DE4105080C1 - Centrifugal casting device with reduced alloy loss - has inductively heated crucible at an acute angle with horizontal centrifuging plane - Google Patents

Abstract

Centrifugal casting device has an inductively heated crucible (1), the wall of which forms an acute angle with the horizontal centrifuging plane (8E). Underneath its horizontal mounting plate (2), the crucible is assymetrical to the vertical centrifuging axis (5A). The acute angle between the front crucible wall (3) and the centrifuging device is 70 deg. or less. ADVANTAGE - Centrifuging time is shortened and alloy material loss is reduced.

Description

The invention relates to a centrifugal casting device an inductively heatable ceramic crucible that is used to create of investment castings is suitable and especially in the dental technology and jewelry industry should.

The known centrifugal casting devices can be describe as follows:

The crucibles for melting the alloys hang on one Centrifugal arm in a holding plate. Located under the crucible an induction coil. To heat the Alloy usually drives the coil over the lower one Part of the crucible. After melting, the coil lowered vertically downwards and the spinning process triggered. The one on the bottom of the crucible increases Melt by the centrifugal force on the crucible wall up and flows through the casting hole into the also mold attached to the centrifugal arm.

Such casting machines are for example from the Publications DE 29 32 681 C3 and US-PS 45 10 987 known. The crucibles used there are rotationally symmetrical designed and vertical, oblique or around a horizontal Axis tiltable on the horizontal sling arm in the Holding plate stored.

The centrifugal casters essentially have the following disadvantages:

• 1. The quality of the casting suffers from the relatively long spinning time. This is essentially determined by the viscosity of the melt, the achievable centrifugal force and the resistance determined by the crucible geometry and inner surface. (The melt must rise from the bottom to the spout opening).
  During the spin cycle, the melt already cools down, the viscosity increases, the mold filling capacity becomes poor, the casting precision drops.
• 2. The crucible stress is very high due to the high forces that the ejecting melt on the Crucible wall exercises. This makes the life of the crucible limited. Suitable crucible materials that last Withstand loads are not known.  
• 3. With each casting depends on the spinning speed Alloy material on the crucible wall. On Because of the high prices of the commonly used Precious metal alloys are not to be underestimated Costs for the operator.

The present invention is based on the object a centrifugal casting device of the type mentioned create, in which the ejection time is reduced and Crucible load and loss of alloy material reduced will.

The problem is solved by the in claim 1 Centrifugal casting device described.

The advantages achieved with the invention are above all in that the ceramic crucible because of the small Wear can be used more often than before that Little residual melt remains in the crucible, which is considerable Cost savings, and that by a accelerated casting time the quality of the castings (Precision, freedom from voids, homogeneity) increases.

In the dependent claims there are meaningful forms of ceramic crucible and the corresponding adjustment of the Induction coil and its direction of withdrawal in the invention Spinner described which the Quality of the castings and the life of the crucibles improve further.

Exemplary embodiments of the Invention shown. It shows

Fig. 1, the centrifugal casting apparatus with a cut shown crucible,

Fig. 2 shows another crucible, cut,

Fig another crucible cut. 3,

Fig. 4 is matched to the crucible of FIG. 3 induction coil,

Fig. 5 different views of induction coils for different crucible cross sections (circular, elliptical, asymmetrical).

In Fig. 1, the centrifugal casting device is shown with a ceramic crucible ( 1 ) which can be heated inductively. Its wall forms an acute angle (β) with the horizontal spin plane (SE). Below the holding plate ( 2 ), the crucible is designed asymmetrically to the vertical centrifuge axis (SA). The acute angle (β) between the front crucible wall ( 3 ) and the centrifugal direction is 70 ° or less.

The change in the crucible shape has the effect that the pulling direction (AR) of the coil ( 5 ), which in the previously known devices was perpendicular to the direction of the spin, is changed.

The bobbin is pulled off the crucible at an acute angle (minimum zero degrees) to the direction of the spin. This makes it possible to incline the back wall of the crucible at the same angle and thus to increase the volume of the alloy material ( FIG. 2).

The change in the shape of the crucible due to the asymmetrical design of the part lying below the holding plate has the effect that at least the part of the crucible wall which comes into contact with the melt forms an angle (β) of less than or equal to 70 degrees with the centrifuging direction. In the case of existing devices, the downward angle is limited by the fact that, given the coil size and a vertical crucible rear wall (opposite to the direction of ejection), the bottom surface ( 4 ) approaches zero ( FIG. 3).

The changes of the crucible mold of FIG. 5 require that the shape of the induction coil is better adapted. This is done by their circular, elliptical or asymmetrical cross section. The coils are no longer cylindrical here, but have the shape of a truncated cone or pyramid with a circular, elliptical or asymmetrical base. Some possible exemplary embodiments are outlined in FIGS. 4 and 5.

Reference symbol list

1 ceramic crucible
2 holding plate
3 front crucible wall
4 bottom surface of the crucible
5 induction coil
6 crucible longitudinal axis
7 fling arm
AR pulling direction of the induction coil
SA centrifugal axis
SR spin direction
SE spin level
β acute angle <= 70 ° between SR and 3

Claims (4)

1. Centrifugal casting device with an inductively heatable ceramic crucible, the wall of which forms an acute angle with the horizontal centrifuge plane, characterized in that the crucible ( 1 ) below its horizontal holding plate ( 2 ) is designed asymmetrically to the vertical centrifugal axis, such that at least the at Throwing out the crucible wall part ( 3 ) touched by the melt forms an acute angle β70 ° with the holding plate. 2. Centrifugal casting device according to claim 1, characterized characterized in that the crucible is cylindrical or conical Sidewalls with circular, elliptical or has asymmetrical cross sections. 3. Centrifugal casting device according to claim 1 or 2, characterized in that the bottom surface ( 4 ) of the crucible goes to zero. 4. Centrifugal casting device according to claim 1 or 2, characterized in that the induction coil ( 5 ) is adapted to the outer wall shape of the crucible and is removable in the direction of the longitudinal axis of the crucible ( 6 ).