A roller cutter and its mode of operation

Abstract

 The proposed cutter comprises a cutting roller (21) mounted on a powered movable carriage (16) and a fixed switch means (13) sensing the end of the stroke and placed at one end of the stroke of carriage (16), while at an intermediate location of the stroke an adjustable and slidable stop means (25) is provided, against which the cutting carriage (16) at least once comes to a stop, and an electronic apparatus measuring, storing and controlling the length of the cutting stroke. When said apparatus has no stored data relating to the stroke to be travelled by the carriage (16), the latter moves towards the stop means (25), then after abutting thereagainst, it reverses the travel and measures the travelled distance, then stores this distance after subtracting a fixed amount therefrom. An elastic web holding plate (27) is also provided which automatically releases the web C not pressed by the thrust rollers (26).

Description

[0001] This invention relates to cutters, in which the cut is carried out by means of a roller cooperating with a counterblade, said roller being driven by mechanical means, such as a stepping motor or a D.C. motor.

[0002] Several cutters of this type are known, but such cutters either provide a cutting stroke always in a same direction, or, if bidirectional, require complicated adjusting devices for the cutting stroke, whereby a production shut-down is necessary whenever a stroke variation is desired.

[0003] Another problem of the conventional cutters consists in the web holding plate which, as well known, is effective for blocking the web during the cutting operation. Thus this plate must be lifted whenever the web has to advance. Therefore, it is necessary to provide for actuating the plate both in blocking and in releasing direction, if it is desired that at least one stroke end may occur at any location of said plate.

[0004] It is the primary object of the present invention to provide a powered roller cutter which may cut in both directions webs having any width, without requiring complicated adjustment of the cutting stroke.

[0005] It is another object of the present infvention to provide a web holding plate enabling the automatic lifting of said plate as soon as no pressure is applied thereon.

[0006] The above mentioned primary object has been achieved by providing that a cutting roller cutter mounted on a powered movable carriage and fitted with a fixed conventional type switch means sensing one end of the stroke and of the carriage, also comprises at an intermediate location of said stroke a , slidable adjustable stop means, against which the cutting carriage comes at least once to a stop, as well as an electronic apparatus for measuring, storing and controlling the cutting stroke. When the apparatus has no stored data for the stroke that the carriage should travel, it moves the . carriage urging it against the stop means, then after the carriage abuts against it, the apparatus reverses the carriage run and measures the travelled distance, travelled till the switch means, then stores this distance after subtracting a fixed amount therefrom. The value obtained will correspond to the normal stroke length that the carriage will travel, upon command in any direction until the machine is requested to make a new adjustment. The fixed switch means sensing one end of the stroke will be the starting location for the forward stroke of the carriage, while in the return stroke this same switch means will serve as a reset member for the apparatus. The carriage will continue to carry out these cutting strokes upon command until the memory of the stroke length in the electronic apparatus is not erased by a reset button.

[0007] Preferably, the stop means is connected with one of the side guides of the web, so that the movement of this guide provides at the same time for moving said stop means.

[0008] According to the invention, an embodiment provides that the web holding plate is resilient and arranged so as to face, but not touch, the web when not pressed. Preferably, the plate is cantilevered secured at some distance from the counterblade edge. The free portion of the plate is preferably pressed by two thrust rollers arranged just before the cutting roller on both cutting sides thereof, that is the arrangement is such that the web is pressed just prior to or at same time of cutting.

[0009] Provision is also made for possible addition of an electric signalling device which measures the web length being unwound and then controls the cut operation. Where the web carries or supports a series of labels, it is provided that this signalling device can also count a number of labels.

[0010] The use of a keyboard is also provided enabling also to manually preset the cutting stroke and possibly also the web length or the number of labels which must remain connected.

[0011] The invention will now be better explained with reference to an ' exemplary embodiment which has been shown in the accompanying drawing, in which:

Fig. 1 is a diagrammatic perspective view showing the cutter according to the invention;

Fig. 2 is an enlarged diagrammatic front view showing only a portion of the device near the cutting roller and the web holding plate; and

Fig. 3 is an enlarged sectional view taken along line III-III of Fig. 2.

[0012] A cutter according to the invention comprises a somewhat rectangular base member 10 having two shoulders 11 and 12 mounted at the ends thereof. An electronic switch means 13 sensing one end of the stroke is provided adjacent to the shoulder 12, for example a lamp and photoelectric cell. This switch means will cause the stop of the cutting stroke at a fixed location at the right end, as seen in the drawing, and will serve as zero reference location for both strokes, that is for forward and return strokes. Said base member 10 further carries a counterblade 22 for cooperation with the cutting roller 21. On the outlet side of the web, just above said counterblade 22, an elastic web holding plate 27 is provided, which is secured to an elongated support 28 and cantilever projects over the counterblade 22, as shown in Fig. 3. The web C runs between said counterblade 22 and the web holding plate 27.

[0013] Two shafts 14 and 15 are secured between said two shoulders 11 and 12 and are effective as a guide for a carriage 16. This carriage is driven by a motor 17, which may be a stepping motor, or a D.C. motor. In this case, an encoder is mounted for calculating the number of revolutions effected and acuordingly the distance travelled by the carriage. A friction is also provided on the pulley 18 mounted on the output shaft of motor 17. A looped belt 19 the ends of which are secured to said carriage 16, passes around said pulley 18 and around an idle pulley 20 located at the other end of the cutter, that is adjacent to said shoulder 11. Said carriage 16 is provided with a cutting roller 21 for cutting the web C coming from a roll, not shown. The carriage 16 is also provided with two thrust idle rollers 26 arranged, as shown in Fig. 2, so as to press the web immediately before the latter is cut by roller 21. Thus, during the cutting operation, said elastic plate 25 will hold said web C always pressed and fixed. What is important is that as soon relieved from the pressure of said thrust rollers 26 said plate 25 moves away, thus allowing the web C to pass between the counterblade and the elastic plate 25. This will occur when the carriage is at the end of its stroke. The thrust rollers 26 will be placed as close as possible to the longitudinal edge of the web, while allowing freedom to the same, but providing that the carriage travels the shortes possible distance.

[0014] The web C is caused to slide between two guides one of which, the guide 23, is fixed and arranged near shoulder 12 and switch means 13, while the other guide 24 can slide so as to remain parallel to guide 23. This guide 24 is integral with a stop means 25, slidable on shafts 14 and 15, which already carry and guide carriage 16. The stop means 25 is located at such a position as to minimize the stroke of the carriage 16, when said guide 24 is in contact with the left edge 31 of web C.

[0015] The operation of the above described cutter is as follows.

[0016] The web C is placed between the guides 23 and 24. Particularly, one edge 30 of web C is adjacent to the guide 23, while the other guide 24 is displaced until coming in touch with the other longitudinal edge 31 of web C. Thus, the stop means 25 will also be displaced. Assume that the electronic apparatus has no data stored. It will then command the carriage 16 to move towards said shoulder 11, that is towards the stop means 25. This first movement is controlled by causing the motor 17 to rotate through a number of revolutions corresponding to at least the maximum admitted stroke. At some time during this moviment, said carriage 16 will strike the stop means 25. The motor will idle for a further short time, then will reverse the movement and calculate the distance travelled from the beginning of this reversal until the carriage 16 reaches the switch means 13 and therefore stops. The electronic apparatus provides for subtracting a predetermined fixed amount from this measured value, then stores the distance obtained, which will be considered by the cutter as the stroke length that the carriage 36 must carry out from now on until it looses its memory due to a manual reset operation. The switch means 13 is the start location for the forward stroke of the carriage, and the arrival location for the return stroke. In other terms, said switch means 13 will reset the stroke length at the end of every return stroke.

[0017] When a manual control, the electronic apparatus or the electric signalling device 33 will inform that a cut must be carried out, the carriage will move travelling a distance or stroke which is just as long as that stored in the memory.

Claims

1. A cutter having the cutting roller (21) mounted on a powered movable carriage (16) and a-fixed switch means (13) located at one end of the carriage stroke, characterized by further comprising at an intermediate location of the stroke also a slidable and adjustable stop means (25), against which the cutting carriage (16) at least once comes to a stop, and an electronic apparatus for measuring, storing and controlling the length of the cut stroke.

2. A cutter according to Claim 1, characterized in that said stop means (25) is connected to one (24) of the side guides for the web (C), so that the movement of said guide (24) causes at the same time the movement of the stop means (25).

3. A cutter according to Claim 1 or Claim 2, characterized in that the fixed switch means (13) comprises an electric device sensing the proximity of the carriage (16), particularly a photoelectric cell.

4. A cutter according to any of the preceding claims, characterized in that the fixed switch means (13) is used as start location for the forward stroke of the carriage (16) and as resetting member for the return stroke of the carriage.

5. A cutter according to any of the preceding claims, characterized in that the web holding plate (27) is resilient and cantilever arranged so as at rest it faces, but does not touch the web, said plate coming in touch with the web only when pressed thereagainst.

6. A cutter according to any of the preceding claims,. characterized in that an electric signalling device (33) is provided, which device measures the length of the unwound web and controls the cut.

7. A cutter according to any of the preceding claims, characterized in that a keyboard is provided, by means of which the cutting stroke can be manually preset and in case also the web length or the number of labels to be maintained connected.

8. A cutter according to any of the preceding claims, characterized by being further provided with a reset button erasing the stored data in the electronic apparatus.

9. A process for operating a cutter, according to any of the preceding claims, characterized by the steps of providing that when devoid of memory the cutting carriages (16) will move against the stop means (25), then after striking there. against will reverse its run or travel and measure the travelled distance necessary to reach the switch means (13), then stores the value obtained subtracting a fixed amount from the sensed distance, which value will correspond to the normal stroke to be travelled by the carriage in any direction until a new adjustement is requested.

10. A process according to Claim 9, characterized in that a manual erasion of the memory is also provided, so that the machine can provide for a new stroke to be travelled.

Drawing