Adaptive composite molding system

Abstract

A system for molding products from multiphase composite lubricants and other source materials sensitive to temperature and sheer. A press unit includes a pair of mold parts that are selectively moveable between an open position and a closed position. A pair of mold inserts are associated with the mold parts, respectively. Each mold insert includes a heater and a passage formed therethrough for receiving a cooling liquid. The system can precisely control the pressure being applied as well as the heating and cooling of the mold inserts to more carefully mold products from material such as multiphase composite lubricants.

Description

TITLEADAPTIVE COMPOSITE MOLDING SYSTEMBACKGROUND OF THE INVENTION1. FIELD OF THE INVENTION

[0001] The present invention relates to lubricants and, more specifically, to a molding system for manufacturing lubricant composition products.2. DESCRIPTION OF THE RELATED ART

[0002] Composite lubricants have been used for many years and range from waxbased products to solid lubricant filled composites. Thermoplastic lubricants soften or melt when heated, while thermoset resin lubricants remain solid. Thermoplastic composites are used for low speed and thus low temperature applications and thermosets may be used for higher speed and thus higher temperature application. More recently, multiphase composite lubricants have been developed that can be used in both low and high temperature applications. Products made from the new multiphase composite lubricants require more careful control during the molding process to ensure that the integrity of the multiphase composite lubricants are preserved.

[0003] Current molding processes, such as injection and compression molding, are well understood to have some limitations when molding high solid loaded composites as they rely on high pressure and shear to form parts. These forces can create wear and require structures to retain these forces, making machines and molds large and heavy. For example, in the compression molding process, a pre-measured amount of material is loaded into a hot mold and the hydraulic press is closed, forcing the material to quickly flow into the mold and creating a large pressure spike that is quickly reduced as the material is heated and flows. With injection molding, the material is compounded into a shot size by using a reciprocating feed screw being heated using shear and heat. This shot is held at molding temperature until the part is ready to be molded. It is then injected into a cooled mold under high pressure that can exceed 15,000 psi. The high-pressure nature of both designs creates high shear and can destroy delicate additives that rely on their structure to function in the end product. The additives used can also affect the process. For example, lubricants being molded in an injection molding system can slip as they are being compounded, creating erratic shot sizes and air entrapment in the material, leading to porosity in the finished product. These processes may also be affected by inconsistent materials. Variables such as moisture content can create problems that are hard to overcome and lead to inconsistent parts or increased failures. The compounding nature of injection molding can also limit the materials that canbe molded as materials such as bioplastics can crosslink when heated, thereby creating a thermoset composite. If these materials are molded in an injection molding machine, they will crosslink in the extruder instead of the mold, thus damaging the molding machine. Accordingly, there is a need in the art for a system that can be used to properly manufacture lubrication products from multiphase composite lubricants.BRIEF SUMMARY OF THE INVENTION

[0004] The present invention allows for the manufacture of lubrication products from multiphase composite lubricants by more carefully controlling pressure and temperature during the molding process and thereby allowing for the use of materials such as multiphase composite lubricants without adverse consequences. The system includes a press unit having a pair of mold parts that are selectively moveable between an open position and a closed position. The mold includes a mold insert having a pair of heaters and a passage formed therethrough for receiving a cooling liquid. The system can precisely control the pressure being applied as well as the heating and cooling of the mold inserts to allow for the manufacture of lubrication products from multiphase composite lubricants and other materials that are otherwise not amenable to molding via conventional processes.BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

[0005] The present invention will be more fully understood and appreciated by reading the following Detailed Description in conjunction with the accompanying drawings, in which:

[0006] FIG. l is a front perspective view of a press unit according to the present invention.

[0007] FIG. 2 is a rear perspective view of a press unit according to the present invention.

[0008] FIG. 3 is a side perspective view of a press unit according to the present invention.

[0009] FIG. 4 is a schematic of a mold insert according to the present invention.

[0010] FIG. 5 is a thermal image of heat transfer in a mold insert according to the present invention.

[0011] FIG. 6 is a graph of the relationship between the temperature of the heater and the temperature of the mold according to the present invention.

[0012] FIG. 7 is a front perspective view of a rack supporting multiple press units according to the present invention.

[0013] FIG. 8 is a series of schematics of different feeder options for a press unit according to the present invention.

[0014] FIG. 9 is a schematic of a material injector controlled by a servo motor with position and force feedback according to the present invention.

[0015] FIG. 10 is a graph of the pressure and temperature contour for molding a composite part.

[0016] FIG. 11 is a series of graphs of temperature and pressure curves for cycles for three different moisture contents.

[0017] FIG. 12 is a series of graphs showing the control adjusting for the increased moisture by taking longer to meet the final position of the insert.

[0018] FIG. 13 is a schematic showing two different modular racks for a press unit according to the present invention.

[0019] FIG. 14 is a schematic of differently configured and dimensioned press units installed in a common rack according to the present invention.

[0020] FIG. 15 is a schematic of a control system for a press unit according to the present invention.DETAILED DESCRIPTION OF THE INVENTION

[0021] Referring to the drawings, wherein like numeral refer to like parts throughout, there is seen in FIGS. 1 and 2 an adaptive composite molding system 10 according to the present invention. System 10 comprise a press unit 12 having a material inlet 14, a step motor 16 with feed screw 18 for selectively controlling the supply of molding materials to a mold 20 via a mold insert 22 according to the present invention. Mold 20 comprises a pair of mold parts 20a and 20b that can be opened and closed using a mold clamp 24 driven by the clamp cylinder 26. Press unit 12 includes appropriate sensors 90 and is programmed to provide for pressure feedback for precise control of a linear actuator 92 to tightly control the molding variables and, as a result, drastically reduce the pressure and shear needed to mold parts. Press unit 12 may be designed to provide the particular clamping force needed for the product being made by system 10. As seen in FIG. 3, mold insert 22 comprises two insert halves 22a and 22b that are carried by mold parts 20a and 20b and moveable therewith. An ejector system 94 may be used to extract the molded article from system 10.

[0022] Referring to FIG. 4, each half 22a and 22b of mold insert 22 has a pair of electric heaters 30 and a central passage 32 having an inlet and an outlet through which a cooling liquid, such as water, may be passed. Mold insert 22 drastically reduce the thermal mass of the mold components to allow for more responsive control of heat during moldingprocesses, thereby allowing for heat and shear sensitive components to be more easily placed into system 10 and molded. Mold insert 22 is shown with a product material cavity 28 that receives the material to be molded and then produces the desired molded products in mold 20, such as a locomotive lubrication stick, from a multiphase composite lubricant source material. Cavity 28 is aligned with a mold transition 44 that extends from the location where step motor 16 with feed screw 18 supplies molding material so that the material can be provided into cavity 28 for molding by mold insert 22. Cavity 28 could be configured and dimensioned for other desired products as system 10 is not limited to use for any specific products. As described herein, mold insert halves 22a and 22b can be quickly changed in press unit 12 to allow for different shapes to be molded on demand.

[0023] Referring to FIG. 5, the heat transfer in mold insert 22 to the material to be molded is shown. By isolating the heat in the manner seen in FIG. 4, the material is heated directly, giving greater control over the heat profile. The relationship between the temperature of the heater and the temperature of the mold can be very closely controlled, as seen in FIG. 6, which was recorded directly from an actual molding cycle.

[0024] FIG. 7 depicts that press units 12 can be configured to provide for different molding requirements for composite parts. For example, as seen in FIG. 7, one rack 40 can support multiple press units 16 (show with four) with different tooling installed. As further seen in FIG. 7, a larger dimensioned set of four press units 16 can be racked with a smaller dimensioned set of four press units 16 that has an electric actuator for clamping. Thus, press units 12 may be installed racked in many different ways so that the number of press units 12 can vary depending on production requirements with each station varied depending on the size of part(s) needed.

[0025] Referring to FIG. 8, different configurations may be used to feed materials into press unit 16. In the example of FIG. 1, a step motor 16 and a volumetric feeder with feed screw 18 can be used to control the shot size required for the part being molded by delivering powder or granulated molding compound into mold insert 22. As further seen in FIG. 8, a hopper feeder system 42 may also be used to supply materials to system 10.

[0026] Referring seen in FIG. 9, mold operator 50 for injecting material into mold insert 22 is controlled by a servo motor 52 with position and force feedback. Operator 50 may thus apply the force needed to form the part. FIG. 10 shows a pressure and temperature contour for molding a composite part, and FIG. 11 shows temperature and pressure curves for cycles for three different moisture contents. The temperature curves are very similar, but the pressure profiles are quite different. As the material is heated the moisture turns to steam,which creates an increase in pressure. This pressure is allowed to vent from system 10. FIG. 12 shows the control adjusting for the increased moisture by taking longer to meet the final position of the insert.

[0027] Referring to FIG. 13, two different modular racks 40 are seen, one with an integrated material blender 54 and one without. Illustrated in a four station configuration, racks 40 can be configured in increments of two press units. This approach can support two to eight press units 12, but more could be added. Racks 40 include the controls for press units 12 and can be configured as master and slave units, thereby allowing system 10 to be easily expandable to meet production needs. FIG. 14 illustrates how differently configured or dimensioned press units 12a and 12b may be installed in a common rack 40, allowing for different parts to be run in the same equipment quickly by changing press units 12.

[0028] System 10 can process a wide variety of materials, from lubricant and friction modifiers to carbon fiber and ceramic filled composites. Modular press units 12 can be configured to make a certain type of part. Mold inserts 22 can be interchanged and used to make different shapes as needed, adding flexibility and lowering the transition costs. The use of conformal heated molds and in-mold pressure feedback allow for tight control over the molding process using an adaptive molding profile. Modular press units 12 also allow for controlled expansion and flexibility not possible with the conventional systems. Production expansion can be controlled by adding only as many press units 12 as are needed to meet specific production needs, scaling investment costs to precisely match capacity requirements. Modular press units 12 also allow for greater process design possibilities for molding composite parts. The ability to quickly change press units 16 also allows for custom prototype units and efficient revisions to meet the requirements of the product being molded. Modular press racks 40 can include integrated control systems to allow different configurations and sizes. Modular press racks 40 can be expanded using slave units that include remote IO for the added press units 12.

[0029] Referring to FIG. 15, press unit 12 preferably includes a programmable controller or microcontroller 60 that is responsible for supervising the various pressure and temperature sensor outputs and controlling press unit 12 according to the desired molding profile and characteristics of the material being used. For example, controller 60 can receive mold pressure feedback 62, heater temperature feedback 64, mold temperature feedback 66, insertion position feedback 68, and insert current feedback 70. Controller 60 can then dictate system conditions by providing a mold pressure output 72, mold temperature output 74, moldtemperature output 76, insertion speed output 78, shot size output 80, and insert current output 82 according to a mold profile 84 and process data 86.

[0030] The adaptive control of the heat, pressure and movement of system 10 reduces negative effects from environmental variables such as excessive moisture. Conversely, adaptive control allows for moisture to be added when required in a molding process to react with acid or base crosslinking agents. The low shear and pressure afforded by system 10 allow molding of materials that would not be possible using conventional molding approaches.

Claims

CLAIMSWhat is claimed is:

1. A system for molding products, comprising: a press unit having a material inlet; a mold associated with the press unit and aligned with the material inlet; a pair of mold parts supported by the mold and moveable between an open position and a closed position by the mold; and at least one mold insert associated with one of the pair of mold parts, wherein the mold insert includes a first side having a cavity dimensioned to form a molded product and a second side having a heater and a cooling passage that extends along the cavity.

2. The system of claim 1, further comprising a feed screw aligned with the material inlet and having an output in communication with a mold transition that extends to the cavity of the at least one mold insert.

3. The system of claim 2, further comprising a step motor operatively coupled to the feed screw.

4. The system of claim 3, further comprising a mold operator coupled to the mold transition and a servo motor operatively coupled to the mold operator to selectively apply pressure to any material in the mold transition.

5. The system of claim 4, further comprising a pressure sensor for outputting an amount of force applied by the mold operator.

6. The system of claim 5, further comprising a temperature sensor for outputting a temperature of the mold.

7. The system of claim 6, further comprising a microcontroller coupled to the heater, the pressure sensor, the temperature sensor, the servo motor, and the step motor.

8. The system of claim 7, wherein the microcontroller is programmed to control the heater, the servo motor, and the step motor according to a molding profile and the amount of force that is output by the pressure sensor and the temperature of the mold that is output by the temperature sensor.

9. A method of molding a composite lubricant product, comprising the steps of: feeding an amount of material for a product into a press unit having a material inlet; injecting the amount of material into a mold having a pair of mold parts that are moveable between an open position and a closed position by the mold, wherein the mold includes at least one mold insert having a cavity dimensioned to form a molded product fromthe amount of material, a heater positioned proximately to the cavity, and a cooling passage extending along the cavity; and molding the molded product from the amount of material by controlling an amount of pressure used when injecting the amount of material into the cavity and controlling a temperature of the mold insert using the heater and the cooling passage of the mold insert.

10. The method of claim 9, wherein the step of feeding the amount of material comprises driving a feed screw aligned with the material inlet to move the amount of material from the material inlet into a mold transition.

11. The method of claim 10, wherein the step of inj ecting the amount of material into the mold comprising using a mold operator coupled to a mold transition and a servo motor operatively coupled to the mold operator to selectively apply the amount of pressure to the amount of material in the mold transition to move the amount of material into the cavity of the mold insert.

12. The method of claim 11, wherein the mold includes a pressure sensor for outputting an amount of force applied by the mold operator and a temperature sensor for outputting a temperature of the mold.

13. The method of claim 12, further comprising a microcontroller coupled to the heater, the pressure sensor, the temperature sensor, the servo motor, and a step motor operatively coupled to the feed screw.

14. The method of claim 13, wherein step of molding the molded product from the amount of material by controlling the amount of pressure used when injecting the amount of material into the cavity and controlling a temperature of the mold insert using the heater and the cooling passage of the mold insert comprises using the microcontroller to control the heater, the servo motor, and the step motor according to a molding profile and the amount of force applied by the mold operator that is output by the pressure sensor and the temperature of the mold that is output by the temperature sensor.

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