or chambers. Transport devices formed in other ways can also be used.

Embodiments of the present invention are described in more detail by the following figures.

1 shows an apparatus 1 used for making a casting from a dispersible granular preliminary material. In this figure in particular magnesium granules can be processed in a similar way as extrusion or injection molding.

1 shows in particular an injection device 2. The injection device 2 is softened, ie a flowable material is supplied by the melting device 3. The melting apparatus 3 has, on the one hand, a screw conveyor for heating the preliminary material by friction. In addition, the melting apparatus 3 is heated to further heat the preliminary material, and finally the screw conveyor carries the heated flowable material through the inlet 4 into the injection apparatus 2.

In addition, the said melting apparatus 3 can be called a conveying apparatus first. Since granular preliminary materials are used, the melting apparatus 3 is used for the transportation of the materials as well as for the softening or melting of the materials. In contrast, when using thick preliminary materials in the liquid phase, the melting apparatus 3 may optionally be formed as a conveying apparatus having an additional mixing or homogenizing function, but is not used for the purpose of weakening or softening the material. .

Subsequently, material is injected from the injection device 2 through the outlet 5 into the mold 6, shown schematically. The mold 6 can be cooled to solidify quickly and to quickly withdraw castings from the mold 6.

The injection device 2 has a chamber 7 which can be filled or emptied through the inlet 4 and the outlet 5. The wall of the chamber 7 is formed on the one hand with a cylindrical tube 8 and on the other hand with two moving walls 9, 10, so that the cylindrical chamber 7 with the front wall as a whole is movable. Are manufactured.

The moving walls 9, 10 are also referred to as plungers 9, 10, similarly to the state in internal combustion engines, pumps or compressors, and correspondingly actuating bars capable of moving the plungers 9, 10 are connecting rods ( 11, 12). The connecting rods 11, 12 can be fixedly coupled to the plungers 9, 10, for example only when they are moved axially and vibrated, for example by hydraulic pressure. However, for example, when the connecting rods 11 and 12 are mechanically driven by cranks, cams or the like, and are arranged so as to lie in the same plane with each other in the axial direction shown in FIG. Pivoted connections of the connecting rods 11, 12 and plungers 9, 10 may be provided.

1 shows the beginning of the filling process for the chamber 7. The screw conveyor carries the fluidized material from the melting apparatus 3 into the inlet 4. Correspondingly, the raised position of the upper plunger 9 and the lowered position of the lower plunger 10 open the inlet 4 up to the chamber 7, so that the material can enter the chamber 7. First of all, the plunger 9 is further raised by the connecting rod 11-as shown by the vertical arrow-to increase the volume of the chamber 7, so that the chamber 7 can accommodate the increased amount of material. . During this filling process, the lower plunger 10 supported by the connecting rod 12 stays in a position to wear out the outlet 5.

2 shows the start of the casting process. The lower plunger 10 in this figure is pulled down by the connecting rod 12 and releases the outlet 5. The upper plunger 9 is moved in the same direction so that the pressure which appears in the chamber 7 causes the material to flow through the outlet 5 into the mold 6. This applies when both plungers 9 and 10 are moved at the same speed and the chamber 7 is moved to the same volume due to the filling pressure applied in the chamber 7. Faster compared to the lower plunger 10, but the chamber volume is reduced by the movement of the upper plunger 9 in the same direction, so that the pressure in the chamber 7 is raised or based on a faster casting process. The pressure lowered by the discharge of the material is maintained.

The movement of the plungers 9, 10 in this step is preferably such that the pressure from the chamber 7 exceeds the filling pressure, ie the pressure in the region of the melting apparatus 3, so that the material from the chamber 7 is released. Backflow through the inlet 4 can be controlled to avoid. At this time, a unique check valve or the like need not be provided.

3 shows a second stage of the casting process in which the upper plunger 9 wears out the inlet 4. The relative speed between the lower plunger 10 and the upper plunger 9 can be increased, so that a pressure higher than the pressure generated in the melting apparatus 3 can be generated in the chamber 7. For this purpose, the lower plunger 10 can be fully held or moved in the opposite direction towards the upper plunger, or the speed of the upper plunger 9 can be increased. By blocking the inlet 4, the backflow of the material from the chamber 7 into the melting apparatus 3 is blocked.

In addition, in FIG. 3, the screw conveyor of the melting apparatus 3 is pulled back from the inlet 4, so that the screw conveyor can first convey the material toward the inlet 4 only by rotational movement and then refresh the chamber 7. Particularly rapid filling of the chamber 7 can be achieved by being able to be switched in the direction of the inlet 4 in a switchable manner with respect to the rotary conveying movement for filling. However, the screw conveyor can only be driven rotary because of the simplified structure. This is because the screw conveyor is not involved in generating pressure in the chamber 7 during the casting process.

4 shows after the casting process has ended, in which the lower plunger 10 is fully raised to the upper end of the tube 8, so that the remainder of the casting present in the injection device 2 is sprayed in a lateral view. It can be withdrawn from the device 2 via a recess 14 provided in the machine plate 15. For this purpose, the upper plunger 9 is pulled upwards as far as possible in correspondence with the arrow marked on the plunger 9, so that a corresponding discharge opening for the chamber 7 can be created.

Subsequently, in the discharge position shown in FIG. 4, the upper plunger 9 is arranged as close to the lower plunger 10 as possible, such that the chamber contents 7 are minimized or zero such that there is no external space between the two plungers 9, 10. No air can enter. Subsequently, both plungers are operated jointly downwards to a position where a new work cycle of the injector 2 can begin.

As an alternative to this, the receiving chamber 14, which is connected to the recess 14 and the recess 14, for the remainder of the casting discharged through the recess 14, can be sealed against external air, for example in the form of a closed container. Can be. Here, the closed vessel must receive the remainder of the casting and have to be emptied for a relatively long time, or the recess 14 can be connected to a region shielded from outside air by a protective gas, so that both plungers 9 and 10 can be turned off. Even when it can be operated into the lower tube 8 continuously, it is possible to prevent the introduction of external air into the chamber 7.

Unlike known methods of operation, the plungers 9, 10 are configured to operate downward as closely as possible to each other to form the cavity of the chamber to be as small as possible or no longer present. Alternatives that can be simply formed are much more complex than if the injection device 2 had to be completely shielded from outside air.

Claims (13)

After the at least partially softened material is pressurized in the chamber, it is conveyed from the chamber and finally sprayed into the mold, The material is pressurized in a chamber having a moving wall, and The movement of the wall allows the volume of the interior of the chamber to be changed in such a way that the volume of the chamber increases as it feeds material into the chamber through the inlet, thereby decreasing during the casting process A method for producing a casting of dispersible flowable preliminary material, initially heated and at least partially flexible, Of the material contained in the chamber 7 so that the volume of the chamber 7 becomes almost zero when there is no melt in the chamber 7, such as before the filling of the chamber 7 or after the injection process. Characterized in that it corresponds as accurately as possible to the volume. The method of claim 1, The wall (9, 10) is the opening and closing time of the inlet (4) and outlet (5) is controlled by the movement of the wall (9, 10), the inlet (4) and outlet (5) Moving while passing. The method according to claim 1 or 2, The material is supplied to the chamber (7) by a conveying device having a screw conveyor, wherein the screw conveyor is only driven in rotation. The injector has an inlet opening for material supply and a outlet opening guided to the mold, The injection device has a chamber with a movable wall, the wall being movable such that the interior of the chamber is variable with respect to volume, An apparatus for producing a casting made of a dispersible flowable preliminary material having an injection device capable of injecting at least partially liquefied material into a mold, The chambers 7 of the injection device 2 are two moving walls 9, 10 which are moved together in one direction or in opposite directions with respect to each other so that the interior can be variable and / or movable with respect to volume. And the interior of the chamber (7) can be reduced to almost zero. The method of claim 4, wherein The inlet (4) and outlet (5) are characterized in that they are arranged continuously and spaced apart from each other in the direction of movement of the moving wall (9, 10). The method according to claim 4 or 5, The moving wall (9, 10) is characterized in that it is formed as two opposing plungers of the tubular chamber (7). The method of claim 6, The interior of the chamber (7) is characterized in that it has a round cross section. The method according to any one of claims 4 to 7, The upper part of the injector (2) is characterized in that a melting device (3) used for at least partially liquefied preliminary material is connected. The method of claim 8, The melting device (3) is characterized in that it is formed as a heatable screw conveyor melt joint. The method of claim 9, The melting device (3) is characterized in that it has two screw conveyors continuous to each other. The method of claim 9 or 10, And said screw conveyor can only be driven in rotation. The method according to any one of claims 4 to 11, On top of the chamber (7) two or a plurality of conveying devices are connected, said conveying device being connected to the chamber (7). The method according to any one of claims 4 to 12, And said plurality of chambers are connected to a mold.