Method for resin delivery including metering introduction of external air to maintain desired vacuum level.

METHOD OF SUPPLYING RESIN INCLUDING MEASUREMENT OF INTRODUCTION OF OUTSIDE AIR TO MAINTAIN A VACUUM LEVEL

WANTED

ÍbC ίη/77Π7/Ε/ΥΙΛΙ

Background of the Invention

The plastics industry is very diversified; There are thousands of different products, hundreds of materials, dozens of processes, and they are all very different from each other. The only thing all of these differences have in common is that the source material is some type of plastic.

The equipment sold to this industry is, therefore, very diversified in its design. Plastics factories have multiple processing machines, sometimes several hundred in one location. Virtually all plastics manufacturing operations require that each process machine, i.e. a molding press or extruder, be automatically supplied with the necessary resin feedstock on a continuous basis. This resin can be supplied in large boxes, called Gaylords Corrugated Containers, in fiber drums, in 50 pound (22.68 kg) bags, or more typically it can be supplied by bulk truck or rail car, with the material of resin which is then transferred in bulk into storage silos. In all cases the resin material must be additionally distributed throughout the plant to each and every process machine. For this reason, a large amount of design and capital expenditure is dedicated to the automatic distribution of resin raw materials throughout the plant.

These resin distribution systems, more commonly known as Loading Systems, must deal with many variables. One set of variables includes the type, shape, size and consistency of the granular material.

Resin pellets, nominally about 1/8 inch (0.32 cm) in size, come in various shapes, the most common being round, square, and cylindrical.

Flowing resin powder is also an option, and very fine but free-flowing resin pellets and other granular materials can be transported as well.

Design variables that must be considered for each client include:

1. Type of resin that is transported.

2. Size and consistency of resin pellets.

3. Distances over which the resin pellets will be transported.

4. Variability of these distances from the shortest to the longest.

5. Acceptable range for speed

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ movement of resin material through the lines.

6. Resin throughput rate required for each machine.

7. Total resin yield rate for the entire plant.

8. Excess capacity performance margin so a molding or extrusion process is not interrupted by short-term loading issues.

9. Loss of resin material from, or in the supply, so that only air is extracted, thereby reducing system vacuum levels and reducing overall design performance.

10. Sequence loading, or priority, when multiple receiving stations demand material.

eleven. Detection of problems and alarm conditions.

12. The proper air to material ratio for resin transportation.

13. Detection of clogged lines due to poor resin flow or overfeed of resin material.

14. Dust condition and filter requirements.

fifteen. Reliability.

16. Functional capacity.

17. Easy to use.

18. Cost.

19. Type of vacuum pump i.e. displacement

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ positive, regenerative, and others.

twenty. Vacuum pump power and rated CFM capacity, as well as vacuum levels.

In all of these areas, system designers seek to find better methods and solutions wherever possible.

One of the most important considerations is maintaining a correct speed for the resin material being transported. The type of resin material dictates the target transport speed. To maximize the resin material transfer rate, a high conveying speed is preferred, and the air speed should in any case be sufficient to keep the resin pellets suspended and moving in the airstream. However, the speed must be limited in order not to damage the pellets. The hard, brittle pellets can fracture and break when transported, resulting in excess dust.

Softer pellets can slide along the duct walls, causing so-called angel hair as a result of the plastic resin melt at the high velocity point contacting the duct wall; this leaves a thin film on the wall. Very thin strings of angel hair accumulate, thereby

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ effectively reduces the diameter of the duct and thus causes problems in the system.

Air velocity and resin conveying rate are directly related to pump capacity (nominal CFM) and power, as well as conveying line diameter. There is always a correct speed range for each type of resin material. It is a design challenge to ensure that the resin material is transported within a correct speed range.

Transportation distances affect system design. Transport over short distances requires a less powerful vacuum source than over longer distances. Systems are generally sized to produce the best balance for material speed between the shortest and longest conveying distance. The required conveyance rate typically dictates the line size (tube diameter), and this in turn determines the CFM required to maintain the correct velocity in a given diameter conduit. This means that different tube sizes in the same system can be a problem if a vacuum pump is to draw air and resin through several conveying lines of different diameters. Pumps have known CFM ratings. Exhausting air through a small tube will result in a higher velocity flow than extracting the same CFM through a larger tube.

LfrP ίη/77Π7/Ε/ΥΙΛΙ

Excessive speed can damage the pellets.

The type of vacuum pump to be selected is important. Regenerative blowers deliver a wide CFM range dependent on vacuum level. Positive displacement type pumps provide high vacuum levels, and have a flatter CFM curve over their vacuum range. Regenerative blowers are quieter and generally lower cost. Positive displacement blowers may require sound enclosures and tend to cost more, but they are generally more reliable and more tolerant of airborne dust.

The simplest systems employ a fixed speed motor to drive the vacuum pump, and a single size conveying line to service all receivers regardless of distance, rate requirement, or material.

Inventive technology offers controls and devices that can maximize performance for the variety of conditions that actually exist in a plant.

VFD (Variable Frequency Drive) motors allow vacuum pumps to be operated at different speeds, and therefore different CFM rates, with the vacuum pump drawing different levels of vacuum depending on the information

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ preset on each receiver being serviced, and/or make adjustments based on real-time feedback from vacuum sensors located at various locations in the system.

The addition of a SCFM (standard cubic feet per minute (m)) limiter³ standards per minute)) in the air flow line allows large vacuum pumps to be used without risk of transport at excessive speed. SCFM limiters restrict airflow to a preset SCFM. This maintains the desired airflow SCFM at the inlet, which is critical for proper conveying for a given sized conveyor line. This concept is the subject of US patent application 14/185,016.

Vacuum levels read at various points indicate to the control processor whether the line is open, meaning that only air and no material is present and that air is flowing freely. This is a sign of a loss of material at the source. A high vacuum reading indicates a plugged or nearly plugged line. Normal conditions are present when the material is flowing correctly at the detected semi-vacuum levels.

One line size for all receivers ensures that the resin transport rate is most likely to be in the acceptable range. However, the majority

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ processes require that the base resin material be supplied at 50 times the rate of additives, such as color concentrate. Virgin (or natural) pellets may have to be loaded at a rate of 1,000 pounds (453.39 kg) per hour, requiring a line size of 2.5 or 3 inches (6.35 or 7.62 cm), while color is required It should only be delivered at a rate of 20 to 40 pounds (9.07 to 18.14 kg) per hour. A smaller receiver is used for color, that is, a receiver that carries perhaps 5 pounds (2.27 kg) at a time, while the receiver for the virgin resin material will be larger, perhaps carrying 50 pounds (22.68 kg). pounds) in each load cycle. A 2.5 inch (6.35 cm) line on a 5 pound (2.27 kg) receiver would be too big. A 1.5 inch (3.81 cm) line would be standard, and using a 1.5 inch (3.81 cm) resin transport line would be best. However, there is a risk that speeds may be excessive. This results in solutions that compromise the design.

By placing a flow restrictor at the pump suction inlet, the maximum SCFM airflow can be limited to the design limit of the airflow limiting device; This is described and claimed in US patent application 14/185,016, indicated

ÍbC Ln/77Ω7/Β/ΥΙΛΙ above.

Summary of the Invention

In one of its aspects, this invention provides an apparatus for pneumatically transporting granular plastic resin material wherein the apparatus includes a vacuum pump having a suction inlet, a resin supply, a conduit connecting the resin supply to the suction inlet, a means for monitoring a vacuum level that is drawn by the vacuum pump at the suction inlet, and a valve for supplying air to the conduit at a location proximate to the resin supply location to maintain a desired suction level.

The valve for supplying air to the duct is preferably located at a position downstream of the first receiver; that is, the receiver furthest from the vacuum pump. Alternatively, the valve for supplying air to the duct may be located upstream of at least one of the receivers. The vacuum pump may be a constant speed vacuum pump. The use of a variable speed vacuum pump is also within the scope of this invention.

In yet another of its aspects, this invention provides an apparatus for pneumatically transporting plastic resin material, wherein the apparatus includes a vacuum pump having a suction inlet, a conduit connecting a supply of resin to the inlet of

ÍbC ίη/77Π7/Ε/ΥΙΛΙ suction, means for measuring the velocity of the air stream that is drawn by the vacuum pump at the suction inlet of the vacuum pump and a valve for supplying air to the duct at a nearby location to the resin supply to maintain a desired suction level. In this aspect of the invention, the valve for supplying air to the duct is preferably located in a position downstream of the first receiver. Alternatively, the valve for supplying air to the duct may be located upstream of at least one of the receivers. In this aspect of the invention, the vacuum pump may be a constant speed pump, or a variable speed vacuum pump. In this aspect of the invention, the apparatus may further optionally include one or more digital devices, preferably one or more microprocessors, for regulating the operation of the invention with respect to the delivery of granular plastic resin material to a given receiver or receivers when The given receiver or receivers require additional plastic resin material. The connection between the digital device, preferably a microprocessor, and the receivers, and, further optionally, the valves that regulate the input and discharge through such receivers, may be wireless, over the Internet, or otherwise through a

ÍbC Ln/Zznz/E/YIAI Ethernet connection.

In yet another of its aspects, this invention provides a method for conveying granular resin material from a supply thereof through a conduit to a receiver for supplying granular resin to a processing machine wherein the method includes measuring the velocity of air moving through the duct at a selected position, comparing the measured air velocity to a pre-selected acceptable range of air velocities, and introducing air into the duct when the measured air velocity is outside the pre-selected acceptable velocity range to maintain a desired suction level. The method may further include introducing air into the duct in an amount measured as it is introduced. The dosing of air in the duct can be carried out upstream of the first receiver, or at another location.

In yet another of its aspects, this invention provides a method for transporting granular resin material from a supply thereof through a conduit to a receiver for supplying granular resin material to a processing machine wherein the method includes measuring vacuum level within a conduit that carries the granular resin material from the supply to a receiver, and/or measure the vacuum level in a conduit that draws vacuum from the receiver to a vacuum pump,

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ comparing the measured vacuum level at a pre-selected acceptable range of vacuum levels at the measurement position, and the introduction of air into the duct when the measured vacuum level is outside the acceptable range preselected to maintain desired efficient transport within the duct.

The foregoing describes in general terms features of the present invention so that the detailed description of the invention that follows can be better understood. Additional features and advantages of the invention may be described below which may form the subject of some of the claims of the application. It should be appreciated by those skilled in the art that the specific concepts and embodiments described herein can readily be used as a basis for modifying or designing other structures or methods to carry out the objectives and results achieved by this invention. It should also be noted by those skilled in the art that such equivalent constructions do not depart from the spirit and scope of the invention as set forth in the appended claims.

Brief Description of the Figures

Figure 1 is a schematic representation of a resin delivery system that manifests aspects of the

ÍbC ίη/77Π7/Ε/ΥΙΛΙ invention .

Figure 2 is a schematic representation of an alternative resin delivery system embodying aspects of the invention.

With reference to the Figures wherein like reference numerals are identical to those used in this description to designate the same or similar elements in all the various views, illustrative embodiments of the invention are shown and described. The Figures are not to scale, and in some cases, the Figures have been exaggerated and/or simplified in part for illustrative purposes only. A person skilled in the art will appreciate the many possible applications and variations of the invention that are possible based on the following illustrative embodiments of this invention.

Detailed description of the invention

In this application, unless otherwise evident from the context it should be understood by the person skilled in the art that the use of the term vacuum means air at slightly below atmospheric pressure. Vacuum (i.e., air at slightly below atmospheric pressure) provides a suction effect that is used to extract granular plastic resin material from a supply and to transport that granular plastic resin material through various conduits. to the

ÍbC ίη/77Π7/Ε/ΥΙΛΙ receivers where the granular resin material can be temporarily stored before being molded or extruded. Therefore, when reading this application it is helpful for the reader to mentally equate the term vacuum with the term suction.

Referring to Figures 1 and 2, apparatus for transporting granular plastic resin material from the supply to receivers that retain and dispense the resin material when needed by a processing machine is illustrated. The apparatus, which is generally designated 88 in Figure 1, preferably includes a vacuum pump generally designated 92 and is shown schematically in Figure 1.

Still referring to Figures 1 and 2, the vacuum extraction conduit 100 is connected to a plurality of receivers 16, each of which receives, retains and dispenses, as necessary, granular plastic resin material to a machine. process, such as a granular mixer, or an extruder, or a molding press as preferably located below a receiver 16. Arrows A in the drawing figures are provided to schematically indicate the downward discharge of granular resin material from a receiver 16. The downward discharge of granular resin material is regulated by a controller, desirably a controller such as

ÍbC ίη/77Π7/Ε/ΥΙΛΙ microprocessor 200. The discharge of granular plastic resin from a receiver 16 to an associated process machine in the downward direction indicated by arrow A occurs when the process machine and controls Associated with it requires resin material which is supplied. Process machines are not illustrated to improve the clarity of the Figures. The receivers 16 are most desirably of the type described in US Patent 8,753,432, incorporated herein by reference as indicated above.

Also illustrated in Figures 1 and 2 is a hopper 18 for storing granular plastic resin material therein and a resin transport conduit 98, which serves to extract the resin from the hopper 18 and to supply the resin to through the resin transport conduit 98 to the respective receivers 16 while vacuum is drawn by the vacuum pump 92, with vacuum propagating through the vacuum extraction conduit 100, the various receivers 16, and the resin transport conduit 98, back to the hopper 18. In the Figures, the resin transport conduit 98 is shown to include a number of resin transport conduit valves designated 99 in the Figures. The valves 99 are desirably controlled by the microprocessor 200 and are optional, but desirable as in relation to the apparatus and

ÍbC ίη/77Π7/Ε/ΥΙΛΙ method of the invention. The resin transport line valves 99 are preferably of the open-close type. Resin transport line valves 99 are not used, during normal operation of the invention, to meter granular resin transported pneumatically into an associated receiver 16 through a segment of resin transport line 98. The resin transport line valves 99 are provided primarily for shutdown purposes in the event that system shutdown is necessary due to apparatus malfunction.

The vacuum extraction line 100 is optionally equipped with a vacuum extraction line valve 101. The valve 101 is preferably of the open-close type and is primarily used for shutdown purposes in the event of a system malfunction. The vacuum extraction line valve 101 is optional with respect to the operation of any of the embodiments of the apparatus illustrated in Figures 1 and 2.

In the embodiment of the apparatus illustrated as 88A in Figure 2, a main resin transport line valve 109 is illustrated. The main resin transport line valve 109 is desirably of the open-closed type and is provided primarily for safety and security purposes. protection of equipment in the event of a malfunction

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ operation of a system or device. The main resin transport line valve 109 is preferably controlled by the microprocessor 200. The main resin transport line valve 109 is optional with respect to the apparatus 88A illustrated in Figure 2.

During the operation of the resin transport systems shown schematically in Figures 1 and 2, during the operation of the vacuum pump 92, a vacuum is drawn to the suction head of the vacuum pump 93. This vacuum, As it spreads back to the hopper 18, it serves to draw resin out of the hopper 18 and into the respective receivers 16.

Referring specifically to Figure 1, an air supply conduit 106 connects with the resin transport conduit 98 in the position shown in Figure 1. A valve 102 admits air through inlet air supply 104 to the conduit. of air supply 106 and therefore in the resin transport duct 98. Valve 102 is preferably a purge valve that can be adjusted, preferably automatically using a solenoid or other valve adjustment means, more desirably by microprocessor 200, to meter a desired variable amount of air into resin transport conduit 98. In Figure 1 the air supply duct 106, the air supply inlet 104,

ÍbC ίη/77Π7/Ε/ΥΙΛΙ and valve 102 are all upstream of all receivers 16. In other words, all the air metered into the resin transport line 98 to maintain a desired vacuum level within the transport line of resin 98 will pass through at least one of the receivers 16. In Figure 1 the cable connections between the microprocessor 200 and the receivers 16 and the vacuum pump 92 have not been illustrated to improve the clarity of the Figures. As noted above, the connection between the microprocessor 200 and the other elements in the system, including the valve 102 and potentially other optional valves, may be wireless, most preferably over the Internet.

In Figure 1, the point 30 located on the suction head of the vacuum pump 93 can be a vacuum indicator or a vacuum sensor to measure and monitor the level (in the case of a vacuum indicator) or presence ( in the case of a vacuum sensor) vacuum is drawn by vacuum pump 92 to the suction head inlet of vacuum pump 93. In such a case, the vacuum indicator is preferably connected electronically or wirelessly, preferably via the Internet, to a control and feedback system including the microprocessor 200 to regulate the valve 102 and the amount of air supplied to the transport duct. resin 98 through

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ of the air supply duct 106, thereby to maintain a desired level of vacuum in the suction head of the vacuum pump 93. Alternatively, point 30 in Figure 1 may be a anemometer or a similar device to measure the speed of the air stream that is drawn by the vacuum pump 92 at the suction head of the vacuum pump 93. Similar to the vacuum gauge/vacuum sensor approach discussed immediately above, the anemometer approach preferably utilizes a digital anemometer connected with feedback loops or wirelessly, preferably over the Internet, to the valve 102 in order to regulating the amount of air supplied to the resin transport duct 98 through the air supply duct 106, thereby to maintain a desired vacuum level in the suction head of the vacuum pump 93.

Referring to Figure 2, the apparatus is similar to that illustrated in Figure 1, except for the air supply inlet position 104, the air metering valve 102 and the air supply duct 106. In Figure 2, The air supply duct 106 supplies air to the resin transport duct 98 at a position upstream of at least one of the receivers 16. Other than the position of the air supply duct 106, the air supply inlet 104, and the valve 102,

ÍbC ίη/77Π7/Ε/ΥΙΛΙ as shown in Figure 2, the apparatus illustrated in Figure 2 is preferably identical to that shown in Figure 1 and described above.

In the illustrated apparatus, the vacuum pump 92 may be a constant speed vacuum pump as schematically illustrated in Figure 1 and Figure 2, or the vacuum pump 92 may have a variable speed drive or speed component. variable thereof.

Although the embodiments of the present invention and at least some of its advantages have been described in detail above, it should be understood that various changes, substitutions and alterations can be made to the apparatus and methods described herein without departing from the spirit and scope of the invention. invention as defined by the appended claims. Furthermore, the scope of this patent application is not intended to be limited to the particular embodiments of the apparatus and methods described in the specification, nor to any of the manufacturing methods, compositions of matter, and the like, which may be described or inferentially understood by persons skilled in the art to be present in the invention as described in this specification.

As a person skilled in the art will readily appreciate from the description of the invention as set forth herein above, processes,

ÍbC ίη/ΖΖΠΖ/Ε/ΥΙΛΙ manufacturers, apparatus, methods and steps currently existing or later developed, which perform substantially the same function or achieve substantially the same result as the corresponding embodiments described above, may be used in accordance with the description of the invention and the claims attached to it.

Therefore, the attached claims are intended to include within their scope such devices, methods and processes that provide the same result or that are, as a matter of law, covered by the doctrine of equivalents respecting the claims of this application.

In the appended claims, the term comprising should be understood to mean including but not limited to, while the term consisting of means having only and no more and the term consisting essentially of means having only and no more except for minor additions that would be known to a person skilled in the art as possibly necessary for operation of the invention.

It is stated that in relation to this date, the best method known to the applicant to put the aforementioned invention into practice is the one that is clear from the present description of the invention.