EP2962785A2 - Filling chamber for a diecasting machine - Google Patents

Abstract

The invention relates to a filling chamber for a die casting machine, whose cylindrical inner surface serves as a sliding surface for a pressure piston and having a feed opening for liquid casting material and a removable cylindrical insert, on the inner surface of the pressure piston slides along and with a radial, with the feed opening of the filling chamber is provided in the associated opening of the lateral surface. According to the invention, the inner surface of the removable insert is at least partially made of a ceramic material.

Description

The invention relates to a filling chamber for a die casting machine according to the preamble of claim 1.

The inner surface of the filling chamber of a die casting machine is most affected by wear in the region of the feed opening. As a result of the mechanical filling of hot casting material through the feed opening, this always impinges on the inner surface of the filling chamber at the same location below the feed opening. After prolonged use of the filling chamber, this can result in washouts in the area below the feed opening, whereby the sliding movement of the pressure piston in the chamber can be hindered and the pressure piston is exposed to greater wear. This is from the publication DE 42 29 338 C2 a filling chamber known, which consists of a shell body with a removable cylindrical insert. An insert that extends only over the area of the feed opening and that can be rapidly replaced with a new one when worn, provides a quick remedy in the most common cases of wear of the sliding surface for the pressure piston. The insert extends from the outer end of the filling chamber to axially within the feed opening and comes into contact at its inner end in a narrow annular region with its peripheral surface with the inner wall of the filling chamber, while at its outer end by a between its outer periphery and the inner wall of the Filling chamber attacking centering is guided coaxially to the filling chamber. As a result, a filling chamber for die casting machines is already created, the main wear zone is replaceable directly on the die casting machine. However, longer service lives would be desirable for such operations.

Furthermore, from the document DE 102 05 246 B4 a filling chamber for a die casting machine with a supply port for liquid casting material is known in which in the filling chamber wall in the region opposite to the feed opening a cooling device is provided. The cooling device is formed from an insertable from the outside into the Füllkammerwand disc, which is provided with at least one guide channel for a coolant. Among other things, this measure is intended to extend the service life of a filling chamber insert.

The invention has the object of developing a filling chamber for a die casting machine for longer life.

The invention is represented by the features of claim 1. The other dependent claims relate to advantageous embodiments and further developments of the invention.

The invention includes a filling chamber for a die casting machine, the cylindrical inner surface serving as a sliding surface for a pressure piston and having a feed opening for liquid casting material and a removable cylindrical insert, on the inner surface of the pressure piston slides along and with a radial, with the feed opening of the Filling chamber is provided in the associated opening of the lateral surface. According to the invention, the inner surface of the removable insert is at least partially made of a ceramic material. With the feed opening of the filling chamber and the associated opening of the lateral surface a recess in the filling chamber is meant to fill melt into the interior.

The invention is based on the consideration that the greatest wear occurs in a filling chamber in the filling area. The reason for the wear, for example in die-cast aluminum, are low-iron aluminum alloys which can attack the steel of the filling chamber or of the exchangeable bushing and form leaching. In order to avoid this effect, the steel used in the filling region of the filling chamber is replaced by ceramic, so that the hot melt initially impinges only on a ceramic surface. Such surfaces are on the one hand thermally stable and resistant to corrosion.

In a preferred embodiment of the invention, the removable insert may be constructed of a metallic shell and an internal ceramic sleeve. The ceramic bushing and the protective device are to be regarded as a related part, which can be mounted as an insert in a filling chamber and also replaced again.

Since the mechanical properties of the ceramic bushing must be considered critically with respect to a mechanical force during installation and removal, a sleeve-like protective device for the ceramic bushing is arranged by the sheathing. Ceramics as relatively brittle materials are thus surrounded on the outer periphery of the mechanically resistant metal. This protection device allows a nondestructive assembly and disassembly of the ceramic bush. The metallic sheath of the insert may preferably consist of a steel, which in practice has only slight or no wear and thus can be used for several ceramic bushings. The preferred geometry of the casing corresponds to a hollow cylinder, in the inner circumferential surface of the ceramic bushing is introduced. Preferably, the outer surface of the Ceramic bushing completely enclosed by the casing and thereby supported. The outer surface of the casing itself comes into contact with the inner surface of the filling chamber. The filling opening is correspondingly recessed for the melt, both in the casing and in the ceramic, so that melt can be introduced into the interior of the filling chamber via the filling chamber opening during operation of the system.

Preferably, the cylinder-like casing and the ceramic bush are made to fit, i. that the metallic casing of the insert in the axial direction has the same length as the ceramic bushing. In other words, the two bushes are identical to two bushings which are pushed into each other with an exact fit and terminate flush with each other in the axial direction, and both have a recess for filling in the melt. However, it can also be carried out axially slightly longer and at least one side with flange surfaces, the metallic shell with which contacts an end face of the inner ceramic sleeve.

The ceramic bushing can be made in one piece or in several pieces. With multi-piece ceramic bushings occurring during operation can be encountered in the material thermally induced stresses. For example, sockets can also be composed of two half-shells or even of several segments. It is important that the metallic sheathing has a supporting effect, which holds the individual parts of the ceramic bushing together.

Advantageously, the internal ceramic bushing can be constructed of several segments. As a result, stresses are reduced in the brittle material. If necessary, the sides of the segments can also be chamfered in order to avoid edge breakouts. Even with chamfered edges, the ceramic surface largely remains as a sliding surface for the pressure piston. In the recesses or cavities formed by a chamfer or a gap can also penetrate some melt. However, the amount is so small that no harmful effects on the surrounding metal are to be feared. On the contrary, a gap filled with die-casting material can also further stabilize the segments and also contribute to a reduction in stress.

In contrast, it is also possible that the metallic sheath of the insert exerts a compressive stress on the ceramic bushing. With the help of this radial bias can be a tensile stress as an undesirable stress state in the material compensate both in one-piece ceramic bushes as well as constructed of several segments ceramic bushings. During operation, the state of stress in the material should be at least below the characteristic values for the tensile stress which are still acceptable for the respective ceramic.

In an advantageous embodiment of the invention, the metallic sheath of the insert can exert a compressive stress on the ceramic bushing even at the operating temperature. As a result, sufficient precautions can be taken even at elevated temperature and as a result of the pressure surges during the pressure casting process that the ceramic material has the longest possible service life without being damaged.

In an advantageous embodiment of the invention, the metallic sheath of the insert may have an axial slot. By choosing the inner diameter of the sheath slightly smaller than the outer diameter of the bushing, the sheath can be slightly widened by the axial slot and pushed over the ceramic bushing. By widening again creates a radially inward bias by the elastic properties of the metal used. The axial slot can also be used to prevent rotation of the entire insert by at least one Part of the resulting through the slot opening cooperates with an existing on the Füllkammerwand guide nipple or other bulge.

Advantageously, the metallic sheath of the insert can engage over the ceramic bushing on the face side and form a uniform cylindrical surface with the inner surface of the ceramic bushing. As a result of this overlap, a uniform planar sliding surface is formed for the pressure piston and the bush is securely fixed in the axial direction.

In a preferred embodiment of the invention, at the inner end of the insert, the metallic sheath may have a retaining ring on the face side, which fixes the ceramic bushing. The retaining ring is firmly bolted, for example, with the rest of the sheath. By means of this re-releasable connection can be easily replaced if necessary, a ceramic socket.

In a particularly preferred embodiment, the removable insert with its inner surface can form only part of the sliding surface for the pressure piston in the region of the feed opening of the filling chamber. In most cases, it is only necessary to set up a ceramic protection in the filling zone, because there the hot molten metal meets the filling chamber inner wall first.

In a further advantageous embodiment of the invention, the removable insert may extend from the outer end of the filling chamber to axially within the feed opening. In this part of the plant, the material is exposed to special thermal and corrosive loads.

Advantageously, the removable insert can be made entirely of ceramic. There are already filling chambers with exchangeable bushes made of steel, whereby then a full ceramic insert the same geometry as an existing Can have change socket. As a result, when handling the ceramic material with care, it is nevertheless advantageous to simply swap a steel bushing with a corresponding ceramic bushing. In this case usually no further adjustments in the geometric design must be carried out.

In a further advantageous embodiment, the removable insert may be constructed of a metallic sheath and an inner thin ceramic layer. Here, a suitable thin ceramic layer may be applied to the inside of the casing, which originally has a slightly larger inner diameter than the rest of the filling chamber. Overall, then the inner diameter of the ceramic surface with layer is in turn aligned with the inner diameter of the rest of the filling chamber. Such layers can be applied by means of plasma spraying or other suitable method for producing thin layers.

Advantageously, the ceramic material may consist of silicon carbide, silicon nitride, aluminum oxide, zirconium oxide, boron nitride or boron carbide. Depending on the temperature and the corrosive properties of the molten metal, different materials can be considered. Silicon carbide and densely sintered silicon nitride are particularly preferred materials that withstand both high temperatures and mechanical stresses in the operation of a die casting machine.

Embodiments of the invention will be explained in more detail with reference to the schematic drawings.

• Fig. 1 schematisch einen Längsschnitt durch eine Füllkammer mit Einsatz,
• Fig. 2 schematisch eine Ansicht der einer Gießform abgewandten Stirnseite einer Füllkammer,
• Fig. 3 schematisch eine Seitenansicht eines Einsatzes,
• Fig. 4 schematisch einen Längsschnitt durch einen Einsatz, und
• Fig. 5 schematisch eine Schrägansicht eines Einsatzes.

Show:

• Fig. 1 schematically a longitudinal section through a filling chamber with insert,
• Fig. 2 2 is a schematic view of the front side of a filling chamber facing away from a casting mold;
• Fig. 3 schematically a side view of an insert,
• Fig. 4 schematically a longitudinal section through an insert, and
• Fig. 5 schematically an oblique view of an insert.

Corresponding parts are provided in all figures with the same reference numerals.

Fig. 1 schematically shows a longitudinal section through a filling chamber 1 with insert 10 and the feed opening 3 as a filling area for casting material. The insert 10 has a cylindrical shape and extends from the outer right end of the filling chamber 1 to within a feed opening 3 in the filling chamber 1 in the coaxial direction. The filling chamber 1 is a hollow cylindrical body with a front portion 5, whose inner diameter corresponds to the diameter of the pressure piston, wherein the cylindrical inner surface 2 as a sliding surface for the in Fig. 1 not shown further pressure piston is used. At this front portion 5, a rear portion 6 connects, in which the feed opening 3 is arranged for the casting material and which serves to receive the insert 10. For this reason, the rear portion 6 has a larger inner diameter than the front portion 5. Here, the inner diameter of the rear portion 6 is designed so that the insert 10 is held securely and can still be removed with simple means.

On the front side of the filling chamber 1, a clamping ring 4 is releasably secured, which is pressed against the insert 10 to fix its position inside the filling chamber 1. In this case, the clamping ring 4 may conveniently be fastened by means of a quick release to the filling chamber 1. As a result, a quick removal and replacement of the insert 10 of the filling chamber 1 is ensured. The clamping ring 4 has a central recess, through which the pressure piston can be guided into the filling chamber 1.

In Fig. 1 is the removable insert 10 of a metallic shell 20th and an internal ceramic sleeve 30 constructed. In this case, the metallic casing 20 of the insert 10 engages on the ceramic bushing 30 on the front side and forms with the inner surface 31 of the ceramic bushing 30 a uniform cylindrical surface. In this way, the holding force for the fixation of the insert 10 is exerted by the end face of the clamping ring 4 on the metallic shell 20. The brittle ceramic experiences no undesirable holding forces here.

At the inner end of the insert, the metallic sheath is closed at the end by a retaining ring 25 which fixes the ceramic bushing. By means of this re-releasable connection can be replaced if necessary, a ceramic bush with little effort.

Fig. 2 schematically shows a view of a mold facing away from a front side of a filling chamber 1. The clamping ring 4 is chamfered at the central recess to form an inclined guide plane for the pressure piston.

Fig. 3 schematically shows a side view of an insert 10. The insert 10 has adjacent to the feed opening 3 from Fig. 1 for the molten metal of the filling chamber 1 has an opening 11 of the lateral surface, which has a slightly larger diameter than the tapered feed opening. 3

Fig. 4 schematically shows a longitudinal section through an insert 10 viewed from below, in which the opening 11 can be seen as a rectangular section. The insert 10 has a total of a uniform inner diameter, wherein the inner surface 31 of the ceramic bushing and the inner surface of the overlying portion of the casing with the cylindrical inner surface 2 of the filling chamber 1 from Fig. 1 exactly aligned and together with this forms the sliding surface for a pressure piston.

The outer diameter of the insert 10 is also constant over wide areas. Only at the front end of the transition from the end face to the outer shell of the insert 10 is chamfered to facilitate the insertion of the insert 10 into the filling chamber 1. In addition, the outer diameter of the insert 10 is reduced at the outer end to make room for the arrangement of the clamping ring 4, as in Fig. 1 is shown.

Fig. 5 schematically shows an oblique view of an insert 10 suitable for mounting in the filling chamber. 1

LIST OF REFERENCE NUMBERS

1

filling chamber

2

cylindrical inner surface

3

feed

4

clamping ring

5

front area

6

the backstage area

10

commitment

11

Opening of the lateral surface

20

metallic sheath

25

retaining ring

30

ceramic sleeve

31

Inner surface of the ceramic bush

Claims (13)

Filling chamber (1) for a die casting machine, whose cylindrical inner surface (2) serves as a sliding surface for a pressure piston and which has a feed opening (3) for liquid casting material and a removable cylindrical insert (10) on the inner surface of the pressure piston slides along and with a radial, with the feed opening (3) of the filling chamber (1) communicating opening (11) of the lateral surface is provided
characterized,
that the inner surface of the removable insert (10) at least consists of a ceramic material part. Filling chamber (1) according to claim 1, characterized in that the removable insert (10) of a metallic sheath (20) and an inner ceramic bushing (30) is constructed. Filling chamber (1) according to claim 2, characterized in that the inner ceramic bush (30) is constructed of a plurality of segments. Filling chamber (1) according to claim 2 or 3, characterized in that the metallic casing (20) of the insert (10) exerts a compressive stress on the ceramic bushing (30). Filling chamber (1) according to claim 4, characterized in that the metallic casing (20) of the insert (10) also exerts a compressive stress on the ceramic bushing (30) at the operating temperature. Filling chamber (1) according to one of claims 2 to 5, characterized in that the metallic casing (20) of the insert (10) has an axial slot (21). Filling chamber (1) according to one of claims 2 to 6, characterized in that the metallic sheath (20) of the insert (10) on the ceramic bushing (30) engages over the front side and with the inner surface (31) of the ceramic bushing (30) has a uniform cylindrical Surface forms. Filling chamber (1) according to one of claims 2 to 7, characterized in that at the inner end of the insert (10), the metallic sheath (20) frontally a retaining ring (25) which fixes the ceramic bushing (30). Filling chamber (1) according to one of claims 1 to 8, characterized in that the removable insert (10) with its inner surface only part of the sliding surface for the pressure plunger in the area of the feed opening (3) of the filling chamber (1) forms. Filling chamber (1) according to claim 9, characterized in that the removable insert (10) extends from the outer end of the filling chamber (1) to axially within the feed opening (3). Filling chamber (1) according to claim 1, characterized in that the removable insert (10) consists entirely of ceramic. Filling chamber (1) according to claim 1, characterized in that the removable insert (10) of a metallic sheath (20) and an inner thin ceramic layer is constructed. Filling chamber (1) according to one of the preceding claims, characterized in that the ceramic material consists of silicon carbide, silicon nitride, aluminum oxide, zirconium oxide, boron nitride or boron carbide.

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