Abstract:
This invention relates to an electromechanically operable apparatus for severing strip, such as a paper tape or plastic film tape, which is dispensed by a power-operated dispenser. A swingable cutter blade is connected to a crank, which is operated by a gear train via an eccentric drive and a connecting rod, which is provided with a cam track cooperating with the crank. In dependence on the condition of the cam track and the sense of rotation of a motor for driving the gear train the extent of the angular movement imparted to the swingable cutter blade can be selected for the making of a complete cut or a partial cut through the strip.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to an electromechanically operable apparatus for severing strip, such as paper tape or plastic film tape, which is dispensed by a power-operated dispenser, which apparatus comprises a helical swingable cutter and a stationary cutter for cooperating with the swingable cutter. 
     2. Description of the Prior Art 
     Such apparatuses for severing strip, which comprise a slightly helically distorted, swingable cutter blade and a stationary cutter blade, which is spring-urged against the swingable cutter blade, are known from German Utility Model No. 87 16 108. That known apparatus comprises an angle bar formed in one leg with an external recess for receiving the swingable cutter blade whereas the second leg constitutes a bottom member and a motor is accommodated in the angle between the two legs. The angle bar is adapted to be cut to a length corresponding to the width of the strip to be cut. That severing apparatus is intended to be attached to or installed in suitable equipment and is only adapted to make full cuts through the strip, such as printed strip, moving through the apparatus. 
     German Patent Specification No. 29 31 634 discloses a severing apparatus which can make also partial cuts. The apparatus comprises reciprocating cutter blades, which are actuated by means of rocker levers preceded by a gear segment. An electromagnet and a number of mechanically acting members are required for such actuation and involve a high expenditure. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide an electromechanically operable apparatus for severing strip, such as paper tape or plastic film tape, which is dispensed by a power-operable dispenser, which apparatus should permit a free selection of the mode of operation as regards a complete cut or a partial cut, as an alternative to perforating, to be effected in a simple manner by a suitable control of the drive motor without an alteration of the cutting means. 
     It is another object to provide such an apparatus which can easily be adjusted for cutting a strip in a desired width. 
     In an apparatus which is of the kind described first hereinbefore said objects are accomplished in accordance with the invention in that the apparatus comprises drive means which are operable to drive the swingable cutter and comprise a crank connected to the swingable cutter, an eccentric drive, a gear train for driving said eccentric drive, a connecting rod connecting said eccentric drive to said crank and provided with a cam track, which has a portion extending in the direction of the axis of the connecting rod and containing an adjusting screw, which is adjustable to control the operation of the crank and the range of the angular movement of the swingable cutter for making a complete or partial cut through the strip. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a top plan view showing a severing apparatus partly cut open. 
     FIG. 2 is a transverse sectional view taken on line I--I in FIG. 1. 
     FIGS. 3 to 5 are elevations showing the apparatus, partly cut open, as viewed in the direction indicated by the arrow X in FIG. 1, in an initial position, in a position for making a complete cut and in a position for making a partial cut, respectively. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Further features of the severing apparatus in accordance with the invention will become apparent from the following description of a preferred embodiment shown by way of example in the drawing. 
     The illustrated apparatus for severing strip consisting in the present case of a paper tape 1 comprises two end walls 2 and 3, between which a stationary cutter blade 4 and a slightly helically distorted swingable cutter blade 5 for cooperating with the stationary cutter blade 4 are disposed, which are mounted in said end walls 2 and 3. The stationary cutter blade 4 is preferably spring-urged against the swingable cutter blade 5. A drive motor 6, a gear train 7 driven by the motor 6, and a hood 8 covering the motor 6 and the gear train 7 are also disposed between the end walls 2 and 3. The swingable cutter blade 5 is driven via the gear train 7 and an eccentric drive 9 for driving a connecting rod 10, which is provided with a cam track 11, which cooperates with a crank 12 for driving the swingable cutter blade 5. The cam track 11 is generally L-shaped and has a first leg, which extends in the direction of the axis a--a of the connecting rod 10 and is adjustable by means of an adjusting screw 13. The second leg of the cam track 11 is generally at right angles to the first leg and has a slightly concavely curved forward edge and a slightly convexly curved rear edge 14. 
     When the swingable cutter blade 5 is in its initial position shown in FIG. 2, a detent pawl 15 enters a notch 16 formed in the body of the cutter 5 to release the switch 17 for turning off the drive motor 6. When the gear train 7 drives the eccentric drive 9 in the sense indicated by the arrow A in FIGS. 3 and 4, i.e., in a counterclockwise sense, the crank 12 for driving the swingable cutter blade 5 will cooperate with the cam track 11 of the connecting rod 10 in the second leg thereof, which extends in the direction b--b, and will impart to the swingable cutter blade 5 an angular movement in the clockwise sense for making a complete cut through the paper tape 1. 
     The connecting rod 10 is pivoted to the eccentric drive 9 on a pin, which is formed with an annular groove 19. The connecting rod 10 contains a ball 20, which is urged into the groove 19 by a spring 18 so that a rotation of the eccentric drive 9 in the clockwise sense as viewed in FIGS. 3 and 5 will cause the connecting rod 10 to be raised so that the crank 12 for driving the swingable cutter blade 5 will cooperate with the cam track 11 in its first leg extending in the direction of the axis a--a of the connecting rod 10 and will impart to the swingable cutter blade 5 a smaller angular movement in the clockwise sense for making a partial cut through the paper tape 1. The making of a complete cut or of a partial cut will thus depend on the rotation of the eccentric drive 9 in the sense indicated by the arrow A or B, i.e., on the sense of rotation of the motor 6, which can properly be controlled. The extent of the angular movement of the swingable cutter blade 5 for making a partial cut can be adjusted by an adjustment of the adjusting screw 13 provided in the first leg of the cam track 11, which first leg extends in the direction of the axis a--a of the connecting rod 10. 
     The severing apparatus is shown in FIGS. 2 and 3 in an initial position with the paper tape 1 threaded through the apparatus between the cutter blades 4 and 5. When a control pulse is delivered via the lead 21, which by-passes the switch 17, to the drive motor 6, the latter imparts via the gear train 7 to the eccentric drive a rotation in the sense indicated by the arrow A in FIG. 3. Before the eccentric drive 9 reaches its dead center, the distance between the knife edge of the swingable cutter blade 5 and the knife edge of the stationary cutter blade 4 will slightly be increased because the motor 6 has previously been de-energized. As the rotation of the eccentric drive 9 proceeds, the upper portion of the cam track 11 of the connecting rod 10 engages the crank 12 to impart to the swingable cutter blade 5 an angular movement in the clockwise sense until the position shown in FIG. 4 has been reached and the paper tape 1 has entirely been cut through. 
     As the rotation of the eccentric drive 9 is continued until the initial position has been reached, the swingable cutter blade 5 is also moved to its initial position. At that time the detent pawl 15 snaps into the recess 16 so that the switch 17 is actuated to turn off the motor 6. The severing apparatus is now again in its position of rest. 
     When the paper tape 1 which has been threaded through the apparatus is to be cut only in part of its width, the drive motor 6 is controlled to impart to the eccentric drive 9 a rotation in the sense indicated by the arrow B in FIGS. 3 and 5. Owing to the frictional coupling established between the connecting rod 10 and the eccentric drive 9 by the ball 20 that is biased by the spring 18, the connecting rod 10 is raised so that the crank 12 for driving the swingable cutter blade 5 engages the cam track 11 in its first leg, which is horizontal in FIG. 5. The swingable cutter blade 5 is again moved in the clockwise sense. Because the cam track 11 is now in a different position and the drive crank 12 strikes against the inner end face 22 of the adjusting screw 13 the swingable cutter blade 5 is now moved through an angle α, which is smaller than the angle β of the angular movement imparted to the swingable cutter blade 5 for making a complete cut and only a partial cut is now made through the paper tape 1. The width of the cut can be adjusted within a wide range by means of the adjusting screw 13. The adjusting screw 13 can be screwed into the first leg of the cam track 11 to such an extent that the inner end face of said screw is flush with the forward edge of the second leg of the cam track 11. In that case a complete cut can be made by a rotation of the motor 6 in either sense and the motor 6 will also be turned off in that the switch 17 is released by the detent pawl 15. 
     The stationary cutter blade 4 may serve also to guide the strip and is preferably urged against the swingable cutter blade 4 by a spring 13 for an automatic readjustment in order to compensate wear. 
     The stationary cutter 5 has a helical first knife edge. The stationary cutter 4 has a second knife edge for cooperating with said first knife edge. The crank 12 is connected to the swingable cutter 5 and cooperates with the cam track 11 for imparting to the swingable cutter 5 an angular cutting movement, in which said first knife edge cooperates with said second knife edge, and for providing between the crank 12 and the cam track 11 a lost motion generally in the direction of the axis a--a of the connecting rod 10. The adjusting screw 13 is longitudinally adjustably mounted in the first leg of the cam track 11 to adjust the extent of said lost motion and thus to control the extent of said angular cutting movement. The recess 16, the detent pawl 15 and the switch 17 constitute means for de-energizing the motor 6 when the eccentric drive 9 and the swingable cutter 5 are in a predetermined initial position, in which the first knife edge is clear of said second knife edge. The crank 12 is arranged to cooperate with the cam track 11 in said first leg upon a rotation of the eccentric drive 9 from said initial position in a first sense indicated by the arrow A and in said second leg upon a rotation of the eccentric drive 9 from said initial position in a second sense, which is opposite to said first sense and indicated by the arrow B. The eccentric drive 9 comprises a disk, which is adapted to be rotated by the motor 6 via the gear train 7, and a pin, which is eccentrically mounted on said disk. A first end portion of the connecting rod 10 is pivoted and frictionally coupled to said pin. Said pin is formed with an annular groove 19. The first end portion of the connecting rod 10 is formed with an axially extending bore, which is open to the groove 19 and contains a ball 20, which protrudes into the groove 19, and a compression spring 18, which urges the ball 20 into the groove 19 to establish a friction fit between said ball and groove.