EP3810357B1 - Device and method for removing at least one cooling element from an at least partially demoulded cast part, method for introducing at least one cooling element into a mould core of a cast part mould, cooling element and cast part - Google Patents

Description

The invention relates to a device for removing at least one cooling element from an at least partially demolded cast part, in particular from a cast housing formed from a light metal alloy for an electric motor, which has a device for removing the at least one cooling element. The invention also relates to a method for removing at least one cooling element from an at least partially demolded casting, a method for introducing at least one cooling element into a mold core of a casting mold, a cooling element and a casting.

Out DE 10 2006 006 132 A1 an assembly method for a casting mold formed from sand cores is known, in which metal inserts are introduced into the casting mold by means of a magnet and outer sides of the metal inserts form contact surfaces with a molten metal.

Out DE 10 2006 053 404 A1 a multi-part casting mold formed from sand cores is known in which a hollow cylindrical cooling mold is seated on one of the sand cores. Outer sides of the mold are in contact with a molten metal during the production of the cast part.

Another mold, which is provided with cooling elements, is off DE 10 2014 101 080 B3 known.

Out US 2014/319956 A1 a casting method for producing a rotor for an electric motor is known, in which cooling irons can be used.

It is also known from the prior art to introduce so-called cooling irons made of gray cast iron or a free-cutting steel into a casting mold. As a result, there is an improvement in particular during the solidification in an effective area of the cooling iron mechanical properties and a reduction in porosity in the casting achieved. After at least partial demolding, in particular partial desanding, the cooling irons adhering to the cast part can be manually removed or removed and used again.

The present invention is based on the object of creating a device of the type mentioned at the outset which enables the at least one cooling element to be removed automatically.

According to the invention, this object is achieved in that the removal device comprises a means for gripping a removal projection attached to the at least one cooling element. The removal device is preferably designed to be movable in order to remove the at least one cooling element from a cast part arranged in a stationary manner. It is also conceivable that a removal device is arranged in a stationary manner and a cast part for removing the cooling element is moved relative to a removal device. A manual removal of the cooling elements is advantageously not necessary. Furthermore, centering can advantageously be brought about by the removal device, which allows the at least one removed cooling element to be positioned in the same way at all times. This enables automated storage in a storage pallet for reuse.

Particularly in the production of cast parts that are made of a light metal alloy, preferably an aluminum or magnesium alloy and are provided as a housing for an electric motor, special properties such as low porosity are found in areas that are used to accommodate a stator or a stator carrier and / or high strength is required. In order to enable a compact housing and reliable cooling during engine operation, the housing must have particularly low porosity, especially in the area of cooling ducts, in order to avoid loss of coolant. In order to meet these requirements, it is necessary to introduce at least one cooling element into a mold core, which can be a sand or salt core, for example, into a casting mold with which a casting is produced. The casting mold can be a permanent mold such as a permanent mold or a sand mold intended for one-time use.

The removal projection is formed in one piece on the cooling element, connected to it in a materially bonded manner, or can be detachably connected to the cooling element. A particularly simple exchange of a removal projection is advantageously possible through a releasable connection. Any maintenance and / or repair work required is reduced. The cooling element is preferably made of gray cast iron or a steel, in particular a free-cutting steel.

It is also conceivable that a cooling element has several removal projections. Should one of the removal projections be damaged, another can advantageously be used to remove the cooling element from the cast part. An immediate exchange is not necessary.

A one-piece molding advantageously enables simple production, while a material connection enables a damaged removal projection to be replaced or repaired by welding and soldering.

The gripping means expediently comprises at least one pair of rails which are spaced apart from one another and which are designed to grip behind the removal projection. The removal projection can advantageously be gripped by a pair of rails in such a way that only removal forces are transmitted which preferably act perpendicularly or almost perpendicularly to a longitudinal direction of the rails. A transmission of transverse forces or bending moments, for example, which could damage the projection or the rails, is advantageously avoided.

In one embodiment of the invention, the removal projection of the at least one cooling element comprises at least a pair of spaced apart rails which are designed to be gripped from behind by the gripping means. The removal device is advantageously structurally simplified and thereby enables longer service lives.

In one embodiment of the invention, the gripping means has several pairs of rails which are arranged next to one another in the circumferential direction of a rotationally symmetrical, preferably cylindrical or frustoconical removal head and in particular extend parallel or obliquely to its longitudinal axis. Can be beneficial several cooling elements can be removed at the same time in a single work step and centered when they are removed by the removal head. The cooling elements are introduced into a rotationally symmetrical, preferably cylindrical or frustoconical mold core of a casting mold, which forms a cavity for receiving the rotor or a rotor carrier of the electric motor.

If several cooling elements are provided, which preferably form flush surface sections of a mold core and are in contact with a melt when a casting mold is being filled, each has a surface whose outer contour is almost identical to a functional inner contour section of a cavity of a casting from which the cooling element can be removed . A near net shape production of a cast part is advantageously possible.

A particularly good fixation of the cooling elements in the mold core as well as their particularly good graspability when removing from the casting are achieved if a removal projection is arranged on a side of a cooling element that faces away from a side that is in contact with the when filling a casting mold Melt is. As a result, the removal projection can on the one hand form a latching connection with the mold core and can also be gripped by the gripping means.

A mold core that is particularly suitable for the method according to the invention can be designed in one piece or in several parts, in particular in two parts. There is advantageously a particularly high degree of design freedom.

So that the at least one cooling element can be introduced into the mold core in such a way that a plurality of surface sections are formed, at least one of which is formed by an outside of the cooling element, it can be inserted into a mold core production tool before molding sand is introduced. A stationary arrangement in the mold core production tool can be brought about by the removal projection, which for this purpose engages in a holding device in the tool. As a result, the fixed arrangement is ensured even when the molding sand is shot into the tool under pressure. The removal projection advantageously acts for fixation in the mold core production tool and as a counter holder for a gripping means of a Device for removing at least one cooling element from an at least partially sanded cast part.

By arranging the rails parallel or obliquely to the longitudinal axis of the rotationally symmetrical removal head, each pair of rails can engage behind an associated removal projection when the removal head moves in a straight line into the cavity. Several cooling elements can advantageously be removed in one work step. The cooling elements are also advantageously centered when they are removed. As a result, it is possible, in particular, to automatically insert it into a cooling iron storage pallet and to re-feed it for core production. A fully automated manufacturing process without manual intervention is possible.

In one embodiment of the invention, each of the rails can be detachably connected to a rotationally symmetrical, preferably cylindrical or frustoconical removal head of the removal device or to the at least one cooling element. Damaged rails are advantageously easy to replace. Maintenance and / or repair work is reduced.

In a further embodiment of the invention, a diameter of a frustoconical removal head of the removal device increases in a direction in which the removal head can be moved into a casting cavity for removing cooling elements, and which is preferably coaxial with a longitudinal direction of the removal head. This enlargement causes the formation of a draft angle, which ensures that the forces required to remove cooling elements from a cast part are applied in a linearly increasing manner. Voltage peaks that could damage the removal head are advantageously avoided.

So that voltage peaks can be reduced further, a removal projection of a cooling element has a T-shaped cross section and preferably extends in a longitudinal direction of the cooling iron. T-legs can advantageously be gripped or gripped from behind by the gripping means, in particular by a pair of rails, in such a way that no transverse forces or bending moments occur that could damage the removal projection.

If the thickness of the T-legs increases, preferably linearly, from a first end to a second end, in particular in the longitudinal direction of a cooling element, a linear movement of a removal head or that of the cast part relative to a stationary removal head with a gripping means that a Has a pair of rails for engaging behind the T-legs, are converted into a movement of the cooling elements with a movement component perpendicular to the direction of movement of the removal head. A detachment of cooling elements from the cast part is advantageously effected. A linear movement of the cast part or of the removal head can also advantageously be converted into a movement of the at least one cooling element in a different direction. The rails, which are preferably flat and have a constant thickness, slide along the T-legs for this purpose.

If the removal head also has a draft angle, for example between 2 and 5 degrees, preferably 4 degrees, a particularly short path is required in combination with T-legs of varying thickness during a removal movement in order to apply a sufficiently high force to the at least one cooling element to be released from the casting, to be centered and finally to be taken along for removal from a casting cavity.

By using at least one cooling element, a cast part wall section is formed in a cast part which, during casting production, rests with one side against the at least one cooling element and which has a secondary dendrite arm spacing between 3 and 30 μm, preferably between 15 and 25 μm. A particularly high strength with low porosity is advantageously achieved. A low porosity is particularly necessary when the cast part wall section delimits a cooling channel in which a liquid cooling medium is guided during engine operation.

If a cast part comprises a groove which is provided for receiving a sealing ring, pores have a maximum diameter of 0.9 mm, preferably between 0.5 and 0.8 mm. A particularly dense cast part can advantageously be produced. Loss of coolant during engine operation is prevented.

Fig. 1

eine erfindungsgemäße Entnahmevorrichtung in mehreren Ansichten,

Fig. 2

ein erfindungsgemäßes Kühlelement in verschiedenen Ansichten,

Fig. 3

eine erfindungsgemäße Entnahmevorrichtung bei einer Entnahme von Kühlelementen aus einem Gussteil,

Fig. 4

ein mit erfindungsgemäßen Kühlelementen versehener zweiteiliger Formkern,

Fig. 5

ein mit erfindungsgemäßen Kühlelementen versehener einteiliger Formkern sowie ein zugehöriges Formkernherstellungswerkzeug.

The invention is explained in more detail below with reference to exemplary embodiments and the accompanying drawings relating to the exemplary embodiments. Show it:

Fig. 1

a removal device according to the invention in several views,

Fig. 2

a cooling element according to the invention in different views,

Fig. 3

a removal device according to the invention when removing cooling elements from a cast part,

Fig. 4

a two-part mold core provided with cooling elements according to the invention,

Fig. 5

a one-piece mold core provided with cooling elements according to the invention and an associated mold core production tool.

One in Fig. 1a Device (1) shown in a perspective illustration for removing eight identical metallic cooling irons (2) arranged in a circle next to one another from an in Fig. 1a Cast part, not shown, comprises a frustoconical, in Figures 1c-e The removal head (3) shown in detail, in the in Fig. 1a + b, eight longitudinal grooves (4) shown are introduced, in which a removal projection (5), which is T-shaped in cross-section and is integrally formed on the cooling iron (2), is attached to the side (6) of the cooling iron (2) facing the removal device (1) ) protrudes, is guided.

The removal device (1) comprises rails (8, 9) of constant thickness, which extend in the longitudinal direction of the removal head (3) and are formed from hardened steel ) are releasably connected. It is also conceivable that the rails (8, 9) have a varying thickness in their longitudinal direction.

The rails (8, 9) are tapered at both ends and are intended to support the removal projections (5) as in FIG Figure 1b shown in a plan view to reach behind from two opposite sides.

To remove the cooling irons (2), the removal head (3) of the removal device (1) is moved in the direction of an in Fig. 1a arrow (11) shown is moved parallel to its longitudinal axis into the casting, whereby a movement of the cooling iron (2) in the direction of in Figure 1b arrows (12) shown by way of example. This will remove the chill irons (2) from an in Fig. 3 The cast part shown is loosened, centered and can be removed in the same work step.

An extraction device (1) is shown in detail in Figure 1c in a perspective view as well as in Fig. 1d shown in an exploded view.

With an in Fig. 1e In the frustoconical removal device (1) shown in a side view, a surface line (13) inclined by 4 degrees with respect to the cone axis can be clearly seen. This forms a draft angle.

It is now on Fig. 2 Reference is made where the same or equivalent parts have the same reference numbers as in Fig. 1 and the letter a is attached to the relevant reference number.

An in Fig. 2a The cooling iron (2a) shown in a perspective top view of an outer side has a curved surface (14), the outer contour of which is almost identical to a functional inner contour section of an in Fig. 3 with (23) designated cavity of a cast part (22) from which a cooling element (2a) can be removed. The surface (14) is also intended to come into contact with a molten metal with which a casting mold is filled. This results in a particularly good casting quality, in particular high strength and low porosity in a casting area adjoining the cooling iron (2a). This can for example extend up to 25 mm away from the cooling iron (2a) and have a porosity with pores with a Feret diameter of a maximum of 0.8 mm.

A first projection (16) is integrally formed on a first end face (15), while two further projections (18, 19) are integrally formed on a second end face (17). The projections (16, 19) are intended to be gripped from behind by a mold core into which the cooling iron (2b) is inserted. This achieves both a fixation in the mold core and a flush termination of a surface of the mold core with the curved surface (14) of the cooling iron (2a).

An in Figure 2b The cooling iron (2a) shown in a perspective view of an inside comprises a removal projection (5a) which has a T-shaped cross section and extends in the longitudinal direction of the cooling iron (2a). A thickness of T-legs (7a) increases linearly from a first end (20) to a second end (21). This creates an inclined plane along the in Fig. 1 rails shown and designated (8, 9) during an insertion movement of a in Fig. 2 Removal device, not shown, slide in the direction of an arrow (11a). As a result, a linear movement of the removal device is converted into a movement of the cooling irons (2a) with a radial directional component away from the cast part in the direction of in Figure 1b with (12) indicated arrows causes.

It is now on Fig. 3 Reference is made where the same or equivalent parts have the same reference numbers as in Fig. 1 and 2 and the letter b is added to the relevant reference number.

An in Fig. 3a Shown in a plan view, formed from an aluminum alloy housing (22) for an electric motor comprises a frustoconical cavity (23) with a surface line inclined by 1 degree with respect to the cone axis, which is intended to accommodate an in Fig. 3 not shown stator or a stator of the electric motor is provided.

A removal device (1b) for cooling irons (2b) is inserted into the cavity (23), the rails (8b, 9b) of which engage behind T-shaped removal projections (5b) of the cooling irons (2b) and which in Fig. 3a is in an initial position in which no extraction forces act on the cooling iron (2b). Each cooling iron (2a) lies and adheres with an in Figures 2a and b with (14) designated surface against an associated cast part wall section (24).

When the removal device (1b) moves linearly into the cavity (23), the rails (8b, 9b) slide along an in Fig. 2 shown inclined plane of the removal projections (5d), whereby a movement of the chill irons (2b) away from the casting wall portion (24) against which they abut and adhere, with a movement component in a radial direction of the cavity (23) is effected. In an in Figure 3b The end position shown, the cooling irons (2b) are separated from the cast part (22). A gap (25) is formed between the cooling iron (2b) and the associated cast part wall section (24). In this position, the cooling irons (2b) are held by the removal device (1b) and can be taken out of the cavity (23) by a direction of movement opposite to an insertion direction.

The regular arrangement of the rails (8b, 9b) and the movement of the removal device (1b) into an end position also cause the cooling irons (2b) to be centered, which enables automated insertion into an in Fig. 3 not shown cooling iron storage pallet is possible.

It is also conceivable that the removal device (1b) is inserted into the cavity on a first side and emerges from the cavity (23) on a side facing away from the first side and takes the cooling iron (2b) with it. This advantageously prevents individual cooling irons (2b) from getting stuck when they are moved out in a direction of movement opposite to the insertion direction and from causing a standstill in an automated removal process.

It is now on Fig. 4 Reference is made where the same or equivalent parts have the same reference numbers as in Figs. 1 to 3 and the letter c is added to the relevant reference number.

An in Figure 4a The two-part, frustoconical sand core (26) shown in an exploded view and formed from a molding sand has two sand core parts (27, 28) which can be connected to one another and which can be connected to one another by a plug-in and adhesive connection by a ring-like projection (29) of a first mold core part ( 27) into an in Fig. 4 not shown, an adhesive having groove is inserted.

Several material recesses (30) are set up to accommodate cooling irons (2c) in the sand core (26), T-legs (7c) of a removal projection (5c) being gripped from behind by two sand webs (31). While an in Figure 4c The projection (16c) of the cooling iron (2c) shown is intended to be inserted into a pocket (32) in the sand core part (27), a further projection (19c) engages in a pocket (33) in the sand core part (28) .

In an in Figure 4b A total of eight cooling irons (2c) are introduced into the assembled sand core (26) shown in a perspective view. The surfaces of sand bars (34) are flush with the cooling iron surfaces (14c) and form a flat overall surface, which is intended to be in contact with a molten metal with which the casting mold is filled when a casting mold is being filled. A cast part produced with such a core is manufactured near net shape.

With an in Figure 4c The composite, two-part sand core (26) shown in the longitudinal section engage behind T-legs (7c) of retaining projections (5c) sand webs (31) of a sand core part (27).

It is now on Fig. 5 Reference is made where the same or equivalent parts have the same reference numbers as in Figs. 1 to 4 and the letter d is added to the relevant reference number.

An in Figure 5a in a perspective view and in Figure 5b The sand core (35) shown in a partially sectioned side view is formed in one piece. Cooling irons (2d) are used in an in Figure 5c Mold core production tool (36) shown in a sectional side view is introduced and shot in during core production, that is to say, hardenable molding sand flows around it until the mold is completely filled.

The mold core production tool (36) comprises an upper part (37) and a lower part (38) which enclose a space in which molding sand and cooling irons (2d) can be introduced for core production and which can be moved relative to one another in order to remove a produced mold core be able.

A top (14d) of the chill iron (2d) rests against a mold wall surface (39).

Furthermore, retaining recesses (40) are provided, into which retaining projections (5d) of the cooling irons (2d) engage, whereby a stationary arrangement in the mold core production tool (36) is ensured.

Although in the exemplary embodiments a removal device (1; 1b) with a movable removal head (3; 3b), which was shown for removing cooling elements (2-2d from a fixedly arranged cast part (22)), it is conceivable that the removal head (3; 3b) is arranged in a stationary manner and the cast part (22) can be moved to remove the cooling elements.

Claims (15)

1. Device for removing at least one cooling element (2-2d) from an at least partially demoulded cast part (22), in particular from a housing (22) for an electric motor formed from a light metal alloy, which has an apparatus (1; 1b) for removing the at least one cooling element (2-2d), characterised in that the removal apparatus (1; 1b) comprises a means for gripping a removal protrusion (5-5d) attached to the at least one cooling element (2-2d).
2. Device according to claim 1, characterised in that the gripping means comprises at least one pair of rails (8, 9; 8b, 9b) spaced apart from one another, which are configured to engage behind the removal protrusion (5-5d).
3. Device according to claim 1, characterised in that the removal protrusion (5-5d) of the at least one cooling element (2-2d) comprises at least one pair of rails spaced apart from one another, which are configured for the gripping means to engage behind them.
4. Device according to claim 1 or 2, characterised in that the gripping means has a plurality of rail pairs (8, 9; 8b, 9b), which are arranged next to one another in the circumferential direction of a rotationally symmetrical, preferably cylindrical or truncated cone-shaped removal head (3; 3b) and extend in particular parallel or obliquely to the longitudinal axis thereof.
5. Device according to any one of claims 2 to 4, characterised in that each of the rails (8, 9; 8b, 9b) is detachably connectable to a rotationally symmetrical, preferably cylindrical or truncated cone-shaped removal head (3; 3b) of the removal apparatus (1; 1b) or to the at least one cooling element (2-2d).
6. Method for removing at least one cooling element (2-2d) from an at least partially demoulded cast part (22), characterised in that a removal apparatus (1; 1b) is introduced preferably parallel, coaxially or obliquely to a longitudinal axis into a rotationally symmetrical, preferably cylindrical or truncated cone-shaped hollow space (23) of the cast part (22), wherein at least one removal protrusion (5-5d) attached to the at least one cooling element (2-2d) is gripped by a gripping means (8, 9; 8b, 9b) of an apparatus (1; 1b) for removing the at least one cooling element (2-2d).
7. Method according to claim 6, characterised in that the at least one cooling element (2-2d) is also removed from the hollow space (23) in the case of a movement of the removal apparatus (1; 1b).
8. Method according to claim 6 or 7, characterised in that, through a movement of the removal apparatus (1; 1b) into the rotationally symmetrical hollow space (23), a movement of the at least one cooling element (2-2d) is effected in a direction (12) of the hollow space (23), which has a radial movement component (12).
9. Method for introducing at least one cooling element (2-2d) into a mould core of a cast part mould, which is provided for manufacturing a cast part (22), from which the at least one cooling element (2-2d) can be removed in the at least partially demoulded state, wherein the at least one cooling element (2-2d) is introduced into the mould core (26; 35) in such manner that a plurality of surface sections (14c, 34; 34d) are formed, which are provided for contact with a melt when filling the cast part mould, wherein at least one of the surface sections is formed by an outer side (14; 14c; 14d) of the at least one cooling element (2-2d), characterised in that the at least one cooling element (2-2d) is introduced into a mould core manufacturing mould (36) prior to introducing forming sand and is held stationary in the mould core manufacturing mould (36) while the forming sand is introduced.
10. Method for introducing at least one cooling element (2-2d) into a mould core of a cast part mould, which is provided for manufacturing a cast part (22), from which the at least one cooling element (2-2d) can be removed in the at least partially demoulded state, wherein the at least one cooling element (2-2d) is introduced into the mould core (26; 35) in such a manner that a plurality of surface sections (14c, 34; 34d) are formed, which are provided for contact with a melt when filling the cast part mould, wherein at least one of the surface sections is formed by an outer side (14;
    14c; 14d) of the at least one cooling element (2-2d), characterised in that the at least one cooling element (2-2d) is introduced into the mould core manufacturing mould (36) in such a manner that a side facing at least a removal protrusion (5-5d) abuts against a mould core manufacturing mould wall (39).
11. Cooling element (2-2d), which is provided to be introduced into a mould core (26, 35) of a cast part mould for manufacturing a cast part (22) formed from a light metal alloy, characterised in that a removal protrusion (5-5d), which is configured to be gripped by a gripping means (8, 9; 8b, 9b) of a removal apparatus (1; 1b) when removing the cooling element (2-2d) from an at least partially demoulded cast part (22), protrudes from a side facing a side in contact with a melt when filling the cast part mould.
12. Cooling element according to claim 11, characterised in that the removal protrusion (5-5d) has a T-shaped cross-section and preferably extends in a longitudinal direction of the cooling element (2-2d) or is formed in the manner of a rail.
13. Cooling element according to any one of claims 11 to 12, characterised in that the removal protrusion (5-5d) is formed in one piece, connected in a materially bonded manner to the cooling element (2-2d) or detachably connectable to the cooling element (2-2d).
14. Cooling element according to any one of claims 11 to 13, characterised in that a surface (14; 14c; 14d) is provided, the outer contour of which is virtually identical to a functional inner contour section of a hollow space (23) of a cast part (22) from which the cooling element (2-2d) is removable.
15. Cast part (22), in particular a cast part (22) formed from a light metal alloy, which has a rotationally symmetrical, preferably cylindrical or truncated cone-shaped hollow space (23) for receiving a component of an electric motor, which can be manufactured or is manufactured by way of a mould core (26, 35) provided with at least one cooling element (2-2d) according to any one of claims 11 to 14, wherein a cast part wall section (24) delimiting the hollow space (23), which abuts against the at least one cooling element (2-2d) with one side during the manufacture of the cast part, has a secondary dendrite arm spacing of between 3 and 30 µm, preferably of between 15 and 25 µm, characterised in that the cast part wall section (24) comprises a groove provided for receiving a sealing ring with a groove wall preferably protruding from the cast part wall section (24), said groove wall having pores with a Feret diameter of at most 0.9 mm, preferably between 0.5 and 0.8 mm.

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