Device for regulating the evacuation of air and gas from casting dies

Abstract: The present invention pertains to a device for regulating the evacuation of air and gas from a casting die. It comprises two complementary bodies (11, 12), which can be closed, face to face, one on top of another, and which delimit an evacuation channel (13), which is defined by a static surface (16) of the first of the said bodies (12) and by a movable surface (18) that is arranged in front of and in parallel to the static surface (16) and that consists of the front surface of a movable element (17), which is arranged in the second of the said bodies (11) and can be moved at right angles to the said static surface (16) in order to vertically adjust the section of the evacuation channel.

Description: The present invention pertains to devices for an evacuation of air and gas from the dies used in the casing of pieces. In the die-casting process, one of the most difficult problems to be solved is the correct and complete evacuation of air and gas from the die for forming the piece. The presence of air and gas is also due, among other things, to the effect of evaporation from cooling and/or of splashes on the surface during the phase of filling of the die. If they are not eliminated, the air and gas can remain included in the casting, compromising the structure and quality of the finished piece. Various systems for the evacuation of air and gas from casting dies which are connected to a suction apparatus or vacuum apparatus already exist on the market. These prior-art systems do not, however, have adjustability features; therefore, they do not have the versatility either to be adapted to the different conditions of operation that may be found in the casting process. In fact, in die-casting, the variables may be varied, linked with the velocity of the injection piston, with the state of wear and tear, with the passages of the gate section, with the thicknesses of the mold, which are not always uniform, with the temperatures of the lubricants, with the insistence times, and with the many other modifiable features, all of which together contribute to changing and requiring a specific response of evacuation of gaseous fluids over time and because of the amount. Therefore, the object of the present invention is to propose and to provide a device, which is improved and which can be readily and easily adjusted, even during use, to effectively regulate the evacuation of air and gas from the casting dies and therefore to efficiently solve the problems stated above of the prior art. Another object of the present invention is to produce a device for regulating the discharge of air and gas from the casting dies, which has high flexibility and adaptability, with a channel, whose section can be finely adjusted for a correct action of evacuation of air and gas and with the purpose of obtaining the most excellent productivity and quality results possible, which can, moreover, be verified by means of a test analysis of the finished pieces. Said objects are accomplished in accordance with the present invention with a device which comprises two complementary bodies which can be closed face to face one on top of another, which has, between said bodies, an evacuation channel, which is connected, on the one hand, to a casting die, and on the other hand, possibly to a vacuum gearcase, and where said channel has a section that can be adjusted, at least in the direction of its height, by means of a movement of an element that is movable in relation to a static surface with which it contributes to delimiting the said channel. This movable element is arranged between the two bodies of the device facing one another, and the fixed surface of the channel is that of one of the said bodies. The movable element can be moved at right angles to said fixed surface by means of a wedge-shaped member, which is moved by a drive shaft. Greater details of the present invention shall become more evident from the description that is provided below with reference to the attached indicative and nonlimiting drawings, in which: Figure 1 shows a longitudinal section of the device in its entirety; and Figure 2 shows a partial cross section of the device of Figure 1. The device under examination comprises two complementary bodies 11, 12, which can be closed one on top of another and which delimit between them an evacuation channel 13. One body 11, which is the top one in the drawings, is fixed and is joined to a fixed plane of a casting die (not shown). The other body 12 is movable and can be moved towards and away from the fixed body, and is joined to a movable plane of the said die. The said evacuation [sic, "avacuazione" is a typo for "evacuazione" - Tr.Ed.] channel 13 has a wavy, comb-like, or similar flow and extends from an inlet 14 which is connected according to the arrow E, to the mold for molding a piece in the die, to an outlet 15 which is connected, according to the arrow U , optionally to a vacuum gearcase (Figure 1). The channel 13, between the inlet 14 and the outlet 15, is delimited by a static surface 16, which, in the example shown, corresponds to the internal surface of the movable body 12, and by a movable element 17 having in its turn a front surface 18 in front of and with a flow parallel to the static surface 16. More specifically, the movable element 17 is arranged in a cavity 19, if need be, provided in the fixed body and it can be moved at right angles to the static surface 16 for vertically varying the section of the evacuation channel 13. For this movement, the movable element 17 has, on its face opposite the front surface 18, a longitudinal guide 20, e.g., dovetail or T-shaped, extending into a plane that is sloped with respect to the plane in which the evacuation channel lies. By means of said guide 20, the movable element 17 is joined to a longitudinally movable, wedge-shaped positioning member 21. This wedge-shaped member 21 has a sloped counterguide 22, which interacts with the guide 20 of the movable element 17 and a second guide 23 guided on slide gibs that are connected to the fixed body 11 in the cavity 19 and extend in parallel to the plane in which the evacuation channel lies. In this way, thanks to the sloped guides 20, 22, vertical movements of the movable element 17 with respect to the static surface 16 of the channel 13 and correspondingly the height variation of the section of the evacuation channel 13 correspond to the longitudinal horizontal movements of the wedge-shaped member 21 in one direction or the other along the slide gibs 24. For its longitudinal movements, a drive shaft 26 guided in the fixed body 11 and extending outside of same on one side, e.g., on the side of the outlet of the channel 13, which may or may not be connected to the vacuum gearcase, is connected to the wedge-shaped member 21 by means of a rotating coupling [sic, "accoppiaemnto" is a typo for "accoppiamento" - Tr.Ed.] 25. Said shaft 26 has an intermediate threaded portion 27, which is joined to a corresponding threaded hole 28 made in the said fixed body 11. The shaft may be rotated by any manual or non-manual pressing means, and thanks to this threaded coupling 27, 28, its axial translation and a corresponding longitudinal horizontal movement of the wedge-shaped member for the vertical adjustment, as needed and as stated above, of the section of the evacuation channel, corresponds to its rotation. Finally, reference signs 29 that are visible and are indicative of the position of the movable element 17 inside the device and correspondingly of the height of the evacuation channel 13 may be provided along the drive shaft 26. The air and gas coming from the die are evacuated by means of this channel, which may be adjusted depending on the conditions of the casting process, as well as during this process, especially while making adjustments to achieve the maximum balance between quality and the rest of the variables. However, molten metal may enter the channel, which, once it has solidified, forms an element that can then be extracted by opening the two bodies and with the possible aid of an extractor 30.

Claims: Device for regulating the evacuation of air and gas from a casting die, comprising two complementary bodies (11, 12), which can be closed face to face one on top of another, and a wavy, comb-like or similar evacuation channel (13) arranged between said two bodies, which can be connected, on the one hand, at the inlet (14), to a die, and on the other hand, at the outlet (15), to a vacuum gearcase, wherein said evacuation channel (13) is delimited by a static surface (16) represented by the internal surface of a first of said bodies (12) and by a movable surface (18), which is arranged in front of and in parallel to the static surface (16) and represented by the front surface of a movable element (17), which is arranged in the second of said bodes (11) and can be moved at right angles to said static surface (16) to vertically adjust the section of the evacuation channel, characterised in that said movable element (17) is arranged in a cavity of the second of said bodies (11) and is joined to a wedge-shaped positioning member (21), which is guided in the second body and can be longitudinally moved in a plane that is parallel to the plane in which the evacuation channel lies (13), said movable element (17) and said positioning member (21) being coupled by means of guides which are sloped with respect to the plane in which said evacuation channel lies such that a vertical movement of said movable element above the static surface of the channel corresponds to each longitudinal movement of said member (21). Device in accordance with claim 1, in which said wedge-shaped positioning member (21), for its longitudinal movements, is connected to a drive shaft (26), rotating and translating in the second body (11), said shaft being manually or mechanically actuated and having a threaded portion (27), which is joined to a corresponding threaded hole (28) provided in said body. Device in accordance with claim 2, in which said drive shaft (26) has references, which are visible and are indicative of the position of the movable element (17) with respect to the static surface (16) and of the height of the section of the evacuation channel.

Inventors: ARRIGOTTI FAUSTO, ARRIGOTTI SERGIO, ARRIGOTTI, FAUSTO, ARRIGOTTI, SERGIO
Applicants: UNITECNO S R L, UNITECNO S.R.L.
Application year: 2000
Main classification: B22D17
IPC codes: B22D17