TORASSO, Mauro (Via Gallarà 6, Sommariva Perno, I-12040, IT)
| CLAIMS 1) A decoring machine for removing residual moulding material from foundry castings (2), the machine (1) comprising a frame (3) defining a housing (4) for at least one casting (2) to be decored; and two unbalanced motors (24) mounted on the frame (3) to rotate about respective vertical axes of rotation (25) and impart a vibratory movement to the frame (3); the machine (1) being characterized in that the frame (3) has a vertical axis of symmetry (B) , and comprises two parallel U- shaped plates (9) connected rigidly to each other to define a bottom base member (13), and two top shoulders (15) located on opposite sides of said plane of symmetry (B) and bounding said housing (4) laterally; and in that each motor (24) is fitted to the respective said plate (9) so that the respective axis of rotation (25) lies in the plane of symmetry (B) . 2) A machine as claimed in Claim 1, wherein each motor (24) is connected to the respective plate (9) at the base member (13) of the frame (3) . 3) A machine as claimed in Claim 1 or 2, wherein the frame (3) has a further plane of symmetry (A) perpendicular to said plane of symmetry (B) and parallel to said axes of rotation (25); the motors (24) being arranged symmetrically with respect to the further plane of symmetry (A) . 4) A machine as claimed in Claim 3, wherein the plates (9) are arranged symmetrically with respect to the further plane of symmetry (A), and the motors (24) are located outside the assembly defined by the plates (9) . 5) A machine as claimed in one of the foregoing Claims, wherein each motor (24) has a centre; the frame (3) and the casting (2) define, in use, an assembly having a barycentre; and locking means (18) are provided inside the housing (4) to lock the casting (2), with respect to the frame (3) , in such a position that the centre of each motor (24) is substantially on a level with the barycentre of said assembly. 6) A machine as claimed in one of the foregoing Claims, and also comprising a fixed base block (5) ; the frame (3) being supported by the base block (5) with the interposition of elastic bearings (6). 7) A machine as claimed in Claim 6, wherein the base block (5) comprises two pairs of uprights (7); each upright (7) supporting a respective elastic bearing (6); and each pair of uprights (7) being associated with a respective said plate (9) . 8) A machine as claimed in one of the foregoing Claims, and comprising a percussion unit (21) located outside the frame (3) and having a number of hammers (23) , which are movable, in a direction perpendicular to said plane of symmetry (B) , through one of the shoulders (15) to strike the casting (2) inside the housing (4) . 9) A machine as claimed in one of the foregoing Claims, and comprising crumbling means (27) for crumbling the moulding material removed from the casting (2) . 10) A machine as claimed in Claim 9, wherein said crumbling means (27) comprise a grate (27), which is fitted to the frame (3), extends between the plates (9), under the housing (4), and has a rough surface facing the housing (4) . |
TECHNICAL FIELD
The present invention relates to a decoring machine.
BACKGROUND ART
More specifically, the present invention relates to a decoring machine for removing residual moulding material from foundry castings, the machine being of the type comprising a frame defining a housing for at least one casting to be decored; and two unbalanced motors or electric vibrators fitted to the frame to rotate, in use, about respective vertical axes of rotation and impart to the frame a vibratory movement, which may be straight or an oscillating movement about an axis, depending on whether the unbalanced motors rotate in opposite directions or the same direction.
Because effective decoring in a machine of the above type depends on subjecting the casting to relatively severe vibration, the frame is subjected, in use, to severe shear and bending stress.
For this reason, and because the design of commonly used known machines does not normally enable accurate prediction of the degree and direction of such stress, the frame is invariably massive, heavy, and normally oversized.
This solution obviously poses many problems, mainly due to high manufacturing cost, the massive size of the machine, and the energy required to operate the machine.
A partial solution to the problem of the masses involved is provided in Patent Application
US2006/0272792, which describes a decoring machine in which the frame comprises two lateral supporting plates, each fitted with a respective unbalanced motor. Because the motors subject the respective plates to shear stress, i.e. in the planes of the plates themselves, the thickness of the plates may be greatly reduced. Consequently, the frame may have a relatively lightweight, though strong, structure, thus reducing the vibrating force applied to achieve the same result.
Controlling vibration of a relatively lightweight structure, however, poses far more serious problems than controlling vibration of a relatively heavy structure. These problems are not solved in Patent Application US2006/0272792, which describes a decoring machine so structured that the vibrating force applied to a casting in the housing may change direction and even result in a combined rotation-translation movement that may even be counterproductive in terms of effectively decoring the casting. DISCLOSURE OF INVENTION
It is an object of the present invention to provide a decoring machine of the type described above designed to eliminate the above drawbacks.
According to the present invention, there is provided a decoring machine as claimed in Claim 1 and preferably in any one of the following Claims depending directly or indirectly on Claim 1. BRIEF DESCRIPTION OF THE DRAWINGS
A number of non-limiting embodiments of the invention will be described by way of example with reference to the accompanying drawings, in which:
Figure 1 shows a view in perspective of a preferred embodiment of the decoring machine according to the present invention; Figures 2 and 3 show side and end views respectively of the Figure 1 machine;
Figure 4 shows a plan view of the Figure 1 machine; Figure 5 shows a larger-scale view in perspective of a detail of the Figure 1 machine. BEST MODE FOR CARRYING OUT THE INVENTION
Number 1 in Figure 1 indicates as a whole a decoring machine for removing residual moulding materials from foundry castings 2 by subjecting castings
2 to a combination of vibratory movement and hammering. This type of machine is used to advantage, for example, for decoring aluminium alloy cast engine cylinder heads.
Machine 1 comprises an upward-facing, fork-shaped supporting frame 3 defining a housing 4 for castings 2 to be decored. In the example shown, machine 1 is set to simultaneously decore two castings 2 arranged side by side in housing 4, but may obviously also be used to decore one casting 2 at a time, or more than two castings 2 simultaneously, depending on the size of castings 2.
Frame 3 rests on a base block 5 with the interposition of four elastic bearings 6, which are fitted to respective uprights 7 integral with a horizontal portion 8 of base block 5, are in the form of convex cylinders coaxial with respective parallel vertical axes, and flex elastically in a direction crosswise to their respective axes.
This system reduces the force resisting vibration, and at the same time reduces downtime of machine 1.
As shown in more detail in Figure 5, frame 3 comprises two U-shaped metal plates 9 located on opposite sides of and parallel to a vertical plane of symmetry A of frame 3, and each defined by a substantially rectangular bottom portion 10, and by two upright portions 11 extending upwards from respective opposite lateral portions of the free top edge of bottom portion 10.
The two bottom portions 10 are connected rigidly to each other by a number of tubes 12 perpendicular to plane A, so as to define as a whole a rigid base member 13 of frame 3.
The upright portions 11 of each plate 9 are connected to the upright portions 11 on the opposite side of plane A by bars 14, so as to define two shoulders 15, which define housing 4 laterally, and are located on opposite sides of a vertical plane of symmetry B perpendicular to plane A. Each upright portion 11 of each plate 9 is fitted, with the interposition of a respective brace 16, with an appendix 17 projecting outwards of frame 3 and perpendicular to plate 9. As shown in Figure 1, the four appendixes 17 are connected integrally to the top of respective bearings 6, and define respective coplanar feet by which frame 3 rests on base block 5.
To lock castings 2 inside housing 4, frame 3 comprises a gripping device comprising a plate 18, which is connected to one of the two shoulders 15, and is located inside housing 4, adjacent to said shoulder 15. Plate 18 is parallel to plane B, and is movable, parallel to itself and by means of four pneumatic actuators 19 located between said shoulder 15 and plate 18, towards the other shoulder 15 to grip castings 2 against fixed locators 20 fitted to bars 14 of the other shoulder 15.
As shown in Figures 1 to 3, machine 1 also comprises a known percussion unit 21 for vigorously hammering castings 2 to break off the moulding material compacted inside castings 2 and so enable its removal by vibration .
Percussion unit 21 is fitted to a vertical portion 22 of base block 5 facing the shoulder 15 fitted with locators 20, and comprises a number of known pneumatic hammers 23, which extend from vertical portion 22 towards said shoulder 15 in a direction perpendicular to plane B, and have respective heads which, when hammers 23 are operated, move between bars 14 to strike castings 2.
Machine 1 also comprises a vibration unit in turn comprising two known unbalanced motors 24, each of which has a vertical axis of rotation 25, and is mounted on base member 13, at a respective plate 9, so that respective axis 25 lies in plane B. Each motor 24 is fitted to and projects from respective plate 9 by means of four fastening members 26 which, in addition to supporting motor 24, also prevent it from moving crosswise to respective axis 25.
Castings 2 and motors 24 are preferably fitted to frame 3, so that the centre of each motor 24 is substantially on a level with the barycentre of frame 3 and castings 2 as a whole.
By virtue of this symmetric and barycentric arrangement, the stress generated by each motor 24 is discharged in the plane of respective plate 9, which is thus subjected to mainly shear stress and practically no bending stress, and can therefore be made relatively thin; and the resultant of the forces generated by motors 24 is perfectly controlled.
In fact, in the event motors 24 are operated in phase opposition to each other (as in the example shown) , the resultant of the forces generated by motors
24 is a force substantially in plane A and extending in a direction D perpendicular to plane B; and the forces in other directions are eliminated by compensation. Conversely, in the event, as in a variation not shown, motors 24 are operated in phase with each other, the resultant of the forces generated by motors 24 is a pure moment which causes frame 3 to oscillate about an axis parallel to axes 25 of motors 24 and defined by the intersection of planes of symmetry A and B.
In other words, by virtue of the symmetric and barycentric arrangement described above, motors 24 subject frame 3 to a controlled movement in a given direction, as opposed to separate, uncontrolled movements .
As shown in Figures 2 to 5, machine 1 also comprises a crumbling device for crumbling the moulding material removed from castings 2. The crumbling device comprises a grate 27, which is fitted to frame 3, extends between plates 9, perpendicularly to planes A and B, is positioned facing housing 4, and has a rough surface on the side facing housing 4. Grate 27 being integral with and therefore vibrating together with frame 3, the moulding material detached from castings 2 is "grated" on grate 27 into powder or small pieces, which drop through the openings in grate 27 into a fixed bin 28 underneath.
To prevent the moulding material removed from castings 2 from falling outside frame 3 before reaching grate 27, frame 3 is equipped with two deflectors 29, each located beneath a respective shoulder 15 and extending between and crosswise to plates 9. Operation of machine 1 will be clear from the above description, with no further explanation required.