Abstract
A venting device for venting a casting mold in the form of a chill vent having two mold halves which oppose each other and are complementary to each other in form and function, each mold half having a plurality of elevations and indentations in the areas facing each other and the elevations of one mold half engaging with the indentations of the second mold half, and a gap being formed between the two mold halves when the mold halves are placed on each other, air and surplus molten material flowing out through said gap when the casting mold is being filled, the gap having, in the flow direction of the molten material, a saw-toothed course having several sawtooth portions disposed in a row in the flow direction, each sawtooth portion having a leading edge inclined in the flow direction and a trailing edge inclined against the flow direction.
Claims
1. A venting device for venting a casting mold in the form of a chill vent having two mold halves which oppose each other and are complementary to each other in form and function, each mold half having a plurality of elevations and indentations in their areas facing each other and the elevations of one mold half engaging with the indentations of the second mold half, and a gap being formed between the two mold halves when the mold halves are placed on each other, air and surplus molten material flowing out through said gap when the casting mold is being filled, wherein the gap has, in the flow direction of the molten material, a saw-toothed course having several sawtooth portions disposed in a row in the flow direction, each sawtooth portion having a leading edge inclined in the flow direction and a trailing edge inclined against the flow direction, and wherein the sawtooth portions are disposed in a row along an arc.
2. The venting device according to claim 1, wherein the leading edges of the sawtooth portions are inclined with an inclination angle (α), which is smaller than a self-locking angle of the material pair composed of a solidified material in the gap and the material of the mold halves, with respect to a mold parting line of the two mold halves.
3. The venting device according to claim 1, wherein an inclination angle (α) of the leading edges of the sawtooth portions is smaller than or equal to 45 degrees.
4. The venting device according to claim 3, wherein the inclination angle (α) of the leading edges of the sawtooth portions is smaller than or equal to 35 degrees.
5. The venting device according to claim 1, wherein an inclination angle (α) of the leading edges of all sawtooth portions is of the same size.
6. The venting device according to claim 1, wherein the trailing edges of the sawtooth portions are inclined with an inclination angle (β), which is greater than 70 degrees, with respect to a mold parting line of the two mold halves.
7. The venting device according to claim 6, wherein the inclination angle (β) of the trailing edges of the sawtooth portions is between 80 degrees and 90 degrees.
8. The venting device according to claim 1, wherein an inclination angle (β) of the trailing edges of all sawtooth portions is of the same size.
9. The venting device according to claim 1, wherein one mold half of the venting device is driven linearly parallel to a mold parting line of the two mold halves.
Description
(1) An embodiment of the disclosure is schematically illustrated in the drawings and is exemplified below.
(2) FIG. 1 shows a perspective lateral view of a venting device according to the disclosure;
(3) FIG. 2 shows a longitudinal section of the venting device according to FIG. 1 before it is filled with molten material;
(4) FIG. 3 shows the venting device according to FIG. 1 after it has been filled with molten material;
(5) FIG. 4 shows the venting device according to FIG. 3 after the two mold halves have been opened;
(6) FIG. 5 shows the upper mold half of the venting device according to FIG. 4 after the venting device has been opened;
(7) FIG. 6 shows the upper mold half of the venting device according to FIG. 5 after a slide has started to move outward;
(8) FIG. 7 shows the upper mold half of the venting device according to FIG. 6 at the end of the outward movement of the slide;
(9) FIG. 8 shows a cast part having two sprues, each of which has been produced by means of a venting device according to FIG. 1.
(10) FIG. 1 shows a venting device 01 having an upper mold half 02 and a lower mold half 03. The two mold halves 02 and 03 can be put together in a mold parting line 04, elevations and indentations in the two mold halves 02 and 03 forming a gap 05. If the venting device 01 is filled with molten material through a channel 06, the air present in the gap 05 can escape out of the venting device 01 through a channel 07. After that, the gap 05 fills with the molten material which solidifies there and closes the venting device 01 in this manner.
(11) FIG. 2 shows the venting device 01 having the two mold halves 02 and 03 after said mold halves 02 and 03 have been installed in the mold halves 08 and 09 of a casting mold, which are only partially illustrated. It can be seen that the gap 05 has a saw-toothed course which is formed by several sawtooth portions 10 disposed in a row in the flow direction. Each sawtooth portion 10 has a leading edge 11 and a trailing edge 12. The leading edges 11 are inclined with an inclination angle (α) in the flow direction. The trailing edges 12 are inclined with an inclination angle (β) against the flow direction.
(12) In the venting device 01 the inclination angle (α) is 34 degrees. This inclination angle of 34 degrees, thus, is smaller than the self-locking angle of the material pair composed of the material to be processed in the venting device 01 and the material which is used for producing the two mold halves 02 and 03. Furthermore, it can be seen in FIG. 2 that the inclination angles (α) and (β) are of the same size at all sawtooth portions 10, that is all sawtooth portions 10 have an inclination angle (α) of 30 degrees and an inclination angle (β) of 80 degrees. In order to be able to dispose as many sawtooth portions 10 as possible along the gap 05 within the venting device 01, the sawtooth portions 10 are disposed along an arc 13 which is hinted at in FIG. 2 with a dashed line. Furthermore, by means of the arc-shaped arrangement of the sawtooth portions 10, an easier demolding is achieved since there is pressure on all edges only in the first moment of the demolding. After only a short movement of the slide, the solidified molten mass starts to move out/bend out of the mold in such a manner that fewer and fewer sawtooth portions 10 are in mesh. The large sawtooth portion 10 at the very front bears the main load. Thereby, the friction is reduced and, thus, the resistance which counteracts demolding is reduced.
(13) FIG. 3 shows the venting device 01 after the casting mold formed by the mold halves 08 and 09 has been filled with a molten material 14. By the solidification of the molten material 14, a sprue 15 is produced within the venting device 01. Due to the design of the gap 05, the sprue 15 receives a saw-toothed course having several sawtooth portions 10.
(14) FIG. 4 shows the venting device 01 after the casting mold formed by the mold halves 08 and 09 has been opened. The sprue 15 remains in the upper mold half 02 as soon as the lower mold half 03 together with the mold half 09 of the casting mold has been opened.
(15) FIG. 5 shows the sprue 15 after the lower mold half 03 has been removed. In the embodiment shown in FIGS. 1 to 7, it is provided that the upper half 02 of the venting device 01 can be moved parallel to the mold parting line 04 of the two mold halves 02 and 03 and, thus, forms a slide in the casting mold formed by the mold halves 08 and 09.
(16) FIG. 6 shows the upper mold half 02 after it has partly been moved out of the mold half 08 parallel to the mold parting line 04 in the direction of the arrow 16. The saw-toothed course of the sprue 15 guarantees that the sprue 15 is pressed out of the mold half 02 transversely to the gap 05 when the upper mold half 02 is moved with respect to the mold half 08. For this, an additional ejector is not necessary. Rather, the ejecting movement is realized by the geometry of the gap 05 and the geometry of the sprue 15 produced thereby.
(17) FIG. 7 shows the sprue 15 after it has been essentially completely demolded from the upper mold half 02. After that, the workpiece together with the sprue 15 can be demolded and can be further processed.
(18) FIG. 8 exemplarily shows a workpiece 17 which has been produced in a casting mold having two venting devices 01. After the demolding of the workpiece 17, two sprues 15 having an arcuate saw-toothed course have formed at the end of the casting channels, said sprues 15 having to be cut off before the workpiece 17 is further processed.
