WO2021148432A1

WO2021148432A1 - Heating unit for plastic preforms

Info

Publication number: WO2021148432A1
Application number: PCT/EP2021/051129
Authority: WO
Inventors: Denis Gillet; Philippe GILSOUL
Original assignee: Sidel Participations
Priority date: 2020-01-22
Filing date: 2021-01-20
Publication date: 2021-07-29
Also published as: FR3106294A1; FR3106294B1

Abstract

The invention relates to a heating unit (1) for plastic preforms (2), comprising: - a frame (3); - a movable chain (4) comprising a plurality of links (41), the chain (4) circulating along the frame (3) along a predetermined path (T); - at least one shaft (5) mounted for rotation on a link (41) of the chain (4), and having a first end to which a retaining member (8) of a preform (2) is secured, the heating unit (1) further comprising means for angular reorientation of the shafts (5) at an outlet of the heating unit (1), characterised in that the angular reorientation means are movably mounted on the frame (3), and in that the frame (3) carries means for adjusting the position of the angular reorientation means.

Description

Title of the invention: Heating unit for plastic preform

The field of the invention is that of the design and manufacture of machines for manufacturing plastic containers.

[0002] More specifically, the invention relates to the design and manufacture of means for orienting preforms at the outlet of a heating unit, to enable the body of the preforms to be treated, for example to be heated, selectively or uniformly. .

Conventionally, plastic containers can be obtained by heating a plastic preform to a glass transition temperature.

[0004] A preform usually comprises:

- a body, of substantially cylindrical shape of revolution about a central axis;

a neck, which extends in the extension of the body from a first end thereof, the neck being separated from the body by a collar;

- a bottom, which closes the body at a second end thereof.

[0005] By analogy:

- the body of the preform becomes the body of the container;

- the neck and the flange of the preform remain unchanged during the container forming process;

- the bottom of the preform becomes the bottom of the container.

[0006] The heated preforms are inserted into a mold imprinted with the final container or an intermediate container, to be blown therein by injection of a fluid. Specifically, air is injected into the preform to deform it and stretch the plastic until it comes into contact with the walls of the mold.

To heat the preforms, heating units, also called "ovens", are used.

[0008] These heating units use light sources, generally laser diodes or halogen lamps, which emit radiation aimed at heating the plastic material, and therefore at softening it to promote its stretching and its deformation in the mold.

[0009] Conventionally, heating units include:

- a frame;

- a toothed wheel rotatably mounted on the frame;

a movable chain comprising a plurality of links, the chain entraining with the toothed wheel along a predetermined path;

- at least one shaft rotatably mounted on a chain link, WO 2021/148432 PCT / EP2021 / 051129 the or each tree having:

- a first end to which is secured a member for holding a preform,

- a second end, opposite the first end, to which is secured a drive end for rotating the shaft.

[0010] The heating unit also includes drive means integral with the frame, cooperating with the drive end of each shaft to drive it in rotation.

[0011] The preforms thus circulate in parade in the heating units while being held by a holding member, in this case a finger engaging the inside of the neck of the preforms.

[0012] In the heating unit, the shafts are at least partly rotated by the drive means to enable the body of the preforms to be heated selectively or evenly.

Two types of heating of the preforms can then be carried out.

A first type concerns the manufacture of containers of revolution about a central axis.

For the manufacture of containers of revolution, the preforms are heated uniformly over their entire periphery. This allows the plastic material to be distributed evenly in the mold.

This homogeneous heating is obtained by rotating the preforms around their axis of revolution (which will become the central axis of the container) as they move past the light sources.

For this, the shaft rotation drive end piece is intended to engage with a chain integral with the frame to ensure the rotation of the shafts carrying the preforms.

[0018] Thus, as they travel through the heating unit, the shafts are driven in rotation, which then ensures the rotation of the preforms and therefore the exposure of the entire periphery of the preforms to the light sources.

On the other hand, for certain applications, it may be necessary to heat the preforms in a non-homogeneous manner, also called preferential heating.

This is particularly the case for containers having an oval shape, for example, such as bottles of washing-up liquid in particular.

For this, the oven can include:

- masking elements for at least partially masking the minor sources;

- reflectors to intensify the projection of the light radiation in a localized manner on the preforms, and / or

- one or more temporary stops of the rotation of the preforms during their parade WO 2021/148432 PCT / EP2021 / 051129 in front of light sources.

On leaving the heating unit, the preform therefore has an alternation of so-called hot zones (that is to say strongly heated) and of so-called cold zones (that is to say slightly heated) on its periphery.

The orientation of the preforms in the molds is then important to allow the manufacture of the containers.

[0024] In fact, the areas of the preform that are the most heated are those in which the rate of bi-orientation in the mold is the highest (that is to say the areas intended to be the most stretched). The greater heating of these zones is therefore necessary in order to stretch them better and to avoid an extra thickness of material in the final container.

By bi-orientation is meant an orientation of the material in two directions, that is to say parallel to a central axis of the container and transversely to this central axis.

Conversely, the colder areas are those that have the least bi-orientation (that is to say the areas intended to be the least stretched). It is therefore less necessary to heat these zones, in particular to avoid refining them or even piercing them by over-stretching when the container is blown into the mold.

[0027] It is therefore understood that in the event of incorrect orientation of the preform in the mold, the risk that the container exhibits a defect at the outlet of the mold is increased.

To achieve correct orientation of the preform in the mold, means for orienting the preforms are known.

These orientation means act on a small range of rotation of each shaft to orient it as desired.

Conventionally, these orientation means of the preforms are positioned at the inlet of each heating zone of the heating unit and / or at the outlet of the heating unit, just upstream of the means for conveying the preforms from the heating unit to the molds.

These orientation means comprise a pin integral with the shaft drive end piece, intended to cooperate with a guide integral with the frame.

[0032] More specifically, each shaft includes a pin, offset from the axis of rotation of the shaft, which cooperates with the cam track to rotate the shaft and position it in the desired orientation.

[0033] The guide is itself fixed to a frame of the heating unit and remains in a fixed position to ensure an identical orientation of the shafts and therefore of the preforms.

[0034] However, these means of orientation are not reliable under all circumstances.

[0035] Indeed, it was found that despite the presence of these orientation means, manufacturing defects of the containers persisted.

This can in particular be explained by two known factors. WO 2021/148432 PCT / EP2021 / 051129

The first factor is a maladjustment of the chain integral with the frame.

More specifically, the position of the chain on the frame or its tension may vary as the production cycles progress, for example because of the vibrations produced by the relative movement of the various moving parts.

[0039] As a result, there may be an offset in the angular orientation of the preforms, which results from poor cooperation between the chain and the shaft rotational drive end.

To adjust this poor guidance, repositioning the chain on the frame can be done, but this is tedious for the operators and requires significant downtime of the machine.

The second known factor is an angular offset of the preforms during their transfer between the heating unit and a container blowing unit or during their entry into molds of the blowing unit.

[0042] In fact, transfer units are then used to take charge of the preforms at the outlet of the heating unit, and to convey them to the blowing unit, and more precisely to a mold of the blowing unit.

[0043] The transfer units then include gripping means, for example grippers, which grip the preforms to convey them and release them into the molds of the blowing unit.

[0044] When they come into contact with the preforms to grasp them, the gripping means may abut slightly against the preforms, which can disorient them.

Likewise, when the gripping means release the preforms in the molds, the latter may slightly rebound, slide and therefore become disoriented.

Such a disorientation, even slight, will then generate the manufacture of defective containers, or those presenting risks of aesthetic and / or structural failures, in particular in terms of mechanical strength and / or stability.

The object of the invention is in particular to overcome the drawbacks of the prior art.

[0048] More specifically, the invention aims to provide a solution which allows angular reorientation of the preforms as a function of production hazards.

The invention also aims to provide such a solution which is easy to implement.

[0050] The invention further aims to provide such a solution which is reliable.

These objectives, as well as others which will appear later, are achieved thanks to the invention which relates to a heating unit for plastic preforms, comprising:

- a frame;

a mobile chain comprising a plurality of links, the chain circulating along the frame according to a predetermined path; WO 2021/148432 PCT / EP2021 / 051129

- at least one shaft rotatably mounted on a chain link, the or each shaft having:

- a first end to which is secured a member for holding a preform,

- a second end, opposite the first end, to which is secured a drive end in rotation of the shaft, the heating unit also comprising drive means integral with the frame, the drive means cooperating with the drive end of each shaft to drive it in rotation, the heating unit further comprising means for angular reorientation of the shafts at an outlet of the heating unit, these angular reorientation means being carried by the frame, characterized in that the angular reorientation means are movably mounted on the frame, and in that the frame carries means for adjusting the position of the angular reorientation means.

The angular reorientation means and the position adjustment means associated therewith make it possible to reorient the preforms according to production hazards.

[0053]

The position adjustment means therefore make it possible to reposition the angular reorientation means as needed so that the preforms are properly oriented despite the change in production conditions.

According to a preferred embodiment, the angular reorientation means include:

- a pin secured to the drive end of each shaft,

- a guide carried by the frame and intended to cooperate with the pin of each tree.

These angular reorientation means are simple to make and allow angular reorientation of the preforms automatically and purely mechanically so that, when the angular reorientation means are suitably positioned, they provide an identical angular reorientation for each of the preforms. .

Advantageously, the position adjustment means comprise:

- an endless screw rotatably mounted on the guide of the angular reorientation means,

- a nut integral with the frame and intended to receive the worm.

These adjustment means are easy to handle and make it possible to finely adjust the position of the angular reorientation means.

Preferably, the heating unit comprises a pair of cams mounted on the frame at one end of the angular reorientation means, the pair of cams forming a WO 2021/148432 PCT / EP2021 / 051129 guide path of the pin in the angular reorientation means.

[0060] This pair of cams then works like a funnel to guide the pins towards the angular reorientation means.

This is particularly useful when the heating unit is suddenly stopped and the free rotating preforms can be turned manually. Furthermore, such sudden stops of the heating unit can cause vibrations or jerks in the chain which affect the rotation of the preforms. As a result, each of the preforms can have a different orientation from the others.

The pair of cams thus makes it possible to ensure an identical orientation of all the preforms leaving the heating unit.

In this case, each cam of the pair of cams is preferably mounted to rotate on the frame.

[0064] This makes it possible to adapt the size of the funnel formed by the pair of cams to production needs.

Preferably, each link of the chain carries a roller, and the heating unit comprises a support integral with the frame, on which are rotatably mounted the angular reorientation means, the support having a guide groove for the rollers. each link.

[0066] Under the effect of its own weight, the chain may deform slightly so that the pins are outside a zone of cooperation with the guide.

The cooperation between the rollers and the groove of the support therefore ensures optimum positioning of the pins for their cooperation with the guide.

[0068] This therefore results in a good angular reorientation of the preforms at the outlet of the heating unit.

[0069] According to another advantageous embodiment, the heating unit comprises means for maintaining the angular reorientation means in position.

Thanks to these means for holding in position, the vibrations due to the operation of the heating unit have no influence on the positioning of the angular re-orientation means.

This therefore guarantees an identical orientation for each of the preforms leaving the heating unit, throughout the production cycle.

Advantageously, the means for holding in position comprise a clamping member and means for handling the clamping member.

Such a design of the means for maintaining in position is simple and easy to use.

Preferably, the clamping member is in the form of a screw mounted in an internal thread formed on the frame, the screw being movable towards a bearing position against the angular reorientation means in order to immobilize them. WO 2021/148432 PCT / EP2021 / 051129

By acting on the screw, it is therefore possible to block the angular reorientation means in the desired position, and, by releasing the bearing force of the screw on the angular reorientation means, to allow repositioning of the means of angular reorientation.

The invention also relates to an angular reorientation device for a heating unit of plastic preforms, the heating unit comprising a frame, characterized in that the angular reorientation device comprises:

- a support intended to be mounted on the frame,

means for angular reorientation of the preforms, mounted to move on the support, and in that the angular reorientation device comprises means for adjusting the position of the angular reorientation means, mounted on the support.

[0077] Such a device makes it possible to reorient the preforms according to production hazards

(for example a disruption during operation, or a production stoppage).

Furthermore, such a device can be mounted or removed from a heating unit easily, whether for its maintenance or because it is not intended to be used, in particular when the preforms have a homogeneity of heating on their periphery.

Finally, such a device can be installed on an already existing heating unit and devoid of angular reorientation means.

Other characteristics and advantages of the invention will emerge more clearly on reading the following description of a preferred embodiment of the invention, given by way of illustrative and non-limiting example, and the accompanying drawings. among which :

[fig.l] is a perspective view from above of a plastic preform heating unit, according to the invention, comprising a device for angular reorientation of the preforms at the outlet of the heating unit;

[Fig.2] is a view of the angular reorientation device of the heating unit of Figure 1;

[fig.3] is a perspective view from below of the device for angular reorientation of the heating unit according to the invention;

[Fig.4] is a perspective view from above of the device for angular reorientation of the heating unit according to the invention.

[0081] Figure 1 illustrates a unit 1 for heating plastic preforms 2 according to the invention.

More specifically, this heating unit 1 comprises:

- a frame 3; a chain 4 mobile along a predetermined path T and comprising a plurality of links 41;

- at least one shaft 5 rotatably mounted on a link 41 of the chain 4 to carry a preform 2;

- drive means 6 in rotation of the shafts 5;

- a device 7 for angular reorientation of the preforms 2.

More particularly, the heating unit 1 comprises a toothed wheel 11 making it possible to drive the chain 4 in motion along its predetermined path T. Each tooth of the toothed wheel 11 cooperates with the links 41 to ensure the movement of the chain 4.

Each tree 5 presents:

- a first end 51 to which is secured a member 8 for holding a preform 2,

- a second end 52, opposite the first end 51, to which is so lidarized a tip 9 for driving the shaft 5 in rotation.

The rotational drive end piece 9 is intended to cooperate with the drive means 6 in rotation, integral with the frame 3, previously presented.

For simplicity, the drive means 6 in rotation are schematically shown by a parallelepiped in Figure 1. However, according to an advantageous embodiment, the drive means 6 in rotation comprise a series of fixed teeth integral of the frame 3, and each tip 9 for driving in rotation comprises a pinion 91 intended to cooperate with the fixed teeth of the drive means 6 in rotation.

Thus, when the chain 4 is driven in movement along its predefined trajectory T, the links 41 circulate vis-à-vis the drive means 6 in rotation so that the pinions 91 of the drive end pieces 9 of each shaft 5 can cooperate mechanically and automatically with the fixed teeth to drive the shaft 5 in rotation.

This makes it possible to be able to rotate the preforms 2 around their axis of extension so as to generate either a uniform heating of the periphery of the body of the preforms 2, or a preferential heating, that is to say an alternation so-called hot sectors and so-called cold sectors. This alternation of hot and cold sectors is obtained by the rotation of the preforms 2 in front of the heating radiation emitting means (not shown in the figures).

More particularly, the drive means 6 in rotation allow the drive in rotation of the members 8 for holding the preforms 2, via the shafts 5.

To ensure a good orientation of the preforms 2 at the outlet of the heating unit 1, in particular when they have a preferential heating, the device WO 2021/148432 PCT / EP2021 / 051129

7 angular reorientation is used.

More particularly, the angular reorientation device 7 comprises angular reorientation means 71 of the preforms secured to the frame via a support 10.

Referring to Figures 2, 3 and 4, the support 10 comprises a first part 101 intended to be secured to the frame 3, for example by means of screws, and a second part 102, also secured to the frame 3 and forming, with the first part 101, a tunnel.

More particularly, the second part 102 has a substantially inverted U shape and is secured to the frame 3 on the one hand and to the first part 101 from above the latter on the other hand. The inverted U typically includes a base and two wings extending from the base.

The angular reorientation means 71 comprise a first part secured to the drive end 9 of each shaft 5 and a second part secured to the frame 3.

More precisely, as it appears in FIG. 2, the angular reorientation means 71 comprise a pin 72 integral with the drive end 9 of each shaft 5, and forming the first part, as well as a guide 73 carried by the frame 3 and intended to cooperate with the pin 72 of each shaft 5.

Preferably, the pin 72 is located on the drive end 9 and offset with respect to a central axis of the shaft 5 to be able to allow the rotation of the shaft 5 by its cooperation with the guide 73.

As seen in Figures 2 and 3, the guide 73 has a groove 74 forming a cam track intended to cooperate with the pin 72 of each shaft 5 to be able to rotate the shaft 5.

The heating unit 1 also comprises a pair of cams 111 mounted on the frame 3 at one end of the angular reorientation means 71.

This pair of cams 111 is more precisely mounted upstream of the guide 73 along the predetermined path T of the chain 4, and forms a guide path for the pin 72 in the angular reorientation means 71.

In other words, the pair of cams 111 forms a funnel intended to receive the pin 72 prior to its entry into the angular reorientation means 71 to guide said pin 72 towards the groove 74 of the angular reorientation means 71, c ' i.e. guide 73.

Preferably, each cam 111 of the pair of cams is rotatably mounted on the frame 3.

[0102] It is thus possible to be able to modify the orientation of each of the cams 111 of the pair of cams so as to adapt the shape of the funnel precisely, in order to create optimal guidance of the pins 72 towards the means of angular reorientation 71. [0103] The angular reorientation means 71 are movably mounted on the frame 3 to allow adaptation to different cases such as, for example, a forced or unwanted stop of the production machine in which the production machine is located. heating unit 1, or an identified and evolving maladjustment over time.

For this, the angular reorientation means 71, and more particularly the guide 73, is rotatably mounted on the frame 3 via the support 10.

Referring to Figure 4, the guide 73 is rotatably mounted on the base of the second part 102 of the support 10.

[0106] The heating unit 1 also comprises means 12 for maintaining the angular reorientation means 71 in position.

[0107] Thus, once the position of the angular reorientation means 71 has been determined, that is to say that the guide 73 is correctly oriented, the holding means 12 in position are activated to make it possible to maintain the guide 73 in position. .

[0108] As illustrated in Figure 4, the holding means 12 in position comprise a clamping member 121 and handling means 122 of the clamping member 121.

[0109] More particularly, with reference to Figures 2 and 4, the holding means 12 in position comprise two clamping members 121 and two handling means 122 each secured to one of the clamping members 121.

[0110] More precisely, each clamping member 121 is in the form of a screw mounted in an internal thread formed on the support 10 integral with the frame 3, the screw being mounted movably towards a position of support against the reorientation means. angular 71 to immobilize them.

[0111] In order to facilitate guidance and in particular to allow good positioning of the preforms 2 at the outlet of the heating unit 1, each link 41 of the chain 4 carries a roller 42 and the support 10 integral with the frame 3 has a groove 103 for guiding the rollers 42 of each link 4L

More particularly, the roller 42 of each of the links 41 is intended to circulate in the guide groove 103 of the support 10 when the pin 72 cooperates with the guide 73 of the angular reorientation means 71.

[0113] This makes it possible to ensure the correct orientation of the preforms 2 at the outlet of the heating unit 1, in particular by ensuring that each pin 72 cooperates with the guide 73 of the angular reorientation means 71.

As specified above, to mitigate production contingencies, for example an unwanted shutdown of the production machine, or even a modification of the final orientation of the preforms 2 at the outlet of the heating unit 1, the means of angular reorientation 71 are coupled to means 13 for adjusting the position of the angular reorientation means 71.

[0115] More particularly, the adjustment means 13 in the position of the adjustment means. he

WO 2021/148432 PCT / EP2021 / 051129 angular orientation 71 are carried by the frame 3 and more particularly by the first part 101 of the support 10.

As can be seen in Figures 2, 3 and 4, the adjustment means 13 in position comprise:

- A worm screw 131 rotatably mounted on the guide 73 of the angular reorientation means 71,

- A nut 132 integral with the frame 3, and intended to receive the worm 131 for helical cooperation.

[0117] More precisely, the nut 132 is integral with the first part 101 of the support 10.

A handling member 133, for example a wheel integral with the worm 131, allows easy manipulation of the worm 131 to translate it relative to the frame 3 via its helical cooperation with the nut 132 integral with the frame 3.

[0119] The rotational mounting of the worm 131 on the guide 73 of the angular re-orientation means 71 is in particular provided by a tip 134 integral with the worm 131 and pivotally mounted on the guide 73.

[0120] Thus, when the endless screw 131 is manipulated to be rotated, by its helical co-operation with the nut 132, it makes it possible to bring the guide 73 closer to or away from the first part 101 of the support 10.

[0121] The position of the groove 74 of the guide 73 is then modified, which causes the modification of the orientation of the preforms 2 at the outlet of the heating unit 1 by the cooperation of the pin 72 with the guide 73 .

[0122] According to an embodiment not illustrated in the figures, the manipulation of the screw

Endless 131 can be controlled by control means controlled automatically by a central unit of the manufacturing machine.

The heating unit 1 and the angular reorientation device 7 which have just been described make it possible to ensure a precise angular orientation of the preforms 2 at the outlet of the heating unit 1, in particular when the latter have a preferential heating, that is to say different temperatures on their periphery, for the realization of a non-symmetrical container of revolution.

[0124] Furthermore, the adjustment in position of the guide 73 and therefore the modification of the orientation of the preforms 2 at the output of the heating unit 1 is facilitated by the adjustment means 13 in the position of the angular reorientation means 71 which can be manual or slaved to a central unit of the manufacturing machine.

Finally, this system, thanks to the support, can be integrated into an already existing machine in order to update said manufacturing machine.

[0126] In addition, in the event of maintenance or modification of production, the device can, as desired, be mounted or removed from the production machine as required.

Claims

[Claim 1] Preform heating unit (1)

(2) of plastic, comprising:

- a frame (3);

- a movable chain (4) comprising a plurality of links (41), the chain (4) circulating along the frame

(3) along a predefined trajectory (T);

- at least one shaft (5) rotatably mounted on a link (41) of the chain

(4), the or each tree (5) having:

- a first end (51) to which is secured a holding member (8) of a preform (2),

- a second end (52), opposite the first end (51), to which is secured a tip (9) for driving the shaft (5) in rotation, the heating unit (1) also comprising drive means (6) integral with the frame (3), the drive means (6) cooperating with the drive end (9) of each shaft (5) to drive it in rotation, the unit ( 1) heater further comprising angular reorientation means (71) of the shafts (5) at an outlet of the heating unit (1), these angular reorientation means (71) being carried by the frame (3), characterized in that the angular reorientation means (71) are movably mounted on the frame (3), and in that the frame (3) carries adjustment means (13) in the position of the angular reorientation means (71).

[Claim 2] Heating unit (1) according to the preceding claim, characterized in that the angular reorientation means (71) comprise:

- a pin (72) integral with the drive end (9) of each shaft

(5),

- a guide (73) carried by the frame (3) and intended to cooperate with the pin (72) of each shaft (5).

[Claim 3] Heating unit (1) according to any one of the preceding claims, characterized in that the adjustment means (13) in position comprise:

- an endless screw (131) rotatably mounted on the guide (73) of the angular reorientation means (71),

- a nut (132) integral with the frame (3) and intended to receive the endless screw (131). [Claim 4] A heating unit (1) according to any one of the preceding claims, characterized in that it comprises a pair of cams (111) mounted on the frame (3) at one end of the angular reorientation means ( 71), the pair of cams (111) forming a guide path for the pin (72) in the angular reorientation means (71).

[Claim 5] Heating unit (1) according to the preceding claim, characterized in that each cam (111) of the pair of cams (111) is rotatably mounted on the frame (3).

[Claim 6] Heating unit (1) according to any one of the preceding claims, characterized in that each link (41) of the chain (4) carries a roller (42), and in that the unit ( 1) heater comprises a support (10) integral with the frame (3), on which the angular reorientation means (71) are rotatably mounted, the support (10) having a groove (103) for guiding the rollers (42) of each link (41).

[Claim 7] Heating unit (1) according to any one of the preceding claims, characterized in that it comprises holding means (12) in position of the angular reorientation means (71).

[Claim 8] Heating unit (1) according to the preceding claim, characterized in that the holding means (12) in position comprise a clamping member (121) and handling means (122) of the clamping member (121).

[Claim 9] Heating unit (1) according to the preceding claim, characterized in that the clamping member (121) is in the form of a screw mounted in an internal thread formed on the frame (3), the screw being movable towards a position of support against the angular reorientation means (71) to immobilize them.

[Claim 10] Device (7) for angular reorientation for a unit (1) for heating plastic preforms (2), the heating unit (1) comprising a frame (3), characterized in that the device (7 ) of angular reorientation includes:

- a support (10) intended to be mounted on the frame (3),

- Angular reorientation means (71) of the preforms (2), mounted movably on the support (10), and in that the angular reorientation device (7) comprises adjustment means (13) in the position of the angular reorientation means (71), mounted on the support (10).