Package making – Apparatus for contraction of cover by stretching or shrinking – By heat shrinking
Reexamination Certificate
2000-05-18
2003-02-25
Rada, Rinaldi I. (Department: 3721)
Package making
Apparatus for contraction of cover by stretching or shrinking
By heat shrinking
C053S567000, C053S585000, C053S296000, C493S273000, C493S288000
Reexamination Certificate
active
06523331
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a machine for fitting heat-shrink plastics material sleeves on objects, in particular elongate objects of small section, the sleeves being taken from a continuous sheath that is rolled up flat.
BACKGROUND OF THE INVENTION
In a technique that is conventionally used in this field, this type of machine for fitting sleeves has a shaping mandrel over which the sheath is passed in order to open it, sheath drive means using motor-driven wheels which co-operate with an associated portion of the shaping mandrel to fit the open end of the sheath on an object, and cutter means that act between the shaping mandrel and the object to form a sleeve that is associated with said object.
Thus, over the last score or so years, a concept has been developed of shaping mandrels that are mounted floating and that extend vertically. On this topic, reference can be made to the following documents: FR-A-2 490 590, U.S. Pat. Nos. 3,792,807, 3,910,013, 4,016,704, 4,600,371, GB-A-1 430 090, and EP-A-0 109 105.
To transfer the sheath continuously around the shaping mandrel, the machines described in the above-specified documents use motor-driven presser wheels co-operating with backing wheels carried by the shaping mandrel, with the sheath that surrounds the shaping mandrel while traveling along it being clamped between the motor-driven presser wheels and the backing wheels which are mounted idle on axles associated with the mandrel. Those techniques are now thoroughly understood and in widespread use for fitting sleeves on objects such as flasks, bottles, and other containers.
Nevertheless, if it is desired to use sheaths of small diameter for putting on objects that are fine and elongate, i.e. sheaths of a diameter considerably smaller than 20 mm, the above technique using backing wheels mounted idle on the shaping mandrel becomes impractical. It is not possible to envisage mounting backing wheels on a shaping mandrel of diameter significantly smaller than 20 mm since such backing wheels would then be very small in diameter which would require them to rotate at very high speeds of rotation as the sheath travels along the shaping mandrel, and that would give rise to phenomena of wear and overheating that are incompatible with reasonable use on an industrial scale.
Proposals have also been made to organize the travel of the sheath over a shaping mandrel by pinching the sheath between two motor-driven wheels at an intermediate opening in the shaping mandrel.
Thus, document JP-A-1 410 808 discloses a floating mandrel type shaper having, in addition to an arrangement of wheels and idle backing wheels, a central window in which two motor-driven wheels pinch the walls of the sheath. However, the floating mandrel continues to be supported by the wheels and the backing wheels provided further up the shaper. Using the same approach, document U.S. Pat. No. 2,765,607 illustrates a floating mandrel which is constituted by two portions interconnected by side rods, with a central gap being formed in which the motor-driven drive rollers pinch the walls of the sheath. The floating mandrel is then supported by a rounded surface of the flattened top portion (which also forms an insertion spatula) bearing against the two motor-driven rollers. The bottom portion having a circular base then serves as a shaper and as a counterweight. Reference can also be made to document FR-A-2 738 797 which shows a shaper having two torpedoes interconnected by a plate where the sheath is pressed by driven wheels, or indeed to document EP-A-0 368 663 which shows a shaper having two floating mandrels, one of which is flat with a window (through which the sheath is pinched by drive wheels), while the other is torpedo-shaped, and disposed downstream from the cutter device.
In a variant, as shown in document FR-A-2 061 240, proposals have also been made to use a vertical shaper made up of two torpedoes interconnected by a rod, with drive wheels that pinch the flattened sheath in the vicinity of the rod, and with contact via four idle wheels being provided on each of the torpedoes. In that case also, the use of bearing wheels prevents the use of sheaths of small diameter.
Finally, the shaping mandrels shown in the above-mentioned documents do not really serve to solve the problem of transferring sheaths of very small diameter since inevitable phenomena of overheating and wear arise, which phenomena run the risk of damaging or even tearing the continuous sheath while it is being transferred over the mandrel. This is particularly true when it is desired to use such a machine at high rates of throughput, e.g. one hundred to two hundred sleeves fitted per minute. A sheath of diameter lying in the range 5 mm to 20 mm gives rise to a flat ribbon of narrow width (8 mm to 31 mm), and the flat ribbon is then relatively rigid and difficult to pull. The high mechanical strength gives rise to high forces that need to be overcome, from which the above-mentioned phenomena of overheating and wear arise. In addition, when rates of throughput are high, the positions of objects traveling beneath the shaper need to be controlled by using clamps or the like, thereby further complicating the structure of the fitting machine.
In general, the above-described techniques do not genuinely make it possible to optimize expanding the sheath while accurately controlling the section of the sheath as it leaves the shaping mandrel to engage on the object concerned. This makes it necessary to provide sheaths of diameter that is considerably greater than that of the objects they are to cover. Consequently, it is not possible to control the position of the sleeve in satisfactory manner, either axially or transversely. This becomes particularly critical when the sleeve is to be shrunk onto the object, in so far as the sleeve can be poorly positioned on the object and in any event shrinking needs to be that much greater. The person skilled in the art is well aware of the difficulties encountered under such circumstances, and in particular concerning attempts to control the position and the shrinking of the sleeve, above all when such a sleeve has printed wording and/or decoration thereon.
SUMMARY OF THE INVENTION
The invention seeks specifically to resolve that problem by designing a sleeve-fitting machine that gives higher performance while avoiding the above-mentioned drawbacks.
Thus, the object of the invention is to design a machine for fitting sleeves of heat-shrink plastics material on objects starting from a continuous sheath that is rolled up flat, the machine being entirely compatible with sheaths of small diameter, e.g. diameters lying in the range 5 mm to 20 mm, while nevertheless being capable of operating at high rates of throughput, i.e. considerably exceeding 200 sleeves fitted per minute, with the positions of the sleeves as fitted on the objects nevertheless being properly controlled.
According to the invention, this problem is resolved by a machine for fitting sleeves of heat-shrink plastics material on objects, the sleeves being taken from a continuous sheath that is rolled up flat, the machine including a shaping mandrel over which the sheath passes in order to be expanded, sheath drive means using motor-driven wheels which co-operate with an associated portion of the shaping mandrel to engage the open end of the sheath on an object, and cutter means intervening between the shaping mandrel and the object so as to form a sleeve associated with said object, the shaping mandrel being substantially horizontal and comprising two torpedoes in axial alignment interconnected by a thread-like central element, with an upstream torpedo having an upstream end forming an insertion spatula and a downstream end with a pair of smooth chamfers, and a downstream torpedo presenting an upstream end with a pair of smooth chamfers and a downstream end with a straight edge adjacent to the cutter means, each torpedo of said mandrel resting freely in an associated V-support, and the sheath drive means comprising, between the two V-su
Friedman Stuart J.
Nixon & Peabody LLP
Rada Rinaldi I.
Sleever International Company
Truong Thanh
LandOfFree
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