EP3184203B1 - Filling chamber for a diecasting machine - Google Patents

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 of a between its outer periphery and the inner wall the filling chamber attacking centering is guided coaxially to the filling chamber. As a result, a filling chamber for die casting machines is already being created, whose main wear zone is interchangeable directly at 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.

In addition, from the document US Pat. No. 3,786,552 A a filling chamber for a die casting machine is known, whose cylindrical inner surface serves as a sliding surface for a pressure piston and which has a feed opening for liquid casting material. The filling chamber consists of a base material made of an iron alloy on the inside of which an inner layer of molybdenum or a molybdenum alloy is applied over the entire surface.

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 molybdenum or a molybdenum alloy.

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 are, for example, in die-cast aluminum, low-iron aluminum alloys, the attack the steel of the filling chamber or the exchange socket and can form leaching. To circumvent this effect, the commonly used steel is replaced in the filling of the filling chamber by molybdenum or a molybdenum alloy, so that the hot melt initially impinges only on a molybdenum or molybdenum alloy surface. Such surfaces are on the one hand thermally stable and resistant to corrosion.

Pure molybdenum has a linear thermal expansion coefficient of 5.2x10 ^-6 1 / K at room temperature. These values are considerably lower than those of commercially available steels.

Advantageously, the molybdenum alloy may be a so-called TZM molybdenum. TZM molybdenum is a hardened and particle-reinforced molybdenum based alloy. The formation of a Mo-Ti mixed crystal and finely divided Ti carbides are responsible for the excellent strength properties at temperatures up to 1400 ° C. TZM molybdenum is an alloy of 0.50% titanium, 0.08% zirconium and 0.01-0.04% carbon, balance molybdenum. Due to its high strength, TZM molybdenum is particularly suitable for high temperature applications. TZM molybdenum has a higher recrystallization temperature, higher strength, hardness and good toughness at room temperature and elevated temperatures than unalloyed molybdenum. In addition, TZM molybdenum has good thermal conductivity and is easy to process.

Alternatively, the following molybdenum alloys may be suitable: Material designation Chemical composition [in% by weight] MHC 1.2% Hf, 0.05-0.12% C, balance Mo Mon-lanthanum oxide ML 0.3% La ₂ O ₃ , balance Mo MLR (recrystallized) 0.7% La ₂ O ₃ , balance Mo MLS (low tension) 0.7% La ₂ O ₃ , balance Mo MolLQ 0.03% La ₂ O ₃ , balance Mo Mon-yttria MY 0.47% Y ₂ O _3, 0.08% Ce ₂ O ₃ , balance Mo MoRe more5 5% Re, rest Mo MoRe41 41% Re, rest Mo MoW MW20 20% W, balance Mo MW30 30% W, rest Mo MW50 50% W, rest Mo MoCu MoCu30 30% Cu, balance Mo MoCu15 15% Cu, balance Mo MoZrO ₂ MZ17 1.7% ZrO ₂ , balance Mo monb MoNb10 9.71% Nb, rest Mo MoTa MT11 10.75% Ta, rest Mo

The molybdenum alloy MHC contains carbides as in TZM, which positively influence the mechanical properties. In particular, admixtures in the form of oxides increase the recrystallization temperature and creep resistance of molybdenum. Rhenium in molybdenum ensures better ductility. Whereas copper increases the thermal conductivity and only slightly changes the thermal expansion coefficient.

In a preferred embodiment of the invention, the removable insert may be constructed of a metallic sheath and an inner sleeve of molybdenum or a molybdenum alloy. The socket and the protective device are to be regarded as a connected part, which can be mounted as an insert in a filling chamber and also replaced again.

Since the mechanical properties of the sleeve made of molybdenum or a molybdenum alloy with respect to a mechanical force during installation and removal must be considered critical, a sleeve-like protection device for the sleeve made of molybdenum or a molybdenum alloy is arranged by the sheath. This protection device allows a nondestructive assembly and disassembly of the socket. The metallic sheath of the insert may preferably consist of a steel, which in practice has only slight or no wear and can thus be used for several bushes. The preferred geometry of the sheath corresponds to a hollow cylinder, in the inner circumferential surface of the sleeve made of molybdenum or a molybdenum alloy is introduced. Preferably, the outer surface of the sleeve is completely enclosed by the sheath 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 bush made of molybdenum or a molybdenum alloy, so that melt can be introduced into the interior of the filling chamber via the filling chamber opening when the system is operated.

Preferably, the cylinder-like casing and the sleeve made of molybdenum or a molybdenum alloy are made to fit, ie that the metallic casing of the insert in the axial direction has the same length as the bush made of molybdenum or a molybdenum alloy. In other words: both Bushes are identical to two sleeves which are precisely pushed into one another 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 sleeve of molybdenum or a molybdenum alloy.

The bush made of molybdenum or a molybdenum alloy can be made in one piece or in several pieces. With multi-piece bushings occurring during operation thermally induced stresses in the material can be countered. For example, sockets can also be composed of two half-shells or even of several segments. Here it is important that the metallic sheath takes over a supporting effect, which holds the individual parts of the sleeve made of molybdenum or a molybdenum alloy.

Advantageously, the inner sleeve made of molybdenum or a molybdenum alloy can be constructed of several segments. As a result, voltages are reduced in the material. If necessary, the sides of the segments can also be chamfered in order to avoid edge breakouts. Even with chamfered edges, the surface of the bush largely remains as a sliding surface for the pressure piston. In the recesses or cavities, which arise through a chamfer or a gap, also some melt can penetrate. 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 a compressive stress on the bush made of molybdenum or a Molybdenum alloy exercises. With the help of this radial bias can be a tensile stress as an undesirable state of stress in the material compensate both in one-piece sockets as well as constructed from several segments sockets. During operation, the stress state in the material should at least be below the characteristic values for the tensile stress which are still acceptable for the respective material.

In an advantageous embodiment of the invention, the metallic sheath of the insert can exert a compressive stress on the bush made of molybdenum or a molybdenum alloy, 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 bushing 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 bush, the sheath can be slightly widened by the axial slot and pushed over the 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 a 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 on the sleeve made of molybdenum or a molybdenum alloy overlap the end face and form a uniform cylindrical surface with the inner surface of the sleeve. This overlap forms a uniform plane for the pressure piston Sliding surface and the socket is securely fixed in the axial direction.

In a preferred embodiment of the invention, at the inner end of the insert, the metallic sheathing frontally have a retaining ring which fixes the bush made of molybdenum or a molybdenum alloy. The retaining ring is firmly bolted, for example, with the rest of the sheath. By means of this re-releasable connection, a socket can be easily replaced if necessary.

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 protection in the filling zone, since 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 molybdenum or a molybdenum alloy. There are already filling chambers with exchangeable bushes made of steel, whereby then this type of insert can have the same geometry as an existing exchange socket. As a result, when handling the material with care, it is nevertheless advantageous to simply swap a steel bushing with a molybdenum or molybdenum alloy bush. In this case usually no further adjustments in the geometric design must be carried out.

In a further advantageous embodiment of the removable insert can a metallic sheath and an inner thin layer of molybdenum or a molybdenum alloy. Here, a suitable thin 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 surface with the layer is in turn aligned with the inner diameter of the rest of the filling chamber.

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 Area 5 is followed by a rear area 6, in which the feed opening 3 for the casting material is arranged 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 the removable insert 10 is constructed of a metallic sheath 20 and an inner sleeve of molybdenum or a molybdenum alloy 30. In this case, the metallic sheathing 20 of the insert 10 engages on the socket made of molybdenum or a molybdenum alloy 30 on the front side and forms with the inner surface 31 of the 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.

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

Fig. 2 schematically shows a view of the end facing away from a mold 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 an overall uniform inner diameter, wherein the inner surface 31 of the molybdenum or molybdenum alloy 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

Bush made of molybdenum or a molybdenum alloy

31

Inner surface of the bush

Claims (10)

1. Filling chamber (1) for a diecasting machine, the cylindrical inner surface (2) of which is used as a sliding surface for a piston and which comprises a supply opening (3) for liquid casting material and comprises a removable cylindrical insert (10) along the inner surface of which the piston slides and which is provided with a radial opening in the lateral surface (11) that is connected to the supply opening (3) of the filling chamber (1),
   characterized in that
   the inner surface of the removable insert (10) consists at least in part of molybdenum or a molybdenum alloy, the removable insert (10) being made from a metal casing (20) and an internal liner made of molybdenum or a molybdenum alloy (30).
2. Filling chamber (1) according to claim 1, characterized in that the molybdenum alloy is TZM molybdenum.
3. Filling chamber (1) according to either claim 1 or claim 2, characterized in that the internal liner is made from molybdenum or a molybdenum alloy (30) composed of a plurality of segments.
4. Filling chamber (1) according to any one of claims 1 to 3, characterized in that the metal casing (20) of the insert (10) exerts a compressive stress on the liner made of molybdenum or a molybdenum alloy (30).
5. Filling chamber (1) according to claim 4, characterized in that, even at operating temperature, the metal casing (20) of the insert (10) exerts a compressive stress on the liner made of molybdenum or a molybdenum alloy (30).
6. Filling chamber (1) according to any one of claims 1 to 5, characterized in that the metal casing (20) of the insert (10) has an axial slit (21).
7. Filling chamber (1) according to any one of claims 1 to 6, characterized in that the metal casing (20) of the insert (10) extends over the end face of the liner made of molybdenum or a molybdenum alloy (30) and, together with the inner surface (31) of the liner (30), forms a consistent cylindrical surface.
8. Filling chamber (1) according to any one of claims 1 to 7, characterized in that, at the inner end of the insert (10), the metal casing (20) has, on the end face thereof, a retaining ring (25) which fixes the liner made of molybdenum or a molybdenum alloy (30) in position.
9. Filling chamber (1) according to any of claims 1 to 8, characterized in that the inner surface of the removable insert (10) forms only some of the sliding surface for the piston in the region of the supply opening (3) of the filling chamber (1).
10. 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 inward of the supply opening (3).

Images