The developed preform is then transferred to the product mold in preparation for the blow molding phase. Before inflating the preform, it is first stretched to a specific length by a stretch rod.
After stretching, the plastic melt is then inflated to the shape of the final product. After molding, the product is then cooled and ejected. Stretch blow molding is not limited to plastic injection. Stretching can also be achieved in an extrusion blow molding machine. This is done by partially extruding the parison and stretching it with a pull rod.
It is then enclosed by a die and is inflated to shape. The main objective of stretch blow molding is to create a product with a biaxially oriented plastic. Biaxial orientation is the process in which the plastic is stretched in two directions. In the longitudinal direction, the plastic is stretched by the stretch rod while in the lateral direction, the plastic is stretched by inflation.
A biaxially oriented plastic has many desirable qualities including high impact, tensile, and tear strength, improved barrier properties, and excellent transparency. With the increased mechanical properties, bottles and packaging materials can be made with thinner walls. Note that not all plastics can be biaxially oriented. Moreover, the plastic resin must have the right properties and quality for it to stretch without tearing or producing specks or other defects.
PET is a common biaxially oriented plastic that is used to produce clear plastic bottles. There is a wide array of raw materials that can be used for blow molding. Blow molding materials are commonly thermoplastics that do not easily degrade upon heating. Blow molding is extensively used in the manufacture of plastic bottles which is why most raw materials have properties suitable for such application.
Currently, blow molding is gaining momentum in the transportation, construction, and consumer goods industries. This makes engineering plastics such as polyamides and polycarbonates viable to be blown molded as well. Plastic containers are material storage products made of a variety of plastics. Plastics are an ideal material for creating containers. They are known for their excellent formability, degradation resistance, durability, lightweight, recyclability, and controllable mechanical properties A plastic tank is a large capacity liquid or granular storage unit that can be vertical, horizontal, below or above ground, as well as movable.
They are designed to hold several gallons of a variety of substances for long periods without experiencing wear, weathering, or deterioration Close Contact Companies Please fill out the following form to submit a Request for Quote to any of the following companies listed on. Introduction This article gives comprehensive information about the blow molding process and its raw materials. Overview of blow molding History of blow molding The blow molding process And much more….
Leading Manufacturers and Suppliers. Contact these Companies. Plastic Tanks A plastic tank is a large capacity liquid or granular storage unit that can be vertical, horizontal, below or above ground, as well as movable. Explain why operations such as blow molding and film-bag making are performed vertically.
Dec 18 PM. Assuming the molecules to be small round balls, when together they have large air gaps and small surface Do you need an answer to a question different from the above? We want to correct this solution. Tell us more. Was the final answer of the question wrong? Were the solution steps not detailed enough? Was the language and grammar an issue?
Didn't find yours? Ask a new question Get plagiarism-free solution within 48 hours. Review Please. Next Previous. Specifically, given the memory of the plastic material, if the height H is too large then the effect of adding the secondary VAP material flow 82 to the main parison flow 80 is undermined and, at some height H, virtually no effect on the main parison flow 80 will be exhibited despite the addition of the secondary VAP material flow On the other hand, if the height H is small, then the tooling unit 9 will have only a small structural layer having the height H between the distribution channels 4 and the top of the tooling unit 9.
The relatively high pressures experienced by the tooling unit 9 risk warping that small structural layer of the tooling unit 9. And the extreme where the height H is zero, such that there is no structural layer between the distribution channels 4 and the top of the tooling unit 9 i. The height H that the distribution channels 4 are located below the plane 30 in the tooling unit 9 corresponds to the distance from the outlet of the tooling unit 9 to the point where the secondary VAP material flow 82 joins the main parison flow 80 to form the combined flow The efficiency is measured by the velocity increase between the main parison flow 80 before the secondary VAP material flow 82 is added and the combined flow 84 after the secondary VAP material flow 82 is added to the main parison flow The percent of velocity increase is calculated as maximum velocity minus minimum velocity divided by minimum velocity times In one particular embodiment, the preferred height H is selected from the range of about mm; in another embodiment, about The optimal height H will vary, of course, depending on the size of the tooling unit 9 , the types of materials used for the secondary VAP material flow 82 and the main parison flow 80 , the material flow rates and pressures, and other factors.
The entry point of the distribution channels 4 and, therefore, of the VAP material flow 82 needs to be at a location with respect to the plane 30 and the aperture 44 to create velocity and pressure differentials at the outlet of the tooling unit 9 around the circumference of the aperture 44 i. Rather than the distribution duct 43 formed in the distribution ring 5 and in the bushing cap 2 as before, the embodiment shown in FIGS.
Like the distribution duct 43 , the distribution runner 45 connects the port 42 to the distribution channels 4 and delivers the secondary VAP material flow 82 from the port 42 to the distribution channels 4.
The distribution duct 43 is essentially circular and surrounds the aperture One disadvantage of the distribution duct 43 is that the secondary VAP material flow 82 is delivered from the port 42 first to the distribution channels 4 located closer to the port 42 and only later in time to the distribution channels 4 located farther from the port In contrast, the geometry of the distribution runner 45 allows the distribution runner 45 to inject the secondary VAP material flow 82 in the direction of arrows F into all four distribution channels 4 at the same time simultaneously and, therefore, to achieve a more balanced velocity and pressure distribution.
The inner portions of the distribution runner 45 are located farther from the perimeter of the tooling unit 9 and closer to the aperture 44 than is the outer portion. The outer portion of the distribution runner 45 connects directly to the port 42 at its center; each of the inner portions connect directly to two of the four distribution channels 4.
Each end of the outer portion connects directly to one of the inner portions at the center of the inner portion, about half way between the two distribution channels 4. Thus, the inner and outer portions of the distribution runner 45 are interconnected to form an integral distribution runner 45 and a closed path for the secondary VAP material flow Another difference between the earlier-disclosed embodiment having the distribution duct 43 and the distribution channels 4 and the embodiment having the distribution runner 45 and the distribution channels 4 is the placement of those components in the tooling unit 9.
Specifically, in the earlier-disclosed embodiment, first portions of the distribution duct 43 and of the one or more distribution channels 4 are formed in the distribution ring 5 and mating portions of the distribution duct 43 and of the one or more distribution channels 4 are formed in the bushing cap 2.
In contrast, for the embodiment illustrated in FIGS. The blow molding machine 10 including the SCAT unit 8 and the tooling unit 9 offers several advantages over conventional tooling designs such as the designs discussed in the Background section. Many conventional designs change the thickness of the article by adjusting the die gap. For example, Przytulla et al. The blow molding machine 10 does not alter the die gap; rather, the blow molding machine 10 introduces new additional VAP material to strategic areas of the article radially and intermittently axially.
Both approaches attempt to put material into strategic areas of the article. They differ significantly, however, because Przytulla et al. The blow molding machine 10 avoids the complex and modified die components needed to create a movable die gap. The blow molding machine 10 utilizes the fact that plastic has memory. Specifically, the plastic parison has memory and wants to return to its natural state once it exits the flow head This characteristic allows the blow molding machine 10 to change the thickness of the parison independent of the die gap.
The blow molding machine 10 uses the separate distribution channel 4 for VAP plastic material flow to add axial vertical ribs of material to strategic areas on the parison. Because plastic has memory, the areas where the plastic is injected through the distribution channel 4 maintain their thickness independent of the final die gap opening. The characteristics of the strategic areas are determined by the tooling unit 9. Thus, the tooling unit 9 is engineered to accommodate each particular application.
The added distribution channel 4 for plastic flow is metered onto the parison via the servo-controlled accumulator 1. The servo-controlled accumulator 1 allows the blow molding machine 10 to shut off the axial ribs of plastic in areas where such added material is not wanted such as, but not limited to, the neck threads. The SCAT unit 8 also allows the blow molding machine 10 to vary the thickness of the axial ribs while being applied in the desired areas of the article.
The axial vertical ribs produced by the blow molding machine 10 can be of varying thickness throughout the length of the article. When blow molding certain article shapes, there are some instances where the shape of the article causes the parison to stretch which results in thin spots at certain locations. To account for this stretch, the conventional tooling on the flow head 26 is sometimes designed with an oval shape at the output of the tooling.
Although the oval shape accounts for some of the thin spots on the article, it also draws material from other critical areas on the article. The blow molding machine 10 can be used on various shaped articles to add material to those specific thin spots. This ability can also eliminate the need for oval-shaped tooling and allow for basic round tooling to be used.
In this regard, note that the SCAT unit 8 and the tooling unit 9 can be used to retrofit an existing blow molding machine as well as be incorporated in a new blow molding machine as original components. Where the oval tooling would allow material to be thicker in the critical areas, the blow molding machine 10 performs the same function. The blow molding machine 10 can be implemented on multiple blow molding machines such as shuttle type machines or continuous type wheel machines.
The blow molding machine 10 , with its VAP components, also simplifies the conventional complicated die tooling opening process window. The blow molding machine 10 targets smaller blow-molded articles, such as containers or canisters having a log that weighs less than grams, which run at much higher speeds than larger articles.
The versatility of the blow molding machine 10 allows it to be used, however, to produce larger articles such as liter industrial barrels. The blow molding machine 10 also targets articles with threads that need to be capped and sealed. The following examples are included to more clearly demonstrate the overall nature of the invention.
These examples are exemplary, not restrictive, of the invention. The ribbed corners 70 are shown in white material for purposes of visibility and illustration, highlighting the ribbed corners 70 relative to the body and neck of the article Note that the ribbed corners 70 extend further toward the neck of the article in the article shown at the right in FIG.
This difference illustrates the control provided by the blow molding machine 10 over the extent of the reinforcement created in the article In both articles shown in FIG.
Control over the extent of the ribbed corners 70 is advantageous because problems are avoided, such as interference between the threaded neck and the cap not shown that engages the threaded neck , by limiting the extent of the ribbed corners Many factors, including the ratio and profile of the diverge pin 3 , the size and configuration of the SCAT unit 8 , and the speed of the extruder 24 , must be optimized for each application or setup.
Otherwise, there can be bleeding too much ribbed corner 70 near the neck or the thickness of the ribbed corners 70 will not be consistent throughout the entire article The article illustrates axial ribs being turned on and off at varying thicknesses at different locations of the article Thus, unlike the articles shown in FIG.
As illustrated in FIGS. VAP material was added at the four corners of the articles , while still reducing the weight of the articles To investigate the structural advantage achieved by adding the material, top-load tests were conducted on the articles illustrated in FIG.
Articles intended as packaging for consumable goods must provide product protection. For example, PET bottles, cans, and cartons have to withstand the compressive forces incurred during handling, transportation, and storage.
Manufacturers of beverage containers face the additional challenge of ensuring that containers have sufficient strength to tolerate the capping process. Key to quantifying the design and quality of many containers is measuring resistance to top loading. The results of top-load tests conducted on the articles the motor oil containers or bottles having ribbed corners 70 , as illustrated in FIG.
The material added had a thickness between 0. Tests on a control group bottles having a weight of A bottle of the same weight The test results also showed that the added material provided better top-load performance regardless of the bottle weight. In addition to the improved top-load test results highlighted above, articles formed using the exemplary blow molding machine 10 offer improved environmental stress crack resistance ESCR and improved drop test results as compared to conventionally produced articles.
And these improvements are achieved at equal or reduced material requirements e. Although illustrated and described above with reference to certain specific embodiments and examples, the present invention is nevertheless not intended to be limited to the details shown.
Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the spirit of the invention. It is expressly intended, for example, that all ranges broadly recited in this document include within their scope all narrower ranges which fall within the broader ranges. All rights reserved. Login Sign up.
Search Expert Search Quick Search. A vertical additive processing system for use with a blow molding machine having a flow head from which a plastic parison is delivered to a mold and producing an article. Albers, Martin R. Click for automatic bibliography generation. Graham Packaging Company, L.
Lancaster, PA, US. Download PDF What is claimed: 1. A blow molding machine for producing an article from a plastic parison, the machine comprising: a flow head from which the parison is delivered to a mold; a servo-controlled accumulation technology or SCAT unit including: an accumulator collecting plastic material when in a retracted position and delivering plastic material when in an extended position, and an actuator directing the accumulator to retract and extend; a tooling unit including a bushing body engaging the flow head, a distribution ring, and a bushing cap, the tooling unit having a central aperture defining a main parison flow path and a distribution channel delivering additional plastic material received from the accumulator to the main parison flow path; and a material duct connecting the SCAT unit and the tooling unit through which plastic material delivered by the SCAT unit is transported to and received by the tooling unit.
A vertical additive processing system for use with a blow molding machine producing an article from a plastic parison, the machine having a flow head from which the parison is delivered to a mold, the system comprising: a servo-controlled accumulation technology or SCAT unit including: an accumulator collecting plastic material when in a retracted position and delivering plastic material when in an extended position, and an actuator directing the accumulator to retract and extend; a tooling unit including a bushing body adapted to engage the flow head, a distribution ring, a bushing cap, a central aperture defining a main parison flow path, and a distribution channel delivering additional plastic material received from the accumulator to the main parison flow path; and a material duct connecting the SCAT unit and the tooling unit through which plastic material delivered by the SCAT unit is transported to and received by the tooling unit.
A blow molding machine for producing an article from a plastic parison, the machine comprising: a first flow path connected to a first material source to deliver a first flow of material to a mold; a second flow path connected to a second material source to deliver a second flow of material to the mold; a tooling unit positioned between the second flow path and the mold, the tooling unit having a distribution ring and defining an aperture configured to allow the first flow of material to enter the mold, and at least one channel configured to allow the second flow of material to enter the mold; and a means for selectively controlling the flow of the second flow of material to the mold.
The blow molding machine as recited in claim 3, further comprising a control system directing the means for selectively controlling the flow of the second flow of material to the mold. The blow molding machine as recited in claim 3, wherein the tooling unit defines a top plane and has an exit in the top plane defined by the circumference of the aperture and the height between the top plane and the at least one channel increases the velocity and pressure differentials at the exit which in turn increase the thickness of the parison at the location of the increased pressure and velocity.
The blow molding machine as recited in claim 3, wherein the means for selectively controlling the flow of the second flow of material to the mold includes a servo-controlled accumulation technology or SCAT unit.
The blow molding machine as recited in claim 6, wherein the SCAT unit includes an accumulator collecting the second material when in a retracted position and delivering the second material when in an extended position, and an actuator directing the accumulator to retract and extend.
The blow molding machine as recited in claim 6, further comprising a material duct connecting the SCAT unit and the tooling unit through which the second material is delivered by the SCAT unit to the tooling unit. The blow molding machine as recited in claim 3, wherein the tooling unit further has a bushing body adapted to engage a flow head and has a bushing cap, with the distribution ring mounted between the bushing body and the bushing cap.
The blow molding machine as recited in claim 9, wherein the bushing cap, the distribution ring, and the bushing body combine to define the aperture through which the first flow of material travels from the flow head to the mold. The blow molding machine as recited in claim 9, wherein the bushing cap, the bushing body, and the distribution ring are combined by one or more fasteners to create a seal preventing exit of the first flow of material and the second flow of material from the tooling unit except through the aperture.
The blow molding machine as recited in claim 9, wherein the bushing cap and the distribution ring combine to form the at least one channel. The blow molding machine as recited in claim 9, wherein multiple channels are configured to allow the second flow of material to enter the mold at separate locations and wherein the bushing cap and the distribution ring combine to form a distribution runner configured to deliver the second flow of material to each of the multiple channels simultaneously.
The blow molding machine as recited in claim 13, wherein the distribution runner has a substantially U-shaped outer portion and two, mirror-image, substantially semi-circular inner portions, the inner and outer portions interconnected to form an integral distribution runner and a closed path for the second flow of material. A method for blow molding in a mold a plastic article having one or more vertical material distribution sections, the method comprising: providing a first material source; providing a second material source; placing a tooling unit between the second material source and the mold, the tooling unit including a distribution ring having an aperture configured to allow introduction of a first material from the first material source into the mold, and at least one channel configured to allow introduction of a second material from the second material source into the mold; introducing the first material from the first material source into the mold; and selectively introducing the second material from the second material source into the tooling unit to create predetermined vertical material distribution sections in the plastic article.
TECHNICAL FIELD The present disclosure relates generally to machines for manufacturing hollow articles from thermoplastic materials by blow molding and, more particularly, to a blow molding machine designed to add material to certain portions of an article, thereby strengthening the article without affecting the rest of the article.
Included in the drawing are the following figures: FIG.
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