Note: Descriptions are shown in the official language in which they were submitted.
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3001 0/PCT
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METHOD AND APPAI~TUS FOl~ TI-XE STI~APPING OF PACKAGES
Ol~ STACKS BY USING TAPE OF`HEAT-SE~I,ABI,l~ PLASTIC
The present invention relates to a strapping machine and a method of
strapping packages or stacks.
Methods and strapping machines are disclosed in Federal Republic of
Germany 39 lg 674. In the l~lown method, the upper part of the loop formed by the
loop puller, adjacent to the initial region of the strapping, is heat-sealed to the initial
region of the strapping by means of a heatillg tongue and pressure jaws. The strapping
which is closed in this manner is separated from the rest of the tape on the side of the
heat-sealill, device WhiCIl iS in the direction of feed after the gripper has previously
gripped the new starting end of the tape. In this method, it is necessary that the gripper
which grips the corresponding starting end of the tape be moved upon each operating
cycle from the side of the heat-sealing device which is in the direction of feed to the other
side of the device and turned 360.
The object of the invention is to provide a method of strapping packages
20 ~ or stacks, in particular, stacks of newspaper, in which movement of a gripper from a
position in front of the heat-sealing device into a position behind the heat-sealing device
is not necessary. I
Another object of the invention is to provide a machine for the strapping
of packages or stacks which, at little expense for machinery and with high reliability of
25 operation, can, in rapid sequence, wrap packages or stacks which are advanced along a
conveyor path.
The use of an ultrasonic heat-sealing head has the advantage over a heating
tongue in that it is immediately ready for operation without the need for preheating. An
- ultrasonic heat-sealing head rapidly and dependably seals the two layers of the initial
30 region of the strapping which lies against the backing plate and the loop folded on the
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ultrasonic heat-sealing he~d to the s~rting region of the sLr~pping. By the double overlap
of the in;tial region of the strapping by the folded loop, the result is~t~ jarts
or layers of th~ loop can rcst snugly against the bottom of the package or stack and there
is no elld ~vl~icll pro~rudcs rrom Lhe package or stacl; wllicll can lead to injuries.
Embodiments of the machine of the invention will be described below with
reference ~o tlle drawings, in wllicll:
Figs. l to 6 diagrammatically show six different stages of operation of the
strapping machine of the invention; and
Fig. 7 is a diagrammatic view of the machine after the pulling of the loop
0 - and shortly before the heat-sealing.
In Fig. l, the tape 4 of heat-sealable plastic is conducted ~rom a tape feed,
formed here by the supply roll 3, to a gripper consisting, of bottom part 6 and upper part
7. The tape 4 forms a tensioll strap portion 8 for a package l which is advanced on a
conveyor path 2, arranged betweell the supply roll 3 an~l the gripper 6, 7, against the
tensiolled strap portion 8. The advance of the package l can be effected by conveyor
belts or pushcrs yreferably present on both sides of the strapping plane. The starting end
S of the tape 4 is initially held fast by the gripper 6, 7.
In Fig. 2, the package l, upon its movement to the left, has pushed the
strap portion 8 out to such an extent that the strap portion surrounds the package 1 on its
bottom, front and top. The upper part lO of a clamp 9, 10 and a backing plate 13 are
pushed between the bottom of the package 1 and the initial region 21 of the tape 4, said
clamp and backing plate forming a single part. After the tape has been clamped and held
between the bottom part 9 and the upper part 10 of the clamp, the gripper 6, 7 releases
the starting end 5 of the tape. The upper part 7 of the gripper is pulled back out of ~he
plane of the strapping. A smoothener 14 which moves forward and backward in the
strapping plane smooths out the starting end of the tape 5 which has been released by the
gripper 6, 7, by pressing it against the backing plate 13. This action also insures that the
starting end S of the tape and the initial region 21 come to rest against the backing plate
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13. The initial region 21 and the backing plate 13 extend from the starting end 5 of the
tape up to the clamp g, 10.
Referring to Fig. 3, as soon as the rear of the package 1 has reached the
backing plate 13, the tape feeder 15, which is initially arranged above the tape 4, presses
the tape downward to a position below the conveyor patll 2 so that the package 1 is
surrounded on all sides by the tape 4. Above the downwardly lo.wered tape feeder lS and
below the plane of the initial region 21, a loop puller 16 can be inserted into the
s~raypillg plane, it bcing moveable in direction of advancf~ parallel to the backing plate
13 and pulling, below the initial region 21, a loop which is formed of an upper part 17
Wllicll is adjacent to tlle initial region 21 and a lower part 18 which extends back to the
tape feeder lS.
As shown in Fig. 4, in this stage of operation the opened gripper 6, 7 is
brought into the strapping plane. The upper part 7 of the gripper 6,7 is between the
upper part 17 of the loop and its lower part 18 so that, upon the closing of the gripper
6, 7, the lower part 18 of the loop is gripped in the vicinity of the lowered tape feeder
lS, i.e. in the end region of the loop 17, 18.
, In Fig. 5, an ultrasonic heat-sealing head 12, disposed below the backing
plate 13 and below the loop 17, 18, moves upward and heat-seals the two parts or layers
of the loop 17, 18 against the initial region 21 of the tape. In this connection, the knife
2 o 20 and the lower part 6 of the gripper 6, 7, move rapidly forward so that the tape 4 and
tape starting end 5 of the following operating cycle are clamped before the heat-sealing
head 12 effects the heat-sealing. The ultrasonic heat-sealing head 12 forces the two parts
of the loop 17, 18 against the initial region 21 of the tape Iying against the backing plate
13 and heat-seals Ihe two layers of the folded loop 17, 18 against the initial region 21.
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Referring to Fig. 6, the loop puller 16, the tape feecler 15, the clamp 9,
10, the backing plate 13 witll the upper part 22 of the clamp 7, 22, as well as the
ultrasonic heat-sealing head 12 and the knife 20 return to their individual starting
positions. The strapped package 1 is free and the strap portion 8 is ready for the
5 strapping of the ne~t package. In this connection, the gripper 6, 7 holds the new starting
end of the tape 5 firMly until the clamp 9, 10 takes over, as sho~n in Fig. 2.
In the operating stage shown in Fig. 2, the downward movement of the
tape feeder 15 is triggered by a sensor or a light barrier. The sensor or light barrier
advises the drive of the tape feeder 15 when a package or a stack has passed through the
lo p1ane of movement of the tape -feeder 15. After the clamp 9, lO has grasped tlle tape in
the initial region 21 and the gripper 6, 7 has released the starting end 5 of the tape, the
upper part 7 of the gripper 6, 7 is pulled back from the strapping plane. In the operating
stage shown in Fig. 5, this upper part 7 of the gripper is brought into the strapping plane
in order, together with the lower part 6, to grip that part 18 of the loop 17, 18 which
e~ctends from the loop puller 16 in the vicinity of the tape feeder 15. The parts 6, 7 of
the gripper are displaceable vertically independently of each other so that they can be
shifted from a lower position into the higher position shown in Fig. 5.
In the operating stage shown in Fig. ~, the upper part of the gripper 6, 7
and the end region 22 of the backing plate 13 facing away from the direction of ad\~ance
form another clamp, 7, 22. This structure holds the tape 4 stretched over the package
or stack l in the region of the starting end of the upper part 17 of the loop 17, 18 before
the loop puller 16 is pulled back out of the strapping plane. This upper part of the
gripper 6, 7 and lower part of the second clamp 71 22 also form a cutting device with the
knife 20. The lower edge of the upper part 7 of the gripper 6, 7 Iying in the direction
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- of advance is developecl as a cutting abutment which, togeLher witll the knife 20, prior
to the sealing together, cuts ~he lower part of the loop 17, 18 off from the new starting
end S of the tape gripped by the gripper 6, 7. The l;nife 20 can be moveable vertically
independently of other parts of the machine or can be attached to the lower part of the
gripper 6, 7 in such a manner that the tape is cut shortly before the gripper 6, 7 clamps
the new starting end 5 of the tape.
Fig. 7 shows the stage of operation of Fig. 4 on a larger scale. In this
case, the tapc ~ withdrawll from the supply roll 3 is guided over a roller which serves
as tape feed 11. The strap portion 8 is formed between this tape feed 11 and the gripper
0 6, 7. Before tlle ~lltrasonic heat-sealillg head 20 is moved up to seal the two parts 17,
18 to the starting region 21, the second clamp 7, 22 clamps the starting region of the
upper part of the loop 17, 18 in order to maintain the tension of the strapping when the
tape puller 16 is withdrawn from the strapping plane shortly before the heat-sealing.
In order for the packages or stacks 1 to be strapped continuously, the
strapping machine is moveable in the direction of advance of the packages or stacks 1 at
the speed of said packages or stacks 1 and backward with greater speed in the direction
opposite the direction of advance. The greater this backward speed, the smaller the
distances between the packages 1 on the conveyor path 2 can be.
In order to effect a strapping transverse to the direction of advance of the
conveyor path 2, the conveyor path 2 has a transversely extending slot of, for instance,
8 cm so that a strapping plane can be established in this slot with a gripper 6, 7, a first
clamp 9, 10, a backing plate 13, a second clamp 7, 22 and an ultrasonic heat-sealing head
12 with knife 20. The feeding out of the strap portion 8 present alongside the conveyor
path 2 is effected by means of a pusher which is displaceable transverse to the conveyor
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path 2 and the end of which is somewhat higher than the packages or stacks to bestrapped. Before a pacliage or stac}i reaches the slot, the pusher moves from one side
of the conveyor path 2 to the other so that the package or stack can move into the strap
portion 8. The package or stack 1 then stops above the transversely extending slot and
5 the tape feeder 15 moves into its lower position so that the loop puller pulls a loop 17,
18 below the backing plate 13 and the ultrasonic heat-sealing head 12 heat-seals the
folded loop 17, 18, against the initial region 21 of the strapping. Thepusher contacts the
strap portion 8 via a relatively thin plate which pushes the string out transverse to the
conveyor path 2 and slides without difficulty, upon the further transport of the packages
0 1, out of the slot between the side wall of the package 1 and the strapping. This
crosswise strapping machine was substalltially the same parts and units as described
above.
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