Mold forming apparatus with mold flask bracer means

In mold forming apparatus wherein molding sand contained in a mold flask is subjected to compressive forces, bracer devices acting in opposed relationship against the mold flasks are provided in order to supprt the sides of the flasks against the forces generated therein during compression of the molding sand. The bracer devices act against structural parts of the molding apparatus or machine which are located to be fixed in position relative to the mold flasks during the compression of the sand and the bracer devices are arranged to consist of bracer bolts which are adapted to be brought into engagement against the sides of the mold flasks by wedge devices sliding relative to the fixed structural parts and actuated preferably by fluid pressure means.

BACKGROUND OF THE INVENTION 
The present invention relates generally to apparatus for the production of 
casting molds and more particularly to apparatus wherein material for 
forming a casting mold is compressed within molding flasks containing the 
material. 
In mold forming equipment of the type to which the present invention 
relates, substantial increases in the sizes of the molding flasks which 
are utilized as a result of mechanization or automation of plants within 
which such equipment is operated has effected a considerable increase in 
the degree of deformation or distortion which occurs in the walls of the 
molding flask during the compression therein of the mold forming material 
or molding sand. Plastic or elastic deformation of the molding flasks will 
be subjected to added increase during compression by the introduction of 
high pressure molding. The elastic deformation of the molding flasks 
during compression is further increased during compression as a result of 
the application of new filling methods of the molding sands in the molding 
flasks, the profiled sand filling being stripped off before the 
compression on the top side in adaptation to the pattern volume. 
The elastic deformation which occurs in the walls of the molding flask 
tends to attain a maximum degree of deformation during compression of the 
molding sand particularly when the patterns which are utilized in forming 
the casting molds have a relatively large volume. The deformation of the 
molding flask produces the additional disadvantage in that it enhances 
breakoff of mold balls and mold edges during separation of the casting 
mold parts from the pattern device. 
Furthermore, offset of the castings tends to be increased and the accuracy 
of the dimensions or size of the castings is also impaired as a result of 
the deformation which may occur in the molding flasks. 
Heretofore, the most effective manner for preventing elastic deformation of 
molding flasks has involved the utilization of stiffening means consisting 
of traverses or stiffening devices which are installed to extend across 
the mold flask. The traverses, however, produce the significant 
disadvantage that they reduce the molding flask inner space which is 
available for utilization and that the uniformity of compression of the 
casting mold parts is also impaired. Since such traverses also affect the 
disassembly of the casting moles in that such disassembly is rendered more 
difficult, they are no longer utilized in molding and casting plants. 
Other known approaches have involved attempts to achieve stiffening of the 
molding flasks by increasing the profiles of the molding flasks taken in 
the bending direction and by designing them as hollow bodies. However, 
experience has shown that the desired stiffening effects for molding 
flasks cannot be achieved by measures such as these. 
Accordingly, there exists a need for providing support for molding flasks 
utilized in equipment for forming casting molds. 
The present invention is directed toward achievement of appropriate support 
and bracing for molding flasks utilized in mold forming equipment during 
the compression of casting mold parts. 
SUMMARY OF THE INVENTION 
Briefly, the present invention may be described as an improvement in mold 
forming apparatus for the production of casting molds in molding flasks 
operating to compress the molding material contained in such flasks by the 
provision of bracer means including bracer elements which act in opposed 
relationship to each other against the molding flasks to brace the flasks, 
and structural means located to be fixed in position relative to the mold 
flasks during the compression of the mold forming material contained 
therein, the bracer means operating to brace the mold flasks against said 
fixed structural means. 
In accordance with the invention the object is achieved by providing at 
least one bracer means or supporting device for each mold unit in order to 
support the molding flask of the mold unit against a machine part or 
structural element which does not change position relative to the molding 
flask during the performance of the compression step whereby the mold 
material contained in the flask is compressed. 
In a preferred embodiment of the invention the bracer means are formed to 
consist of bracer bolts which can be adjusted relative to the molding 
flask by wedge means sliding upon a machine part. 
Other preferred embodiments of the invention are provided wherein a spring 
operating to bias the bracer bolt to return to its initial position is 
provided, where the wedge means is actuated by fluid pressure means such 
as pneumatic or hydraulic cylinders preferably in a vertical direction, 
with the height of the wedge being less than the distance between piston 
rod surfaces actuating the wedge. The bracer means are arranged to bear on 
parts of the mold table or on columns which are rigidly connected both 
with the mold table and with the press or with a cross piece. 
With the bracing effect which is achieved according to the invention 
against the molding flask of the casting mold unit during the compression 
of the molding materials there results a condition whereby the molding 
flasks which are used may be made of ordinary sections having no 
stiffening traverses or other like elements, with the elastic deformation 
of the flasks being maintained so small during compression that there does 
not result either breakoff of mold balls or mold edges or increases in the 
offset of the castings or reduction in the accuracy of the size or 
dimensions thereof. 
The various features of novelty which characterize the invention are 
pointed out with particularity in the claims annexed to and forming a part 
of this disclosure. For a better understanding of the invention, its 
operating advantages and specific objects attained by its use, reference 
should be had to the accompanying drawings and descriptive matter in which 
there are illustrated and described preferred embodiments of the invention 
.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now to the drawings wherein similar reference numerals refer to 
like parts throughout the various figures thereof, there is depicted in 
FIGS. 1 and 2 mold forming apparatus wherein the present invention is 
embodied. The apparatus shown in FIGS. 1 and 2 include a mold table 1, a 
press 2 and a pair of columns 3 and 4 which are rigidly connected with 
each other and which essentially comprise a fixed structural part of the 
overall equipment or apparatus which is immovable relative to a molding 
flask to be placed within the apparatus for compression therein of molding 
sand. A pattern device 7 is located upon the mold table 1 and carries 
thereupon a molding flask or box 5 which may be filled with molding sand 
and a sand frame 8 which is detached upon the molding flask 5. The mold 
table 1 bears upon a jarring apparatus 9 which is of known design and 
configuration. The press 2 includes a press cylinder 12 within which there 
is guided a plunger 11 which carries a press plate 10. 
The device represented in FIGS. 1 and 2 has applied thereto the improvement 
of the present invention and indicates the manner whereby the present 
invention may be utilized in application in a compression apparatus which 
operates to effect simultaneous free-fall jarring and pressing of a mold 
unit in accordance with known prior art means and equipment. 
Arranged adjacent the fixed structural elements or columns 3 and 4 there is 
provided on one side thereof a support 14 which provides support for the 
molding box or flask 5 with a bracer bolt 29 of bracing means 63 and a 
bracer bolt 29a of bracer means 64 being correlated. Additional supports 
13 for the molding box or flask 5 are provided wherein bracer bolts 35 of 
bracer device 65 and bracer bolt 36 of bracer device 66 are correlated. 
The supports 14 are shown in greater detail in FIGS. 3-5. A pattern device 
7, a molding flask 5 and a sand frame 8 are shown. On column 4 there is 
secured a machine part 15 with a cylinder 19. The cylinder 19 is so 
connected with a wedge device 22 over a piston 20 and a piston rod 21 that 
the distance between faces 23 and 24 of the piston rod exceed a height 25 
of the wedge 22 so that, when the piston rod 21 is actuated, it will move 
the wedge 22 only after it has traversed a certain distance. The wedge 22 
may be moved from a position 26 into a position 27 and back, and it is 
pressed or biased by a spiral spring 28 over bracer bolts 29 against a 
sliding surface 30 of the machine part 15. Instead of spiral springs 28,28 
a there may be utilized leaf springs or other elastic means for pressing 
against the bracer bolts 29,29 a. The position 26 of the wedge 22 thus 
corresponds to a position 31 of the bracer bolt 29 and the position 27 of 
the wedge 22 corresponds to a position 32 of the bracer bolt 29. An end 
piece 92 of the bracer bolt 29 is preferably movable, that is, it can be 
pressed upon the surface of the molding flask 5. 
Reference numerals 19-32 and 92 refer to the lower supporting device 62 of 
the apparatus which actuates the bracer bolt 29, while the reference 
numerals 19a-32a and 92a refer to an upper supporting device 64 which 
actuates a bracer bolt 29a. Since both the supporting devices 63 and 64 
are provided with identical reference numerals and since they work in the 
same manner, only the lower supporting device 63 will be described in 
detail it being understood that the reference characters having the 
reference letter "a" annexed thereto are intended to be composites of 
comparable elements having reference numerals without the annexed letter 
"a". 
In the operation of the embodiment represented in FIGS. 1 and 2, after the 
pattern device 7 has been deposited upon the mold table 1 together with 
the filled molding flask 5 and with the sand frame 8, the bracing means or 
supporting devices 63, 64 and 65,66 are actuated and the pressure chamber 
101 (see FIGS. 3-5) of the pneumatic or hydraulic cylinder 19 will receive 
pressure and move the piston 20 with the piston rod 21 over piston rod 
face 24 and wedge 22 in the direction of the arrow 102 until the bracer 
bolt 29 has reached the position 31. Thus, the bracer bolt will bear 
against the molding flask 5 without, however, causing elastic deformation 
of the latter. At the same time, pressure chamber 103 of the pneumatic or 
hydraulic cylinder 19a receives pressure and moves piston 20a with piston 
rod 21a over piston rod 24a in the direction of arrow 104 until bracer 
bolt 29a has reached the position 31a, wherein it bears against the 
molding flask 5 again without causing plastic deformation thereof. At the 
same time, and in the same manner, the supporting devices 65,66 are also 
actuated. 
As shown in FIG. 3a, an angle 69 between a parallel 33 of sliding surface 
30 on machine part 15 and sliding surface 105 on wedge 22 and the 
corresponding angle between sliding surface 30 and sliding surface 106 on 
wedge 22a are so selected that the resulting friction prevents wedge 22 
from sliding back opposite to the direction of the arrow 102 and the wedge 
22a from sliding back opposite to the direction of the arrow 104. The 
angles 67 and 68 are selected to be greater so that the path of travel of 
the wedges 22 and 22a does not become overly long. Subsequently, operation 
of the press 2 is initiated and the molding sand contained within the 
molding flask 5 and sand frame 8 is compressed by means of the plunger 11 
and the press plate 10. The jarring apparatus 9 then operates to raise the 
mold table 1 with all of the respective parts thereon in a known manner 
and subsequently drops the raised parts in a free-fall operation with this 
free-fall operation occurring several times on jarring cylinder 95 while 
the press 2 remains applied. The maximum compression which is effected in 
the molding sand when the mold table 1 strikes upon the jarring cylinder 
95 is caused both by the resulting inertial forces in the molding sand in 
press plate 10 and by the compression of press 2. Since, when the mold 
table 1 strikes upon the jarring cylinder 95, inertia forces are produced 
in the wedges 22, 22a and in the piston rods 21,21 a and in the piston 
20,20 a, which tend to press the bracer bolts 29,29 a increasingly against 
the molding flask 5, and since the same effect is also produced at the 
same time in the bracing or supporting devices 65,66, the position of the 
supporting devices 63-66 remains unchanged during the maximum compression 
of the molding sand. Since the columns 3,4 are made so rigid that they are 
practically incapable of exerting any deformation on the forces acting on 
the molding flask 5 during the compression, and the bracer bolts 29,29 a, 
35,36 are stressed exclusively in compression, no elastic deformation is 
possible during the compression at the supporter or bracer points of the 
mold flask 5. 
After the compression operation, the press 2 is reversed and the plunger 11 
operates to lift the press plate 10 and the cylinders 19,19 a of the 
supporting devices 63,64 as well as the cylinders of the supporting 
devices 65,66 66 which are likewise reversed and which operate to lift the 
wedges 22,22 a and the wedges of the supporting devices 65,66, 
respectively, after which the bracer bolts 29,29 a, 35,36 of the 
supporting devices 63,66 are pulled back in a known manner. 
The embodiment of the invention depicted in FIGS. 1 and 2 shows the 
application of the invention in the production of casting mold parts which 
are relatively high and which have relatively smaller mold faces. However, 
the embodiment modification shown in FIGS. 6 and 7 depicts and exemplifies 
an application of the invention wherein relatively low casting mold parts 
are involved having relatively larger mold faces. In the embodiment 
depicted in FIGS. 6 and 7 there is included columns 47 and 48 each of 
which is rigidly connected with a mold table 46 and a press 49 and upon 
which the supporting or bracing devices, respectively, bear. Furthermore, 
columns 50 and 51 are provided which are rigidly connected with the mold 
table 46 and a press 52, upon which the supporting devices 44 and 45 
respectively bear. Furthermore, columns 53 and 54 which are rigidly 
connected with the mold table 46 and with a cross piece 55 are provided 
and supporting or bracing devices 42 and 43 bear, respectively, upon the 
columns 53,54. Upon the mold table 46 there is applied a pattern device 
56, a molding box or flask 57 which is filled with molding sand and a sand 
frame 58. A press plate 59 is associated with the press 49 and a press 
plate 60 is associated with the press 52. The mold table 46 bears on a 
jarring apparatus 61 of known design. 
In the operation of the embodiment of the invention represented in FIGS. 6 
and 7 there exist aspects of operation which differ from the operation of 
the embodiment shown in FIG. 1 only with regard to the arrangement 
involved. The basic mode of operation is the same and thus it will not be 
here described in detail. 
Another embodiment of the present invention is depicted in FIGS. 8 and 9. 
In this embodiment there is shown a molding machine which compresses the 
casting mold parts by a pressing operation without a free-fall jarring 
action. A mold table 71 bears over four columns 70 upon a foundation 72. 
The mold table 71 carries over two columns 72 and 74 a cross piece 75 of a 
press 76. A part of the mold table 71 is designed as a stirrup 77 which 
has on one side a supporting device 78 with a bracer bolt 79, On the other 
side is a bracer or supporting device 80 with a bracer bolt 81. Another 
part of the mold table 71 is likewise designed as a stirrup 82 and has on 
one side thereof a bracer device 83 with a bracer bolt 84. On the other 
side is a bracer device 85 with a bracer bolt 86. The press 76 is 
connected over a plunger 87 with a press plate 88. Upon the mold table 71 
there bears a pattern device 89. Upon the pattern device 89 is attached a 
molding flask 90 which is filled with sand and upon which there is, in 
turn, attached a sand frame 91. 
In the operation of the modification of the embodiment represented in FIGS. 
8 and 9, a conveying apparatus (not shown) first deposits or conveys to 
the mold table 71 the pattern device 89, the molding flask 90 filled with 
molding sand and the frame 91. Thereafter, the supporting or bracing 
devices 78,80, 83 and 85 are actuated in the manner previously described. 
The bracer bolts 79,81,84,86 are applied to bear against the molding flask 
90 and in this manner prevent the elastic deformation of the molding box 
90 at the braced point. This occurs during compression of the casting mold 
part. The compression of the mold is effected by pressing action resulting 
from the starting of the press 76 and pressing plate 88 operating over 
plunger 87 agaist the molding sand to apply the compressive forces 
thereto. After the compression, the press plate 88 is raised in the manner 
described previously in reference to FIGS. 1 and 2, and the bracer bolts 
79,81,84 and 86 are retracted by actuating the bracing devices 78,80 and 
83,85. 
The supporting device according to the present invention, which supports 
the molding flask of the casting mold parts upon a machine part which does 
not change its position relative to the molding flask during compression, 
may be used in all known molding machines which produce molding parts by 
compression operation. 
The supporting or bracing devices according to the invention can be used 
not only to support the longitudinal walls of the molding flasks, but they 
may be also utilized to support all molding flask walls. Experience has 
shown that the molding flask walls wherein there is provided dowel guides 
such as the dowel guides 96 depicted in FIGS. 2, 7 and 9 are preferably 
stiffened by a corresponding increase in the profile of the molding flask. 
While specific embodiments of the invention have been shown and described 
in detail to illustrate the application of the inventive principles, it 
will be understood that the invention may be embodied otherwise without 
departing from such principles.