Test device, in particular for bottle-shaped containers as well as procedure for testing same

The test device (7) serves in particular for testing bottle-shaped containers (4), and is in the form of a piston/cylinder assembly. It has two pistons (41, 53) in order to test simultaneously or consecutively two properties of the container (4), while the position of the container (4) and cylinders (30, 31) remains the same. The two pistons (41, 53) can be operationally connected by a piston rod (42). The piston strokes are different. Containers which are to be filled with a liquid material and are preferably made of plastic can be tested in this way before they are filled with the material thus making it possible to locate quickly and unambiguously any containers which are to be rejected owing to their dimensions, resistance to crushing, sealing property and so on, before the filling process takes place.

BACKGROUND OF THE INVENTION 
The present invention relates to a test device, in particular for 
bottle-shaped containers, fashioned as a piston/cylinder assembly, as well 
as to a procedure for testing especially bottle-shaped containers 
consisting essentially of a synthetic resin. 
During the course of continuously increasing efficiency, efforts are made 
to run certain events within ever shorter time periods in order to reduce 
overall costs and time in, for example, the packaging industry. 
It has been found in this connection that, in the packaging industry, the 
performance of individual working steps entails not only spatial but also 
chronological overloads in that the transit time in, for example, the 
canning industry, from checking the empty container to checking after 
labeling, requires a long treatment path and a long treatment time. 
The present invention has the object, along these lines, to simplify the 
existing conditions in such a way that, in particular, containers to be 
filled with liquid material which preferably consists in the majority of a 
synthetic resin can be tested before being filled with the material in 
order to quickly and unambiguously locate any rejects, for example, with 
respect to dimensioning, crushing resistance, leakproofness, and the like, 
prior to the filling procedure. 
As is known, one strength of such containers particularly synthetic resin 
bottles, is determined with the aid of a compression device. Such testing 
machines, operating with spindle drives or simple pistons, are 
conventional. Thereafter, the leakproofness of the container is then 
tested, for example, in a further machine. 
In this process, there is not only a need for two different devices or 
machines, but also for a corresponding time period for moving the test 
specimens and for conducting the corresponding test. 
The present invention has the object of providing an improvement in this 
respect so that such tests are made simpler in every respect, i.e. with 
regard to space occupied, time requirement, need for machines. 
The present testing device comprises several pistons in order to test 
several properties of the container with the container and cylinder 
remaining in the same position. 
A corresponding procedure is distinguished in that the container and the 
test device are placed into the testing position and subsequently, leaving 
the two items in the testing position, several properties of the container 
are tested.

DETAILED DESCRIPTION 
Referring now to the drawings when like reference numerals are used 
throughout the various views to designate like parts and, more 
particularly, to FIG. 1, according to this figure, a testing installation 
for testing bottle-shaped containers consisting of a synthetic resin 
according to the present invention includes a test specimen in the form of 
a bottle 4 disposed in a test yoke 3 arranged along a revolving or 
linearly moving feed line. The test specimen involves a simple bottle 4 
with a bottleneck 5. A test device 7 is attached in the upper yoke arm 6 
of the test yoke 3, with the test device 7 including a piston/cylinder 
assembly and being operated by compressed air. A compressedair connection 
9 is provided with a pressure regulator 10 for regulating the air pressure 
required for determining the crushing resistance of the bottle 4. The 
compressed air, controlled in this manner, passes via a supply conduit 11 
to a 3/2-way valve 13 which can be switched so that the adjoining conduit, 
containing a manometer 14, is either supplied with compressed air or, 
alternatively, in the position illustrated in FIG. 1, exhausts air into 
the atmosphere from the test device 7. 
The testing installation furthermore includes a limit switch 17 which 
becomes operative in case the bottle 4, the neck 5 of which is exposed to 
axial pressure, does not exhibit the demanded crushing resistance and 
therefore the corresponding part of the test device 7 drops downwards and 
thus actuates limit switch 17. The limit switch 17, activated in this 
manner, ensure that, during the further course of movement, the 
corresponding bottle 4 is carried away as a reject. 
In a conduit parallel to the supply conduit 11, a pressure regulator 20 is 
disposed for regulating the adjustable leakproofness pressure to which the 
bottle 4 is exposed as will be explained below. A supply conduit 21 leads 
to a manometer 22 and to a 4/2-way valve 23, with one connection of the 
valve 23 serving to couple a supply conduit 25 to effect sealing of the 
bottle 4 for its leakproofness test with the use of compressed air, while 
the second supply conduit 26 delivers the compressed air for returning the 
test device into its initial position. 
As shown in FIG. 2, the test device 7 comprises a top cylindrical jacket 30 
and a bottom cylindrical jacket 31. The top cylindrical jacket 30 is 
closed off by a cylinder cover 32. The two cylindrical jackets 30 and 31 
are threaded together by a connecting nipple 34. The bottom cylindrical 
jacket 31 is sealed off by a cylinder sealing nipple 35 with an end of the 
nipple 35 being provided with a thread so that the test device 7 can be 
attached with the air of a mounting ring 37 and a securing ring 38 in the 
upper yoke arm 6. 
The cylinder cover 32 is equipped with a central compressed-air connection 
bore 40, which latter leads into the interior of the cylindrical jacket 30 
wherein an upper piston 41 is displaceably arranged. The piston 41 is 
provided with an inner piston rod 42 having a free end face 43, with the 
piston 41 being sealed with respect to the cylindrical jacket 30 by an 
annular lip seal 44 and an O-ring 45. The piston rod 42 extends into an 
upper guide bushing 47 introduced within the connecting nipple 34 and 
provided with an O-ring seal 48. A compressed-air bore 50 laterally 
arranged in the connecting nipple 34 includes a coupling nipple 51 through 
which compressed air can be supplied from the supply conduit 11, with the 
connecting nipple 34 having a vent bore 52 terminating in the cylindrical 
chamber of the top cylinder jacket 30. 
A lower piston 53 with a piston rod 54 is provided beneath the connecting 
nipple 34, with the piston 53 being equipped with two annular lip seals 55 
and 56. 
The cylinder-closing nipple 35 has a lateral compressed-air bore 58 with a 
nipple 59, sealed by an O-ring 60. The piston rod 54 is guided in a lower 
guide bushing 62 with an O-ring gasket 63 in the cylinder-closing nipple 
35. 
The bottom end of the piston rod 54 is designed as a threaded pin serving 
for retaining a coupling head 65, the threaded pin being threaded into the 
threaded bore 66 of the coupling head 65. Two bores are provided in radial 
extension laterally in the coupling head 65, a compressed-air bore 67 and 
a coupling bore for a manometer 68. The two bores communicate with each 
other through a longitudinal bore terminating in a lower threaded bore of 
the coupling head 65. The threaded bore serves for accommodating a sealing 
cap 70 which, in turn, retains a sleeve 72 with a longitudinal bore 73 
with the aid of a threaded pin 76 so that the compressed-air bore 67 can 
conduct air, via the longitudinal bore 73 of the sleeve 72, into a central 
opening of a size-determining measuring head 71. An inner sealing surface 
75 is provided, for resting on the end rim of the bottleneck 5, for 
example, while the leakproofness test is being performed. 
If the bottle 4 is to be subjected to a leakproofness test, the valve 23 is 
adjusted so that the compressed air passes through the supply conduit 25 
and the compressed-air coupling bore 40 to the free end face of the upper 
piston 41 and moves same downwardly. During this step, the free end of the 
piston rod 42 comes into contact, with its surface 43, with the free 
surface of the lower piston 53 so that the piston rod forces the lower 
piston together with its piston rod 54 and the parts attached thereto in 
the downward direction. During this procedure, the size-determining 
measuring head 71 enters the bottleneck 5 and tests its passage. 
Subsequently, the sealing cap 70, with its sealing surface 75, contacts 
the top rim of the bottleneck 5. During this movement, the upper piston 41 
has entered its bottom abutment position. In this position, the sealing 
surface 75 rests, with a predetermined, settable pressure, on the free rim 
of the bottleneck 5 so that the interior of the bottle is sealed with 
respect to the outside. By corresponding control, compressed air now 
passes through the bores 67 and 73 into the interior of the bottle 4 and 
the latter is filled with air. In this procedure, the final pressure must 
be maintained for a predetermined time period so that the bottle can be 
evaluated as being leakproof. A corresponding control takes care of the 
elimination of leaky bottles 4. These control units, known per se, do not 
constitute the subject of the present invention and thus are not explained 
in detail. 
For testing the resistance to crushing of the bottle 4, correspondingly 
compressed air passes via the supply conduit 11 and the nipple 15, as well 
as the bore 50 into the interior of the connecting nipple 34 where the air 
acts on the free piston surface of the lower piston 53, which opposes the 
surface 43, and urges the piston downwardly. During this movement, as in 
the leakproofness test, the sealing surface 75 of the sealing cap 70 again 
comes into contact with the rim of the bottleneck 5. In this connection, 
the force exerted on the bottle rim and acting in the direction of the 
longitudinal axis of bottle 4 is significantly higher than the force 
required for sealing purposes. In this manner, the bottle 4 is subjected 
to a crushing test. If the structure of the bottle 4 is perfect, it will 
withstand this crushing pressure. If the bottle 4 is flawed due to, for 
example, a thin wall thickness, or an irregularly distributed wall 
thickness, and the like, then the bottle 4 will not withstand the force 
exerted on the bottle 4, and it will buckle. Due to the correspondingly 
large stroke of the lower piston 53, the sealing cap 70, while the bottle 
4 buckles, will come into contact with the limit switch 17 and activate, 
as explained, the reject control. 
For returning the two pistons 41 and 53, the supply conduit 26 is supplied 
with compressed air (switching arrangement in accordance with FIG. 1). The 
compressed air returns the piston 53 and, pushing it in front thereof, the 
piston rod 42 with the piston 41 into the upper abutment positions 
according to FIG. 2. During this step, the corresponding cylinder chamber 
is vented by the bore 50 by setting the valve 13, by switchover, to 
"exhaust" as can be seen in FIG. 1. Correspondingly, air is exhausted into 
the atmosphere through the conduit 25 by the valve 23, as illustrated. In 
order to prevent formation of a vacuum in the upper cylinder chamber, air 
from the atmosphere flows into the interior of the cylinder via the 
venting bore 52. 
Leakproofness test and crushing test can be performed as desired in a 
freely selectable fashion in succession or simultaneously. In order to 
ensure independence of the two tests, the stroke of the upper piston 41 
is, therefore, smaller, for example by 20 mm, than that of the lower 
piston 53. In this context, it should be noted, in principle, that the 
measure of the crushing force, to be employed as the limit force, must be 
larger in case of an internal excess pressure in the bottle 4, i.e. when 
performing the leakproofness test at the same time, than in case of normal 
pressure being ambient in the bottle 4. However, this circumstance can be 
taken care of by an appropriate setting of the pressures for operating the 
pistons. 
If the two tests are to be conducted in succession, for example first the 
crushing step and then the leakproofness testing step, then the crushing 
piston must be relieved after performing the crushing step, which is 
accomplished by the switching of the valve 13 as shown in FIG. 1. 
If the bottle 4 can withstand the crushing force during the crushing test, 
then the piston 53 is relieved after the crushing pressure testing period 
has elapsed; optionally, only the contact force according to the load of 
the upper piston 41 acts on the bottle 4 for sealing the same and for 
performing the leakproofness test. 
It is accordingly possible to carry out additional functional tests, 
especially also other tests, such as holding of the bottle for imprinting 
same, a height control of the bottle, and the like. The sequence of the 
tests and/or functions to be effected can be freely chosen, it being 
basically possible to perform other, additional functions on the bottle 4 
by the arrangement of further pistons. 
This combined installation with the test device along the lines of the 
structure of the test device 7 is very suitable, in particular, for 
high-performance machines, for example for testing carrousels, since in 
this case it is possible to provide that, per testing station, with a time 
stagger, the tests can follow one another in series and/or they can be 
performed simultaneously without an additional movement of the cylinder of 
the test device and of the container to be tested. 
In a carrousel testing machine, also called testing wheel, with four and 
more testing stations, mechanical engineering is substantially simplified 
by this device. It is, of course, likewise possible to perform only 
individual ones of the provided testing possibilities; this is a choice 
that can be made at the corresponding switchboard and selection board.