EP1387755A1

EP1387755A1 - Device for injecting clean fluid into a plastic preform

Info

Publication number: EP1387755A1
Application number: EP02732865A
Authority: EP
Inventors: Jean Sattler; Régis BECHEN; Marc Michelet; Daniel Dagorn
Original assignee: Sidel SA
Current assignee: Sidel SA
Priority date: 2001-05-17
Filing date: 2002-05-14
Publication date: 2004-02-11
Also published as: FR2824775B1; FR2824775A1; WO2002092324A1

Abstract

The invention concerns a device for injecting clean fluid into a plastic preform whereof a portion is received in a housing (3), through a cannula (6) mobile in a bore (4) emerging inside the housing (3); a tubular sheath (23) enclosing the cannula (6) is mobile in the bore (4) to be urged to be tightly pressed against the wall of the preform empty housing, so that the cleaning fluid can be blown through the cannula, then recovered and evacuated, so as to clean the cannula.

Description

DEVICE FOR INJECTING CLEAN FLUID INTO A PLASTIC MATERIAL

The present invention relates to improvements made to the devices for injecting fluid into a plastic parison, and in particular to the devices for blowing a plastic parison for the purpose of manufacturing a container, such as a bottle, flask. , ...

More specifically, the invention relates to improvements made to those of these fluid injection devices which comprise a body provided with a housing for receiving a portion of a parison and

• a bore extending transversely to said housing and opening laterally

20 therein, and - a tubular cannula holder fixedly supporting an injection cannula, said cannula holder being axially displaceable in the bore 25 • between a retracted position for which the cannula is withdrawn in the bore and

• a projecting position for which the end of the cannula is out of

30 bore and is located in the above housing. In the remainder of the description, the term "portion of a parison" is intended to denote part of a parison which is intended to be pierced by the cannula so that fluid is injected into the parison. In particular, it may be an end portion (single parison) or a central portion (double parison) which is pierced by a needle of a blowing device and which, once the (s) final container (s) shaped, is sectioned and disposed of.

Furthermore, one will designate by "front" or "anterior" a part of an element which is situated on the side of the above-mentioned housing, while one will denote by "rear" or "posterior" a part of an element which is situated opposite to the above accommodation.

The object of the invention is essentially to propose an original technical solution which allows the injection of a clean, even sterile fluid, with a faculty of cleaning the end of the cannula only by circulation of a cleaning fluid adapted to the degree of cleanliness or sterility required without manual intervention.

For these purposes, a device as mentioned in the preamble is characterized, being arranged in accordance with the invention, in that it further comprises a tubular sheath which surrounds the cannula holder and the cannula and which is axially displaceable in the bore independently of the cannula holder so as to selectively occupy

A retracted position in the bore in which the cannula is housed in said sheath when the cannula holder is in its retracted position and

• a projecting position in which it leaves the bore and passes through the housing while being in watertight frontal abutment against the wall of said housing opposite the bore, said sheath comprising at least one lateral orifice • normally closed by the cannula holder when the sheath is in the retracted position and • uncovered only when simultaneously the cannula holder is in its fully protruding position and the scabbard is in its completely protruding position.

Thanks to this original arrangement, for cleaning the end of the cannula a clean cleaning fluid can be injected through the cannula while, no portion of a parison being present in the housing, the cannula holder is in the projecting position and the sheath is in the projecting position in sealed frontal abutment against the opposite wall of said housing: thus the aforesaid lateral orifice of the sheath is discovered through which the cleaning fluid leaving the cannula is directed, externally to the sheath, towards a evacuation passage in the body; then the blowing of the cleaning fluid is interrupted and the sheath is returned to its retracted position, causing the concomitant obturation of the aforesaid lateral orifice.

In a compact embodiment, the cannula holder is, in its rear part opposite the end of the cannula, arranged in the form of a piston suitable for cooperating in leaktight sealing with the rear part of the bore and at least one pressure control fluid delivery orifice is provided in the bore on one side of the said piston to control the unidirectional movement of the cannula holder; advantageously then, two pressure control fluid delivery orifices are provided in the bore on either side of the aforesaid piston to control the selective bidirectional movement of the cannula holder. Advantageously, the pressure control fluid is a gas, such as compressed air normally available in this type of installation.

In a preferred embodiment, the bore, in its front part (that is to say that located on the housing side), houses a fixed jacket cooperating in leaktight manner with the cannula holder, said jacket and the cannula holder defining between them an annular chamber in which the sheath is installed and which is sealingly isolated from the rear part of the bore in which the piston of the cannula holder is movable; the sheath is, in its rear part, shaped as a piston cooperating in a sliding leaktight manner with the jacket; and at least one pressure control fluid delivery orifice is provided in the jacket on one side of the barrel piston to control the unidirectional movement of the barrel. It is then possible to provide for a return spring to be interposed between the sheath, on one side, and the jacket and / or the body, on the other side, to recall the sheath moved under the action of the control fluid under pressure. In this context, it is advantageous that the spring is arranged to return the sheath in the retracted position inside the jacket and that a pressure control fluid delivery orifice is provided in the jacket between the bottom of the latter. ci and the piston of the sheath to control the movement of the sheath towards its extended position; we can then ensure that the jacket, in its part located in front of the sheath piston, has a passage crossing located opposite a channel, dug in the body, for the evacuation of the control fluid.

In a very advantageous embodiment because of its structural and functional simplicity, the front end of the sheath is formed in the form of an annular seal, for example made of elastomer, capable of being in leaktight abutment against the wall of the housing opposite to the hole in the bore when the sleeve is in the extended position. In practice, provision is made for the housing suitable for receiving the aforementioned parison portion to be substantially round and for the bore to open out substantially radially in said housing, the sheath extending substantially diametrically in said housing when it is in the extended position.

A preferred application of the provisions of the invention which have been mentioned above relates to a device for blowing clean a plastic container from a parison. A blowing needle capable of piercing the aforementioned parison portion constitutes the aforesaid cannula and a needle holder constitutes the aforesaid cannula holder.

The invention will be better understood on reading the following detailed description of a preferred embodiment given by way of non-limiting example. In this description, reference is made to the appended drawings in which:

- Figures 1 to 3 are sectional views of a preferred embodiment of the invention shown respectively in three different functional positions, respectively in the inactive position, in the filling position and in the cleaning position; and FIG. 4 is a view on a larger scale of a part of the device in the functional position of FIG. 3.

Referring first to Figure 1 which shows the device of the invention in the rest position or inactive position, said device, generally designated by the reference numeral 1, comprises a body

2, here constituted in the form of two parts 2a and 2b.

The part 2b comprises a housing 3, blind and open towards the bottom, suitable for receiving a portion (not shown) of a parison made of plastic material (in particular PVC, high density polyethylene, etc.) intended for the manufacture of a container, such as a bottle, flask or the like, by a blowing process. The part 2a and a part of the part 2b have an elongated bore 4, extending transversely to the housing 3 and opening laterally into the latter. In the illustrated embodiment, the housing 3 is substantially round and the bore 4 opens substantially radially into said housing 3.

Inside the bore 4 is disposed, slidingly, a tubular cannula holder 5 fixedly supporting an injection cannula 6 (here shown in the form of an injection needle). The injection cannula 6 is blocked axially in the cannula holder 5 by a tight plug 7 so that the cannula holder 5 and the cannula 6 constitute a functional unit which will be considered as such in the following description.

At the rear (i.e. opposite the active end of the cannula or needle 6, the active end being that located on the side of the housing 3), the cannula holder 5 is provided with an enlarged head 8 cooperating sealingly with a cylindrical part 9 of enlarged diameter of the bore 4. The rear end of the bore 4 is closed by a tight plug 10. Two orifices respectively 11, 12 open into the cylindrical part 9 at the rear and front ends thereof, c 'is to say on either side of the enlarged head 8 of the cannula holder which forms piston. The selective introduction of a pressurized control fluid through the orifice 11 or the orifice 12 makes it possible to move the cannula holder 5 respectively forwards or backwards. The cannula holder 5, being tubular, remains hollowed out in its rear part at 13 and an axial fixed arm 14, for example integral with the plug 10 or with an insert against it, extends in the central recess 13 of the cannula holder 5. A finger 15 projecting radially at the end of the arm 14 is engaged in a longitudinal groove 16 of the recess 13, so that the cannula holder 5 can slide freely in the body 2, but is blocked rotating in it.

In front of the cylindrical part 9 of the bore 4 is provided a part 17 of the bore 4 radially distant from the cannula holder 5 and defining therewith an annular chamber 18. A seal 19, for example of the lip seal type, is interposed between the bore 4 and the cannula holder 5 to physically separate the parts 9 and 17 and make the chamber 18 autonomous with respect to the cylinder 9 in which the piston 8 moves.

In the chamber 18, there is an orifice 20 for supplying pressurized fluid for blowing the container. In its part in correspondence with the chamber 18, the cannula holder 5 is provided with one or more through radial bores 21 and, opposite, the cannula 6 is itself provided with one or more radial bores through 22 which open into its axial central channel 30.

In its front part (that is to say on the side of the housing 3), the cannula holder 5 is surrounded in a leaktight manner by a tubular sheath 23 movable axially and which, in the rest position shown in FIG. 1, extends beyond the active end of the cannula 6.

To ensure the functioning of the sheath 23, there is in the bore 4, in front of the chamber 18, a fixed jacket 24 forming a cylinder with which a rear portion 25 of enlarged diameter of the sheath 23 forming the piston cooperates. One or more radial passages 26 pass through the jacket 24 behind the piston 25 and communicate, through an annular chamber 27 provided at the interface of the jacket 24 and the part 2a of the body, with an orifice (not visible) of the body delivering a pressurized control fluid. A helical return spring 28, surrounding the sheath 23, is interposed between the piston 25 and a shoulder of the part 2b.

Thanks to the arrangements which have just been exposed, the sheath 23 is constituted as an axially movable element which is functionally independent of the cannula holder 5 and of the cannula 6. At its anterior end, the sheath 23 is provided with a frontal seal 29, for example made of elastomer.

In its part close to the piston 25, the sheath 23 has one or more radial through passages 33, which, in the rest position illustrated in Figure 1, are located in correspondence with the cannula holder 5 and are therefore closed. These radial passages 33 open into an annular chamber 34 defined between the sheath 23 and the shirt 24 radially spaced from one another. At the front end of the chamber 34 open one or more evacuation orifices 35 corresponding to one or more evacuation channels 36 drilled in the part 2b of the body.

The operation of the device which has just been described is as follows.

In Figure 1, the device is illustrated in its rest or inactive position. The cannula holder 5 is held in the retracted position towards the rear under the effect of the control fluid supplied by the orifice 12 and acting on the piston 8. The needle is then erased in the bore 4. Similarly , under the action of the return spring 28, the sheath 23 is held in the retracted position and is erased inside the bore 4. The housing 3 is thus released and ready to receive a portion of a parison to be blown .

In FIG. 2, the device is illustrated in its functional blowing position, a parison portion (not shown) being assumed to be in place in the housing 3. Pressure fluid under pressure introduced through the rear orifice 11 acts on the piston 8 and pushes the cannula holder 5 forward until it comes into abutment against the sleeve 24. In this position, the anterior end of the cannula or of the needle 6 is introduced radially into the housing 3 and pierces the portion of parison which is maintained there.

Pressure blowing fluid is then admitted into the chamber 18 through the orifice 20 and from there into the needle 6 through the passages 21 and 22. This fluid is thus introduced into the container so that it is blown . At the end of the blowing process, pressure control fluid is introduced through the orifice 12 to act on the piston 8 and push the cannula holder 5 and the needle 6 backwards. In FIG. 3, the device is illustrated in the cleaning position of the cannula or needle 6. No portion of parison is introduced into the housing 3, which is therefore empty. The cannula holder 5 is moved in the direction of the housing 3 and the cannula or needle 6 is introduced into the housing 3 by proceeding as described above with reference to FIG. 2. In addition, by introducing control fluid under pressure by the chamber 27 and the orifice (s) 26, the sheath 23 is moved forward until the front seal 29 comes to press against the wall of the housing 3 which is opposite the bore 4. Thus, the cannula or needle 6 is enclosed in the internal volume 31 of the sheath 23 closed in a sealed manner.

Through the orifice 20 and the passages 21 and 22, it is then possible to bring into the axial channel 30 of the cannula or needle 6 a clean cleaning fluid, or even a sterilization fluid which exits through the end of the cannula 6 in the above volume 31.

As best seen in Figure 4 on a larger scale, the cannula holder 5 has its front end which has a reduced diameter and which defines, with the facing surface of the sheath 23, an annular gap 32. In the position illustrated in Figures 3 and 4, the sheath 23 being moved forward, the through passages 33 of the sheath are located opposite the annular gap 32 above (while in the retracted position of the sheath 23 illustrated in Figures 1 and 2 , the passages 23 are located behind the annular gap 23, thus being closed off by the wall of the cannula holder 5 as already indicated). Under these conditions, the cleaning fluid which leaves the cannula or needle 6 in the volume 31 flows in the annular gap 32, passes through the passages 33 in the annular chamber 34 formed between the cannula holder 5 and the jacket 24, and from there exits through the evacuation orifice 35 provided in the jacket 24 and in communication with an evacuation channel 36 drilled in the part 2b of the body. Once the cannula or needle 6 has been cleaned by passing the cleaning fluid, the application of pressure control fluid to the orifice 26 is interrupted and the sheath 23 is brought back, in the retracted position, by the spring of reminder 28. It will be understood, from the foregoing explanations, that the provisions of the invention can find application in any device capable of blowing a clean fluid (in particular a clean gas) into a plastic container using '' an elongated hollow rod of the cannula type which needs to be regularly cleaned by circulation of a cleaning fluid which, being ultimately polluted, is not released into the ambient atmosphere within the installation

(supposed to operate in a clean, even sterile atmosphere), but is directed by a specific circuit to recovery means (for example reprocessing, filtration, ...). The provisions of the invention find a particularly advantageous application in devices for blowing a plastic container (for example PVC, high density polyethylene, etc.) by blowing a fluid (generally a gas) under pressure in a parison pierced with a needle blower whose perforating tip can get dirty on contact with the plastic material it pierces.

Claims

1. Device for injecting clean fluid into a plastic parison, said device comprising:

- a body (2) provided

• a housing (3) for receiving a portion of a parison and • a bore (4) extending transversely to said housing (3) and opening laterally therein, and a tubular cannula holder (5) fixedly supporting an injection cannula (6), said cannula holder (5) being axially displaceable in the bore (4)

• between a retracted position for which the cannula (6) is withdrawn in the bore (4) and • a projecting position for which the end of the cannula (6) is pulled out of the bore (4) and is located in the above housing (3), characterized in that it further comprises a tubular sheath (23) which surrounds the cannula holder (5) and the cannula (6) and which is axially displaceable in the bore (4) independently of the cannula holder (5) so as to selectively occupy

• a retracted position in the bore (4) in which the cannula (6) is housed in said sheath (23) when the cannula holder (5) is in its retracted position and

• a projecting position in which it exits the bore (4) and passes diametrically through the housing (3) while being in sealed frontal abutment against the wall of said housing (3) opposite to the bore (4), said sheath (23) ) comprising at least one lateral orifice (33)

• normally closed by the cannula holder (5) when the sheath (23) is in the retracted position and

Discovered only when simultaneously the cannula holder (5) is in its fully protruding position and the sheath (23) is in its completely protruding position, whereby, for cleaning the end of the cannula (6), a clean cleaning fluid can be injected through the cannula (6) while, no portion of a parison being present in the housing (3), the cannula holder (5) is in the projecting position and the sheath

(23) is in the projecting position in sealed frontal abutment against the opposite wall of said housing (3) thereby uncovering the aforesaid lateral orifice (33) of the sheath through which the cleaning fluid leaving the cannula (6) is directed, externally to the sheath (23), towards an evacuation passage (35, 36) practiced in the body, then the blowing of the cleaning fluid is interrupted and the sheath (23) is returned to its retracted position, causing the concomitant obturation of the aforesaid lateral opening (33).

2. Fluid injection device according to claim 1, characterized in that the cannula holder (5) is, in its rear part opposite the end of the cannula (6), arranged in the form of a piston (8) capable of cooperating in a sliding leaktight manner with the rear part (9) of the bore (4) and in that that at least one orifice (11, 12) for delivering pressurized control fluid is provided in the bore (4) on one side of the above-mentioned piston (8) to control the unidirectional movement of the cannula holder (5) .

3. Fluid injection device according to claim 2, characterized in that two orifices (11, 12) for delivering pressure control fluid are provided in the bore (4) on either side of the said piston (8) to control the bidirectional selective movement of the cannula holder (5).

4. Fluid injection device according to claim 2 or 3, characterized in that, in its front part located on the side of the above-mentioned housing (3), the bore houses a fixed jacket (24) cooperating sealingly with the cannula holder (5), said sleeve (24) 'and the cannula holder (5) defining between them an annular chamber (34) in which the sheath (23) is installed and which is sealingly isolated from the rear part

(9) of the bore (4) in which the piston (8) of the cannula holder (5) is displaceable, in that the sheath (23) is, in its rear part, shaped as a piston (25) cooperating with sealingly sliding with the jacket (24), and in that at least one orifice (26) for delivering pressure control fluid is provided in the jacket (24) on one side of the piston (25) of the sleeve ( 23) to control the unidirectional movement of the sheath (23).

5. Fluid injection device according to claim 4, characterized in that a return spring (28) is interposed between the sheath (23), on one side, and the jacket (24) and / or the body (2), on the other side, to recall the sheath (23) moved under the action control fluid under pressure.

6. fluid injection device according to claims 4 and 5, characterized in that the spring (28) is arranged to return the sheath (23) in the retracted position inside the jacket (24) and in that '' a pressure control fluid delivery orifice (26) is provided in the jacket (24) between the bottom of the latter and the piston (25) of the sleeve (23) to control the movement of the sleeve (23) towards its extended position.

7. Fluid injection device according to any one of the preceding claims, characterized in that the front end of the sheath (23) is formed in the form of an annular seal (29) capable of being in sealed contact against the wall of the housing (3) opposite the orifice of the bore (4) when the sleeve (23) is in the extended position.

8. Fluid injection device according to any one of the preceding claims, characterized in that the housing (3) suitable for receiving the projecting end of a container is substantially round and in that the bore (4) opens out substantially radially in said housing (3), the sheath (23) extending substantially diametrically in said housing (3) when it is in the extended position.

9. Fluid injection device according to any one of claims 6 to 8, characterized in that the jacket (24), in its part located in front of the piston (25) of the sleeve, has a through passage (35) located opposite a gas discharge channel (36) formed in the body (2).

10. Device for blowing clean a plastic container from a parison, characterized in that it is constituted according to any one of claims 1 to 9, a blowing needle (6) suitable for piercing the portion of said parison constituting the aforesaid cannula and a needle holder (5) constituting the aforesaid cannula holder.