Continuous arcuate feed assembly

Abrasive grinding apparatus having a continuously revolving turret assembly to which a plurality of workpiece holding platens are affixed. Associated with the turret are angularly positioned stationary grinding assemblies having drum driven abrasive belts. Work enters and leaves the grinding stations at an acute angle with intermediate, complete belt coverage, whereby necessary system drive power is minimized.

BACKGROUND OF THE INVENTION 
The present invention relates to abrasive grinding apparatus and, in 
particular, to apparatus wherein the workpieces are continuously fed in an 
arcuate fashion and along an arcuate path so as to pass beneath the 
complete width of an orbitally driven endless abrading belt. 
In the production and finishing of various metallic parts, endless abrasive 
belts are oftentimes used to perform various rough and finish grinding 
operations. Such apparatus produces parts at high production speeds with 
relatively accurate flat, finished dimensions and desireable surface 
characteristics. Exemplary applications are in the grinding of cast parts 
such as in the automobile industry for water pumps, transmissions, 
cylinder heads, etc. Such equipment also typically comprises one or more 
driven belts, along with associated liquid cooling and waste removal 
mechanisms, with such equipment being positioned relative to the work so 
as to perform the various desired surface grinding operations. 
Most typically with such apparatus, the stationary grinding assemblies are 
positioned such that the workpieces pass orthogonal to the direction of 
travel of the abrasive belt or alternatively in line with the direction of 
belt travel. However, depending upon the amount of material to be abraded 
from each workpiece, such arrangements for large metallic workpieces are 
energy intensive and may require excessively large power plants, 
particularly when single pass operation is to be achieved. 
Alternatively though if the workpieces are fed to the belt at an angle and 
thus exposed to the abrading belt at an angle, the actual work surface 
exposed at any given time is relatively small due to the averaging effect 
of the angulated infeed. It is therefore a primary object of the present 
invention to take advantage of this characteristic via a turret assembly, 
to which a plurality of workpiece holding platens are affixed and whereby 
the workpieces are rotatably passed through the apparatus where multiple 
operations may be accomplished, such as through exposure to "rough" 
grinding and "finish" grinding abrasive operations. In this fashion, the 
workpieces are moved continuously through the apparatus and exposed to the 
abrading belts at an angle which requires less overall system power than 
would otherwise be required. 
Rotational or arcuately driven feed assemblies for various grinding 
apparatus have been employed previously, as for example in U.S. Pat. Nos. 
2,406,728 and 2,855,730. The apparatus disclosed in each of these patents, 
however, is distinguishable from the present apparatus. In particular, 
which the U.S. Pat. No. 2,406,728 has an arcuate infeed assembly, it 
follows the common practice of presenting the workpiece in an orthogonal 
fashion to the abrading belt. U.S. Pat. No. 2,855,730 on the other hand, 
presents the workpiece in an angular fashion; however, it is 
distinguishable from the apparatus of the present invention in its 
structure and application. 
The above objects, advantages and distinctions of the present apparatus as 
well as others will however, become more apparent upon a reading of the 
following description with respect to the following drawings. 
SUMMARY OF THE INVENTION 
A continious feed endless belt abrading system having an arcuate feed 
assembly supporting a plurality of platens to which desired workpieces are 
attached for exposure to one or more grinding operations. Loading and 
unloading of the workpieces may be accomplished either manually or through 
automatic equipment. Portioned about and apart from one another and 
relative to the feed assembly are a pair of workpiece-abrading stations, 
each station comprising a resiliently biased adjustable endless belt 
abrading mechanisms disposed relative to the path of the workpieces such 
that the workpieces are introduced into and exposed to the abrading 
surfaces of the belts at an angle relative to the belt motion. This 
arrangement has been found to significantly reduce system power 
requirements.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to FIG. 1, a generalized perspective view is shown of the present 
apparatus and the relative positioning of its primary components. In this 
regards, the apparatus is generally comprised of a cabinet 2 which 
contains a "rough" endless belt grinding assembly 4 and a "finish" endless 
belt grinding assembly 6. Each grinding assembly comprises a driven lower 
contact drum 8, an upper idler drum 10 and an abrading belt 12. The belts 
12 typically have an abrasive grit selected for the material of 
construction of the work and the nature of the operation, such as a coarse 
grit for rough work and a finer abrasive grit for finish work. Each belt 
also typically is 5 to 50 inches wide sufficiently to handle the operation 
selected. The grinding assemblies 4 and 6 are, in turn, driven via 
associated drive motors (not shown) which are positioned on the respective 
right and left sides of the cabinet 2 and which are coupled to the 
grinding assemblies 4 and 6 via associated drive pulleys and belt 
mechanisms. 
Positioned beneath the grinding assemblies 4 and 6 is a work piece 
supporting turret assembly 16 which revolves about a center axis 18 via an 
appropriate drive mechanism and motor (not shown). Attached to the table 
20 of the assembly 16 are a plurality of platens 22 of various desired 
shapes and sizes and having various indexing holes and pegs formed therein 
for subsequent alignment with various types of work pieces that will be 
mounted thereto such turret assemblies are known in the art. 
Thus, upon mounting the workpieces to the platens at an infeed station, the 
platens are revolved so as to bring the workpieces first beneath the rough 
grinding assembly 4 and then beneath the finish grinding assembly 6, after 
which the workpiece is removed at the outfeed station. It should be noted 
too that a coolant (typically water) is supplied to the drums of the 
individual grinding assemblies 4 and 6 via a coolant inlet port continued 
on the back of the cabinet 2 and sprayed on the work pieces during normal 
operation so as to cool the abrasive belts 12 and workpieces. Also and not 
shown, the cabinet 2 contains associated waste removal apparatus for 
collecting the waste water and material abrasively removed from the 
workpieces so as not to unduly contaminate the grinding operations of 
subsequently treated workpieces. It is should also be noted that typically 
spaced about the periphery of the table 20 are mounted a number of safety 
switches (not shown) for detecting positions, including the elevation and 
radial positions of the workpieces as well as a part gauge for detecting 
the extent of abrasive belt wear. 
Referring next to FIG. 2, a generalized top view is shown of the apparatus 
and the relative positioning of the grinding assemblies 4 and 6 with 
respect to the rotating turret 16. From this figure, the grinding assembly 
drive motors 24 and associated V-belt drive pulleys 26 and V-belts 28 can 
more readily be seen. More particularly though, it is to be recognized 
that as the workpiece containing platens 22 move on their arcuate paths 
along with turret table 20, they initially meet and pass under the 
abrading belts 12 at an acute angle, which angle gradually changes as the 
work is rotated through its path and exposed to the surface of the belt. 
Thus, the work enters along the bias relative to the path or axis of the 
abrasive belt 12 so as to incrementally expose more and more surface area 
of the workpiece to the belt as the work passes thereunder. For the 
present embodiment, it has been determined that when abrading 
approximately 0.100 inches from aluminum or iron castings of approximately 
60 square inches, an initial acute angle of 15 degrees to 60 degrees is 
preferred in that the horsepower requirements of the drive motors 24 can 
be reduced from about 65 horsepower to about 50 horsepower. Such a power 
reduction is further significant in that significant costs are saved not 
only from the initial purchase, but also over a span of time, due to the 
reduced power demands. 
Referring next to FIG. 3, a partially cut-away and sectioned end view is 
shown of a typical grinding head assembly, such as illustrated at 4 and 6 
in FIG. 1, with this figure illustrating the detail of the adjusting 
mechanism utilized in the head assembly. In addition to the contact drum 8 
and idler drum 10, each assembly is comprised of an intermediate 
extendable air cylinder 34 used to properly tension the endless abrasive 
belt. 
With continuing reference to FIG. 3, and also with reference to FIG. 4, the 
contact drum 8 may be adjusted either upwardly or downwardly in relative 
position from the center bar 48 via two screw-jacks 40, with drum 8 being 
laterally guided via four individual guide posts (not shown). The 
screw-jacks 40 operate concurrently, or cooperatively via couplings 46 and 
jack-shaft 42 and 44. 
Normally, controlled adjustment of contact drum 8 is required in order to 
change and/or establish the grinding plane of that head independently of 
the grinding plane of the other grinding heads of the overall apparatus. 
For example, the first grinding head is normally set with its grinding 
plane contacting the work to establish a rough dimension, with the 
grinding plane of the second grinding head being established to remove a 
modest amount of additional material to provide the work with a finished 
part dimension. In the embodiments illustrated in FIGS. 1 and 2, the first 
grinding head is included in assembly generally designated 4, with the 
finish grinding being accomplished by the grinding head included in 
assembly generally designated 6. 
Air bladders are included in the adjustment system, with such bladders 
being shown at 30--30. These air bladders function as a machine overload 
protection device. The force created by the air bladders hold the drum 
guide and assembly in place against a positive stop. This arrangement 
provides a means for holding the contact drum 8 on or along the 
pre-established or desired grinding plane. 
In FIG. 3, the positive stop is illustrated at 49, which is the ledge or 
lower-most surface of the groove 49A formed in center bar 48. Plate 51, 
which is coupled to the open-end edges of inverted channel 53 forms a 
box-like support frame for applying normal grinding force to the grinding 
head, while at the same time providing overload protection in the event of 
an overly thick or mis-fixtured part passing under the drum. In such an 
event, the box-arrangement consisting of plate 51 and channel 53 will 
raise upwardly off of stop surface 49, thus achieving overload protection 
for the machine. It may be seen, therefore, that air bladder 30 is 
provided to hold the entire adjusting unit downwardly against stop 49. 
The vertical adjustment for establishing the grinding plane for drum 8 is 
obtained with adjustable screw-jacks 40--40. Thus, jacks 40 along with 
guide posts 41--41 which are coupled thereto by means of plate 43 are 
utilized to establish the vertical elevation or disposition of drum 8. 
When a plurality of screw-jacks such as screw-jacks 40 are utilized, it may 
be desirable to gang the jack shafts together, such as jack shafts 42 and 
links 46 so as to achieve equal motion on the individual jack shafts. Such 
an arrangement expedites change-over, as well as providing a means for 
maintaining control of the grinding plane. It should also be noted that an 
appropriate bracket 52 supports the bearings 54 and axle shaft 56 of the 
lower contact drum. Similarly, an axle 58 and bearings 60 rotatably 
support the idler drum 10. 
The air pressure maintained in bladders 30 is regulated and maintained 
remotely. The force created by the bladders 30--30 determines the 
available grinding force. Should an excessive grinding pressure be 
encountered, the bladder will accomplish relief by permitting contact drum 
8 to rise, thereby preventing over-stress or overload conditions from 
occurring on the machine. 
The brake 38 is provided for use in emergency situations, and achieves 
emergency stops when appropriate. Brake 38 is activated by the machine 
operator pushing or energizing the emergency stop button, or automatically 
in the event the abrasive belt should sever or move too far out of its 
normal operating path. In the event of a fracture of the abrasive belt, 
idler drum 10 would normally continue to rotate for an extended period of 
time due to inertia forces alone. In order to reduce the time required for 
installation of a fresh abrasive belt, brake 38 is energized automatically 
when the system senses that an abrasive belt has ruptured, separated, or 
broken, or is not found in its normal operating path or position. 
With attention being briefly directed to FIG. 2 of the drawings, bracket 32 
is an outboard support bracket used to stabilize the grinding head while 
grinding is occurring, and to prevent the grinding head from deflecting 
upwardly and laterally in response to forces created by the normal 
resistance to the grinding load. This support may be defined as a swing 
support, and is normally hingedly secured, as indicated, to permit the 
support to be removably positioned to permit abrasive belt loading. 
In operation, power is applied to the lower contact drum 8 and axle shaft 
56 via the associated drive motor 24 and the pulley sheave 26 attached 
fast on axle shaft 56. Thus, as the contact drum 8 rotates it causes the 
abrasive belt 12 to remove the desired thickness of material from the 
workpiece. A self-center tracking assembly 64 associated with the idler 
drum 10, also permits the apparatus to electronically monitor the belt 
position relative to the drums 8 and 10 so that it remains centered. 
Electrical belt-tracking systems are commercially available. 
While the present invention has been described with respect to its various 
preferred components and configuration, it is to be recognized that 
various modifications may be made without departing from the scope of the 
presently described invention. It is therefore contemplated that the 
following claims should be interpreted in conjunction with the present 
description to include all such equivalent structures.