Vent plug

A vent plug used in a chamber for manufacturing sand molds by a blow-squeeze process is configured to provide turbulent swirling flow of air vented from the chamber past the vent plugs to minimize build-up of deposits on the surfaces of the vents and vent plugs.

BACKGROUND OF THE INVENTION 
This invention relates to the art of venting and, more particularly, to 
venting of air from a chamber through holes which are restricted by vent 
plugs. Although the invention is particularly applicable for use in 
chambers for manufacturing sand molds by a blow-squeeze process and will 
be described with specific reference thereto, it will be appreciated that 
the invention has broader aspects, and may be used in other environments 
for other purposes. 
Sand molds are commonly manufactured by blowing sand onto a pattern located 
within a chamber from which the air is vented in a controlled manner for 
properly distributing and packing the sand in the pattern. The location 
and number of vent openings achieve proper or predetermined distribution 
of the sand. The vents are defined by holes or passages extending through 
the walls of the chamber which, in turn, are restricted by vent plugs. The 
outlet vent passages thus defined are dimensioned to be smaller than the 
sand particle size so that substantially all of the sand will remain in 
the chamber. 
However, and notwithstanding the foregoing dimensional relationships, there 
is a considerable amount of dust or sand fines which pass through the 
restricted vent passages and build up on the passage walls. The build-up 
of these deposits restricts the vent passages to such an extent that the 
sand will not be properly distributed throughout the pattern, and the sand 
mold thereafter produced may have insufficient density due to excessive 
entrained air. Therefore, frequent removal of the vent plugs and cleaning 
of the vent passages is necessary for production of satisfactory sand 
molds. 
It has been considered desirable to develop a vent plug arrangement that 
would minimize build-up of deposits on the walls of the vent passages. The 
subject invention is believed to meet these needs and others in providing 
a vent plug having a new and novel conformation. 
SUMMARY OF THE INVENTION 
According to the subject invention, vent plugs of the type described are 
configured for providing turbulent swirling flow of air through the vent 
passages to thereby minimize build-up of deposits on the walls of such 
passages. 
In a preferred arrangement, the improved vent plug of the present invention 
includes a substantially circular head having a central axis, a 
substantially flat front face, an outer peripheral surface, and a rear 
portion. The outer peripheral surface of the head is substantially 
cylindrical and extends parallel to the central axis. 
In accordance with one aspect of the invention, the rear portion of the 
vent plug includes sloping rear surface means which slopes toward the 
central axis in a direction away from the front face. This advantageous 
arrangement changes the direction of air flow as it moves past the outer 
peripheral surface of the head so that the air flow is directed inwardly 
toward the central axis and its velocity substantially increased. The 
change in direction and increased velocity help to minimize build-up of 
deposits and also help to produce a turbulent swirling motion of the air 
in a vortex-type of motion. This directs the air flow through the center 
of the vent hole so that dust particles entrained in the air stream do not 
contact the walls of the vent holes. The vortex-type of flow also scours 
the walls of the passages and produces a vacuum for positively exhausting 
air from the chamber. 
In accordance with an important aspect of the invention, the sloping rear 
surface means includes intersecting inner and outer rear surface areas 
which slope at different angles relative to the central axis, and 
intersect one another at an included angle substantially greater than 
90.degree. and less than 180.degree.. The inner rear surface area 
preferably slopes at a substantially greater angle than the outer rear 
surface area. In one arrangement, the outer rear surface area slopes at an 
angle of approximately 40.degree.-50.degree. relative to the central axis, 
while the inner rear surface area slopes at an angle of approximately 
10.degree.-20.degree. with respect to the central axis. 
In accordance with another aspect of the invention, the outer rear surface 
area has a width measured parallel to the central axis which is 
substantially greater than the width of the inner rear surface area. Also, 
the width of the peripheral surface of the head is preferably 
substantially less than the width of the outer rear surface area. 
According to yet another aspect of the invention, the rear portion of the 
vent plug includes mounting means for mounting same in a vent hole while 
providing air flow past the outer peripheral surface of the head. The 
mounting means divides the inner rear surface area into a plurality of 
individual segment areas. The mounting means may take the form of a spider 
having a plurality of spokes extending generally radially of the central 
axis and terminating at outer spoke ends which lie on the periphery of a 
circle having a diameter greater than the circular head. The sidewalls of 
the spokes intersect at smoothly curved juncture portions such that each 
individual segment area of the inner rear surface area is bounded by a 
generally U-shaped periphery. The generally U-shaped periphery lies on the 
periphery of a circle whose center is located inwardly of the outer 
peripheral surface of the circular head. The length of the generally 
U-shaped periphery is less than one-half the circumference of the circle 
on which it lies. 
The principal advantage of the present invention is the provision of an 
improved vent plug which minimizes build-up of deposits on the surfaces of 
vent passages. 
Another advantage of the invention resides in an improved vent plug which 
provides turbulent swirling flow of air in a generally vortex-type of 
motion which scours the surfaces of the vent passages and positively draws 
air from a chamber being vented. 
Yet another advantage of the invention is found in an improved vent plug 
which is economical to manufacture and install. 
Still other advantages and benefits of the subject invention will become 
apparent to those skilled in the art upon a reading and understanding of 
the following detailed description.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring now to the drawings wherein the showings are for purposes of 
illustrating a preferred embodiment of the invention only and not for 
purposes of limiting same, FIG. 1 shows a generally rectangular chamber A 
comprised of top and bottom plates 12, 14, and opposite side plates 16, 
18. During manufacture of a sand mold, the front of chamber A is closed by 
a movable door (not shown) while the rear of the chamber is closed by a 
movable ram (not shown). Typically, the inner or opposing faces of the 
door and ram include pattern portions thereon as is known. Sand and air 
are blown into chamber A through an inlet opening 22 in top plate 12 for 
depositing the sand therein. Filling of the pattern with sand may take 
one-six seconds, and the ram is then moved toward the door for squeezing 
the sand to form a mold half. The pattern portions on the door and ram 
generate the desired cavities on opposite sides of the mold as is also 
known in the art. Each mold half is cooperable with the next adjacent mold 
halves. One apparatus of this general type is marketed by Disamatic Inc. 
of Hinsdale, Ill. under the trademark DISAMATIC. Since this apparatus is 
known in the art, a further detailed description thereof is deemed 
unnecessary to a full and complete understanding of the subject invention. 
During the filling and squeezing steps, air is exhausted from chamber A 
through vent holes 24 which are distributed and located to achieve proper 
distribution of the sand throughout the chamber. Vent holes 24 are 
restricted by vent plugs having outlet openings smaller than the particle 
size of the sand being used so that most of the sand will remain within 
the chamber. However, dust and sand fines are exhausted through the vent 
passages where they build up to restrict proper venting flow of the air 
which results in molds of improper density or improper distribution of 
sand throughout the pattern. 
In accordance with the present invention, a vent hole 24 in a side plate 18 
is shown as a stepped hole which includes a large diameter bore 30 which 
intersects and opens outwardly at inner face 32 of plate 18 which faces 
inwardly of chamber A. An intermediate diameter bore 34 concentric with 
large diameter bore 30 extends inwardly from large diameter bore 30. A 
small diameter bore 36 concentric with intermediate bore 34 extends from 
intermediate diameter bore 34 to intersect outer face 38 of plate 18 and 
open outwardly thereat. The length of intermediate diameter bore 34 is 
substantially greater than the length of large diameter bore 30, and the 
length of small diameter bore 36 is substantially greater than the length 
of intermediate diameter bore 34. Large diameter bore 30 has a diameter of 
approximately 1.004 inches and a depth of approximately 0.10 inches. 
Intermediate diameter bore 34 has a diameter of approximately 0.995 inches 
and a depth of approximately 0.322 inches. Small diameter bore 36 has a 
diameter of approximately 0.875 inches. 
Improved vent plug B of the present invention as shown in FIGS. 4-6 
includes a substantially circular head C having a central axis 40, a 
substantially flat outer face 42, a substantially cylindrical outer 
peripheral surface 44 extending substantially parallel to central axis 40, 
and a rear portion which will be described hereafter. 
The rear portion of vent plug B includes mounting means D for mounting the 
plug B in a vent hole while providing air flow past outer peripheral 
surface 44. The rear portion of vent plug B also includes sloping rear 
surface means which slopes toward central axis 40 in a direction away from 
flat front face 42. In the arrangement shown, the rear surface means is 
defined by intersecting outer and inner rear surface areas 46, 48 which 
intersect one another at an intersection line 50 and at an included angle 
52 which is substantially greater than 90.degree. and less than 
180.degree.. 
Intersection line 50 between outer and inner rear surface areas 46, 48 is 
located substantially less than one-half the radial distance from outer 
peripheral surface 44 to central axis 40. When widths are described, it is 
to be appreciated that what is meant is widths as measured parallel to 
central axis 40. To that end, the width of outer rear surface area 46 is 
substantially greater than the width of inner rear surface area 48 and is 
also substantially greater than the width of outer peripheral surface 44. 
Outer rear surface area 46 intersects the rear edge of outer peripheral 
surface 44 and slopes at an included angle with central axis 40 of 
approximately 40.degree.-50.degree., with 45.degree. being the optimum. 
Inner rear surface area 48 is inclined at an included angle with central 
axis 40 of approximately 70.degree.-80.degree., with approximately 
75.degree. being the optimum. Thus, included angle 52 between outer and 
inner rear surface areas 46, 48 is approximately 140.degree.-160.degree., 
with approximately 150.degree. being the optimum. It will be seen that the 
slope of inner rear surface area 48 is substantially greater than the 
slope of outer rear surface area 46 and that the length of inner rear 
surface area 48 is also substantially greater than the length of outer 
rear surface area 46. 
Mounting means D comprises a spider having a plurality of spokes 54 
circumferentially spaced equidistantly from one another and extending 
generally radially of central axis 40. Spokes 54 terminate at outer spoke 
terminal end 56 which lie on the periphery of a circle having a diameter 
greater than the diameter of circular head C. Spoke terminal ends 56 are 
longitudinally grooved as generally indicated at 58 to provide teeth 
thereon extending substantially parallel to central axis 40. Thus, the 
teeth will, in effect, bite into the peripheral wall of intermediate 
diameter bore 34 of FIG. 2 when vent plug B is mounted therein as shown in 
FIG. 3. 
As shown in FIG. 5, spokes 54 divide the inner rear surface area into a 
plurality of individual inner rear surface segment areas 48, 48a and 48b. 
However, as shown in FIG. 6, spokes 54 extend outwardly beyond outer rear 
surface area 46 so that outer rear surface area 46 is circumferentially 
continuous while the inner rear surface area is circumferentially 
interrupted by the spokes of the mounting means. As shown in FIG. 6, 
spokes 54 have flat surfaces 60 which extend substantially perpendicular 
to central axis 40 in facing relationship to outer rear surface area 46. 
The spider defined by mounting means D has a substantially flat rear face 
62 extending substantially perpendicular to central axis 40. The 
intersections between spoke terminal ends 56 and spider rear faces 62 are 
chamfered at 45.degree. angles as indicated at 64. 
Referring again to FIG. 5, spokes 54 have opposite side surfaces 70, 72 
which extend parallel to central axis 40 and substantially perpendicular 
to rear face 62 of spider D. Side surfaces 70, 72 of adjacent spokes 54 
intersect or merge at smoothly curved juncture portions 74 whose surfaces 
also extend substantially perpendicular to spider rear face 62. Side 
surfaces 70, 72 and juncture portions 74 between adjacent spokes 54 define 
a generally U-shaped periphery or configuration. Each U-shaped periphery 
is curved to lie on the periphery of a circle whose center 76 is located 
inwardly from outer peripheral surface 44. Each U-shaped periphery 
intersects terminal spoke ends 56 at intersections 78. The width of each 
generally U-shaped periphery across intersections 78 as measured along 
line 80 in FIG. 5 is less than the depth of the generally U-shaped 
periphery as measured from line 80 to the center of the base thereof. The 
total length of each U-shaped periphery along its curved path between 
adjacent intersections 78 is less than one-half the circumference of the 
circle on which it lies. Each U-shaped periphery intersects a segment area 
48, 48a, 48b at a generally U-shaped intersecting line. 
As shown in FIG. 6, inner rear segment area 48 intersects smoothly curved 
juncture portions 74 at an intersecting line 82. The width of juncture 
portions 74 as measured parallel to central axis 40 is substantially 
greater than the width of inner rear surface portion 48. Each generally 
U-shaped periphery between adjacent spokes as described includes opposite 
legs and a base portion. The width of spider D at this base portion as 
indicated at 74 in FIG. 6 is substantially greater than one-half the width 
of spider D at terminal spoke ends 56 thereof. The generally U-shaped 
intersecting line between each inner rear surface segment area 48, 48a, 
48b with spider D lies in a plane which intersects central axis 40 at an 
included angle substantially less than 90.degree.. 
With a vent plug of the type described, air flows past outer peripheral 
surface 44 and is then directed inwardly generally along inclined outer 
and inner surface areas 46, 48. This creates a tremendous increase in 
velocity. Also, the changing directions of air flow create turbulent 
swirling flow in a vortex-type of motion so that a plurality of individual 
turbulent and swirling air flows leave spider D along juncture portions 74 
inwardly of the peripheral surface of small diameter bore 36. Thus, 
particles are carried along in these individual turbulent air streams 
instead of engaging the walls of the vent hole. The many changes in 
direction of the air flowing past outer peripheral surface 44 scour the 
surfaces of vent plug B to minimize build-up of deposits thereon and 
minimize any dead air spaces. 
In a typical vent plug sized for use with the hole of FIG. 2, head C has a 
diameter of approximately 0.974 inches while the diameter of the circle on 
which spoke ends 56 lies is approximately 1.004 inches. The circles on 
which the U-shaped peripheral portions are formed in FIG. 5 have a radius 
of approximately 0.313 inch and centers 76 lie approximately 0.875 inches 
from central axis 40. 
For the size of the hole mentioned in FIG. 2, reference is had to FIG. 6 
for a plurality of width dimensions for vent plug B. Dimension 90 is 
approximately 0.383 inch. Dimension 92 is approximately 0.188 inch. 
Dimension 94 is approximately 0.125 inch. Dimension 96 is approximately 
0.07 inch as manufactured. However, when plug B is installed in a vent 
hole, the inner surface of the plate and outer faces 42 of the vent plugs 
are machined smooth so that when a plate with plugs installed is ready for 
use, dimension 96 of outer peripheral surface 44 is approximately 0.010 
inches-0.030 inches with the optimum being approximately 0.019 inches. 
Thus, the final size of dimension 90 is approximately 0.323-0.343 inch 
with the optimum being approximately 0.332 inch. 
The invention has been described with reference to the preferred 
embodiment. Obviously, modifications and alterations will occur to others 
upon a reading and understanding of this specification. It is intended to 
include all such modifications and alterations insofar as they come within 
the scope of the appended claims or the equivalents thereof.