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Title:
UNIT, STATION AND METHOD FOR WEIGHING CONTAINERS
Document Type and Number:
WIPO Patent Application WO/2018/202596
Kind Code:
A1
Abstract:
A weighing unit (1, 2, 3) for containers (A) for packaging machines, comprising - a gripper (4) for retaining the container (A), - a weight measurement device (8) for detecting the weight of the container (A). The gripper (4) can be moved between a measurement position, in which it is functionally coupled to the weight measurement device (8), and a loading position, in which it is functionally uncoupled from the weight measurement device (8). The invention also relates to a weighing station and to a weighing method.

Inventors:
FURLOTTI FILIPPO (IT)
Application Number:
EP2018/060967
Publication Date:
November 08, 2018
Filing Date:
April 27, 2018
Export Citation:
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Assignee:
FILLSHAPE SRL (IT)
International Classes:
G01G21/00; B67C3/24
Foreign References:
US6399901B12002-06-04
EP0001196A11979-03-21
EP1025424A12000-08-09
Attorney, Agent or Firm:
MODIANO, Micaela et al. (Via Meravigli 16, Milano, IT)
Download PDF:
Claims:
CLAIMS

1. A weighing unit (1, 2, 3) for containers (A) for packaging machines, comprising

- a gripper (4) for retaining the container (A),

- a weight measurement device (8) for detecting the weight of the container (A),

characterized in that

the gripper (4) can be moved between a measurement position, in which it is functionally coupled to the weight measurement device (8), and a loading position, in which it is functionally uncoupled from the weight measurement device (8).

2. The weighing unit (1, 2, 3) according to the preceding claim, characterized in that it further comprises a lever (15, 25, 35) and an actuator (61) that acts on said lever (15, 25, 35), said gripper (4) being supported by said lever (15, 25, 35), said actuator (61) being adapted to cause an oscillation of the lever (15, 25, 35), so as to cause the movement of the gripper (4) between said measurement and loading positions, the weight measurement device (8) being fixed with respect to the lever (15, 25, 35).

3. The weighing unit (1 , 2, 3) according to claim 2, characterized in that it comprises a device (7) for stabilizing in position the lever (15, 25,

35), which device (7) is configured to be active in the condition in which the gripper is in the loading position and inactive in the condition in which the gripper is in the measurement position.

4. The weighing unit (1 , 2, 3) according to claim 3, characterized in that the position stabilizing device (7) comprises a seat (71) that is fixed with respect to the lever (15, 25, 35) and an engagement profile (72) which is integral with the lever (15, 25, 35) and is substantially complementary to the seat (71).

5. The weighing unit (1, 2, 3) according to claim 3 or 4, characterized in that the weight measurement device (8) and the position stabilizing device (7) are provided at opposite sides of the lever (15, 25, 35).

6. The weighing unit (1 , 2, 3) according to one or more of claims 2 to 5, characterized in that the fulcrum (16, 26, 36) of said lever (15, 25, 35) comprises a revolute pair provided with at least one fixed rotation seat (16B) and with a pivot (16A) which is engaged rotatably in said seat (16B) and has a diameter D, said weight measurement device (8) being provided at a distance L from said fulcrum (16, 26, 36) measured along said lever (15, 25, 35), the ratio D/L being 0.1 or less, more preferably 0.03 or less.

7. The weighing unit (1) according to one or more of claims 2 to 6, characterized in that the lever (15) is a first-class lever, the gripper (4) being provided on a first arm (15A) of the lever (15) and the actuator (61) acting on a second arm (15B) of the lever (15).

8. The weighing unit (1) according to the preceding claim, characterized in that said first-class lever (15) is a disadvantageous lever, since the first arm (15A) is longer than the second arm (15B).

9. A weighing station comprising a carousel that can rotate about a vertical axis and a plurality of weighing units (1, 2, 3) according to one or more of the preceding claims mounted on said carousel.

10. A method for weighing a container (A) in a machine for packaging containers (A), comprising the consecutive steps of

a. gripping said container (A) by means of a retention gripper (4), keeping the gripper (4) uncoupled from a weight measurement device (8), b. keeping said container (A) supported by said gripper (4) and coupling the gripper (4) to the weight measurement device (8).

Description:
UNIT, STATION AND METHOD FOR WEIGHING CONTAINERS

The present invention relates to a unit for weighing containers, to a station and to a corresponding weighing method, particularly for moving containers.

Weighing units can be provided at dedicated weighing stations (for example at the end of a line or in a line) in a packaging machine, both of the rotary type and of the linear type. These weighing units can also be integrated in processing or conveyance stations of the packaging machine, for example stations for filling or sealing the containers.

The function of these units is indeed to measure the weight of the container (with or without content), for example in order to perform operations for machine calibration, checking or control, such as checking the weight with respect to the preset or expected one following the dispensing of a given quantity of the content.

The containers might be for example jars, bottles, doypacks or the like, while the content might be a food substance such as yogurt, fruit puree, soft cheese or the like, or another substance in fluid and/or granular form.

Weighing units known in the background art are generally not without drawbacks.

One example is shown in patent application EP0001196, in which the station comprises a carousel provided with a filling device and with a weighing device; the station comprises a bottom support for the bottle, said support being connected to a load cell for weighing. In changing the format of the bottle, however, it becomes necessary to move the bottom support, due to the new dimensions, and this requires an intervention on the machine, entailing a certain unwanted setup time.

A mechanically simpler solution, again in the field of rotary machines, is described in patent application EP 1025424, wherein the bottle is retained by its neck by a gripper and there is no bottom support for the container. The load cell for weighing is therefore coupled directly to the grip gripper, so as to measure the weight of the container that it supports. Although in this case the intervention time for a format change is reduced, it has been observed however that this solution has the drawback of leading to rapid deterioration of the load cell or to poor weighing precision.

The Applicant has in fact noticed that when the containers are loaded onto the gripper for weighing, they can have incorrect orientations or can have shapes that are not suitable for gripping (this is the case, for example, of plastic containers that have not been thermoformed correctly).

Furthermore, in the step for loading onto the gripper for weighing, the speed of the latter and of the container might vary significantly (in modulus, orientation or direction), so that impacts on the gripper occur even in the absence of defects of the container.

These impacts are inevitably transmitted to the load cell coupled to the gripper and can lead rapidly to the deterioration of the load cell itself, which might easily be stressed beyond the maximum load threshold.

The only solution currently available for this state of things is to mount load cells with a very high maximum threshold, but this solution reduces the precision of the measurement.

The aim of the present invention is to provide a weighing unit, a station comprising said unit and a corresponding weighing method that are capable of improving the prior art in one or more of the aspects indicated above.

Within this aim described above, an object of the invention is to perform precise weighing operations and to preserve the service life of the load cell.

A further object of the invention is to provide a weighing station and a corresponding weighing method capable of giving the greatest assurances of reliability and safety in use.

Furthermore, an object of the present invention is to overcome the drawbacks of the prior art in a manner which is alternative to any existing solutions.

A still further object of the invention is to provide a weighing station and a corresponding weighing method that are easy to provide and economically competitive if compared with the prior art.

This aim, and these and other objects which will become better apparent hereinafter are achieved by a weighing unit for containers for packaging machines, comprising a gripper for retaining the container and a weight measurement device for detecting the weight of the container, wherein the gripper can be moved between a measurement position, in which it is functionally coupled to the weight measurement device, and a loading position, in which it is functionally uncoupled from the weight measurement device.

A further object of the invention is achieved by a weighing station that comprises said weighing unit or a plurality of said weighing units.

A further object of the invention is achieved by a method for weighing a container in a machine for packaging containers, comprising the consecutive steps of:

a. gripping said container by means of a retention gripper, keeping the gripper uncoupled from a weight measurement device,

b. keeping said container supported by said gripper and coupling the gripper to the weight measurement device.

Further characteristics and advantages will become better apparent from the description of three preferred but not exclusive embodiments of a weighing unit, illustrated by way of nonlimiting example with the aid of the accompanying drawings, wherein:

Figure 1 is a lateral sectional view of part of a first preferred embodiment of a weighing unit according to the invention in a first operating condition;

Figure 2 is a lateral sectional view of the weighing unit of the preceding figure in a second operating condition; Figure 3 is a schematic view of a second preferred embodiment of a weighing unit according to the invention;

Figure 4 is a schematic view of a third preferred embodiment of a weighing unit according to the invention.

With reference to the cited figures, they show three preferred embodiments of the weighing unit according to the invention, designated respectively by the reference numerals 1 , 2 and 3.

While the first embodiment of the unit 1 is shown in greater detail, schematic figures are proposed for the second and third embodiments in order to avoid encumbering the description.

In its features which are common to all the embodiments, the weighing unit 1, 2, 3 is designed to measure the weight of containers A, since the weighing unit is or can be mounted on packaging machines.

The containers A can be for example jars, bottles, doypacks and the like and can be filled with fluid or granular substances, such as yogurt, purees, soft cheese or similar food products. These containers are fed with at a speed which has an orientation, direction and/or modulus that is different from that of the weighing unit.

As will become apparent also hereinafter, the weighing unit 1, 2, 3 can be provided equally on packaging lines of the linear type or of the rotary type, i.e., provided with carousels.

The weighing unit 1, 2, 3 comprises a gripper 4 for retaining the container A and a weight measuring device 8 in order to detect the weight of the container A.

The gripper 4 is of a type that is per se known in the prior art for these uses and it is usually provided with means to cause at least its opening or closure. These means can be of a purely mechanical type (for example cams, cam follower rollers and return springs) or pneumatic, hydraulic or electric servo-actuation devices.

However, the gripper 4 can be simply a fork having a fixed size which is adapted to retain the container in an axial direction, without the need to close itself in order to retain the container also in a radial direction.

The gripper 4 grips the container 4 preferably at its neck (if provided) or at a flange thereof (such as the one of yogurt jars) and retains it stably at least in an axial direction. It should be noted that the weighing unit 1, 2, 3 preferably lacks bottom walls for supporting the container A, which is therefore supported only by the gripper 4 at least during the weighing step.

The weight measurement device 8 comprises preferably at least one load cell of the type per se known in the prior art and which is not discussed further.

According to the invention, the gripper 4 can be moved between a loading position (shown for the unit 1 in Figure 1), in which the gripper 4 is functionally uncoupled from the weight measurement device 8, and a measurement position (shown for the unit 1 in Figure 2), in which the gripper 4 is functionally coupled to the weight measurement device 8.

In this manner, at least during the step for loading the gripper 4 (i.e., when the container A is gripped by the gripper 4), the weight measurement device 8 does not undergo impacts or stresses.

In the preferred and illustrated embodiments, the unit 1 , 2, 3 comprises for this purpose a lever 15, 25, 35 and an actuator, for example with a pusher rod 6, which acts on the lever 15, 25, 35.

The gripper 4 is supported by the lever 15, 25, 35, while the pusher rod 6 is adapted to cause an oscillation of the lever 15, 25, 35 so as to cause at least the movement of the gripper 4 between the measurement position (Figure 2) and the loading position (Figure 1).

In particular, the two positions, the measurement one and the loading one, constitute two extreme positions of the oscillation of the lever 15, 25, 35.

Preferably, the pusher rod 6, in the measurement position, is uncoupled (separated) from the lever 15, 25, 35, so as to not influence the weight measurement performed by the device 8, while in the loading position the pusher rod 6 is in contact with the lever 15, 25, 35 and keeps it in this position.

Preferably, the movement of the lever 15, 25, 35 is not forced but is free, in the sense that the pusher rod 6 retracts and the lever 15, 25, 35 oscillates in the measurement position by virtue of the weight of the container A alone.

The weight measurement device 8 is fixed with respect to the lever 15, 25, 35, i.e., the lever can move with respect to the measurement device 8. For example, the weight measurement device 8 is coupled to a frame 9, which in the preferred embodiment also supports the fulcrum 16, 26, 36 of the lever 15, 25, 35 and the actuator 61 to which the pusher rod 6 belongs.

In order to further strengthen the unit and absorb the impacts and stresses produced during loading, the unit 1 , 2, 3 optionally comprises a device 7 for stabilizing in position the lever 15, 25, 35, which is configured to be active in the condition in which the gripper is in the loading position and inactive in the condition in which the gripper is in the measurement position.

In the preferred and illustrated embodiment of the weighing unit 1, 2, 3, the position stabilizing device 7 comprises a seat 71 which is fixed with respect to the lever 15, 25, 35 and an engagement profile 72 which is integral with the lever 15, 25, 35 and whose shape and dimensions are substantially complementary with respect to the seat 71. Preferably, the latter is coupled to the frame 9 and lies on the oscillation plane of the engagement profile 72 with respect to the fulcrum 16, 26, 36.

When the lever 15, 25, 35 is in the loading position (Figure 1), the engagement profile 72 is accommodated in the seat 71 and is kept thereat by the retention of the thrust force applied by the rod 6. A consequence of this is that any impacts or stresses in the step for loading the container A are unloaded mainly onto the position stabilizing device 7 without stressing preponderantly the fulcrum 16, 26, 36.

For this purpose, preferably, the position stabilizing device 7 is arranged, along the lever 15, 25, between the fulcrum 16, 26 and the gripper, as in the embodiments 1 and 2 of the unit according to the invention, but it might also be arranged at the end of the lever 35, as in the third embodiment 3 of the weighing unit according to the invention.

Furthermore, preferably the weight measurement device 8 and the position stabilizing device 7 are provided at opposite sides of the lever 15, 25, 35, so that when the rotation axis of the lever is horizontal (as in the examples of the accompanying figures), the two (7 and 8) are substantially aligned on the same vertical axis; this minimizes any transverse oscillations of the lever 15, 25, 35, facilitating the precision of the subsequent weight measurement.

The engagement profile 72, in the preferred and illustrated embodiment, has a shape and dimensions which are complementary to those of the seat 71, so that once they are coupled a situation of substantially complete contact occurs which is capable of preventing mutual movements.

Preferably, assuming as a reference a Cartesian set of three axes which is integral with the lever 15, 25, 35, the position stabilizing device 7 is capable of preventing movements of the lever in the two directions that lie on the plane of the lever itself, whereas with reference to the direction that is normal to the lever it is capable of preventing the movement in the direction of approach of the lever to the seat 71. Movement along the latter direction, but with the opposite sense, i.e. away from the seat 71, is instead prevented by the pusher rod 6, which pushes the lever into a condition of engagement of the profile 72 with the seat 71.

Preferably, the profile 72 is or comprises a spherical dome and the seat 71 also is or comprises a spherical dome. For example, the convex surface of the profile 72 and the concave surface of the seat 71 are hemispherical surfaces. The fulcrum 16 of the lever 15, 25, 35 comprises a revolute pair which is provided at least with one fixed rotation seat 16B and with a pivot 16A which is rotatably engaged in the seat.

Friction forces are naturally produced between the rotation seat 16B and the pivot 16A and might in turn influence the weight measurement.

Advantageously, in order to further improve the precision of the measurement, if "D" designates the diameter of the pivot 16A of the fulcrum 16 and "L" designates the distance, measured along the lever, of the weight measurement device 8 from the fulcrum 16, 26, 36, the ratio D/L is 0.1 or less, more preferably 0.03 or less.

Moving on now to describe the three embodiments 1, 2 and 3, the main difference among them resides in the class of lever 15, 25, 35 that is used.

For example, in the first embodiment of the unit 1, the lever 15 is a first-class lever. The gripper 4 is provided on a first arm 15A of the lever 15 and the pusher rod 6 acts on a second arm 15B of the lever 15. Of course, in this type of lever the fulcrum 16 is interposed between the arms 15 A and 15B.

Although in principle the lever 15 might be of various kinds (advantageous, neutral, disadvantageous), the first-class lever 15 is preferably a disadvantageous lever, since the first arm 15A is longer than the second arm 15B: this facilitates oscillation without forcing from the loading position (Figure 1) to the measurement position (Figure 2), actuated only by the weight of the container A.

In this solution, the rotation axis of the fulcrum 16 is horizontal and the rod 6 is arranged above the lever 5, while the device 8 is arranged below.

In the second embodiment of the unit 2, shown schematically in Figure 3, the lever 25 is a third-class lever: it should be noted in fact that the actuation force applied by the rod 6 acts between the fulcrum 26 and the resistance force (constituted by the weight of the container A on the gripper 4)ยท

In this embodiment also, as already in Figures 1 and 2, the gripper 4 is mounted at the free tip end of the lever 25; this embodiment finds a preferred application when the weighing unit 1 or 2, and preferably a plurality of weighing units, is mounted on the peripheral region of a carousel of a rotary machine, for example at a weighing carousel, or at a filling/weighing carousel in which the two functions are performed simultaneously.

Other embodiments (not shown) are also possible in which the gripper 4 is mounted in an intermediate point of the lever and the weight measurement device 8 (and optionally the position stabilizing device 7) are mounted on the terminal end of the lever 15, 25; these solutions have a larger space occupation and are therefore less advantageous in the case of rotary machines, but they might be applicable in linear machines.

In the third embodiment of the unit 3, shown schematically in Figure 4, the lever 35 is a second-class lever: it should be noted in fact that the resistance force (constituted by the weight of the container A on the gripper 4) is applied between the fulcrum 36 and the actuation force applied by the rod 6.

As mentioned, the weighing unit 1, 2 or 3 finds a preferred and advantageous application in a weighing station which comprises a carousel which can rotate with a continuous motion about a vertical axis and a plurality of weighing units 1, 2, 3 which are mounted on the peripheral region of said carousel and are circumferentially mutually spaced. In this case, due to the continuous rotation of the carousel, the kinetic energy transmitted upon the impact of the gripper 4 with the respective container A that is fed to the carousel becomes particularly important. This kinetic energy is, in a particularly advantageous manner, absorbed by the supporting structure of the weighing unit 1 , 2, 3, without affecting the weight measurement device 8, which is advantageously uncoupled from the gripper 4 that grips the incoming container A during the loading step.

The weighing station can be integrated with processing and/or packaging devices; for example, it can be integrated in a filling station of the carousel type, or the like.

The method according to the invention, preferably performed in a unit 1, 2 or 3 as just described, entails that the weighing of a container A is performed in a machine for packaging containers A and comprises the consecutive steps of:

a. gripping the container A by means of a retention gripper 4, keeping the gripper 4 uncoupled from the weight measurement device 8,

b. keeping the container A supported by means of the gripper 4 and coupling the latter to the weight measurement device 8, in order to perform the desired weight measurement.

Preferably, step b. is performed by supporting the container A only and exclusively by means of the gripper 4.

According to the method of the invention, in case of application to a carousel station of a continuous rotary machine, step a. is performed at an initial circular arc, which is followed by the container A in its integral motion with the weighing or filling/weighing carousel, which coincides with and immediately follows the moment when it is gripped by the gripper 4. Step b. is performed at a second and adjacent circular arc of operation of the same carousel.

The operation of the invention is clear and evident from what has been described.

In practice it has been found that the invention achieves the intended aim and objects, since it allows to provide a weighing station that performs weighing operations of the container which are precise and without reducing the service life of the weighing device, which is uncoupled from the gripper during the step for loading the container onto the latter. Advantageously, mechanically relatively simple devices are used. Advantageously, the change of format of the container does not entail long setup times.

The weighing unit, the station and the method thus conceived are susceptible of numerous modifications and variations, all of which are within the scope of the appended claims.

All the details may furthermore be replaced with other technically equivalent elements.

In practice, the materials used, so long as they are compatible with the specific use, as well as the contingent shapes and dimensions, may be any according to the requirements and the state of the art.

The disclosures in Italian Patent Application No. 102017000047920 from which this application claims priority are incorporated herein by reference.

Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly, such reference signs do not have any limiting effect on the interpretation of each element identified by way of example by such reference signs.