Core box for manufacturing casting cores

Abstract

The invention relates to a core box for manufacturing casting cores from a moulding material rigidified by supply of heat, including at least two core box parts, which together provide the shape of the casting cores to be manufactured and a heating device for heating the core box parts. The heating device has at least one oil line in thermal contact with at least one of the core box parts and connected to an oil supply feeding the oil line with a tempered oil for heating the core box parts. The invention divides at least one of the core box parts into a contour plate, providing the shape of the casting cores to be manufactured, and a heating plate connected to the contour plate, said heating plate extending flat over the contour plate and in which the oil line is provided.

Claims

1. A core box for manufacturing casting cores from a moulding material rigidified by a supply of heat, comprising at least two core box parts, which together provide the shape of the casting cores to be manufactured, wherein at least one of the core box parts is divided into a contour plate providing the shape of the casting core to be manufactured and a heating plate coupled to the contour plate which extends flat over the contour plate, wherein an open groove is moulded into the material of the heating plate on a side of the heating plate which extends parallel to the associated contour plate and the open groove together with the contour plate defines at least one oil line which is connected to an oil supply which feeds the oil line with a tempered oil for heating the at least one of the core box parts, and wherein the at least one oil line is guided in a plurality of coils such that temperature-critical regions of the contour plate are covered by the at least one oil line and the at least one oil line avoids venting nozzles extending through the contour plate.

2. The core box according to claim 1, wherein the heating plate consists of a thermally conductive material.

3. The core box according to claim 2, wherein a sealing plate is located on the side of the heating plate into which the groove is moulded.

4. The core box according to claim 3, wherein the sealing plate consists of a thermally conductive material.

5. The core box according to claim 4, wherein at least one of the contour plate and the heating plate consist of a material having a conductivity of at least 40 W/(m*K).

6. The core box according to claim 2, wherein at least one of the contour plate and the heating plate consist of a material having a conductivity of at least 40 W/(m*K).

7. The core box according to claim 3, wherein at least one of the contour plate and the heating plate consist of a material having a conductivity of at least 40 W/(m*K).

8. The core box according to claim 1, wherein the groove is moulded into a side of the heating plate which is associated with the contour plate.

9. The core box according to claim 8, wherein a sealing plate is located on the side of the heating plate into which the groove is moulded.

10. The core box according to claim 9, wherein the sealing plate consists of a thermally conductive material.

11. The core box according to claim 10, wherein at least one of the contour plate and the heating plate consist of a material having a conductivity of at least 40 W/(m*K).

12. The core box according to claim 8, wherein at least one of the contour plate and the heating plate consist of a material having a conductivity of at least 40 W/(m*K).

13. The core box according to claim 9, wherein at least one of the contour plate and the heating plate consist of a material having a conductivity of at least 40 W/(m*K).

14. The core box according to claim 1, wherein a sealing plate is located on the side of the heating plate into which the groove is moulded.

15. The core box according to claim 14, wherein the sealing plate consists of a thermally conductive material.

16. The core box according to claim 15, wherein at least one of the contour plate, the heating plate and the sealing plate consist of a material having a conductivity of at least 40 W/(m*K).

17. The core box according to claim 1, wherein at least one of the contour plate and the heating plate consist of a material having a conductivity of at least 40 W/(m*K).

18. The core box according to claim 14, wherein at least one of the contour plate, the heating plate and the sealing plate consist of a material having a conductivity of at least 40 W/(m*K).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is explained further below with reference to a drawing showing an example embodiment. The figures thereof respectively schematically show:

(2) FIG. 1 a core box in a longitudinal section;

(3) FIG. 2 a contour plate of the core box according to FIG. 1 in a top view;

(4) FIG. 3 a heating plate of the core box according to FIG. 1 in a top view; and

(5) FIG. 4 a core box part of the core box according to FIG. 1 in a lateral view.

DETAILED DESCRIPTION OF THE INVENTION

(6) The core box 1 comprises an upper core box part 2 and a lower core box part 3.

(7) The upper core box part 2 is composed of a contour plate 4, which bears contour-defining moulding elements 5, 6 on the side thereof associated with the lower core box part 3, a sealing plate 7 located on the contour plate 4, a heating plate 8 situated on the sealing plate 7 and a shooting plate 9 supported thereon.

(8) The shooting plate 9 is coupled via coupling elements to the contour plate 4 in a manner known per se by means of mortise joints 10, 11 and aligned in this regard such that the shooting funnel 12 of the shooting plate 9 sits perfectly into the associated shooting openings 13, which are moulded in a vertical direction flush to each other into the contour plate 4, the sealing plate 7 and the heating plate 8.

(9) In order to ensure a correctly-positioned coupling to the lower core box part 3, pins 14 pointing in the direction of the lower core box part 3 are fixed in the edge region of the contour plate 4, said pins engaging into correspondingly formed depressions when the upper core box part 2 lowers, said depressions being moulded in the edge region of the upper side of the lower core box part 3 associated with the upper core box part 2.

(10) The lower core box part 3 comprises a base frame 15, which bears a contour plate 16 of the lower box part 3 on the side thereof associated with the upper core box part 2. The contour plate 16 bears contour-defining moulding elements 17, 18 on the free side thereof associated with the upper core box part 2.

(11) In the case of a closed core box 1, i.e. in the state in which the upper core box 2 sits on the lower core box 3, the contour plates 4, 16 enclose a mould cavity in which a plurality of cores, for example the cores for the inlet channel, the outlet channel, the water jacket, the lid and the oil chamber of a cylinder head for a combustion motor can be simultaneously shot. The shapes of the cores are, in this regard, determined by the moulding elements 5, 6, 17, 18, of which only two moulding elements 5, 6 are shown in FIG. 2 for the sake of clarity for the contour plate 4 of the upper core box part 2. Assembly openings 19 provided on the contour plate 4, 16 allow for the fixing of the most varied of moulding elements such that different casting core programmes can be produced by means of the core box 1.

(12) Conventionally designed slotted nozzles 20, 21 are respectively arranged in the upper and lower core box part 2, 3, said slotted nozzles reach, in the case of the upper core box part 2, from the upper side thereof to the side of the contour plate 4 associated with the lower core box part 3 and, in the case of the lower core box part 3, from the lower side thereof to the side of the contour plate 16 associated with the upper box part 2. In this way, gases present or forming in the mould cavity then surrounded by the contour plates 4, 16 can escape via the slotted nozzles in the case of a closed core box 1.

(13) The contour plate 16 sits over a sealing plate 22 on a heating plate 23 of the lower core box part 3. The packet formed by contour plate 16, sealing plate 22 and heating plate 23 sits in a seating of the base frame 15.

(14) An ejector plate 24 is arranged below it, which bears ejectors 25 pointing in the direction of the contour plate 16. The ejectors 25 engage through through-openings moulded into the lower contour plate 16. After curing the casting cores formed in the core box 1, the ejector plate 24 is raised in the direction of the contour plate 16 in the case of the open core box 1 such that the ejectors 25 raise the completed casting cores from the moulded parts 17, 18. The completed casting cores can then be freely removed from the core box 1.

(15) While the contour plates 4, 16 having the moulded elements 5, 6, 17, 18 borne thereby respectively consist of a high-value, wear and temperature-resistant tool steel, the heating plates 8, 23 respectively consist of an aluminium material. Alternatively, they can also consist of a conventional unalloyed structural steel, such as for example the steel with the material number 1.0050.

(16) In the side 26, associated with the contour plate 4, of the heating plate 8 of the upper core box 2 depicted in FIG. 3, an oil line 27 is milled in the shape of a channel open to the side concerned. The oil line 27 is, in this regard, guided in a plurality of coils via the side 26 such that on the one hand all the temperature-critical regions of the contour plate 4 in the core shooting operation are covered, on the other hand however the regions through which the slotted nozzles 20, 21 are guided are also avoided. The inflow 28 and the outflow 29 are connected to an oil supply not depicted here, which conducts heated oil through the oil line 27 in the circuit at the required temperature.

(17) An oil line 30 is moulded into the heating plate 23 in a corresponding manner.

(18) The sealing plates 7, 22 also consist of a highly temperature-conductive material such as an Al material or a suitable steel such that the heat carried along by the flowing, hot oil through the oil line 27, 30 is transferred approximately free of losses to the respective contour plate 4, 16.

(19) 24 kg of quartz sand is mixed in a mixer with 2.2% of an inorganic binder and 0.9% of a powder additive added to improve the flow properties for manufacturing the already mentioned cores in the core box 1. To this end, the sand is firstly provided with the powder additive and then the liquid binder component is added while the mixer is running.

(20) After a mixing time of approx. 30 s, the material mixture thus obtained is transferred into a storage tank of a conventionally constructed core shooter, but equipped with the core box 1.

(21) The contour plates 4, 16 and the moulding elements 5, 6, 17, 18 are pre-heated by the heating plates 8, 23 to a temperature of 130 C. The material mixture is then shot into the mould cavity of the closed core box 1 by means of 5 bar applied pressure and remains there for 32 s.

(22) In order to accelerate the curing, 2 s after the injecting, hot air is directed through the core box 1 with a pressure of 3.5 bar and a temperature of 160 C. for 30 s upon entering the tool.

(23) After the curing time has concluded, the core box 1 is opened and the ejectors 25 are actuated. The fully cured cores can now be removed.

(24) Practical tests carried out in the previously described manner have shown that in the case of the core box 1 according to the invention slotted nozzles can be introduced at any positions for optimising ventilation. Even in the case of using oil heating for heating the core box 1, the invention thus allows the contour plates thereof 4, 16 and the moulding elements 5, 6, 17, 18 borne thereby to be configured just as freely as is customary for core boxes which are used for so-called cold box methods, in which no heating is required, but rather in the case of which the curing takes place by a chemical reaction as a result of gassing with a reaction gas.

(25) The freedom of shaping provided by the invention provides the possibility here of introducing additional slotted nozzles in the condensation areas, determined by the experiments and critical for the removal of the moisture, of the cores produced in the core box 1. By optimising the ventilation for the core boxes, the hot air rinse time could be reduced after the first optimisation loop and the cycle time thus reduced by 5 s.

LIST OF REFERENCE NUMERALS

(26) 1 Core box 2 Upper core box part 3 Lower core box part 4 Contour plate of the upper core box part 2 5,6 Contour-defining moulding elements of the upper core box part 2 7 Sealing plate of the upper core box part 2 8 Heating plate of the upper core box part 2 9 Shooting plate of the upper core box part 2 10,11 Mortise joints 12 Shooting funnel of the shooting plate 9 13 Shooting openings 14 Pins 15 Base frame of the lower core box part 3 16 Contour plate of the lower core box part 3 17,18 Contour-defining moulding elements of the lower core box part 3 19 Assembly openings 20 Slotted nozzles 21 Slotted nozzles 22 Sealing plate of the lower core box part 3 23 Heating plate of the lower core box part 3 24 Ejector plate 25 Ejectors 26 Side of the heating plate 8 associated with the contour plate 4 27 Oil line of the heating plate 8 28 Inflow of the oil line 27 29 Outflow of the oil line 27 30 Oil line of the heating plate 23