Abstract:
A method for producing a tube section from thermoplastic material, in which a tube section is extruded by means of an extruder which is provided with an extruder die having an inner core, which inner core defines an axial hollow space in the tube section, the tube section coming out of the extruder die downstream of the extruder die being internally cooled by means of an internal cooling member and externally cooled by means of an external cooling device. Immediately after the tube section leaves the extruder die, the internal cooling member brings about internal cooling of the tube. The external cooling device is positioned downstream of the internal cooling member, so that the external cooling of the tube section is brought about after the internal cooling.
Abstract:
Heating and extruding a polymeric sheet having a predetermined thickness and introducing it into and through a gap between cooling rolls, measuring directly by laser beam and without reflection the gap between the cooling rolls, and controlling the gap to control minimal pressure on the softened and heat-plastified sheet.
Abstract:
A system and method for forming an article from thermoplastic material and fiber. The method includes heating thermoplastic material to form a molten thermoplastic material for blending with the fiber. The molten thermoplastic material is blended with the fibers to form a molten composite material having a concentration of fiber by weight. The molten composite material may then be extruded through dynamic dies to deliver discrete controlled material that is gravitated onto a lower portion of a mold. The lower portion of the mold may be moved in space and time while receiving the flow of composite material to deposit a predetermined quantity of molten composite material thereon conforming to mold cavities of the lower and an upper portion of the mold. The upper portion of the mold may be pressed against the predetermined quantity of molten composite material and closing on the lower portion of the mold to form the article.
Abstract:
The invention is an extruder temperature controller for an extruder barrel. The extruder temperature controller includes means for determining an actual screw speed and has means for storing a plurality of screw speeds. Each member of the plurality of stored screw speeds has a corresponding stored temperature reset value. The extruder temperature controller has a means for comparing and selecting that compares the actual screw speed to each of the plurality of stored screw speeds and selectes a default screw speed. The default screw speed has a smaller deviation from the actual screw speed than any other member of the compared, stored screw speeds. The controller further includes a means for generating a control output driver signal to the heat exchange means. The control output driver signal is the corresponding stored temperature reset value for the default screw speed. The invention further includes a means for delaying a control alarm for a predetermined time when the means for generating a control output driver signal to the heat exchange means operates at or near maximum capacity. The invention includes a method for controlling the temperature of an extruder barrel.
Abstract:
A sheet processing system for continuously producing plastic sheet which is continuously supplied to an intermittent take-up device, utilizing a sheet forming apparatus, a conveyor, an accumulator and take-up apparatus, the sheet being fed along the conveyor to an accumulator positioned integrally with the conveyor, the accumulator being controlled in a cyclic operation which provides for the accumulation of the continuously fed sheet material to permit intermittent operation of the take-up apparatus, and the edge trimming of the sheet subsequently to the action of the accumulator.
Abstract:
Heating and extruding a polymeric sheet having a predetermined thickness and introducing it into and through a gap between cooling rolls, measuring directly by laser beam and without reflection the gap between the cooling rolls, and controlling the gap to control minimal pressure on the softened and heat-plastified sheet.
Abstract:
A method for designing an extrusion process and extrusion die includes the steps of first determining the optimal extrusion process parameters and then designing an extrusion die based on those optimal parameters. The optimal extrusion process parameters are determined by identifying the geometric characteristics of the selected extrusion profile, determining the physical characteristics of the material to be extruded, determining the physical characteristics for the extrusion processor, and detrmining the extrusion process limitation chart for the selected extrusion profile, selected extrusion material, and the selected extrusion processor. After the extrusion process limitation chart has been determined, a preferred extrusion process window is determined for the extrusion process limitation chart. A series of simulations are then run to determine if the selected temperatures and speeds result in an entire extrusion process falling within the extrusion process window. If the selected criteria result in a process that extends beyond the window, new selections are made and the simulation is repeated until the process falls entirely within the extrusion process window. The criteria are then used in a feed forward set up to run the extrusion process.
Abstract:
An extrusion system utilizes single or tandem extruders and a mixer-cooler to extrude a foamable extrudate through a die in a sealable chamber. The foamable extrudate is shaped and calibrated within the chamber. The die is mounted on the end of a gel tube projecting through a gland seal in a fixed bulkhead forming the upstream end of the chamber. The gel tube and mixer-cooler are mounted on a movable carriage, movement of which may be used to adjust the die with respect to shaping and calibrating equipment inside the chamber. The mixer-cooler achieves a selected narrow range of uniform viscosity of the melt at the die depending on the size of the product and density. The chamber is preferably a vacuum chamber producing low density foams. The product exits the chamber to atmosphere on a continuous basis through a submerged orifice in a water baffle immersion seal. The mixer-cooler enables a large size low density product to be produced with uniform cellular structure without cell collapse or density gradients, as the product is subjected to the pressure and temperature transformations passing from the chamber to atmosphere through the water. The seal includes the submerged orifice with a free wheeling guiding system upstream of the orifice. Immediately ahead of the guiding system, the parameters of the foam extrudate are sensed to control the configuration of the orifice on a continuous basis. Before the extrudate passes into the water baffle seal it moves over a floating dancer roll, the position of which controls a haul-off such as a vacuum belt at the tail end of the system. This avoids pushing on the extrudate.
Abstract:
Process for forming a dimensionally variable tubular member for use in catheterization procedures. The process includes a mechanism for extruding a tubular member. A variable speed puller pulls the tubular member through or from the extrusion means at a selectively variable speed. A variable air or gas pressure supply supplies pressurized air or gas to the extrusion mechanism at a selectively variable rate. The dimensionally varying tubular member may be cut to desired lengths for use as catheter shafts or catheter soft tips. The process may include forming a tubular member having a dimensionally varying first layer and a dimensionally varying second layer, wherein a portion of the first layer at a distal end of the tubular member is removed.
Abstract:
In the present invention, a preliminary extruding operation is carried out for each section of a movable die moving pattern DA corresponding to the configuration of an article, thereby determining a suitable back pressure at which a desired cross-sectional dimension is obtained. The movable die is secured to a position DA1 corresponding to a side section of the article, then screw revolutions are changed while extruding a molding material. Thus, determined as a suitable back pressure BPO for the side section is a specified value of the back pressures BP at which the molded product has the desired cross-sectional dimension. Likewise, a suitable back pressure for the upper section is also determined, so that a pattern of the suitable back pressures BPO is determined. In view of the time delay, timings of change in an initial setting pattern R1 for the screw revolutions are advanced for periods of times T.sub.11, T.sub.12, T.sub.13 and T.sub.14 from the timings of change in the pattern DA. In the present extruding operation, an actual pulling speed is detected. If the actual pulling speed is different from a pulling speed in the preliminary extruding operation, the movable die moving pattern DA is corrected. After several cycles of extrusion molding are carried out, if the detected back pressures BP are deviated from the pattern of the suitable back pressures BPO, the pattern R1 of the screw revolutions is modified.