Apparatus and method for fabricating and filling containers

Abstract

An apparatus for the fabrication of a container, comprising a mold defining the form of said container and container and configured to accommodate a substantially tubular preform, an injection head configured to interface with the preform and establish fluid communication with a cavity thereof; an injection valve configured to selectively permit fluid communication through said injection head, and a stretching rod slideably disposed within the injection head; said apparatus further comprising a displacement plunger being disposed coaxially about and mobile relative to said stretching rod between a retracted position substantially within the injection head and an extended position wherein said displacement plunger projects at least partially from said injection head.

Claims

1. An apparatus for the fabrication of a container from a preform, comprising: a mold defining a mold cavity in the form of a container; an injection head configured to establish fluid communication between a liquid supply and a mouth of a preform accommodated in the mold; an injection valve located within the injection head, the injection valve having a valve body moveable between an open position permitting fluid communication through the injection head and a closed position preventing fluid communication through the injection head; a stretching rod slideably disposed within the injection head, the stretching rod being moveable between a retracted position and an extended position, in the extended position the stretching rod projecting from the injection head into the preform; and a displacement plunger slideably disposed in the injection head, the displacement plunger being moveable between a retracted position and an extended position, in the extended position the displacement plunger projecting from injection head into the preform.

2. The apparatus of claim 1, wherein the displacement plunger is slideably disposed relative to at least one of the stretching rod and the injection valve.

3. The apparatus of claim 1, wherein the injection valve is disposed within the injection head and is coaxial with a nozzle of the injection head, the injection valve sealingly engaging a portion of the nozzle in the closed position.

4. The apparatus of claim 3, wherein the injection valve seats in a portion of the nozzle in the closed position.

5. The apparatus of claim 1, wherein the displacement plunger extends longitudinally adjacent to the stretching rod.

6. The apparatus of claim 1, wherein a surface of the displacement plunger is coaxial with the stretching rod.

7. The apparatus of claim 1, wherein the displacement plunger is coaxial with the valve body.

8. The apparatus of claim 1, wherein the displacement plunger is coaxial with the stretching rod and the valve body.

9. The apparatus of claim 1, wherein the stretching rod and the displacement plunger are configured to move independently relative to the valve body.

10. The apparatus of claim 1, wherein the stretching rod and the displacement plunger are configured to move independently relative to the each other.

11. A method of fabricating a container from a preform, the method comprising the steps of: providing a tubular preform having a closed first end, a mouth at an open second end and a body therebetween defining preform cavity; positioning the preform at least partially within a mold defining a mold cavity in the form of a container the mold cavity; inserting a stretching rod into the preform cavity; injecting a volume of liquid into the preform to expand the preform into conformity with the mold cavity and to produce a container; inserting a displacement plunger into the container, the displacement plunger being distinct from the stretching rod and expelling a portion of the volume of liquid from the container; and withdrawing the stretching rod and the displacement plunger from the container.

12. The method of claim 11, wherein during insertion of the displacement plunger, the liquid is expelled through an annular gap between the displacement plunger and the mouth.

13. The method of claim 11, further comprising the step of establishing fluid communication between an interior of the container and surrounding atmosphere before withdrawing the displacement plunger from the container.

14. The method of claim 13, wherein the step of establishing fluid communication between an interior of the container and surrounding atmosphere is performed before withdrawing the stretching rod from the container.

15. The method of claim 11, wherein the step of inserting the displacement plunger is done independently of the step of inserting the stretching rod.

16. The method of claim 11, wherein the step of inserting the displacement plunger occurs after beginning the step of injecting the volume of liquid.

17. The method of claim 11, wherein the step of inserting the displacement plunger is done after the step of inserting the stretching rod.

18. The method of claim 11, wherein the step of injecting the volume of liquid begins after beginning the step of inserting the stretching rod.

19. The method of claim 11, wherein step of inserting the displacement plunger is done coaxially relative to the stretching rod.

20. The method of claim 11, wherein during insertion of the displacement plunger, the liquid is expelled through an annular gap defined in part by the displacement plunger.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the accompanying drawings, given by way of non-limiting examples:

(2) FIGS. 1A and 1B are perspective depictions of an exemplary stretch blow molding apparatus, in a partially-exploded and assembled disposition, respectively;

(3) FIGS. 2A and 2B are orthogonal section views of an injection head of the embodiment of FIGS. 1A and 1B, having an injection valve that is closed in FIG. 2A and open in FIG. 2B; and

(4) FIGS. 3A through 3F are a series of orthogonal section views depicting a container before, during, and after the insertion of a displacement plunger.

DETAILED DESCRIPTION

(5) FIGS. 1A and 1B are perspective views of an exemplary stretch blow molding apparatus 100 according to an embodiment of the invention. FIG. 1A depicts the apparatus in a partially-exploded disposition. The apparatus 100 comprises a base mold segment 101 and the two lateral mold segments 102A and 102B. The base mold segment 101 is provided with a base depression 103 substantially defining the base of a container, while the lateral mold segments 102A and 102B are respectively provided with the lateral depressions 104A and 104B, each substantially defining half of the body of a container. The base depression 103 and lateral depressions 104 together form the mold cavity 105, which substantially defines the form of a container.

(6) The lateral depressions 104A and 104B each communicate with a top face 106 of their respective lateral mold segments 102A and 102B, cooperating to form a mold hole 107 communicating with the mold cavity 105. Into the mold hole 107 is disposed a preform 108, which is substantially tube-shaped and comprises a closed end 109 and a mouth 110 at an open end 111 communicating with a preform cavity 112 within said preform 108.

(7) In this embodiment of the invention, the mold segments 101, 102A, and 102B are depicted as substantially independent components, each being capable of a full range of motion independent from the other two. It may be preferable, however, to provide linkages or other such connections between the mold segments so as to restrict their range of motion relative to each other, or to provide that the mold segments are linked together by means such as rails or sliders.

(8) In FIG. 1A the preform 108 is shown removed from the mold cavity 105 for clarity; however, it should be understood that the preform 108 is disposed so that it is substantially within the mold cavity 105. Preferably, the preform 108 is provided with a flange 113, which will rest on the top faces 106 of the lateral mold segments 102. The top faces 106 may be further provided with a preform seat 114 disposed about the mold hole 107, which locates the flange 113 of the preform 108, positioning and centering the preform 108 within the mold cavity 105.

(9) Preferably, the open end 111 of the preform 108 protrudes from the top faces 106 of the lateral mold segments 102A and 102B, while the rest of the preform 108 is thus disposed within the mold cavity 105 defined by the base depression 103 and lateral depressions 104.

(10) The apparatus 100 further comprises an injection head 115. The injection head 115 is provided with a nozzle 116 which is configured to mate with the mouth 110 of the preform 108 and create a fluid-tight seal therewith. The injection head 115 is further provided with a stretching rod 117, here depicted slightly extended from the nozzle 116. The injection head 115 is connected to a fluid supply 118, such that a volume of fluid may be conducted from said fluid supply 118 through the injection head 115 and out the nozzle 116. The fluid supply 118 is controlled by an injection valve, which may be disposed within the injection head 115 as here, or optionally outboard of the injection head, for example in a pumping unit or other such fluid handling system. Furthermore, In FIG. 1A, the injection head 115 is affixed by the arm 119 to a positioning mechanism, such that it may translate in each of the six principal axes 120 and position itself upon the mouth 110 of the preform 108. However, it should be understood that the injection head 115 need not necessarily be so configured: depending on the integration of the molding apparatus 100 into the production line as a whole and the configuration of the molding apparatus in particular, it may only be necessary to provide, for example, a means for the injection head 115 to translate along a vertical axis relative to the mold segments 101 and 102. The exact configuration of the apparatus may be determined by one skilled in the art, according to the particular demands of the implementation.

(11) FIG. 1B depicts the mold apparatus in an assembled disposition, with the mold segments 101, 102A, and 102B brought together in abutment to form the mold 121 which defines the mold cavity 105. The preform 108 is disposed substantially within the mold cavity 105, and the injection head 115 is positioned over the mouth (not shown) of the preform 108 which protrudes from the mold cavity 105. At this point, the injection head 115 is ready to inject a quantity of liquid into the preform 108 and expand it into the contours of the mold cavity 105, forming a container.

(12) FIGS. 2A and 2B depict a section view of the injection head 115 according to the embodiment of the invention of FIGS. 1A and 1B. FIG. 2A depicts the injection head 115 in a closed state as prior to an injecting step, and FIG. 2B depicts the injection head 115 in an open state as during an injection step.

(13) As shown in FIGS. 2A and 2B, the injection head 115 comprises an outer shell 200, comprising generally a body section 201 and the nozzle 116, the latter being configured to mate with the mouth 110 of the preform 108 and communicate with a preform cavity 112 within said preform 108 as described above. The injection head further comprises the injection valve 202, disposed within the outer shell 200 and defining the injection head cavity 203 between the two. The injection head cavity 203 is thus provided in fluid communication with the nozzle 201.

(14) The injection valve 202 is comprised of the valve body 204 which is provided with a taper 205 at said nozzle 201, and a valve seat 206 formed from a portion of an inner wall 207 of the outer shell 200 configured to mate with the taper 205. When in the closed position as shown in FIG. 2A, the valve body 204 will thus block fluid communication between the injection head cavity 203 and the preform cavity 112.

(15) In some embodiments, it may also be advantageous to provide the injection head 115 with a means for sealing the joint between it and the preform 108, ensuring fluid-tightness between the two. In other embodiments, as here, the fluid-tightness between the injection head 115 and the preform 108 is furnished by the force 208 with which the injection head 115 is pressed into the preform 108.

(16) The injection head 115 is also provided with a displacement plunger 209 about the stretching rod 117. The stretching rod 117 is disposed coaxially within the displacement plunger 209. The stretching rod 117 and displacement plunger 209 are both disposed coaxially within the valve body 204 and are configured to be independently mobile relative to both the valve body 204 and each other. The valve body 204 is itself disposed coaxially with the valve seat 205 and the nozzle 201, such that the entire group of nozzle 201, valve body 204, valve seat 205, displacement plunger 209, and stretching rod 117 are disposed in alignment along the longitudinal axis 211. The displacement plunger 209 and stretching rod 117 are preferably displaced by an electric actuator, though other means such as hydraulic cylinders, pneumatic actuators, and the like may alternately be employed.

(17) FIG. 2A shows the injection head 115 prior to an injecting step. The valve body 204 is seated in the valve seat 206, blocking fluid communication through the injection head 115 and preventing flow of the liquid 212 through the nozzle 201. Both the stretching rod 117 and the displacement plunger 209 are fully retracted within the injection head 115.

(18) Preferably, there is a sealing means 213 disposed at the joint between the stretching rod 117 and the displacement plunger 209. This may take the form of a circumferential rod seal, as here, or alternately other sealing means may be employed as appropriate to the construction of the apparatus.

(19) FIG. 2B shows the injection head 115 during an injecting step. The stretching rod 117 is advanced into the cavity 112. The stretching rod 117 is advanced into the closed end (not shown) of the preform 108 and causes the preform to stretch along the longitudinal axis 211.

(20) Shortly thereafter, the valve body 204 is retracted from the valve seat 206, permitting the liquid 212 to flow through the nozzle 201 of the injection head. The liquid 212 is injected with a flow 214 into the cavity 112 of the preform 108, further expanding the preform 108 and causing it to assume the form of the mold cavity (not shown) in which it is disposed. The displacement plunger 209, however, remains in its retracted position throughout the injecting step.

(21) FIGS. 3A to 3F are a series of section views which detail the operation of the injection head 115 of the embodiment during a process for fabricating and filling a container 300.

(22) FIG. 3A depicts the injection head 115 and container 300 immediately following the completion of its fabrication. The stretch rod 117 has been advanced to its fully-extended position, but the valve body 204 remains retracted from the valve seat 206 and fluid communication is still maintained between the injection nozzle and the container cavity 301 of the container 300. The container 300, having been completely formed during the injection step, is filled with the liquid 302.

(23) FIG. 3B depicts the injection head 115 and container 300 during a step for inserting a displacement plunger 209. The displacement plunger 209 is advanced into the container cavity 301 of the container 300, inducing a portion of the liquid 302 to be expressed from the container cavity 301 and into the injection head 115. The liquid 302 is expressed in a flow 303, which proceeds from the container cavity 301 through an annular gap 304 between the displacement plunger 209 and the mouth 305 of the container 300.

(24) FIG. 3C depicts the injection head 115 and container 300 at the conclusion of the step for inserting the displacement plunger 209. The displacement plunger 209 is in its extended position, having expelled a desired volume of the liquid 302 from the container and leaving the rest therein.

(25) The volume of the liquid 302 which is expelled from the container will vary with the degree to which the displacement plunger 209 is advanced into the cavity 301 of the container 300. One may thus adapt the process to the characteristics of the container sought to be fabricated, in part by altering the extension of the displacement plunger 209.

(26) For instance, the same injection head may be employed to fabricate containers of different volumes by altering the extension of the displacement plunger during the step for inserting the displacement plunger into the container, such that the displacement plunger is extended to a greater degree when fabricating larger containers where a greater volume of liquid must be expressed to provide the proper void space, and to a lesser degree when fabricating smaller containers requiring less expression of liquid.

(27) In any event, however, the volume of liquid expelled from the container 300 will be substantially equal to the combined volume of the portions of the displacement plunger 209 and stretching rod 117 which extend into the cavity 301 of the container 300.

(28) FIG. 3D depicts the injection head 115 and container 300 during a subsequent step for closing the injection valve within the injection head 115. The valve body 204 is advanced into the valve seat 206, thereby preventing fluid communication between the injection head cavity 203 and the container cavity 301. While FIGS. 2A, 2B, and 3A through 3F depict an embodiment where the injection valve is incorporated within the injection head, it should be understood that the injection valve may be positioned elsewhere in the container fabrication apparatus, so long as when it is closed it prevents any further flow of liquid into the container. For instance, it may be advantageous to instead provide the injection valve outboard of the injection head, such as in a liquid reservoir or pumping unit. The exact disposition of the components of the container fabricating apparatus may be determined by one skilled in the art according to the particularities of each installation.

(29) FIG. 3E depicts the injection head 115 and container 300 during a step for withdrawing the injection head 115, displacement plunger 209, and stretching rod 117 from the container cavity 301 of the container 300. The injection head 115 is first slightly withdrawn from the mouth 305 of the container 300, permitting communication between the container cavity 301 and the surrounding atmosphere. The displacement plunger 209 is then subsequently withdrawn from the container cavity 201, returning to its initial, fully-retracted position as depicted in FIG. 2A. The level of the liquid 302 within the container 300 is thus lowered by the distance 307.

(30) FIG. 3F depicts the injection head 115 and container 300 after the completion of the step for withdrawing the injection head 115, displacement plunger 209, and stretching rod 117. Both the displacement plunger 209 and the stretching rod 117 have returned to their initial, fully-retracted positions as depicted in FIG. 2A, leaving the second void space 308. The withdrawal of the stretching rod 209 will cause the liquid to drop further, receding from the mouth 305 of the container 300 by the distance 309.

(31) In an exemplary implementation of the method of the invention, the volume of the void space 308 is approximately 10 percent of the volume of the liquid 302 remaining in the container 300, or 1/11th of the total interior volume of the container itself. However, this may of course be altered according to the characteristics of the particular container being fabricated, by varying the length by which the displacement plunger 209 is inserted into the container cavity 301 of the container 300. In this way, one may exercise a great deal of control over the exact volume of the liquid 302 remaining in the container 300, whatever the size of the container 300.

(32) The container 300 as shown in FIG. 3F is thus filled with the desired volume of liquid 302 and the proper void space 308, and may be conducted to further apparatuses to be sealed or capped, labeled, and/or packaged for distribution.

(33) Of course, the invention is not limited to the embodiments described above and in the accompanying drawings. Modifications remain possible, particularly as to the construction of the various elements or by substitution of technical equivalents, without thereby departing from the scope of protection of the invention.

(34) In particular, the exact sizes and shapes of the elements discussed in the foregoing description may be varied according to the particularities of the application in which the invention is to be employed. For instance, the dimensions and configuration of the injection head, injection valve, displacement plunger, and stretching rod may be adapted to achieve optimal results in any particular application, while still embodying the inventive principle of this invention.

(35) The exact configuration and operation of the invention as practiced may thus vary from the foregoing description without departing from the inventive principle described therein. Accordingly, the scope of this disclosure is intended to be exemplary rather than limiting, and the scope of this invention is defined by any claims that stem at least in part from it.