Preform gripping device for a heating unit

Abstract

The invention relates to a preform gripping device (1) of a heating unit (14) having: - a mandrel (3) defining a rotation axis (X) of the preform; - a tip (4) mounted on a first end of the mandrel (3) and having an entry portion (41) into the neck of the preform; - a friction contact device (5) in contact by friction with the preform (2), the friction contact device being integral with the tip (4); - a heat sink (6) integral with the mandrel (3) for contact with the tip (4), characterized in that the tip (4) also has a cooling portion (42) in an axial extension of the entry portion (41), the cooling portion (42) having at least one projection (7) in contact for heat exchange with the ambient air; and in that the tip (4) is mounted movably on the mandrel (3). The invention also relates to a heating unit having such a preform gripping device.

Description

Technical Field

[0001] The field of this invention is the design and manufacture of plastic containers.

[0002] More precisely, the present invention relates to a heating unit for heating preforms made of plastic to deform the preforms and obtain finished containers.

[0003] More precisely, the present invention relates to a preform gripping device for a heating unit. Background Technology

[0004] The term "pre-formed part" should be understood as both a molded blank and an intermediate container formed from a blank that has undergone at least one deformation process but does not have the final shape of a container.

[0005] Plastic containers are typically formed from preforms (or preforms) in an apparatus with multiple processing units. The plastic containers are usually blown or stretch blown from the preforms, which have a generally cylindrical body and an open neck. The body is closed by a hemispherical bottom, and the neck, in contrast to the bottom, has its final shape and is separated from the body by a flange.

[0006] In order to form the container, the body and bottom of the preform are heated and plasticized to a temperature higher than the glass transition temperature of the material (called the heating temperature).

[0007] For polyethylene terephthalate (PET), whose glass transition temperature is about 80°C, the heating temperature is generally about 120°C.

[0008] The heating of the preform is usually carried out in a heating unit equipped with a light source (usually a halogen lamp or a laser diode).

[0009] For this purpose, the preform is mounted on a rotating support called a "turntable," which has a shaft with a mandrel at one end that mates with the neck and a pinion at the other end that meshes with a rack. The turntable moves the preform forward in front of the light source while simultaneously driving it to rotate, exposing the entire preform to the light radiation from the light source.

[0010] During heating, heating of the neck of the preform must be limited or even prevented, as it can cause deformation.

[0011] In fact, the neck, which has its final shape, cannot be deformed.

[0012] Neck deformation can render a container unsuitable for sale, especially if it cannot be sealed with a stopper after filling.

[0013] To avoid heating the neck, the developed mandrel can be gripped from the outside using a ring.

[0014] These mandrels do not provide optimal protection for the neck, especially since the light radiation from the light source is reflected off the preform wall and into it, eventually reaching the neck and heating it.

[0015] Therefore, the end, which is located inside the ring and thus inside the neck, is mounted on the mandrel to reflect light radiation directed towards the neck.

[0016] Therefore, the end with the ring has a restrictive annular space in which the neck of the preform is received.

[0017] Therefore, this means that the preform must be positioned very precisely before it enters the heating unit and is picked up by the mandrel.

[0018] Other mandrels ensure that the preform is gripped only from the inside of the neck using only one end.

[0019] In this way, even if the position of the preform must always be precisely adjusted so that the mandrel can grip it, the risk of damage to the preform neck can be limited in particular.

[0020] Although direct light radiation is prevented during preform heating, the mandrel, especially the end, is heated because it is fed into the high-temperature area of ​​the heating unit, near the light source.

[0021] Therefore, the mandrel must be cooled to prevent its heat from deforming the neck of the preform.

[0022] Therefore, as proposed in EP3228438, the spindle has a heat sink that can dissipate heat through air circulation.

[0023] More precisely, the radiator is attached to the shaft and is used to contact the end for heat dissipation through heat conduction.

[0024] When gripping and unloading the preform, the mandrel is kept away from the high-temperature area of ​​the heating unit, so that it can be cooled by the heat sink.

[0025] However, the continuous increase in production speed tends to shorten the cooling time of the mandrel because the gripping and unloading of preforms are becoming faster and faster.

[0026] Therefore, the mandrel continues to be heated, but cannot be cooled as necessary, which could lead to the danger of deformation of the preform neck. Summary of the Invention

[0027] The present invention is particularly intended to overcome these deficiencies of the prior art.

[0028] More precisely, the present invention aims to provide a solution that can reliably grip a preform while avoiding heating the neck of the preform.

[0029] The present invention also aims to provide a solution that is simple to use and maintain.

[0030] These and other objectives, as described below, can be achieved by means of the preform gripping device relating to the heating unit, the preform gripping device for the heating unit having:

[0031] - Mandrel, defining the axis of rotation of the preform;

[0032] - End, mounted on the first end of the mandrel and having an entry portion that enters the neck of the preform;

[0033] - Friction contact device, which contacts the preform through friction, and the friction contact device is integrated with the end;

[0034] - The radiator, integrated with the spindle, is used for contact with the end cap.

[0035] The feature is that the end head further has a cooling portion in the axial extension of the entry portion, the cooling portion having at least one protrusion for heat exchange with ambient air; and the end head is movably mounted on the mandrel.

[0036] The cooling section can cool the end by contacting ambient air and / or forced ventilation air.

[0037] In reality, when the preform is heated relative to the light source, the light radiation heats the end, therefore it must be cooled.

[0038] Therefore, when the preform is unloaded, the air rotating in the gripper is quite cold before a new preform is loaded through the end, and the end is cooled by circulation along the cooling section of the end.

[0039] In addition, the mobility of the end on the mandrel ensures flexible gripping of the preform, and no excessive force is applied to the rotor holding the preform before the gripping device is loaded.

[0040] In addition, this mobility allows the end to contact the heat sink, and cooling can also be achieved through conduction between the end and the heat sink.

[0041] The presence of a cooling section allows the end cap to operate at a low temperature at the start of the heating cycle, even during the temperature rise phase of the furnace. During this rise phase, the protected end cap can convect with the temperature within the furnace, further increasing its temperature. In other words, during production, an end cap with a cooling section can maintain a lower operating temperature than an end cap without one.

[0042] Preferably, the cooling section has at least two protrusions that are axially separated from each other.

[0043] This can in particular increase the heat exchange between the end and the ambient air, providing good cooling for the end.

[0044] Advantageously, the protrusion is formed by annular fins extending radially around the spindle.

[0045] Therefore, a blade has three end faces, which are used to contact the ambient air, increase heat exchange, and thus cool the end.

[0046] Preferably, the overall size of at least one of the protrusions in the cooling section is larger than the overall size of the entry section.

[0047] Therefore, a protrusion whose overall size is larger than that of the entry portion can form a stop that the entry portion inserts into the neck of the preform.

[0048] According to a preferred embodiment, the entry portion and the cooling portion of the end are formed as a single unit.

[0049] This makes it easy to install the end onto and remove it from the shaft, and also facilitates cooling of the part by the cooling section.

[0050] Preferably, the end has at least two angular fan-shaped portions, and for each angular fan-shaped portion, the entry portion and the cooling portion of the end are integrally formed together.

[0051] This allows for the production of a molded end, or at least a molded fan-shaped portion of the end, which is therefore easy to manufacture and inexpensive.

[0052] In addition, this limits the number of components at the end, thus making it easy to install and maintain.

[0053] According to another advantageous embodiment, the inlet portion and the cooling portion of the end are integrally formed together.

[0054] Therefore, a single molded end can be obtained. This facilitates both the manufacture and use of the end and gripping device. Furthermore, it facilitates heat transfer from the entry portion to the reflective portion.

[0055] Advantageously, the friction contact device is integrated into the entry portion and is shaped as at least one radial protrusion.

[0056] This also limits the number of components at the end, making it easy to manufacture, inexpensive, and easy to use.

[0057] Preferably, the mandrel has a solid reflective surface at its first end, which serves as a reflective device for the light radiation from the heating unit's light source.

[0058] Therefore, the solid reflective surface can prevent the light radiation from the light source from heating the end of the gripping device, thereby avoiding excessive cooling of the gripping device, especially the end.

[0059] According to another embodiment, the mandrel has a shoulder at its first end, the shoulder being used to form a stop for the end to translate on the mandrel.

[0060] Therefore, the travel of the end on the mandrel is limited between the shoulder and the heat sink, so that the preform can be smoothly gripped, while ensuring optimal cooling when the end stops on the heat sink.

[0061] Advantageously, the shoulder of the mandrel has an annular groove that receives the annular flange carried by the entry portion of the end.

[0062] The fit between the annular flange and the annular groove allows the end to be centered on the mandrel, guiding the translational movement of the end on the mandrel.

[0063] The present invention also relates to a preform heating unit having at least one of the aforementioned preform gripping devices. Attached Figure Description

[0064] Other features and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention, given as an illustrative and non-limiting example with reference to the accompanying drawings, which are shown below:

[0065] [ Figure 1 [This is a cross-sectional schematic diagram of a preform gripping device in the prior art;]

[0066] [ Figure 2 [1] is a perspective view of the preform gripping device of the present invention;

[0067] [ Figure 3 [ ] is a cross-sectional view of the preform gripping device of the present invention;

[0068] [ Figure 4 [This is a bottom perspective view of the end of the preform gripping device of the present invention;]

[0069] [ Figure 5 [This is a bottom perspective view of the end of the preform gripping device of the present invention.] Detailed Implementation

[0070] like Figure 1 As shown, the prior art preform 2 gripping device 100 has a spindle 101, a support member 102 mounted on the first end of the spindle 101, a friction contact device 103 that contacts the preform 2 which is integrated with the support member 102 by friction, and a heat sink 104 connected to the spindle 101.

[0071] In particular, the friction contact device 103 is formed by a ring installed between the spindle 101 and the support member 102.

[0072] The ring has multiple angular sector sections.

[0073] Each angular sector portion is mounted between the mandrel 101 and the support 102 to radially compress the annular seal 105, which allows the sector portions of the ring to be radially separated outward to force the ring into frictional contact with the inside of the neck of the preform 2.

[0074] During operation, the gripping device 100 is forcibly installed in the neck of the preform 2.

[0075] More precisely, the support 102 is inserted into the neck of the preform 2 such that the friction contact device 103 is radially pushed toward the spindle 101, and the annular seal 105 pushes the fan-shaped portion of the ring onto the neck of the preform 2 through reaction, thus achieving frictional retention.

[0076] Therefore, this operation causes the gripping device 100 to exert a large force on the preform 2 when gripping and releasing it.

[0077] In addition, when the preform 2 is heated, the temperature of the support 102 rises and can only be cooled by contact with the heat sink 104 of the gripping device 100.

[0078] Therefore, as the operating cycle unfolds, the support 102 heats up, which affects its proper cooling and may damage the preform 2, particularly deforming its neck, which would prevent the lid from being placed on the formed container. Furthermore, poor cooling can damage the container manufacturing machinery, for example, by causing improper unloading of the preform at the heating outlet.

[0079] Figures 2 to 5 The preform 2 gripping device 1 of the present invention is shown.

[0080] like Figure 2 and 3 As shown, the preform 2 gripping device 1 of the present invention has:

[0081] - Mandrel 3, which defines the rotation axis X of the preform 2;

[0082] - End 4, installed at the first end of the mandrel 3 and having an entry portion 41 that enters the neck of the preform 2;

[0083] - Friction contact device 5, which contacts the preform 2 through friction, and the friction contact device is integrated with the end 4;

[0084] - The heat sink 6 is integrated with the spindle 3 and is used to contact the end 4.

[0085] The preform gripping device 1 of the present invention differs from the gripping device of the prior art in that the end 4 also has a cooling portion 42 of the axially extended entry portion 41.

[0086] More accurately, such as Figure 2 , 3 As shown in Figures 4 and 5, the cooling section 42 has at least one protrusion 7 that exchanges heat with the ambient air.

[0087] According to this embodiment, the cooling section has at least two protrusions 7 that are axially separated from each other.

[0088] The protrusion 7 is formed by annular, or generally annular, or arc-shaped winglets extending radially around the spindle 3.

[0089] like Figure 3 As shown, the overall size of at least one of the protrusions 7 in the cooling section 42 is larger than the overall size of the entry section 41.

[0090] More precisely, the first diameter D1 of the entry portion 41 of the end 4 is smaller than the diameter D2 of at least one of the protrusions 7 of the cooling portion 42.

[0091] This allows for the cooling of the end 4 firstly, and secondly, the formation of a stop that is inserted into the neck of the preform 2 by the entry portion 41.

[0092] like Figure 2 , 3 As shown in Figures 4 and 5, end 4 has two protrusions 7 that are axially separated from each other, each protrusion 7 having the same diameter D2 as the other protrusions.

[0093] Therefore, the overall size of the two protrusions 7 is larger than the overall size of the entry portion 41, which increases the cooling surface of the end 4 in contact with the air.

[0094] like Figure 3 As shown, end 4 is mounted on mandrel 3 via a pair of annular sealing rings 8. Here, the annular sealing rings 8 are elastically deformable components.

[0095] In particular, the spindle 3 has two annular grooves 9 spaced axially from each other at its first end, and the annular grooves partially receive an annular sealing ring 8.

[0096] More precisely, the annular sealing ring 8 is partially received in each annular groove 9.

[0097] As will be described later, this facilitates the retention of the preform 2 on the end 4 by friction, and also facilitates the positioning and retention of the end 4 on the mandrel 3.

[0098] In addition, such as Figure 3As shown, at the first end of the mandrel, the mandrel 3 has a shoulder 10, which is used to form a stop for the end 4 to translate on the mandrel 3.

[0099] In particular, the shoulder 10 of the mandrel 3 has an annular groove 11, in which the annular flange 12 of the entry portion 41 of the end 4 is received.

[0100] The fit between the annular flange 12 and the annular groove 11, in addition to supplementing the function of the annular sealing ring 8, also keeps the end 4 aligned on the mandrel 3, especially during rotation, and also guides the translation of the end 4 on the mandrel 3.

[0101] like Figure 2 , 3 As shown in Figures 4 and 5, the friction contact device 5 is integrated into the entry portion 41 of the end 4 and has the shape of at least one radial protrusion.

[0102] In particular, the friction contact device 5 is shaped as two radially protrusions spaced axially from each other, which together form a wave-like assembly.

[0103] like Figure 3 As shown in the cross-sectional view, each radial protrusion of the friction contact device 5 has the same diameter.

[0104] However, the diameter of one of the radial protrusions may be smaller than that of the other protrusions. Preferably, the diameter of the radial protrusion furthest from the heat sink 6 is smaller than that of the radial protrusion closest to the heat sink 6.

[0105] like Figure 2 and 3 As shown, the spindle 3 has a solid reflective surface 13 at its first end, which is used to form a reflective device for the light radiation of the light source of the heating unit 14.

[0106] Therefore, the solid reflective surface 13 can prevent the light radiation source of the heating unit 14 from heating the mandrel 3 and the end 4.

[0107] Therefore, thanks to the presence of this solid reflective surface 13, the end 4 does not require extensive cooling.

[0108] Therefore, during operation, although the time spent outside the heating unit 14 is shortened, especially due to the increased production schedule, the simple presence of the wing-shaped protrusions 7 of the cooling section 42 allows the end 4 to come into contact with ambient air and be properly cooled to avoid any damage to the preform 2.

[0109] The wing-shaped protrusion 7 allows for cooling of the end 4 by means of forced air, especially ventilated air, when the end is heated.

[0110] Preferably, the cooling portion 42 and the entry portion 41 of the end 4 form a single integral part.

[0111] In other words, the entry portion 41 and the cooling portion 42 of the end 4 can be manufactured independently of each other, but are to be finally assembled for use on the gripping device 1.

[0112] In particular, the end 4 of the gripping device 1 of the present invention is made of stainless steel or special aluminum, especially for the purpose of contacting the container holding the food.

[0113] Therefore, the assembly of the entry portion 41 of the end 4 with the cooling portion 42 is ensured, for example, by welding.

[0114] According to an advantageous embodiment, the entry portion 41 and the cooling portion 42 of the end 4 are integrally formed together.

[0115] In other words, the entry portion 41 and the cooling portion 42 of the end 4 are formed, for example, by molding or by machining.

[0116] According to the first implementation method, such as Figure 4 As shown, end 4 has at least two angular sector portions 4a and 4b.

[0117] More precisely, end 4 has a first angular sector portion 4a, a second angular sector portion 4b and a third angular sector portion 4c, each extending at approximately 120 degrees.

[0118] The angular fan-shaped portions 4a, 4b, and 4c are held on the spindle 3 by the engagement between the annular groove 11 and the annular flange 12, and by the shoulder 61 inserted into the heat sink 6.

[0119] The heat sink 6 is fixed on the spindle 3, allowing the end 4 to move between the shoulder 10 of the spindle 3 and the heat sink 6.

[0120] according to Figure 5 In the second embodiment shown, the end 4 is formed only by a single angular sector portion with a gap 4d, which allows the end 4 to elastically deform, especially during loading and unloading, i.e. when gripping and releasing the preform 2.

[0121] The single angular fan-shaped portion is held on the spindle 3 by the engagement between the annular groove 11 and the annular flange 12, and by its insertion into the shoulder 61 on the heat sink 6.

[0122] The gripping device 1, especially the cooling section 42, ensures that the end 4 is properly cooled between the heating of the two preforms 2, which helps to maintain the integrity of the preform neck.

[0123] In fact, there is a protrusion 7 on the cooling part 42 of the end 4, which facilitates heat exchange between the end 4 and the ambient air, thereby cooling the end 4.

Claims

1. Preform (2) gripping device (1) for a heating unit (14), comprising: - a mandrel (3) defining an axis of rotation (X) of the preform (2); - a tip (4) mounted at a first end of the mandrel (3) and having an entry portion (41) into a neck of the preform (2); - a friction contact device (5) in contact by friction with the preform (2), the friction contact device being integral with the tip (4); - a heat sink (6) integral with the mandrel (3) for contact with the tip (4), the heat sink (6) being fixedly mounted on the mandrel (3); the tip (4) further having a cooling portion (42) in an axial extension of the entry portion (41), the cooling portion (42) having at least one projection (7) in contact with ambient air for heat exchange; and the tip (4) comprising the cooling portion (42) being movably mounted on the mandrel (3). The cooling portion (42) has at least two projections (7) axially separated from each other. The projections (7) are formed by annular fins extending radially around the mandrel (3). The overall size of at least one of the projections (7) of the cooling portion (42) is greater than the overall size of the entry portion (41). The entry portion (41) and the cooling portion (42) of the tip (4) form a single piece. characterized in that The tip (4) has at least two angular sectors, the entry portion (41) and the cooling portion (42) of the tip (4) being made in one piece with each other for each angular sector.

2. Preform gripping device (1) according to claim 1, characterized in that The entry portion (41) and the cooling portion (42) of the tip (4) are made in one piece with each other.

3. Preform gripping device (1) according to claim 2, characterized in that The friction contact device (5) is integrated into the entry portion (41) in the shape of at least one radial projection.

4. Preform gripping device (1) according to claim 3, characterized in that The mandrel (3) has at its first end a solid reflective surface (13) for forming a reflection device of the light radiation of a light source of the heating unit (14).

5. The preform gripping device of claim 1, wherein The mandrel (3) has at its first end a shoulder (10) for forming a stop for the translation of the tip (4) on the mandrel (3).

6. Preform gripping device (1) according to claim 1, characterized in that The shoulder (10) of the mandrel (3) has an annular groove (11) in which an annular flange (12) carried by the entry portion (41) of the tip (4) is received.

7. Preform gripping device (1) according to any one of claims 1 to 5, characterized in that The heating unit has at least one preform gripping device (1) according to any one of the preceding claims.

8. Preform gripping device (1) according to claim 1, characterized in that ​ 9. Preform gripping device (1) according to claim 1, characterized in that ​ 10. Preform gripping device (1) according to claim 1, characterized in that ​ 11. Preform gripping device (1) according to claim 10, characterized in that ​ 12. Heating unit (14) of a preform (2), characterized in that, ​

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