FR2720678A1 - Device for fixing an elongation rod on a machine for manufacturing containers by stretching and blowing plastic preforms and machine provided with such a device. - Google Patents

Abstract

Device for securing a drawing rod (41) on a machine for the manufacture of containers by drawing and blowing of plastics material preforms and machine comprising such a device for speedily changing said rod and securing it. The device for securing the drawing rod (41) on a machine for the manufacture of plastics material containers by drawing and blowing preforms or intermediate containers includes at least first means secured to said rod at a given location before actual securing of the rod to the machine, at least second means (25) for receiving said first means, said second means being rigidly secured to an element (2) in the machine for driving said rod, and third means (35) for removably locking together said first and second means.

Description

Device for attaching an elongation rod to a machine for manufacturing containers by stretching and blowing plastic preforms, and machine provided with such a device.

 The invention relates to a device for fixing an elongation rod on a machine for manufacturing containers, such as bottles, jars, or any other type of hollow body, by thermal conditioning, then stretching and blowing of plastic preforms or intermediate containers. The invention makes it possible to easily and quickly personalize the machine operating from different preforms. It also relates to a machine for manufacturing easily customizable plastic containers, insofar as it includes such a device.

In the state of the art, machines for manufacturing plastic containers have already been described which successively comprise: a section for entering or loading preforms into the machine, a thermal conditioning oven, a section for handling preforms heated, a mold unit equipped with means making it possible to stretch and blow either a preform to transform it into a final container or into an intermediate container, or a preform or an intermediate container to transform it into a final container, a handling section of the container obtained, and finally an outlet section for finished containers or intermediate containers
Such a machine is capable of producing a considerable quantity of containers per unit of time. Adjusting the operating parameters of such a machine is a complex operation, which means that the machine is generally adjusted according to a single type of container to be manufactured.

 Indeed, the change of a single parameter entails radical changes in the adjustment of the manufacturing process. However, such modifications are now facilitated by computers or programmable logic controllers, for example.

 Therefore, it is now known to adjust in a simpler way than in the past the container manufacturing machine. However, there remains a major difficulty which resides in that, to change manufacturing, the machine must be mechanically adapted to the preform from which one starts to manufacture the container, or to the desired container itself.

 It is therefore necessary to personalize the machine.

 Such a situation can arise in two characteristic situations which are not exhaustive.

 In a first situation, in order not to require a re-study of a complete machine, the manufacturer wishes to offer to its catalog a machine whose design incorporates as many basic elements or components as possible on machines which it has already developed . It thus reduces the time and costs of designing the subsequent machine, and uses components more easily amortized in terms of their cost, and more reliable than entirely redefined components.

 In a second situation, it is the manufacturer who wishes to change container models periodically.

For example, by working on successive campaigns, he wants to produce containers of a first shape, then containers of a second capacity, on the same model.

 It is clear that in these cases the operating parameters of the machine will be changed. It is assumed that the problem is solved by the simple means mentioned above.

 A major problem, shared in the two situations envisaged, is that many mechanical parts of the machine must be modified, to adapt to the new container. However, these changes essentially affect parts which, at one time or the other of manufacturing, are found for a moment in the manufacturing process, in relation, that is to say in contact, with the container or its preform.

 This is the case of the extension rod associated with each blow mold.

 It will be recalled that the elongation rod is an element which stretches the preform in the blow mold in the case of so-called single blow machines, or else an intermediate container, in the case of double blow machines, before blowing . This preliminary stretching makes it possible to facilitate the distribution of plastic material and to obtain good distribution thereof. Its movement, in the machines manufactured by the plaintiff, is produced by cams and / or jacks.

 A synchronism, determined during the development phases of the manufacturing process, exists between the movement of the rod and the pre-blowing and blowing steps allowing the containers to be obtained.

 More specifically, the rod is introduced into the opening (the neck) of the object to be stretched and to blow preform or intermediate container - by sliding through an organ called nozzle in the terminology of the applicant. The nozzle is the device that blows air under low or high pressure into the object to be stretched and blown. To this end, the nozzle has means for circulating air, or more generally of fluid allowing blowing an intermediate container or a final container, connected to the source of distribution of fluid, and a bore centered on its longitudinal axis allowing the passage of the extension rod. In addition, means, such as seals, are provided to ensure an excellent seal between the rod and the nozzle, thus preventing leakage of the blowing fluid when it is blown.

 After placing the object in the blow mold and closing the latter, the nozzle is pressed against the opening of the object, so that a good seal is ensured between the inner edge of the opening and the periphery of the nozzle. Then the rod is lowered, to stretch the object and the blowing fluid is then blown in according to the synchronism determined during the adjustment phases.

 The rest of the manufacturing process will not be described further since it does not directly relate to the present invention.

 However, if the change in manufacture requires the use of a preform of different length and / or inner diameter, an adjustment or a change in the extension rod must be made to adapt the machine to the new preform. It may also happen that it is necessary to use a rod whose end acting on the preform has a shape different from that used during the previous campaign.

 The constraints related to the change in length can be resolved by adjusting the position of a member known as an elongation stop whose role is to limit the stroke of the rod. Thus, by moving this stop, we manage to adapt the length of the rod portion entering the object to be stretched.

 On the other hand, a change in diameter necessarily implies a change in the rod. However, it is recalled that current machines can include a relatively large number of molds and a corresponding number of rods which must be changed. Thus, by way of example, the machines manufactured by the applicant comprise from two to forty molds. It is therefore from two to forty stems that must be changed.

 Figures 1 and 2 schematically illustrate how each rod is currently attached to the machines of the applicant, and allow us to understand how changing the rods can be a slow and difficult operation, which can be contradictory with industrial needs.

 The extension rod 1 is made integral with the upper part of a slide 2 using a clamp 3 for fixing. The clamp, seen from above in FIG. 2 is for example in the form of a parallelepipedal block pierced with two holes 4, 5 of parallel axes for its attachment to the slide using screws 6,7. A third hole 8, with an axis parallel to the first two passes through the central part of the clamp. A slot 9 carried on a plane parallel to the axis of the third hole 8 connects an outer edge of the clamp and this hole 8. Finally, a screw 10 allows the two edges of the slot to be brought together. The diameter of this hole 8 is such that the rod can be inserted therein without forcing when the screw 10 is loosened, and is blocked when the screw 10 is tightened.

The slide is carried by two axes 11, 12 of sliding. The slide is also connected to a means, not shown, allowing its movement along the axes 11, 12. It can be a jack, or any other equivalent device. The lower end of the rod also passes through a member 13 carrying the nozzle 14. The whole is arranged so that the nozzle 14 can, on the one hand,
at the time of closing the mold 15 descend into contact with the opening of the object to be blown and, on the other hand, go back up at the time of opening in order to release the blown object. A stop, carried for example by the axes 11, 12 makes it possible to limit the travel of the slide, therefore of the rod.

 Changing a rod requires at least the following operations, which can be carried out using a tool for loosening the screw 10 of the clamp 3, removing the rod 1, fitting the new rod, moderately tightening the rod in the clamp, measurement and positioning of the rod, final tightening of the rod.

 These operations take almost 3 minutes for a trained technician.

 Furthermore, additional operations may be necessary, such as for example the closing of a control valve of the jack associated with the slide before dismantling, and its opening after.

 Thus, for a machine with forty molds, more than two hours are necessary to change all of the elongation rods, during which it is necessary to immobilize the machine.

 The present invention provides a remedy to this problem by proposing a new method for fixing the rods, allowing their rapid change, and the adaptation of which can possibly be envisaged on existing machines.

 According to the invention, a device for fixing an elongation rod on a machine for manufacturing plastic containers by stretching and blowing a preform or an intermediate container is characterized in that it comprises a first means fixed on the rod at a determined location thereof before the actual fixing operation of the rod on the machine, at least a second means intended to receive the first means, the second means is fixed permanently to an element the machine for ensuring the drive of this rod, and third means for detachably locking the first and second means between them.

 Thus, by using means allowing a removable locking, the use of a tool is avoided, which saves time during assembly and disassembly. In addition, the first means fixed on the rod at a determined location of the latter avoids having to perform the dimensioning and positioning of the rod during its assembly in the machine: in fact, as soon as the locking is assured, the positioning of the rod is necessarily correct since the second means is carried by the rod drive mechanism. However, the positioning of the first means on the second must have been correctly ensured beforehand.

 Thus, by associating at least two sets of rods to a machine, it is possible to envisage at least two different types of manufacturing. By play is meant a sufficient number of rods corresponding to the number of molds carried by the machine.

 According to another characteristic, the element of the machine enabling the rod to be driven, on which the second means is permanently fixed, is the slide.

 Thus, it is possible to modify once for all existing machines, replacing the clamp by the second means.

 According to another characteristic, the first means consists of an element projecting from the periphery of the rod, and the second means consists of a housing making it possible to prevent any translation of the rod on its logitudinal axis.

Other characteristics and advantages of the invention will appear on reading the description which follows, given with reference to the appended figures, in which:
- Figure 3 is a perspective view of a preferred embodiment of the first means, associated with each rod of a machine;
- Figure 4 is a top view of the preferred embodiment of the first means;
- Figure 5 is a top view of a preferred embodiment of the second means intended to be fixed on an element of the machine and to cooperate with the first means of Figures 3 and 4;
- Figure 6 is a bottom view of the second means of Figure 5;
- Figure 7 is a sectional view AA of the second means showing the third means in the locked position;
- Figure 8 is a sectional view AA of the second means showing the third means in the unlocked position;
- Figure 9 is a top view showing the relative arrangement of the first and second means in the locked position;
- Figure 10 is a partial and schematic view of a machine equipped with the device of the invention.

 The first means, the preferred embodiment of which is illustrated in particular in FIGS. 3 and 4, consists of a clamp 16, substantially in the shape of a rectangular parallelepiped. A hole 17 joins two opposite walls of the parallelepiped, and a slot 18 carried by a plane parallel to the axis of the hole 17 is formed between the walls where the hole opens, on the one hand, and between the hole itself and a another wall 19, on the other hand.

 A cylindrical bore 20 is formed in the thickness of the clamp so as to open into the edges of the slot 18. This bore is provided with a thread 21 on one side of the slot 18, and is left smooth 22 of the other side. The function of this drilling, of the thread and of the smooth part is to make it possible to introduce a screw, not shown, on the side of the smooth part, and to bring the edges of the slot 18 together when the screw is tightened. Furthermore, the dimensions of the hole 17 are such that the dedicated rod 41 on the one hand can be inserted therein easily when the screw is absent or loose and, on the other hand, is blocked when the screw is tightened.

 Preferably, as illustrated in FIGS. 3 and 4, on the side of the smooth part of the bore is a recess 23, making it possible to hide the head of the screw.

 Finally, a recess 24 in the form of a half cylinder with an axis parallel to that of the hole 17 is formed on one of the walls of the clamp. Its function is to cooperate with the locking means, the details of which will be explained later.

 It is clear that the clamp, instead of being produced in a single block, could be produced in any other way, for example of two similar or symmetrical parts, which would then be brought together with the aid of of screws, or equivalent means, for blocking the rod 41, while the latter would be in place between the two parts, the unlocking being effected by loosening the screws.

 The second means, in the context of this preferred embodiment, consists of a housing 25, for example of cylindrical shape, although this shape is not limiting.

 The upper part or cover 26 of the housing 25 (FIG. 5) is provided with a central opening or window 27 of dimensions such that the clamp 16 can penetrate this opening by being displaced along the axis of the hole 17, therefore along that of the stem.

 The bottom 28 of the housing (FIG. 6) is provided with a central orifice 29 intended for the passage of the elongation rod when the latter is mounted on the clamp 16.

 Furthermore, the housing has a chamber 30 (Figures 7, 8) whose dimensions are such that, on the one hand, they allow pivoting of the clamp 16 around the axis of the hole 17, after there has been been introduced through the window 27 and, on the other hand, they prevent after introduction and pivoting, any movement of the clamp, in a direction parallel to that of its introduction into the housing, and thereby prevent any movement of the rod 41 elongation along its axis, relative to the housing.

 The cover of the housing 25 is pierced with holes 31, 32 which, when the housing is assembled, are located opposite respective holes 33, 34 of the bottom 28. On the one hand, these holes allow the housing to be fixed using of screws on the slide described with reference to FIG. 1, after the old clamp has been removed. On the other hand, these holes allow them to block, when the screws are in place, the various parts constituting the housing. In fact, due to the presence of the chamber 30 in the housing, it is more economical for the latter to be produced at least in two parts: a first part comprising for example the bottom of the housing and a recess defining the bottom wall and the side walls of the chamber, and a second part forming the cover, thereby delimiting the upper wall of the chamber 30. In order for the screws to block the various parts of the housing, the diameter of their head must therefore be greater than that of the holes 31, 32 formed in the cover.

 Thus, the realization of the case is particularly economical, since it does not need to be assembled in advance.

 Of course, other possibilities are conceivable for producing the housing.

 An embodiment of the third locking-unlocking means associated with each device appears in Figures 7 and 8. These means associated with the cover, are constituted by an assembly formed by a pull tab 35, connected to a first end of a rod 36, for example cylindrical, the second end of which is connected to the base of a conical or semi-conical stud 37. The diameter of the base of the stud is larger than that of the rod.

 The rod 41 passes through a hole 38, of internal diameter such that the rod can slide there freely. This hole 38 opens onto the outer wall of the cover on the one hand and into a cavity 39 formed in the inner wall of the cover. A spring 40 surrounding the rod portion included in this cavity bears on the one hand on the base of the stud 37 and on the other hand on the edge of the cavity surrounding the outlet of the hole 38 therein. Thus, when the pull tab is released, the spring pushes the stud towards the inside of the housing. When the pull tab is pulled by the operator, the stud is brought back towards the interior of the cavity. Also, the depth of the cavity 39 is such that when the pull tab is pulled, the entire stud can be erased in the thickness of the cover, thus allowing the clamp 16 to pivot.

 The establishment and locking of the rod 41 is carried out after its mounting on the clamp, and after the housing has been fixed on the machine.

 The end of the rod intended to penetrate the object to be stretched is first introduced into the case, through the opening 27 of the cover, then leaves the case through the opening 29 of the bottom. As the rod progresses, the clamp is brought closer to the housing, then it is introduced into the opening 27. When the clamp comes into contact with the bottom, the operator causes the rotation of the formed assembly by the rod and the clamp around the axis of the rod, therefore of the housing, simultaneously pulls the pull tab 35, to erase the stud 37, thus allowing the clamp to continue its rotation and bring the recess 24 of the clamp opposite the stud 37. The pull tab can then be released, the stud engaging in the blocking recess 24.

 A device has therefore been produced in a simple manner making it possible to quickly replace the extension rods of a stretch-blow molding machine.

 Figure 9 shows, in top view, the relative position of the clamp 16 and the housing, when the locking is ensured. Any vertical movement of the clamp is prevented, since, after its rotation, it is blocked between the cover and the bottom of the case.

Furthermore, the locking means prevent any rotation and therefore any untimely exit from the housing of the assembly formed by the rod 41 and the clamp.

 FIG. 10 illustrates how the device of the invention can be easily installed on any type of machine, and in particular on machines already in service. In FIG. 10, a single stretching assembly has been illustrated, but it is recalled that the machines manufactured by the applicant can comprise from two to forty sets of this type.

 It suffices to replace the clamp 3 previously existing on the slide 2 the housing, then to put in place the rod previously equipped with its clamp 16.

 Of course, the invention is in no way limited to the embodiments described or claimed, but it includes their equivalents and all the variants or adaptations which would be within the reach of those skilled in the art.

Claims (10)

 1. Device for fixing an elongation rod (41) on a machine for manufacturing plastic containers by stretching and blowing a preform or an intermediate container, characterized in that it comprises at least a first means (16) fixed on the rod at a determined location thereof before the actual fixing operation of the rod on the machine, at least one second means (25) intended to receive the first means, the second means being permanently fixed to an element (2) of the machine making it possible to drive this rod, and third means (24, 35-40) for releasably locking the first and second means together.  2. Device according to claim 1, characterized in that the first means consists of an element (16) projecting from the periphery of the rod, and the second means (25) consists of a housing making it possible to prevent any translation of the stem on its logitudinal axis.  3. Device according to claim 2, characterized in that the third means consist of an assembly comprising a stud (37) which can engage or disengage a recess (24) of the element (16) projecting at the periphery of the rod when this protruding element is in the housing.  4. Device according to claim 2, characterized in that the first means (16) is a clamp clamped on the periphery of the rod.  5. Device according to claims 2 and 4, characterized in that the housing (25) comprises on the one hand a cover (26) provided with an upper opening (27) whose dimensions allow the introduction of the clamp (16 ) through this opening in the housing, the clamp being fixed around the elongation rod, on the other hand a bottom (28) provided with an orifice (29) for passage of the rod, and an interior chamber (30) whose dimensions are such that, on the one hand, they allow pivoting of the clamp (16) and of the rod (41) about the longitudinal axis of the rod, after it has been introduced therein through the window (27) and, on the other hand, they prevent, after introduction and pivoting, any movement of the clamp, in a direction parallel to that of its introduction into the housing, and therefore any movement of the extension rod along its axis by report to the housing.  6. Device according to claims 3 and 5, characterized in that the stud (37) is connected to one end of a rod (36) passing through a hole (38) made in the cover (26) of the housing, the other end can be manipulated by an operator, and in that the stud is erased in a cavity (39) formed in the thickness of the cover (26) during the operations of placing or removing the rod.  7. Device according to claim 6, characterized in that the stud (37) is associated with a spring (40) which pushes it towards the chamber (30) when the rod (36) is not manipulated.  8. Device according to any one of the preceding claims, characterized in that the element of the machine making it possible to ensure the drive of the rod (41), on which the second means is permanently fixed, is the slide ( 2).  9. Device according to claim 2, characterized in that the housing is made in at least two parts and in that the assembly and the maintenance of these two parts is obtained by means of fixing the housing on the element (2) of the machine allowing the rod to be driven.  10. Machine for manufacturing containers by stretching and blowing an object such as a preform or an intermediate container, characterized in that it comprises at least one device according to one of claims 1 to 9.