Metal founding – Means to shape metallic material – United particle type shaping surface
Reexamination Certificate
2001-11-26
2003-07-08
Lin, Kuang Y. (Department: 1725)
Metal founding
Means to shape metallic material
United particle type shaping surface
C164S339000
Reexamination Certificate
active
06588490
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a device for joining all kinds of parts, in particular cores for forming a core assembly, the parts being adapted for insertion into one another with at least one connecting area formed at least in certain regions.
Quite generally, the invention relates to joining all kinds of parts, and to a joining technique, wherein the parts being joined come into mutual surface contact. In most cases, they lie against one another in formfitting engagement, and/or engage one another.
In addition to gluing together the surfaces, it is common to join parts with dowel-type connecting pins. In this connection, it is essential that the parts have suitable recesses, openings, or passages, which are oriented toward one another and in alignment with one another. The connecting pins extend through the recesses, openings, or passages, and are secured therein in force-locking engagement with the parts being joined, thereby interconnecting the parts. Securing of the connecting pins occurs by expansion within the recesses, opening, or passages.
A device of the kind under discussion may also be used, in particular in an advantageous manner, for joining cores into a core assembly, namely in the foundry practice, where for casting all kinds of molded parts, foundry cores or molds are commonly made from separate parts, combined, and joined to a casting mold or a core or mold assembly. These core assemblies are then filled with a molten metal for making, for example, a metallic work piece. In the series production, the core assemblies being filled with the molten metal advance one after the other through a production line.
Core and shell shooting machines for making the cores to be joined have been known from practice for many decades, for example, from DE 31 48 461 C1, which discloses a core and shell shooting machine.
The joining of cores into a core assembly, for example, for casting an engine block, has so far occurred by joining the individual cores by means of screws or tie rods. This is extremely costly because of the manual activity that is required in this instance. Furthermore, it is necessary to eliminate or separate again the screws or tie rods, when removing the cast pieces or when preparing the molding material in this instance mainly sand, including binders.
Furthermore, it is known per se to join cores alternatively with hot-melt adhesives or cold bonding agents. When using hot-melt adhesives, one has to see to it that the kiln temperature be not above the melt point of the hot-melt adhesive during a subsequent passage through a foundry kiln for drying the applied water-based core coating. If so, the adhesive bond would dissolve.
Furthermore, is likewise already known from the prior art to join cores by means of core sand, namely by shooting a so-called key core into hollow spaces provided in the cores being joined, whereby a formfitting engagement is obtained between the respective cores or core parts. This requires a separate shooting operation directly on the already made cores or core parts, which generate quite a considerable expenditure in terms of apparatus.
A device for joining parts, in particular cores for forming a core assembly is also disclosed in DE 197 42 276 A1. This document discloses the use of very special connecting means, namely an expansion body, which is first introduced or inserted with a play into aligning recesses of the parts being joined. In this instance, the expansion body is a so-called expansion element for producing a force-locking engagement between the parts or cores, and one of the recesses is formed in a projection of one of the two parts. The expansion element has the shape of a pin and contains in its wall surface two opposite flats. The expansion element is made of metal, plastic, wood, or even molding sand. For joining the two parts or cores, the expansion element is inserted into the recess provided in one of the two parts. The other part is placed on the projecting portion of the expansion element or slipped on the expansion element. When compressing the cores with their respective front ends by means of a pneumatic or hydraulic device or with a corresponding manipulator, the expansion element spreads, where it has no flats, an annular projection of that part, into which it is inserted. As a result, this part or this projection expands relative to the surrounding wall of the other part, so that a force-locking engagement results between the two engaged parts.
Finally, the known device for joining parts in the manner of a wedge acts in the first place exclusively on two sides upon the areas being expanded, so that as a result of there developing stresses, it is not uncommon that material breakage occurs on the parts being joined. This occurs in particular in such cases, where the parts are brittle, fragile parts, as is the case with cores from molding sand.
It is therefore an object of the present invention to provide a device for joining all kinds of parts, which avoids the risk of damaging brittle or fragile parts to the greatest extent.
SUMMARY OF THE INVENTION
The above and other objects are achieved with the present invention by the provision of a clamping member which is provided between the connecting areas of the parts, and which exerts a clamping effect when and as a result of the parts being inserted into one another.
In an advantageous manner, it has been recognized that it is possible to join with simple means all kinds of parts, in particular cores for forming a core assembly, wherein between engageable connecting areas of the parts, a clamping member is provided, which develops a clamping effect during the engagement. The parts are joined to one another solely as a result of being inserted into each other, and while being inserted into one another, namely because of the clamping effect resulting from the clamping member. Accordingly, the connecting areas of the parts are to be adapted to one another in their shape and size such that the clamping member fits inbetween. In the case of a full engagement of the connecting areas, the clamping effect resulting from the clamping member must be adequate.
In an advantageous manner, the connecting areas of the parts being joined to one another are made as male and female portions that fit into one another. In this connection, it is desired that the parts fit into one another at least largely by formfitting engagement. Each clamping member serves as an insert between two connecting areas, so that a clamping effect results, when the connecting areas engage each other. Provided the clamping members being used as inserts are made adequately soft, it will be possible to reduce the clamping force to a minimum, so that damage to the parts is avoided to the greatest extent.
Within the scope of a particularly suitable configuration of the connecting areas, the connecting area of the one part is realized as a cone or frustrum, and the connecting area of the other part as a conical or frustoconical recess. Many other shapes are possible. In this instance, one will always have to make sure that the connecting areas of the parts fit into one another at least largely in a formfitting manner.
If the connecting areas are realized as cones or frustrums and as corresponding recesses, their respective circumferential surface may have different angles. In this connection, it has been shown that in the case of an only extremely small angle of inclination of the circumferential surface, a particularly satisfactory and adequate connection results because of a force-locking engagement. An adaptation to the respective conditions of the parts being joined is possible.
Specifically, the clamping member may be realized such that it is made as a moldable flat layer or sheet, which is adapted for being placed or slipped at least in certain regions onto the connecting area serving as the male portion, and/or for being placed or inserted at least in certain regions into the connecting area serving as the female portion. For example, the sheet could be realized as a closed or
Beyerer Jürgen
Rommel Reiner
Seiraffi Mohammed A.
Alston & Bird LLP
Lin Kuang Y.
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