Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22C—FOUNDRY MOULDING
  • B22C7/00—Patterns; Manufacture thereof so far as not provided for in other classes
  • B22C7/06—Core boxes

Definitions

• Designation Molded part for the production of molds for foundry purposes using a molding material, in particular a core box
• the invention relates to a molded part for the production of molds for foundry purposes by means of a mold material, in particular core boxes for the production of cores for foundry purposes, in which limited surface areas that are exposed to impermissible wear from the mold material flow when introduced, preferably surface areas in which the mold The material flow moves at high speed and/or with a change of direction towards the mold surface and/or along the mold surface.
• molding in the context of the invention includes both a pattern and a core box.
• core in the context of the present invention includes parts that are placed in a mold and cavities, undercuts and the like in the finished piece - Solve problem areas of mold design, ie G corderei ⁇ cores in the conventional sense.
• the term also includes parts which can be assembled into a complete casting mold and which are produced from the same mold material and by the same method as foundry cores. Depending on the shape of the casting to be produced, both the inner wall and the outer wall of the casting can be delimited by the core parts combined to form the casting mold.
• a molding process is advantageously used in which the binder of the core sand is not heated but heated by chemical-catalytic tables Processes is activated so that the molding material hardens in the mold in a short time without increasing the temperature and can then be removed from the mold.
• cores in the classic sense i.e. parts produced according to the previously known process, which are placed in a sand mold defining the outer contour of the casting
• cores produced according to the process described above represent the complete casting mold, i.e. the inner
• the shape that defines the shape and outer contour of the casting are geometrically very complicated structures that require correspondingly complicated and therefore expensive core boxes for their production, especially since high demands are placed on the precision of these core boxes. Since the above-described "cold" molding process with chemical-catalytic hardening of the molding material in the core box itself only requires the molding material to remain in the core box for a short time, the throughput is high, which is further increased by increasing the filling speed of the molding material stream to be introduced into the core box can be.
• the invention is now based on the object of designing a molded part of the type described initially, in particular a core box, in such a way that, while retaining the materials previously used, an increase in service life with an increase in throughput is possible.
• the limited surface areas susceptible to wear are each formed by inserts made of a non-deformable material with high wear resistance, which are embedded in the base material of the molded part. are.
• corresponding recesses can now be worked into these defined surface areas, into which a correspondingly shaped insert can then be inserted.
• Such inserts can be manufactured with high precision with regard to the mold surface, so that the part of the insert forming the inner wall of the mold can be manufactured with precise dimensions. This is a long service life especially for guarantees such surface areas that protrude as projections into the molding material to be introduced.
• hard metal is used for the inserts. These are hard materials that contain at least one metallic hard material, in particular tungsten, titanium or tantalum carbide.
• the insert piece in order to form a core mark, which appears as a depression in the core to be produced, is formed by a pin, the free end of which protrudes into the mold space. Depending on its position within the mold space, such a pin is surrounded to a considerable extent by the injected mold material. If, according to the invention, a pin with high wear resistance is used for this purpose, which shows practically no wear in the service life under consideration here, there is a guarantee that the depression formed by the pin in the core to be manufactured has a high degree of dimensional accuracy.
• the spigot can have any desired cross-sectional shape adapted to the requirements of the core to be produced.
• the pin is inserted into a recess in the base material of the molded part.
• the insert made of wear-resistant material embedded in the base material is cup-shaped. Due to the high wear resistance of the input material, the compacting molding material stream flowing into the cup with deflection cannot change its dimensions over a long period of operation. As a consequence, that the resulting on the core produced, serving as a core mark projection also has a high dimensional accuracy.
• the core parts can be assembled with dimensional accuracy, so that the castings produced with them have no burrs even after the core molds have been in operation for a long time and thus have a high form quality of the casting can be achieved.
• the time-consuming plastering of casting flashes is therefore no longer necessary.
• a reliable frictional connection of the two core parts is also possible with a corresponding conical design of the core marks formed from the projection and depression which are assigned to one another.
• the bottom area of the cup-shaped insert is designed as a gas outlet nozzle which is connected to the outside of the molded part via at least one outlet channel.
• the gas outlet nozzle is formed by a detachable base piece which has a mushroom-shaped head, the upper head surface of which is closed and the edge of which runs parallel and at a distance from the cross-sectional contour of the cup-shaped insert piece and that the space under the head with the Outlet port is in communication.
• An outlet nozzle designed in this way has a considerable outlet cross-section, so that the gap between the edge of the head and the wall of the cup-shaped insert piece only needs to be 0.2 mm wide, for example, in order to let the gas quantities to be discharged through in the shortest possible time and on the other hand to prevent the passage of the smallest grain fraction of the molding material. Even if individual grains of molding material should settle after a long period of operation, this means only an insignificant one
• the base piece is mounted in the molded part in an axially displaceable manner and is connected to a sliding drive.
• the bottom piece also assumes the function of the ejector, so that a separate element can be omitted here, thus simplifying the production of the mold.
• a further advantage of this configuration is that the gas outlet nozzles in this area are cleaned with each working stroke. Since both the insert piece connected to the molded part and the base piece are made of wear-resistant material, there is no adverse effect on the dimensional accuracy of the core produced.
• a core box that at least the surface area of the core box opposite the injection channel consists of an insert made of a material with higher wear resistance than the material of the core box itself. In this area of the core box occurs the highest Ver ⁇ wear stress, since this area when zeroing practically through the whole to be introduced into the core box
• Amount of molding material is loaded and, in addition, the molding material in this area has the highest kinetic energy. Because the position of the injection channel in relation to the interior of the mold can be freely selected within certain limits, there is also the possibility of arranging the injection channel at a point in the core box at which the area of the inner mold wall opposite the injection channel has a geometrically simple and therefore easy to has generating surface contour.
• Fig. 1 a two-piece core box for
• Fig. 2 shows a cross section through a two-part core box for the production of a
• Kerns with a cone-shaped Kernmark Kerns with a cone-shaped Kernmark
• FIG. 3 shows an insert designed as a combined gas outlet/core ejector on a larger scale.
• FIG. 1 shows a cross section through a two-part core box 1, which can be connected to a core molding machine and consists of an upper box part 2 and a lower box part 3, which can be joined together by means of centering devices (not shown).
• an injection channel 4 which is connected to the molding material supply of the core molding machine.
• the injection channel 4 is formed by a tubular body 5 made of a wear-resistant material, which is embedded in the material of the upper part 2 of the core box.
• the lower part of the core box 3 on the mouth 6 of the
• additional inserts in the form of a pin 10 protruding into the mold space can be arranged in both box parts, or as shown here schematically only for the box bottom part 3 Mold Vertie ⁇ tests, such as core marks are formed.
• the pin 10 is in a recess in the base material of the
• Lower box part 3 is used and can be precisely adjusted in height via a rear feed 11 .
• the flow of molding material enters the interior of the mold at high speed and hits the surface 8 of the insert 7, where it is deflected so that the interior of the mold is progressively filled completely with molding material.
• the pins 10 are flowed around by the molding material. Since the risk of wear essentially only exists on the pin 10 and in the area directly opposite the opening 6, the surface area of the inner wall of the mold covered by the insert 7 needs to be only slightly larger than the projection of the injection opening 6 onto this part of the mold inner wall.
• one part or one side of the core has indentations such as are formed in the molding material with the aid of the pins 10 shown and described in FIG.
• the other part or the other side of the core must have correspondingly associated pin-shaped projections which appear as depressions in the molding box. Since the molding material flows into such depressions with deflection and has to be compacted into the depressions, and on the other hand during molding the peg-shaped projection formed by the depression is moved with its surface relative to the shaping surface of the depression in the box part, this area is also at a high level exposed to wear and tear.
• the box parts in this area are provided with a cup-shaped insert piece 12 made of wear-resistant material, so that the dimensional accuracy of the peg-shaped projection to be formed is also guaranteed here over long periods of operation. Since both the indentation to be formed with the molding box according to Fig. 1 and the peg-shaped projection to be formed with the molding box according to Fig. 2 retain their dimensional accuracy unchanged even with large quantities, the two core or molded parts to be produced can be fitted into one another with dimensional accuracy and without play that there is no offset between the two core or mold parts in the parting plane. As a result, the castings produced in this way have practically no burr .
• the cup-shaped insert 12 in FIG. 2 is designed in such a way that it also forms a gas outlet nozzle. Accordingly, the insert 12 is divided into a tubular wall part 13 and a detachable bottom piece 14, which has a mushroom-shaped - Head 15 has.
• the tubular wall portion 13 has a
• Form cross-section which does not have to be circular, but formed arbitrarily according to the requirements of the core to be produced or the associated core brand of the other part
• the outer contour of the mushroom-shaped head 15 is dimensioned accordingly, with the edge 16 of the head 15 facing the inner wall of the tubular part 13 running parallel and at a small distance from the inner wall 17 .
• the width of the gap formed in this way is only 0.2 mm, for example.
• the space under the mushroom-shaped head is connected to a gas outlet 18, so that when the molding material is injected, the gas can also escape from the interior of the mold through the cup-shaped inserts 12 forming the gas outlet nozzles. This ensures that the peg-shaped projections to be formed on the core or molded part to be formed are fully formed and fully compressed.
• molded parts usually have a large number of gas outlet nozzles, but also a large number of core brands, the shape of the gas outlet nozzles described above also offers the possibility of using them as ejectors at the same time.
• a shaft 19 connected to the base piece 14 is connected to a drive device 20 . After the core box has been opened, the bottom pieces are moved in the direction of the interior of the mold via the drive 20 and the finished core can thus be detached from the mold and then removed.
• the use of the base piece 14 of the cup-shaped inserts 12 as an ejector is not limited to the exemplary embodiment shown.
• the special design of these outlet nozzles consists of a tubular part made of wear-resistant material and a base piece also made of wear-resistant material. This makes it possible to use such gas outlet nozzles as ejectors in which the head surface of the bottom piece is in one plane with the adjacent surfaces of the inner wall of the mould. This has the advantage that the gas outlet nozzle cleans itself as a result of the ejection process, but on the other hand the use of wear-resistant materials ensures that molding material grains wedged in the gap between the head piece and the wall of the insert practically do not lead to wear and thus to a increase the gas outlet gap.
• FIG. 3 shows the construction of such a gas outlet nozzle, which can be actuated as an ejector, on a larger scale.
• the shaft 19 connected to the head 15 is stilför ig and has three or four wing-like projections 21, over which the Boden ⁇ piece is guided centered, so that a constant gap width between the edge 16 and the inner wall 17 is guaranteed.
• the inserts 5, 7, 10, 12 and also the injection channel 4 are made of a non-deformable, wear-resistant material. Hard metals are preferably used for this purpose. The composition also depends on the wear stress. So the bullet channel 4 is subject to the highest stress.

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Molds, Cores, And Manufacturing Methods Thereof (AREA)
• Moulds For Moulding Plastics Or The Like (AREA)
• Mounting, Exchange, And Manufacturing Of Dies (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=6350100

Family Applications (1)

Country Status (8)

Families Citing this family (7)

Citations (6)

Family Cites Families (8)

• 1988
  • 1988-03-18 DE DE3809130A patent/DE3809130A1/de not_active Withdrawn
• 1989
  • 1989-02-14 JP JP1502074A patent/JPH02501546A/ja active Pending
  • 1989-02-14 ES ES198989200414T patent/ES2034575T3/es not_active Expired - Lifetime
  • 1989-02-14 EP EP89200414A patent/EP0338601B1/de not_active Expired - Lifetime
  • 1989-02-14 WO PCT/EP1989/000133 patent/WO1989008513A1/de not_active Ceased
  • 1989-02-14 EP EP89902257A patent/EP0357716A1/de active Pending
  • 1989-02-14 DE DE8989200414T patent/DE58901915D1/de not_active Expired - Fee Related
  • 1989-02-14 AT AT89200414T patent/ATE78732T1/de not_active IP Right Cessation
  • 1989-02-14 US US07/444,125 patent/US5042562A/en not_active Expired - Lifetime
• 1992
  • 1992-10-26 GR GR920401769T patent/GR3006071T3/el unknown

Patent Citations (6)

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