Apparatus for finishing shaped articles

An apparatus for finishing shaped articles which includes a working table, a finishing tool and movable mounting on said table for moving a shaped article toward and away from said finishing tool.

BACKGROUND 
In the manufacturing of shaped articles, for example by compression 
moulding of moulding compounds containing curing resins, some excess 
material is pressed out between the mould parts in the form of a burr. 
This burr must be removed from the article after its release from the 
mould and the edges of the article must be finished by trimming and 
perhaps polishing. This finishing often requires considerable handwork. In 
order to avoid this, finishing apparatus has recently been introduced in 
which the article is placed on a rotating disc whereafter the articles are 
brought into contact with a tool. This contacting has however involved 
many problems. 
In some cases the rotating disc is mounted in a fixed position while the 
treating tools are movably mounted for contact with the article. Since 
tool and motor are usually built into one single unit for practical 
reasons, this arrangement means that a very heavy weight must be moved to 
and pressed against the article, which involves problems in providing 
strong enough holding means for the tool unit to avoid vibrations, 
problems, in the adaption to different article shapes and sizes, problems 
in moving the tool unit quickly into contact with the article, and 
problems in regulating a slight pressure between the article and the heavy 
tool unit. 
In other cases the tool is mounted in a fixed position while the rotary 
article holder is movably mounted and brought into contact with the tool 
by means of a spring pressure. In these cases problems have arisen both 
with the arrangement of the driving means for the rotating article holder, 
which arrangement tends to be complicated, and with the spring pressure 
characteristics, which give rise to bouncing and vibrating effects between 
tool and article and an irregular treating result. 
For these reasons hitherto used finishing apparatus have in general been 
usable only for articles of simple shape, e.g. plain dishes, and have not 
been usable for articles of more complicated shape. 
THE PRESENT INVENTION 
I have found that by placing the article holder movably in one end of a 
pivoting arm it is possible to, by simple means and in a highly controlled 
way, bring the article in contact with the stationary tool unit. By 
actuating the rotary article holding means with the aid of a driving shaft 
extending from the table, and necessary transmission means, the problems 
involved in arranging the driving of the holder is solved in a simple and 
effective way. By creating the necessary contact pressure between tool and 
article by means of a brake system affecting some part of the driving 
system, an even, constant and non-vibrating pressure force is obtained, 
which force can be easily regulated and made independent of the movements 
of the pivoting arm when an irregular shaped article is treated.

A rotary holding disc 2 for supporting the article A to be treated is 
mounted adjacent the outer end of a pivoting arm 4. The disc 2 can rotate 
around a rotary holder shaft 3 that is mounted near the outer end of the 
arm 4. The inner end of the pivoting arm 4 is journalled in bearings to a 
working table 1. This can be achieved by attaching the bearings 5a and 5b 
to a driving shaft 5 that is mounted perpendicular to the table 1. Mounted 
in this way the pivoting arm 4 can rotate freely around the axis of shaft 
5. A driving gear wheel 6 is attached to the upper end of the driving 
shaft 5. The gear wheel 6 engages the lower gear of the double gear wheel 
8. The lower gear of the double gear wheel 8 is located around the lower 
end of the rotary shaft 3a. The upper gear of the double gear wheel 8 
engages a brake wheel 9, which is given a strongly reduced speed through a 
suitable selection of gear ratios between gear wheels 6, 8 and 9. The gear 
wheel 9 is acted upon by a brake lining 10 which is actuated by an 
adjustable brake force e.g., by means of pressure springs 11. The tension 
in the springs can in turn be influenced by means of a hood 12 and an 
adjustable cam 13. 
Any suitable actuating means may be used to rotate the driving shaft 5, and 
this driving force is transmitted to the holder axis 3 via driving gear 
wheel 6, double gear wheel 8 and holder gear wheel 7, thereby causing the 
holder disc 2 and the article A to rotate. The rotation of the driving 
shaft 5 is also transmitted to the brake wheel 9 via driving gear wheel 6 
and double gear wheel 8. By forcing the brake lining 10 against the flat 
surface of brake wheel 9 by means of spring 11, hood 12, and cam 13, a 
braking force is applied to the brake wheel 9 and a reacting force is 
induced in the pivoting arm 4 thereby bringing the article into contact 
with, and maintaining a contact pressure against, the treating tool, 
schematically indicated in the drawing at 14. 
To obtain the best treating results, the gear ratio between the driving 
wheel 6, the double wheel 8 and the brake wheel 9 should be selected in 
such a way that a constant working pressure is obtained independently of 
the shape of the articles, e.g. oval or polygonal. This is achieved when a 
movement of the pivoting arm very little affects the speed of the brake 
wheel 9. In one embodiment of the invention the driving gear wheel 6 has 
14 cogs, the lower gear of the double wheel 8 has 36, the top gear of the 
double wheel 8 has twenty and the brake wheel 9 has thirty cogs. In this 
case, in order to lengthen the pivoting arm, two smaller gear wheels with 
twenty cogs each are inserted between double wheel 8 and holder gear wheel 
7, which has 36 cogs. With this construction a contact pressure highly 
independent of article shape has been obtained. 
Since several treating steps are often necessary to finish an article, it 
is preferred to fix several pivoting arms 4 to the working table 1 so that 
several treating stations, with the same or different treating tools 14 
are arranged around the table 1 and that the table is mounted rotary to 
enable continuous treating of each article on each arm in the different 
treating stations see FIG. 2. 
In this case it is preferred that when shifting treating stations, the hood 
12 of each pivoting arm 4 is run into engagement with separate cams 13 for 
each treating station, thereby making it possible to select the contact 
pressure individually for each treating step. In this way it is also 
possible to release the hood 12 from any influence during the station 
shift and thereby prevent undesired movements of the arm 4 during this 
procedure. Since in this case the arm 4 is released also from all 
stabilizing forces, it may be necessary to provide some kind of dampening 
means or guiding means for the movement of the arm 4. 
The invention is not restricted to the embodiment discussed above, but can 
be varied in many different ways within the limits of the following 
claims. For example the arrangement of shaft and gear wheels can be made 
in many other ways than those shown or entirely different driving means 
can be used e.g., wires. The brake means can affect some other part of the 
driving or transmission system, because the only necessary condition is 
that the brake system gives a reactive force component in the pivoting 
plane of the arm. Although it is in general most practical to let the 
driving shaft be concentric with the journalling axis of the pivoting arm 
in view of the simplicity and movability of the arm other arrangements are 
possible.