This invention relates to controlling the speed and tension of a web of labels supplied to associated labelling apparatus.
Labelling apparatus, such as roll-fed labellers, are commonly provided with reel stands which are adapted to hold a continuous reel of label web intended to be applied to containers, bottles or the like by the apparatus. Reel stand assemblies are used to hold this continuous web and to feed same at the required speed and tension to the other associated apparatus within the labeller. This associated apparatus, in the case of a roll-fed labeller, generally includes a cutter drum and a vacuum drum, which, in use, are desirably rotated at a predetermined speed. It is necessary for effective operation of the labeller to provide the label web to the drums at a proportionate speed. Failure to do this results in tearing of the web or, alternatively, cutting of the web at inappropriate increments such that individual labels are truncated or damaged.
It is envisaged that films used in relation to the aforementioned labels are likely to be increasingly reduced in thickness as material technology improves and this is also likely to be associated with an increase in the elasticity of the labelling material. It is therefore of significant importance to provide efficient and reliable means for regulating the speed and tension of the label web supplied to the associated labelling apparatus.
In the past it has been known to use a weight or mass to provide an appropriate tension. Generally, where this method is used, the use of alternative labelling films require alternative weights or masses to be used in the reel stand assembly. Alternative techniques have involved the use of a spring to tension the web, but this again is a mechanical means which frequently requires the replacement of parts in association with the replacement of labelling films. It has been known to connect these mechanical weights or springs to a dancer arm which is used to correct minor fluctuations in the speed or tension of the web being supplied to the associated labelling apparatus. Movement of the dancer arm in a first direction increases the tension of the supplied web, while movement of the dancer arm in the opposition direction is adapted to reduce the tension of the supplied web. The mean and desired tension of the web on the dancer arm is counter-balanced by the aforesaid mechanical weight or spring.
US Patent No 3,193,211 discloses apparatus for driving a strip, according to the preamble of claim 1, which is adapted to transfer labels from the strip on to bottles. The apparatus includes a feed reel, an intermediate driver and a take-up reel. There is also provided labelling apparatus for applying a label from the strip to the bottles, and means for regulating the speed and tension of the strip to the labelling apparatus. The regulating means comprises in part an arm which is adapted to move in a clockwise or an anti-clockwise direction in order to regulate tension on the strip via tension control means. This includes a pneumatic cylinder which has a variable, regulated air supply. This cylinder encourages the arm in a clockwise direction, and the tension in the strip encourages the arm in an anti-clockwise direction. Thus the arm reaches an equilibrium position where the two forces are balanced. The pneumatic cylinder can be used to adjust the force acting on the arm by regulating the air supplied to the cylinder.
According to the present invention, there is provided a regulating means for regulating the speed and tension of continuous label web for supply to associated labelling apparatus, wherein said regulating means comprises an arm adapted to move in a first direction and a second direction, wherein said arm includes tension control means and is adapted to grip said continuous web while said web is moving, wherein said tension control means comprises a pneumatic cylinder with a variable regulated air supply, wherein said cylinder is adapted to forcibly encourage said arm in said first direction, and wherein tension of said continuous web forcibly encourages said arm in said second direction, wherein said arm moves in the direction most encouraged and consequentially regulates the speed and tension of the web supplied, wherein said regulating means further includes a reel stand assembly having one or more reel bearing housing assemblies for supporting a respective reel of continuous label web, wherein each said reel bearing housing assembly includes braking means for retarding the speed of rotation of a respective said reel, wherein said braking means is controlled by control means characterised in that said control means further includes a rotary sensor communicating with said arm, such that when said arm is caused to move in said first direction the movement is detected by said rotary sensor and a signal is generated by said control apparatus which is adapted to activate said braking means.
Preferably, said reel bearing housing assemblies each further include a motor adapted to drive said reel, wherein when said arm is caused to move in said second direction said rotary sensor generates a signal to said motors, such that said motors accelerate the rotational velocity of the respective said reel.
An embodiment of the invention will now be described, by way of example only, with reference to the accompanying Figures, in which:-
Referring firstly to Fig. 1, a reel stand assembly 1 comprises two label reel-bearing housing assemblies 2a, 2b. Each reel bearing housing assembly 2 is adapted to support a reel of continuous label web 15 which, in use, is guided through a first guide roller 3 around a gripping means 4 on an arm 5 and thereafter again through a further guide roller 6. The label web 15 is then fed to associated labelling apparatus which may include a cutter drum and vacuum drum. As in the embodiment shown, it is common to provide two reel bearing housing assemblies 2a, 2b to enable quick changeover time when one label web has been used. The arm 5 is adapted to pivot about the point 10 such that it may rotate in a first direction, represented by the arrow A, or in a second direction, represented by the arrow B. When the arm 5 rotates in the first direction A, any slack in the continuous label web 15 is taken up. On the other hand, when the arm 5 rotates in the second direction B, the tension of the web is reduced. For this reason, the arm 5 is frequently called a dancer arm or a tension control arm as it dances in both first and second directions about a mean or equilibrium position X in order to regulate the tension of the web supplied to associated labelling apparatus.
It will be appreciated that the web 15 which moves around the gripping means 4 applies a force on the arm 5 which encourages the arm 5 in said second direction B. This is required to be counter-balanced by a tension control means, which in the invention, comprises an actuator such as a pneumatic cylinder 7 with a variable regulated air supply. The cylinder 7 encourages the arm in the first direction A to counterbalance the tension which is inherent in the web 15 which encourages the arm 5 in the second direction B. Thus, the mean force applied by the cylinder 7 is regulated by the air supply to maintain the arm 5 in an equilibrium position X.
It is appreciated in the invention that it is important to supply the label web to the associated labelling apparatus at a constant speed and tension. However, due to several variables, it is necessary to regulate the speed and tension of the supplied label as the label peeling off the reel on the reel-bearing housing assembly 2 may do so at a tension which is greater or smaller than the desired tension. When the tension of the web peeling off the reel is lower than that which is desired, the force applied by the actuator on the arm 5 is caused to exceed the force applied from the tension of the web around the gripping means 4 and the arm 5 is thereby caused to move in the first direction A. However, as this movement of the arm 5 takes place, any slack in the web 15 is taken up and the tension of the web then proceeding to the guide roller 6 is maintained at the optimum level. Conversely, when the tension of the web peeling off the reel is greater than the desired level, the force applied by the cylinder 7 on the arm 5 is less than the force applied on the gripping means 4 by the tension in the web 15 and consequentially the arm 5 is caused to move in said second direction B. This movement reduces the tension in the continuous label web fed through the guide roller 6 to the associated labelling apparatus.
When the arm 5 is caused to remain unduly in a position either in the first direction or the second direction away from the equilibrium position X, the air pressure supplied to the pneumatic cylinder 7 is regulated to correct this state, such that the arm 5 is encouraged to return towards the mean equilibrium position X. It is realised that the arm 5 may only move within certain limits and the invention is preferably caused to operate with the arm in close proximity to this equilibrium position X.
Other apparatus may be incorporated in the regulating means 1 to assist in the control or regulation of the tension and speed of the label web supplied to the associated labelling apparatus. This may include, for example, a braking means 8 on each respective reel bearing housing assembly 2 for slowing down the speed of rotation of the label reels. The brake 8 may be of any appropriate type, although electro-mechanical brakes are suggested as preferable. The brakes 8, in the embodiment shown, are adapted to be activated when the arm 5 is caused to travel in the first direction A. As explained above, this occurs when the speed of the reel is above that which is desired and the tension in the web is therefore reduced. A rotary sensor 9, such as a potentiometer, is adapted to sense the movement of the arm 5 in the first direction A and thereupon to transmit a signal via control apparatus 11 which is adapted to activate the brake 8. Once the arm 5 has returned to the equilibrium position X, the sensor 9 then sends a further signal to the control apparatus 11 which is adapted to deactivate the brake 8.
Further apparatus may be provided which provide regulating or controlling means to produce the opposite effect. A motor, such as a servomotor 14, may be attached to the reel-bearing housing assembly 2; the motor 14 being adapted to drive the reel 15 and, when appropriate, increase the rotational velocity of the reel. This means that when the continuous label web is supplied from the reel at an insufficient speed or velocity, the servomotor 14 can be accelerated such that the reel supplies the web at a greater speed. Again, the arm 5 would be caused to move in the second direction B and this would be sensed by a rotary sensor 9, such as the potentiometer shown, which would send a signal via the control apparatus 11 to the servomotor 14. The servomotor 14 may incorporate the electro-mechanical brake 8 or, alternatively, the brake 8 may be separate.
It will be appreciated by those skilled in the art that the invention provides a means for variably controlling the supply of label web to associated labelling apparatus with far greater control than that which has been known in the past. The variable control is applied to both the dancer arm 5 and the reel-bearing housing assemblies 2 and is adapted to both increase and decrease the tension and/or speed of the web in accordance with optimum levels.