Device for cutting plastic containers

Abstract

The invention relates to a device for cutting plastic containers, comprising a mould (1), a punch holder (2), cutting blades (11, 12) arranged in said mould and / or said punch holder, and an ejector plate (3) performing a nominal stroke between an extended position (A) and a retracted position (C), the nominal stroke being equal to a predetermined allowed thickness of material accumulated in the cutting area. Each ejector plate (3) comprises a protrusion indicator extending axially from the ejector plate (3) towards the rear of the punch holder (2), the device further comprising a position sensor (4) configured to detect when the protrusion indicator reaches a raised position due to a specific build-up of material within the cutting area. The sensor (4) is connected to a control unit (5) comprising a processor (51) and a sound alarm (52) activated by the sensor (4).

Description

Technical Field

[0001] The invention relates to a device for cutting plastic containers, preferably suitable for packaging of food, such as yogurt, mayonnaise, caramel pudding and the like. Background Art

[0002] In the manufacture of containers for the food industry, it is common to use plastic, single-layer or multi-layer sheets to form multi-pack containers. These multi-pack containers have several individual cavities or containers connected by connecting bridges defined in the plastic sheet itself.

[0003] Once formed, filled and sealed, the multipack container is almost simultaneously subjected to a cutting operation, thereby defining a portion of the multipack container shape, and a pre-cutting operation, wherein a pre-cut line is defined, which affects the connecting bridge and facilitates the subsequent tearing and separation of the different individual containers.

[0004] Utility model ES1291175U discloses a device for pre-cutting containers, in particular containers made of multi-layer materials, comprising a base plate and a punch fixing plate, the punch fixing plate having an upper cutting blade for realizing a cutting line in the multi-layer material of the container positioned on the base plate, wherein the upper cutting blade is arranged to form an upper pre-cutting line in the upper layer of the multi-layer material. The base plate comprises a lower cutting blade at a position facing the upper cutting blade, and the lower cutting blade is arranged to form a lower pre-cutting line in the lower layer of the multi-layer material.

[0005] EP3722217B1 discloses a machine for manufacturing multi-packaging containers, which comprises: a lower die associated with a press having vertical movement; a punch support and a pre-cutting device, the pre-cutting device comprising an upper pre-cutting blade associated with the punch support and a lower pre-cutting blade associated with the lower die, for defining an upper pre-cutting line and a lower pre-cutting line on a connecting bridge of the individual containers, suitable for manually breaking the bridge when in use and separating individual containers formed of PET or containing at least one PET layer.

[0006] In particular, document EP 3 722 217 B1 mentions a changing trend with regard to the materials used for manufacturing such containers, and the use of PET (polyethylene terephthalate) which is 100% recyclable and reusable.

[0007] Due to its composition, PET reacts differently when the container is cut, with small pieces of material breaking off from the container.

[0008] With previously used materials, such as polystyrene (PS), the actual accumulation of material that has fallen off in the cutting area does not present a problem, since the material breaks down into small particles.

[0009] With PET materials, the problem is that the released particles gradually form residual cutting material of the plastic material in the cutting area, which presses against the various cutting elements until they are deformed and sometimes even break.

[0010] In view of this problem, blockages on the production line are quite common. The only solution so far has been to assign the monitoring of the cutting area to an operator, who is responsible for fixing the blockage from time to time. However, this solution is not cost-effective, as the operator has to attend to other tasks and thus neglects to monitor the cutting device. Therefore, this solution does not solve the problem and blockages continue to occur until the cutting element is damaged or breaks. Summary of the invention

[0011] The device for cutting plastic containers of the present invention has technical features aimed at solving the above-mentioned problems, including a device suitable for detecting the accumulation of a specific material thickness in the cutting area, and activating an alarm indicating the accumulation of the material before the thickness of the accumulated material poses a risk of damage to the cutting device or the blade.

[0012] The device for cutting plastic containers provided by the present invention comprises a mold and a punch bracket, and is used for cutting a cutting blade of a multi-packaging container arranged in the mold and / or the punch bracket, wherein the mold and the punch bracket are arranged relative to each other and can move axially between an operating cutting position and a non-operating position, in which the cutting blade performs pre-cutting and / or cutting on a separate multi-packaging container placed in the middle, and in the non-operating position, the mold and the punch bracket are separated.

[0013] In addition, the device for cutting a plurality of containers comprises an ejector plate assembled on the punch holder, which is associated with a spring, and the ejector plate can be moved in the axial direction relative to the punch holder between a retracted position and an extended position.

[0014] In the retracted position, residual cutting material of a given thickness generated during pre-cutting and / or cutting accumulates in the cutting area to form a hard block, and the residual cutting material pushes the ejector plate axially toward the retracted position to compress the spring.

[0015] In the extended position, the spring is less compressed than in the retracted position, or is not compressed at all.

[0016] The urging force of these springs helps to eject the remaining cut material by moving the ejector plate from the retracted position to the extended position.

[0017] According to the invention, each ejector plate comprises a projection indicator extending axially from the ejector plate towards the rear of the punch holder, the projection indicator generally comprising the end of a rod connected to the ejector plate.

[0018] The apparatus further comprises one or more position sensors arranged to detect when the protruding indicator reaches a raised position, indicating that the ejector plate reaches a particular retracted position.

[0019] The position sensor is configured to determine when the protruding indicator exceeds a raised position corresponding to a given allowed thickness of residual cut material of accumulated plastic material in the cutting area.

[0020] The given permissible thickness is quantified so that it is not sufficient to cause clogging of the cutting device and damage or breakage of the blade. Exceeding the predetermined permissible thickness, there is a risk of clogging or breakage of the device, requiring a cleaning operation.

[0021] It is worth mentioning that the sensor can be of any type capable of detecting that at least one of the protruding indicators connected to the ejector plate exceeds a raised position of the protruding indicator, the raised position corresponding to a predetermined allowed thickness of residual cut material of the plastic material accumulated on the ejector plate in the cutting area, for example, an optical sensor, a contact sensor, a position sensor or a magnetic sensor capable of detecting a given position of a protruding indicator connected to the ejector plate.

[0022] The optical sensor may include, for example, a light emitter and a light receiver for a light beam.

[0023] A single position sensor can monitor multiple protrusion indicators simultaneously, allowing a single position sensor to detect when any one of multiple ejector plates reaches the retracted position.

[0024] For example, a plurality of protruding indicators may be aligned to interrupt the optical sensor's light beam when the raised position is reached.

[0025] According to the invention, the one or more position sensors are connected to a control unit and the position sensors are configured to send a signal to the control unit upon detecting a raised position of the protruding indicator.

[0026] The control unit in a preferred embodiment comprises a processor having a memory in which all events (including signals emitted by the position sensor) are recorded, which allows obtaining reports related to the emitted signals.

[0027] The control unit may be connected to an audible alarm and may be configured to activate the audible alarm in response to a signal received from the position sensor.

[0028] In this way, the production line operator or supervisor receives an audible signal indicating that the residual cut material has reached a specific accumulation, and the operator is responsible for deciding whether to stop the device to clear the accumulated residual cut material associated with the ejector plate to avoid increasing the material accumulation and causing the risk of breaking the cutting blade and causing a new blockage.

[0029] The arrangement of the sensors, both in number and in specific locations, depends on the nature and number of the containers to be subjected to the cutting operation, and on the arrangement of the die and the punch holder. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] As a supplement to the description provided by the present invention, in order to make the features of the present invention more easily understood, a set of drawings is attached to this specification, which show the following by way of illustration and not limitation:

[0031] Figure 1 A front elevation view showing one embodiment of a device for cutting plastic containers according to the present invention.

[0032] Figure 2 An elevational view of the device of the upper figure is shown partially disassembled in order to observe one embodiment of a sensor responsible for detecting the accumulation of residual cut material of the plastic material in the container cutting area by detecting a protruding indicator connected to the ejector plate.

[0033] Figure 3a Enlarged details showing one of the ejector plates in an extended position with the protrusion indicator (the end of the rod) in position (A), including an optical sensor (emitter-receiver) arranged in the rear area of ​​the punch support, the light beam emitted by the optical sensor being configured to be interrupted by the protrusion indicator when the protrusion indicator reaches a given protrusion position.

[0034] Figure 3b Display and Figure 3a The same, but with the protruding indicator of the ejector plate in a partially retracted position (B), and also including an enlarged detail of the end area of ​​the protruding indicator connected to the ejector plate.

[0035] Figure 3c Display and Figure 3a and 3b Similar view, relative to Figure 3b The position of the protruding indicator (B) of the ejector plate, the protruding indicator (the end of the rod) of the ejector plate is in a further retracted position (C), which activates the sensor due to a certain thickness of residual cut material accumulation of plastic material in the cutting area. The figure also includes an enlarged detail of the rear end position of the protruding indicator on the ejector plate. DETAILED DESCRIPTION

[0036] Figure 1 A device for cutting plastic containers according to the invention is described, which is used for cutting plastic containers made of PET or other materials which release particles in the form of residual cutting material which may accumulate in the cutting area and cause damage to the cutting device. The device comprises a die 1 and a punch support 2 which is vertically movable between an operative cutting position and an inoperative position.

[0037] The device comprises cutting blades 11, 12 for cutting plastic containers, which are arranged in the die 1 and / or the punch holder 2 in a manner known in the art.

[0038] like Figure 2 As shown, the cutting device comprises an ejector plate 3 for ejecting the cut container, and the ejector plate 3 is assembled in the punch support 2 and can move relatively in the axial direction, specifically, in the vertical direction in the figure.

[0039] As shown in Figures 3 and 3a to 3c, the ejector plate 3 mounted on the punch support 2 is connected to the spring 60. The ejector plate 3 can move between a retracted position and an extended position in the axial direction, i.e., the vertical direction in the figure, during operation. In the retracted position, the residual cutting material of the plastic material generated in the pre-cutting accumulates on the cutting area, pushing the ejector plate to move axially and compressing the spring 60. In the extended position, when the spring 60 is no longer compressed, the residual cutting material is ejected by the thrust of these springs 60 on the ejector plate.

[0040] In the depicted embodiment, the spring 60 is arranged around the guide rod, connected to the rear of the ejector plate 3 .

[0041] According to the invention, the ejector plate 3 has a protrusion indicator attached thereto, which in the disclosed embodiment is in the form of a rod 3 a perpendicular to the ejector plate 3 .

[0042] In operation, the ejector plate 3 describes, relative to the punch holder 2, Figure 3a The protruding indicator (the end of the rod 3a) and the extended position (A) of the ejector plate 3 are shown with Figure 3b The nominal travel of the predetermined length between the partially retracted position (B) of the protruding indicator shown. At this time, only an allowable amount of residual cutting material of the plastic material is accumulated in the cutting area corresponding to the pre-cutting of the container, such as Figure 3b shown.

[0043] like Figure 2As shown, the device also includes a sensor 4 in the punch holder 2, in this case shown by an optical sensor with a transmitter 41 and a receiver 42, which is connected to a control unit 5, which includes a processor 51, an audible alarm 52 in a specific embodiment, and a memory 53 for recording events.

[0044] The sensor 4 is disposed in a rearward position relative to the aforementioned position (B) of the protrusion indicator (the distal end of the rod 3a) connected to the ejector plate 3, and in a further retracted position (C) ( Figure 3c ) are separated by a distance (d), which distance (d) corresponds to a predetermined allowable thickness of the accumulated material in the cutting area.

[0045] in this case, Figure 3b The distance (d) shown is the distance between the rear area of ​​the protrusion indicator (the end of the rod 3a) connected to the ejector plate 3 and the light beam 43 emitted by the optical sensor.

[0046] When the residual cut material of the plastic material accumulated in the cutting area exceeds the predetermined allowable thickness, it causes the end of the rod 3a connected to the ejector plate 3 to exceed the aforementioned partially retracted position (B) and reach the further retracted position (C) ( Figure 3c ), cuts off the light beam 43 and is thus detected by the sensor 4.

[0047] This detection, caused by the accumulation of residual cutting material of plastic material in the cutting area, results in, in the disclosed embodiment, the activation of an audible alarm 52 and the recording of the event in a memory 53 of the control unit 5 before a blockage occurs that could damage the device or the cutting blade; it is the responsibility of the production line operator or manager to remove the material to prevent the above-mentioned blockage or damage from occurring in the production line.

[0048] The essence of the present invention having been fully described, except for the preferred exemplary embodiments, it is hereby stated that for relevant purposes, the materials, shapes, sizes and arrangements of the elements described may be modified without thereby implying a change in the essential characteristics of the invention as claimed.

Claims

1. A device for cutting plastic containers, comprising: A die (1) and a punch support (2) movable in the axial direction between an operational cutting position and a non-operating position; a cutting blade (11, 12) arranged in the die and / or the punch holder, and A plurality of ejector plates (3) are assembled in the punch support (2), the plurality of ejector plates (3) being configured to be movable in the axial direction relative to the punch support (2), and to perform a nominal stroke of a predetermined length between an extended position (A) and a retracted position (C) reached by the ejector plates (3) when a given thickness of residual cutting material is accumulated in the cutting area, each ejector plate (3) being connected to at least one spring (60), the spring (60) being configured to be compressed in the axial direction when the ejector plate (3) moves from the extended position (A) to the retracted position (C); It is characterized in that Each ejector plate (3) comprises a protruding indicator connected to the ejector plate (3) and extending axially from the ejector plate (3) toward the rear of the punch holder (2); as well as The device further comprises at least one position sensor (4) arranged to detect when the protruding indicator reaches a raised position, indicating that the ejection plate (3) reaches a retracted position (C).

2. An apparatus according to claim 1, wherein a single position detector (4) can monitor a plurality of protrusion indicators simultaneously.

3. Device according to claim 1 or 2, wherein the at least one position sensor (4) comprises a light transmitter (41) and a light receiver (42) for a light beam (43).

4. The device according to any one of claims 1-2, wherein the position sensor (4) is a contact sensor, a position sensor, or a magnetic sensor.

5. The device according to any one of claims 1-2, wherein the protrusion indicator comprises a rod (3a) perpendicular to the ejection plate (3).

6. The device according to any one of claims 1-2, wherein the position sensor (4) is connected to a control unit (5) and is configured to send a signal to the control unit when the raised position is detected.

7. The device according to claim 6, wherein the control unit (5) comprises a processor (51) and a memory (53) for recording at least the signal emitted by the position sensor (4).

8. The device according to claim 6 or 7, wherein the control unit (5) is connected to an audible alarm (52) and is configured to activate the audible alarm (52) in response to a signal received from the position sensor (4).

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