Multiple pusher liquid color pump
A liquid color pumping includes a housing, a plurality of pushers within the housing, a deformable tube for transporting liquid color from the supply thereof to where the liquid color will be used with the tube being positionably removable in the housing at a location at which of the pushers when displaced squeeze the tube positioning of the pushers resulting in the pushers serially contacting the tube when displaced and the controller repeated actuating the pushers in sequence to draw liquid color into the pumping zone and then to force liquid color out of the pumping zone through the tube at increased pressure.
This patent application discloses subject matter in common with U.S. patent application Ser. No. ______ entitled “Liquid Color Gravimetric Metering Apparatus and Methods”, filed concurrently herewith in the name of Stephen B. Maguire.
BACKGROUND OF THE INVENTION1. Field of the Invention
This invention relates generally to processing of plastic resin material for fabrication into finished plastic parts and more particularly to methods and apparatus for pumping liquid color material used to impart a desired color to the finished plastic parts.
2. Description of the Prior Art
Color is imparted to finished plastic parts by adding a coloring agent, either liquid color material or solid color pellets, to plastic resin material as it is being fabricated into finished plastic parts. The liquid color or the colored pellets control the color of the finished plastic parts. Depending on whether liquid color or solid colored pellets is used, the position at which the coloring agent is added to the plastic resin material during the part fabrication process may change.
Pumps for liquid color are known. Liquid color diaphragm pumping apparatus is disclosed in pending U.S. patent application Ser. No. 10/066,338, published as United States patent publication 2003-0142580, and in pending U.S. patent application Ser. No. 10/856,422, published as United States patent publication 2005-0052945.
Additionally, peristaltic pumps are commonly used for pumping liquid color because all of the liquid color remains in the peristaltic pump tubing, at all times. As a result, when changing colors there is no contamination of the liquid color and no clean up required. When using a peristaltic pump, the only thing required to change colors is to change the tube in the peristaltic pump. However, peristaltic pumps, with these advantages, tend to be unreliable and are expensive.
SUMMARY OF THE INVENTIONThe multiple pusher liquid color pump of this invention in its preferred embodiment uses three pneumatic cylinder driven pushers and three solenoids to operate those pneumatic cylinders in a carefully selected sequence of on and off pulses. When operating the pump, a deformable tube is placed below the pushers. The pushers are desirably positioned side by side in a housing and are attached to the ends of pusher rods connected to the pneumatic cylinders. These desirably plastic pushers periodically press on the tube, which is in front of the pushers, thereby squeezing and compressing the tube against a preferably flat surface.
The three pushers are preferably aligned and adjacent one to another. As a result, in the course of one sequence of pusher operations, the first and second pushers serve as check valves, compressing the tube and thereby shutting off flow through the tube when either of these pushers is activated. Then, when activated and advanced, the center pusher squeezes the tube to displace liquid color forward. When retracted, the center pusher permits the tube to relax. This serves to suck in liquid color from the liquid color supply, for subsequent additional pumping. The sequence is repeated, rapidly, to provide the desired flow of liquid color material.
This pump has many of the advantages of peristaltic pumps, but is simpler and costs considerably less. This pump does not include a drive motor, has no bearings and does not include any DC drive circuitry. The solenoids are preferably driven by simple on/off signals preferably from a simple, low cost, computerized control. Variable output of the pump is achieved by regulating the timing of the pulse sequences, i.e., performing the sequences faster or slower. Like a peristaltic pump, use of different diameter tubes produces different pump ranges for output of liquid color.
Accordingly, in one of its aspects this invention provides a pump for liquid color used in fabrication of plastic parts by molding or extrusion, where the pump preferably includes a housing, pushers, desirably three, within the housing, with the pushers preferably being positioned side by side respecting one another, a compressible tube for transporting liquid color from a supply thereof to where the liquid color is to be used, with the tube preferably being removably insertable into the housing to a position at which each of the pushers, when displaced, squeezes the tube against structure connected to or forming a part of the housing, with the side by side positioning of the pushers resulting in the pushers, upon appropriate actuation, contacting and squeezing the tube in a desired, preselected sequence of operations.
In this aspect, the invention preferably further includes a controller for repeatedly actuating the pushers in sequence whereby a first pusher is preferably displaced to squeeze the tube closed while the second pusher and the third pusher are not displaced, thereby permitting liquid color to flow through the tube from the supply to a first position of tube closure, preferably then the second pusher is preferably displaced to squeeze the tube closed and trap liquid color in the tube between the first position of tube closure and a second position of tube closure, and preferably then the first pusher is preferably permitted to return to its undisplaced position thereby permitting liquid color to flow through the tube past the first position of tube closure and preferably a third pusher is displaced preferably to squeeze the tube and thereby force at least a portion of the trapped liquid color through the tube past the first position of tube closure.
Referring to
First piston-cylinder combination 34 has been shown with the exterior of the cylinder portion of the combination cut away to reveal the inner workings of piston-cylinder combination 34. As visible in
Piston cylinder combination 34 further includes a piston return spring 60, which is preferably of spiral configuration and slidably contacts the curved interior of cylinder 56, serving to return piston 58 to a vertically extreme upwards position when pressurized air is not furnished to piston-cylinder combination 34.
A first solenoid designated generally 40 actuates a first air valve designated generally 46 to supply compressed air via a line 61 to first piston-cylinder combination 34, thereby to push piston 58 downwardly. Fixed to piston 58 is a connecting rod 62 to which first pusher 28 is affixed, at the end of connecting rod 62 remote from piston 58. First, second and third piston-cylinder combinations 34, 36, 38 rest on plate 66 and are retained in position thereon by suitable nut and bushing combinations, one of which is designated 64 in
In comparing
A controller, not illustrated, connects to solenoids 40 via lines 54 and is programmable so as to permit any desired sequence of operation of piston-cylinder combinations 34, 36, 38 thereby to permit any desired sequence of squeezing or unsqueezing of liquid color supply line 22 when positioned within housing 68 in the general manner illustrated in
First and third pushers 28, 32 are configured outer peripheries that are curved, and would appear as cylinders if viewed from the side in
Contrasting, third pusher 30 has a surface 72 facing liquid color supply tube 22 that is flat. Surface 72, being flat, results in liquid color within the portion of tube 22 directly beneath pusher 30 and along the entire length of surface 72 running parallel to liquid color supply line 22, being pushed out of liquid color supply line 22 when third pusher 30 is actuated by associated piston-cylinder combination 36 and pusher 30 squeezes liquid color supply line 22 completely closed, thereby forcing all liquid color material within liquid color supply line 22 beneath the projected area of pusher 30 towards the outlet of liquid color supply line in the direction indicated by arrow B in
Actuation of a given solenoid such as solenoid 40 by the controller, via a signal sent to solenoid 40 through line 54, opens valve 46 thereby allowing pressurized air from a remote source, not illustrated in the drawings, which is furnished to valve 16 via an air line not shown in the drawings, to be applied to the upper surface of piston 58 forcing piston 58 downwardly in
In
Referring to
Next, as illustrated in
Next, first pusher 28 is retracted by release of the air pressure through deactuation of the associated solenoid 40 and action of return spring 60 pushing piston 58 in cylinder 56 upwardly, thereby raising first pusher 28 away from and out of contact with liquid color supply line 22, as illustrated in
As depicted in
Once third pusher 30 has completed squeezing the liquid color that is within tube 22 below the umbrella of pusher 30, first pusher 28 is actuated thereby closing liquid color supply tube 22 at a position of first tube closure, where first pusher 28 has squeezed liquid color supply tube closed, thereby preventing passage thereby of any liquid color. Second pusher 32 and third pusher 30 have been retracted by deactuation of their associated solenoids, which are not numbered in
The controller preferably adjusts the speed of pump 16 so that the desired amount of liquid color preferably is always supplied by pump 16 at the rate needed for a given material recipe. Hence, pump 16 is preferably controlled to run faster or slower in order to maintain a desired rate of liquid color use.
Claims
1. A pump for liquid color, comprising:
- a) a housing;
- b) a plurality of pushers within the housing;
- c) a deformable tube for transporting liquid color from a supply thereof to where the liquid color will be used;
- d) the tube being insertable into the housing and positionable to a location therein at which at least one of each of the pushers when displaced squeezes the tube against a stop; and
- e) a controller for actuating the pushers in sequence whereby the pusher which upon displacement squeezes the tube against a stop thereby forces at least a portion of liquid color through the tube towards the position at which the liquid color will be used.
2. The pump of claim 2 where the controller repeatedly actuates the pushers.
3. A pump for liquid color, comprising:
- a) a housing;
- b) a pusher within the housing;
- c) a deformable tube for transporting liquid color from a supply thereof to where the liquid color will be used;
- d) the tube being removably positionable within the housing to a location at which the pusher when displaced squeezes the tube; and
- e) a controller for actuating the pusher whereby upon pusher displacement squeezing the tube at least a portion of the liquid color is forced through the tube and out of the pump.
4. The pump of claim 4 in which the controller repeatedly actuates the pusher.
5. A pump for liquid color, comprising:
- a) a housing;
- b) three pushers within the housing, positioned side by side respecting one another;
- c) a compressible tube for transporting liquid color from a supply thereof to where the liquid color will be used;
- d) the tube being insertable into the housing to a position at which each of the pushers when displaced squeeze the tube against the housing interior, with the side by side positioning of the pushers resulting in the pushers serially contacting the tube when displaced; and
- e) a controller for repeatedly actuating the pushers in sequence whereby a first pusher is displaced to squeeze the tube closed while a second and a third pusher are not displaced, thereby permitting liquid color to flow through the tube from the supply to a first position of tube closure, then the second pusher is displaced to squeeze the tube closed and trap liquid color in the tube between the first position of tube closure and a second position of tube closure, then the first pusher is permitted to return to its undisplaced position thereby permitting liquid color to flow through the tube past the first position of tube closure and the third pusher is displaced to squeeze the tube and thereby force at least a portion of the trapped liquid color through the tube past the first position of tube closure.
6. A pump for liquid color, comprising:
- a) a housing;
- b) a plurality of pushers within the housing; and
- c) a controller for actuating the pushers in sequence whereby a pusher upon displacement squeezes a deformable tube thereby forcing at least a portion of liquid color through the tube towards a location at which the liquid color will be used.
7. A method for pumping liquid color, comprising repeatedly actuating three pushers, positioned side by side respecting one another, in sequence whereby a first pusher is displaced to squeeze a compressible tube, for transporting liquid color from a supply thereof to where the liquid color will be used, into a closed disposition while a second and a third pusher are not displaced, thereby permitting liquid color to flow through the tube from the supply to a first position of tube closure, then the second pusher is displaced to squeeze the tube closed and trap liquid color in the tube between the first position of tube closure and a second position of tube closure, then the first pusher is permitted to return to its undisplaced position thereby permitting liquid color to flow through the tube past the first position of tube closure and the third pusher is displaced to squeeze the tube and thereby force at least a portion of the trapped liquid color through the tube past the first position of tube closure.
8. The method of claim 7 further comprising removably positioning the compressible tube within a pusher housing to a location at which a displaced pusher squeezes the tube.
9. A method for pumping liquid color, comprising:
- a) repeatedly actuating three pushers, positioned side by side respecting one another, in sequence by, i) displacing a first pusher to squeeze a compressible tube, for transporting liquid color from a supply thereof to where the liquid color will be used, into a closed disposition, and ii) retaining a second and a third pusher from displacement, iii) thereby permitting liquid color to flow through the tube from the supply to a first position of tube closure, iv) displacing the second pusher to squeeze the tube closed and trap liquid color in the tube between the first position of tube closure and a second position of tube closure; and v) returning the first pusher to its undisplaced position; vi) thereby permitting liquid color to flow through the tube past the first position of tube closure; and vii) displacing the third pusher to squeeze the tube and thereby force at least a portion of the trapped liquid color through the tube past the first position of tube closure.
10. The method of claim 7 further comprising removably positioning the compressible tube within a pusher housing to a location at which a displaced pusher squeezes the tube.
Type: Application
Filed: Jun 16, 2006
Publication Date: Dec 20, 2007
Inventor: Stephen B. Maguire (Glen Mills, PA)
Application Number: 11/455,003
International Classification: F04B 43/08 (20060101);