Application of a linear motor to a container blow-molding device

Abstract

Disclosed is a dual carriage linear motor equipped with a controller inside a blow-molding device, a first carriage of the motor ensuring the movements of a first mobile support of a stretching rod equipping the blow-molding device along at least one first course, while a second carriage of the motor ensures the movements of a second mobile support of a nozzle equipping the blow-molding device along at least one second course, each of the first and second courses being controlled independently by the controller.

Claims

1. A dual carriage linear motor equipped with a controller (10) inside a blow-molding device (1), a first carriage of said motor ensuring the movements of a first mobile support (2) of a stretching rod (3) equipping said blow-molding device (1) along at least one first course, while a second carriage of said motor ensures the movements of a second mobile support (4) of a nozzle (5) equipping said blow-molding device (1) along at least one second course, each of said first and second courses being controlled independently by said controller (10).

2. The dual carriage linear motor equipped with a controller inside a blow-molding device according to claim 1, in which the linear motor that is used comprises a single stator on which said two carriages slide, said controller being connected electrically only to said stator.

3. The dual carriage linear motor equipped with a controller inside a blow-molding device according to claim 1, in which the linear motor that is used comprises a single controller designed to control each of said first and second courses independently from one another.

4. The dual carriage linear motor equipped with a controller inside a blow-molding device according to claim 2, in which the linear motor that is used comprises a single controller designed to control each of said first and second courses independently from one another.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Advantageously, the linear motor that is used comprises a single stator on which said two carriages slide, said single controller being connected electrically only to said stator.

(2) Other characteristics and advantages of the invention will emerge from the following detailed description of the nonlimiting embodiments of the invention, with reference to the accompanying figures in which:

(3) FIG. 1 diagrammatically shows a top perspective view of three-fourths of an embodiment of a blow-molding device; and

(4) FIGS. 2 to 4 diagrammatically show simplified views along a vertical cutaway of a blow-molding device, showing different examples of successive positions and relative movements of the first and second shuttles, one part in relation to the other, during a blow-molding operation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) This invention relates to blow molding, in particular preform stretch blow molding. For this purpose, first of all, the object of the invention is a blow-molding device 1. An example of such a blow-molding device 1 is shown in FIG. 1. It comprises at least one first support 2 equipped with a stretching rod 3 and at least one second support 4 of a nozzle 5.

(6) Said first support 2 and second support 4 are designed mobile in vertical movements reciprocally along at least one first course and at least one second course.

(7) To do this, in a nonlimiting way, as can be seen in FIG. 1, said first support 2 can consist of a first bracket 20, mounted to slide in a vertical translation along two shafts 6. These two shafts 6 are parallel and secured to a base 7 in the areas of their upper and lower ends. Said base 7 is designed stationary, integral with a carousel (not shown).

(8) Said first bracket 20 supports on its lower surface the stretching rod 3 in the area of its upper end, in a manner that is offset laterally in relation to the plane containing said shafts 6. Therefore, the stretching rod 3 extends vertically under the first support 2, directed downward.

(9) Said second support 4 can consist of a second bracket 40 that supports said nozzle 5. In particular, a bell 50 equipping this nozzle 5 is mounted under the second bracket 40 of said second support 4.

(10) It will be noted that the second bracket 40 can be provided with an opening that can be passed through by said stretching rod 3 during its movements, allowing it to re-enter and leave in an airtight manner with respect to the bell 50 of the nozzle 5, through openings that are provided and suitable for this purpose.

(11) Said second bracket 40 is mounted to slide in a vertical translation along the same two shafts 6. Thus, the respective movements of the first support 2 and second support 4 take place in a collinear manner.

(12) As previously mentioned, the first support 2 and second support 4 move respectively along at least one first course and along at least one second course. In particular, the second support 4 can move the nozzle 5 along a first descending course, while the first support 2 can move the stretching rod 3 along a second descending course. These descending courses occur from high positions to low positions, through intermediate positions. Then, the first support 2 can move said stretching rod 3 along a first ascending course, while the second support 4 can move the nozzle 5 along a second ascending course. Said ascending courses occur from said low positions to said high positions, through intermediate positions.

(13) Further, each of the descending or ascending courses can take place one time or several times, respectively with or without stopping of the movements of said first support 2 and second support 4.

(14) Each of the descending or ascending courses can also occur at distinct speeds relative to one another.

(15) To do this, said blow-molding device 1 has means for driving said first support 2 and second support 4. Such drive means are designed to be electric. Actually, the electric drive makes possible, in particular, a precision in the indexing of the movements of the supports 2, 4, while offering a significant motor torque for speeds of movements that are suitable for the steps of the blow-molding operations, preferably stretch-blow-molding operations.

(16) Advantageously, said drive means have at least one first actuator 8 of the movements of said first support 2 and at least one second actuator 9 of the movements of said second support 4. In other words, said first actuator 8 is secured to said first support 2 and ensures its first movements, particularly along said second descending course and along said first ascending course, while said second actuator 9 is secured to said second support 4 and ensures its second movements, particularly along said first descending course and along said second ascending course.

(17) The invention envisages not slaving the movements of the second support 4 to those of the first support 2. To do this, said drive means control in a differentiated way each first course and each second course. In short, the first support 2 can be moved upward or downward independently of the second support 4, and vice-versa, by means of the control of their respective first actuator 8 and second actuator 9.

(18) According to the preferred embodiment, said drive means can comprise a single controller 10 of said first actuator 8 and second actuator 9. This controller 10 is therefore able to manage alone the movements of the two actuators 8, 9 of the supports 2, 4.

(19) In particular, said single controller 10 can transmit control signals, in particular electric, to the first actuator 8 and second actuator 9, ensuring individually, on the one hand, the movements of the first support 2 and, on the other hand, the movements of the second support 4.

(20) Further, said controller 10 makes it possible to manage the courses of the first actuator 8 and second actuator 9 as a function of their respective positions, limiting said courses to avoid any collision of said first support 2 and second support 4 between them during their movement.

(21) In a related way, said drive means can comprise means 11 for guiding the first actuator 8 and second actuator 9. These guide means 11 ensure the retaining of the actuators 8, 9 during their movement and transmit the independent driving to each of said actuators 8, 9. In this illustrative case, said guide means 11 are directly connected to said controller 10, the latter being able even to be directly mounted secured to the guide means 11.

(22) According to a preferred embodiment, said drive means can consist of a linear motor provided at least with a first carriage comprising said first actuator 8 and with a second carriage comprising said second actuator 9.

(23) Therefore, said first and second carriages are mounted in a coaxial movement, as can be seen in the figures.

(24) In particular, such a dual carriage linear motor can be commonly termed long linear motor or LLM. Said motor can be a synchronous motor having permanent magnets of the linear type.

(25) The invention also relates to a blow-molding method, in which at least one preform that is provided with a lip that is held inside a mold is introduced. In particular, once introduced, the preform is hermetically clamped until the end of the blow-molding or stretch-blow-molding cycle, when the mold is opened to release it.

(26) Then, the method can consist in any order, successively or at least in part simultaneously, in that the nozzle 5 is moved along a first descending course covering said lip in hermetic application on said mold; the stretching rod 3 is moved along a second descending course until penetrating inside said preform through said nozzle 5; said rod 3 is moved along a first ascending course until being removed from said preform; said nozzle 5 is moved along a second ascending course.

(27) Advantageously, such a method consists in electrically driving and controlling the first and second descending and ascending courses independently for said rod 3 and said nozzle 5. This separation therefore makes it possible to perform one and/or the other of said courses at any time, to the extent that said first support 2 and second support 4 do not collide or that one prevents the movement of the other. By way of example, the end of a descending course of the first support 2 cannot go beyond the current position of the second support 4, comprising a stop; likewise, the end of the ascending course of the second support 4 is restricted and bounded by the current position of said first support 2.

(28) Preferably, according to said method, by means of a single controller 10, at least two separate carriages are controlled that actuate in a differentiated manner, on the one hand, the first descending course and the second ascending course of said nozzle 5, and, on the other hand, the second descending course and the first ascending course of said rod 3. As previously mentioned, said courses can be ensured in a continuous or discontinuous manner, with speeds unique to each support 2, 4.

(29) In this connection, FIGS. 2 to 4 model different phases of the blow-molding cycle, particularly the stretch-blow-molding cycle, representing the first support 2 and second support 4 in different positions, highlighting examples of relative speeds of movement of the supports 2, 4 by means of arrows of different lengths.

(30) In the example of FIG. 2, the speed of movement along a descending course of the first support 2 can be faster than that of the movement along the descending course of said second support 4. Actually, since the stretching rod 3 has a longer course to be covered, it can be actuated so as to move quicker to enter the preform before beginning the stretching. In addition, said nozzle 5 must reach the end of the descending course sealed against the mold and the lip of the preform, a time that can necessitate a reduced speed so as to prevent any impact and damage to said mold and/or to said preform and/or to the seal equipping said nozzle 5.

(31) In the example of FIG. 3, the speed of movement of the first support 2 is reduced, while the second support 4 is stopped, particularly in the position of hermetic capping of the preform in the mold. This minimized speed of the first support 2 can depend on the blow-molding steps, in particular of the previous formation of said bubble during a pre-blow molding, before the speed is maintained or accelerated then to continue and perform the rest of the blow molding.

(32) In the example of FIG. 4, the speed of movement of the first support 2 is greater than that of the second support 4, so that the stretching rod 3 rises and leaves the mold and the blow-molded container, until reaching the high position at the end of the ascending course as fast as possible. Conversely, initially, the nozzle 5 can remain stopped against the mold, before rising more slowly to release the mold and said container that has just been blow molded.

(33) The invention also relates to the application of a dual carriage linear motor equipped with a single controller inside a blow-molding device, a first carriage of said motor ensuring the movements of the first mobile support of the stretching rod along at least one first course, while a second carriage of said motor ensures the movements of the second mobile support of the nozzle along at least one second course. Therefore, said first carriage matches up with said first actuator, while the second carriage matches up with said second actuator.

(34) Thus, each of said first and second courses of the first and second carriages is controlled independently by said controller of such a linear motor.