System for changing and cleaning blowing plates in core blowing machines

The system includes two platforms vertically movable along guides provided on a fixed support. A top platform is swingable between a horizontal position in which it superposes a lower platform, and a vertical position. A blowing plate is positioned on the top platform. The system is provided with a double catch which is selectively engageable with the bottom wall of the top platform when the latter is in the horizontal position, and with the fixed support when the top platform is in the pivoted-away position.

FIELD OF THE INVENTION 
The present invention relates to improvements in foundry core blowing 
machines, and more specifically to systems for changing and cleaning the 
blowing plate under which the corresponding core box must be placed in the 
process for propulsing the sand used to conform such cores. 
BACKGROUND OF THE INVENTION 
As is well known, in core blowing machines, the supply of a strong stream 
of air under pressure causes sand and its corresponding additives, to be 
dragged from a cartridge containing the sand to the inside of a core box 
which has previously been positioned under a blowing plate provided with 
apertures suited to the core to be manufactured in order that the sand 
distribution reaches all the hollows, thereby conforming a perfect core. 
In the light of the foregoing, it is clear that different types of cores 
will require a specific type of blowing plate, and therefore the plates 
must be removably assembled on the blowing machine, at the same time as 
throughout the operative stage of a specific blowing plate, sand residues 
which must be removed regularly are deposited thereon at each phase. 
In order to attain this double objective there are known core blowing 
machines provided with a platform capable of receiving and fixing the 
blowing plates and which may swing, from a horizontal and working 
position, to a vertical position for the sand residues to be eliminated, 
by scraping the plate or by any other means. 
In this respect reference should be made to U.S. Pat. No. 4,572,273 which 
describes a device provided with a swinging platform, the swinging 
movement whereof is provided by a pair of hydraulic cylinders. The 
platform is together with the cited hydraulic cylinders, connected to a 
travelling carriage, which may be displaced through vertical guides on a 
fixed support and with the collaboration of another hydraulic cylinder, so 
that this last hydraulic cylinder affords vertical displacement of the 
platform and consequently of the blowing plate and the core box with 
respect to the top blowing head, inherent in the normal operation of the 
core blowing machine, whereas the first pair of cylinders afford the 
swinging movement of the platform so that the blowing plate may be 
cleaned. 
This device is moreover provided with a fourth hydraulic cylinder, 
positioned transversally, with which the blowing plate is attached or 
released with respect to the swinging platform. 
This solution, albeit affording attainment of the objectives sought from an 
operative point of view, is extremely complex from a structural point of 
view and consequently expensive both as regards manufacture and subsequent 
maintenance thereof. 
SUMMARY OF THE INVENTION 
The improvements set out in the present invention fully solve above problem 
whilst maintaining an optimal operating performance, with full operating 
automatism, but with a considerably simpler and therefore cheaper 
structure, which makes the risk of breakdowns smaller. 
More specifically, and in order to achieve the above, the improvements set 
out in the present invention reside in the provision of two superposed 
platforms, a lower platform which may be vertically displaced on guides 
operatively provided for such purpose, and another top platform which may 
swing with respect to the first platform and connected to the latter 
through a lateral joint. At the same time the two platforms may be 
connected to each other, in the area opposite to the joint, through a 
double catch actuated by a small cylinder which determines two positions 
therefor, namely a first position in which the catch, swingingly supported 
on the lower platform, engages a lower projecting abutment of the swinging 
or top platform which receives the blowing plate, and a second position in 
which the catch is released from such abutment and engages another 
abutment of the fixed and lower support. This exceedingly simple structure 
allows the use of a single hydraulic cylinder, and when the two platforms 
are fixed to each other the single cylinder determines their joint 
elevation, and especially elevation of the top swinging platform whilst 
remaining in a horizontal position, in accordance with one of the services 
to be afforded by the device, whereas when the two platforms are released 
and the double catch connects the lower platform to the support, the 
actuation of the single hydraulic cylinder causes the top platform to 
swing, for which purpose said cylinder must evidently be assembled between 
the lower fixed support and the top swinging platform. 
Complementarily, and as a further characteristic of the invention, in order 
to fix the blowing plate to the top swinging platform, during the cleaning 
operations when such platform swings, two catches are swingingly joined to 
opposite areas of the platform. The catches may block the blowing plate 
against the swinging platform and which normally tend towards this 
position due to the effect of respective springs which assist the catches. 
The lower end of each of the catches is further provided with two rollers 
projecting substantially from the lower surface of the swinging platform. 
The two rollers or block sheaves, when the top platform swings onto the 
lower platform, i.e., when the top platform adopts a horizontal position 
and consequently the catches are inoperative, since the blowing plate 
remains stable due to its own weight, fall upon abutments of the lower 
platform, formed in a slope, the catches being forced to swing towards an 
open position against the corresponding springs and, consequently, the 
blowing plate is released, so that the operations to change or substitute 
the same may be performed, without the necessity to perform any specific 
operation for this purpose, i.e., so that the blowing plate is disengaged, 
for this takes place automatically. 
Finally, the top platform is provided with an abutment projecting from its 
lower base through which it rests on the lower platform when it attains a 
horizontal position. When the top platform is lowered, in a horizontal 
position, a shock absorbing abutment takes place preventing brusqueness in 
the contact of the previously mentioned real rest abutment. 
The aforementioned objects, features and advantages of the invention will, 
in part, be pointed out with particularity, and will, in part, become 
obvious from the following more detailed description of the invention, 
taken in conjunction with the accompanying drawing, which form an integral 
part thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT OF THE INVENTION 
In the light of the figures of the drawings it may be observed that, in 
accordance with the improvements set out herein, a core blowing machine is 
provided, on the corresponding support columns 1, with a fixed support 2 
with respect to which a platform 3 may be displaced with the assistance of 
a pair of side guides 4 which may be axially displaced on bearings mounted 
in vertical apertures provided in the ends of support 2. the platform 3 is 
materialised in a rectangular frame, which is traversed by a rod 5 of an 
actuating cylinder 6 swingingly assembled on support 2, through lugs 7, as 
may be specifically observed in FIG. 3, which rod in turn and through the 
swing joint 8 is connected to a top platform 9 provided for such purpose 
with another pair of lugs 10 for the swing joint, a blowing plate 11 being 
positioned on platform 9. 
Top platform 9 is connected to lower platform 3 through a front joint 16, 
so that platform 9may swing with respect to platform 3, and may also 
accompany the latter during vertical displacements thereof. 
In order that platform 9 may swing or ascend/descend vertically with the 
single actuating hydraulic cylinder 6, it has been foreseen that a double 
catch 17 actuated by a small cylinder 18 connected to platform 3 itself, 
is swingly joined to the edge of the lower platform 3 opposite the joint 
16, as may be specifically observed in FIGS. 1 and 2, so that one of the 
operative ends of the double catch, generally referred to as 19, is 
complementary to an abutment 20 connected to the lower surface of swinging 
platform 9, whereas the other operative end of double catch 17, generally 
referred to as 21, in turn cooperates with an abutment 22 rigidly 
connected to support 2, either end 19 or 21 of double catch 17 therefore 
being operative depending on the position of cylinder 18. 
In accordance with this structure, when cylinder 18 adopts the position 
shown in FIG. 1, catch 17 constitutes a connecting link between platforms 
3 and 9, and therefore actuation of cylinder 6 causes the two platforms to 
be displaced together in an upward or downward direction, top and swinging 
platform 9 consequently remaining perfectly horizontal, which position is 
transmitted to blowing plate 11 connected to platform 9. 
On the other hand, and from the lower limiting position of the two 
platforms and in an opposite actuation position of cylinder 18, double 
catch 17 connects lower platform 3 to support 2, whereby actuation of 
cylinder 6 in an expanding direction, as shown in FIG. 2, and 
immobilisation of lower platform 3, engaging abutment 20 of the support, 
causes top platform 9, and consequently blowing plate 11 attached thereto, 
to swing towards a vertical position which is also shown in figure 2, in 
which position it is easy to clean the plate 11, by scraping same or using 
any other means. 
Attachment of blowing plate 11 to swinging platform 9 so that it does not 
become detached when in its cleaning position, takes place with the help 
of two side catches 23, swingingly assembled on platform 9 with the help 
of lugs 24 which project from the latter. Catches 23 tend towards a 
position of engagement for blowing plate 11 due to the effect of 
respective springs 25 and the lower ends whereof, i.e., the end opposite 
the end which forms the engaging catch itself, are provided with two 
rollers or block sheaves 26 with which engage abutments 27, acting as 
wedges which define slopes or inclined planes, provided on lower platform 
3, whereby when swinging platform 9 is in a horizontal position, when such 
catches 23 are inoperative since the blowing plate remains stable on 
platform 9 due to its own weight, these catches release the plate 11 when 
they are forced to swing against their springs 25, and therefore the 
blowing plate 11 is automatically fully released in such position, so that 
it may be replaced. 
Finally, it only remains to be said that lower displaceable platform 3 is 
obviously further provided, in the area opposite joint 16, with a shock 
absorbing abutment 14 upon which top swinging platform 9 rest when it 
reaches a horizontal position, thereby avoiding brusqueness when abutment 
20 contacts its corresponding support. 
Therefore, and in accordance with the structure described, while cylinder 
18 remains in the position shown in FIG. 1, platform 9 will rise and 
descend whilst remaining horizontal, upon actuation of single driving 
cylinder 6, in a situation where catches 23 are inoperative wherefore the 
blowing plate 11 may be easily replaced, whereas when the cleaning 
position shown in FIG. 2 is desired; cylinder 18 only has to be actuated 
in an opposite direction so that, upon actuation of driving cylinder 6, 
the desired swinging movement is produced and, at the same time as such 
movement begins, and automatically, catches 23 adopt the operative 
blocking position of blowing plate 11 against swinging platform 9. 
It is not considered necessary to extend the present description any 
further for one skilled in the art to understand the scope of the 
invention and the advantages derived therefrom. 
The materials, shape, size and arrangement of the elements may vary, 
provided this does not imply a modification in the essentially of the 
characteristics of the invention. 
The terms used to describe the present specification should be understood 
to have a wide and non-limiting meaning.