ADHESIVE TAPE CUTTING DEVICE FOR TAPING UNIT

Abstract: The adhesive tape cutting device comprises a cutting blade (28) constrained to a moving support (6) which guides said blade (28) to intercept the tape (33) at a predetermined point on the path of travel of the tape. The (28) blade is constrained in a yielding manner to said support (6) in such a manner that said blade (28), following its engagement with the tape (33), is entrained by the latter and then, thanks to the yielding nature of its constraint with the support, follows the travel of the tape until completion of the tape cut.

Description: The present invention relates to an adhesive tape cutting device for a tape applying device, i.e. a so-called taping unit. From the known art are known taping units provided with a cutting device consisting of a blade with pointed cutting teeth which is integral with a lever made to rotate at the moment the box being sealed has reached a predetermined point on its path of travel. An example of said device is described in Italian patent application no. 23191 A/84 filed by the same applicant as of the present application. In said device the blade moves in a transverse direction in relation to the tape and, meeting it along its travel as determined by the box, cuts it and at the same time withholds it in its longitudinal movement, thus causing the penetration of the blade teeth into the adhesive tape until breakage thereof is achieved by traction of the remaining part of the resisting tape not yet cut by the blade. This cutting system, in addition to having a tendency to tear the tape, causes a part of the adhesive material to be withheld by the cutting blade teeth, compromising the cutting effectiveness of said blade. This shortcoming leads to a greater frequency of laborious cleaning of said blade. EP-A-220942 discloses a tape applying device including a mechanism actuated by the taped article to move a blade support at about the same speed that the tape is moved along a travel path. DE-A-2744953 discloses a tape applying device having a cutting blade rigidly mounted on a rotating disk. In view of this state of the art the object of the present invention is to accomplish a very simple adhesive tape cutting device which would eliminate the aforesaid shortcomings and provide a clean, reliable cut of the tape. In accordance with the invention said object is achieved by providing an adhesive tape cutting device for taping units comprising a cutting blade mounted on a moving support which guides said blade to intercept the tape at a predetermined point of a path of travel of the tape, characterized in that said cutting blade is yieldingly mounted on the associated moving support so that its engagement with the tape causes said blade to move with respect to said support in the advancement direction of the tape. With such an arrangement the blade, after engaging the tape, is subject to the entrainment effect of the tape, following its travel for a short distance and consequently remaining in contact with the tape for all the time necessary to secure a complete and accurate penetration of the teeth into the tape until achieving complete separation of the two parts of the tape. The cut takes place progressively with the gentle penetration of the blade teeth into the tape without causing added tension on said tape. In addition, there being no relative movement between the blade and the tape, not only is there no tearing but the accumulation of adhesive material on the blade is avoided and hence the related shortcomings. Lastly, thanks to the increased effectiveness of the cutting effect of the device in accordance with the invention, the feed speed of the boxes can be increased. A possible form of practical accomplishment of the present invention is illustrated as a non limiting example in the annexed drawings wherein: FIG. 1 shows a longitudinal cross section of an adhesive tape cutting device in accordance with the invention along line I-I of FIG. 2, FIG. 2 shows a top view of the aforesaid device, FIG. 3 shows an enlarged partial side view of said device from the left of FIG. 1, FIG. 4 shows an enlarged front view of the blade and associated support along line IV-IV of FIG. 1, FIG. 5 shows an enlarged cross section of the blade and associated support along line V-V of FIG. 1, FIG. 6 shows an enlarged cross section of the blade and associated support along line VI-VI of FIG. 1, and FIGS. 7 to 9 show successive phases of application and cutting of the tape. With reference to FIGS. 1 to 3 there is shown an adhesive tape cutting device fitted in a taping unit of which only the outer frame is indicated with reference number 1. The cutting device, indicated as a whole by reference number 51, is constrained in a moving manner to the frame 1 by a pair of side levers 2 pivoted at 3 on the frame 1 and connected by a transverse shaft 4 (FIG. 2). At the upper ends 5 of said levers 2 are pivoted at 50 two shaped arms 6 which develop in a front portion 7, a central portion 8 and a rear portion 9. Said arms 6 are connected together by a first connecting pin 10 whose ends are fixed to the central portions 8 of the two arms 6 and are subjected to the effect of respective side springs 11 whose upper ends 12 are engaged in grooves 40 made in the end 13 (FIG. 3) of a second pin 14, said ends 13 being held in neutral position by an upper edge 15 of the frame 1. The lower ends of the springs 11 are held by respective stop members 16 with adjustable position while the central part of each spring is wrapped around a pin 37 fixed to the frame 1. The rear portions 9 of said arms 6 bear a common pin 17 on which is mounted in a turning manner a blade holder 18 which is subject to the effect of a spring 19 which is wound around the central part of the pin 17 and whose heads 20 and 21 exert a pushing action against the pin 10 and the support 18 respectively. The rear portion 9 of said arms 6 is provided with a perpendicular tab 22 placed parallel to the pin 17 in a position such as to provide a stop for the blade holder 18 stressed by the spring 19. As better illustrated in FIGS. 4 to 6 the blade holder 18 consists of a supporting plate 23, provided with side arms 24 pivoted at the ends of the pin 17 and placed along the inner sides of the rear portions 9 of the arms 6, and of a blocking plate 25 having seats 26 designed to receive the heads of locking bolts 27 to fix a blade 28 mounted on the external face of said plate 23. For correct positioning of the blade 28 there is provided on said external face a centering element 29 which fits in a notch 45 (FIG. 4) made in the center of the blade 28. Preferably the blade is mounted in a slightly inclined manner so that its teeth do not pierce the tape simultaneously. The blade 28 is also provided with a protective screen 30 having an opening 31 to permit passage of the blade 28 in the phases of approach to the tape and cutting. Said screen 30 is constrained to said side levers 2. The accomplishement shown is the preferred one but it is clear that a different type of yielding constraint can be provided between the blade and the support. For example, in place of the spring 19 between the plate 23 and the pair of levers 6 can be employed an elastic means placed directly between the blade 28 and the associated support 6. The cutting device described is designed to operate as follows. As shown in FIG. 7, while a strip of tape 33 is being applied to the bottom of a box 32 due to the entrainment effect (in a known manner) of said advancing box, the levers 2 are in retracted position inside the frame 1 and press against the bottom of the box due to the effect exerted by the side springs 11 on the pin 14 constrained to the arms 6. The blade 28 is also in a retracted position. When the box 32 passes the upper ends 5 of the levers said levers, due to the effect of said springs 11, emerge from the inner space of the frame 1 and entrain with them the central portions 8 and rear portions 9 of the arms 6, which rotate around the pins 50 until they reach a position at the end of their travel in which the ends 13 of the pin 14 stop against the upper edges 15 of the frame 1 while the front portions 7 of said arms 6 are held beneath the bottom of the box (FIG. 8). Rotation of the arms 6 cause simultaneously extraction of the blade 28 which, as shown in FIG. 8, engages the tape 33 and causes its teeth to penetrate gradually into the tape. At this point the tape 33, which is continuously entrained by the box 32 but is not yet cut, exerts on the blade an entrainment effect thanks to which the blade 28, overcoming the resistance of the spring 19, rotates slightly around the pin 17, accompanying the travelling movement of the tape until the teeth thereof complete the cutting of said tape (FIG. 9).

Claims: Adhesive tape cutting device for a tape applying device, comprising a cutting blade (28) mounted on a moving support (6) which guides said blade (28) to intercept the tape (33) at a predetermined point on a path of travel of the tape, characterized in that said blade (28) is yieldingly mounted on the associated support (6) so that its engagement with the tape causes said blade (28) to move with respect to said support (6) in the advancement direction of the tape. Device in accordance with claim 1 characterized in that said blade (28) is fitted in a blade holder (18) connected in an elastically yielding manner to said moving support (6). Device in accordance with claim 2 characterized in that said moving support (6) consists of a pair of shaped arms (7, 8, 9) connected together. Device in accordance with claim 3 characterized in that said blade holder (18) is mounted in a turning manner on a pin (17) connecting said arms (7, 8, 9) and is yieldingly held by a spring (19) in a predetermined neutral position in relation to said moving support (6). Device in accordance with claim 4 characterized in that said blade holder (18), when in said neutral position, is butted against transversal extensions (22) of said shaped arms (7, 8, 9). Device in accordance with claim 4 characterized in that said blade holder (18) consist of a supporting plate (23) provided with arms (24) pivoted on said second pin (17) and a locking plate (25) provided with openings (26) for passage of bolts (27) for fixing said blade (28) to said blade holder (18). Device in accordance with claim 6 characterized in that said supporting plate (23) is provided with a centering element (29) of said blade. Device in accordance with claim 1 characterized in that said blade (28) is mounted directly in an elastically yielding manner on said moving support (6).

Inventors: MARCHETTI, AUGUSTO
Applicants: MARCHETTI, AUGUSTO
Application year: 1988
Main classification: B65H35
IPC codes: B65H35