Polymer tube forming device with multi-dimensional control system

Abstract

To provide a polymeric tube forming apparatus with an automated system for adjusting a tube wall thickness and concentricity.SOLUTION: A tube forming apparatus (10) for multi-dimensional controlled forming of polymeric tube includes a housing (12) that extends around a longitudinal axis (L) and between a rear end (12A) and a discharge end (12B) thereof. The tube forming apparatus includes a core tube assembly (14). The tube forming apparatus includes a die (18). A diverter tip (16) extends from a first inner tube end into the die (18). The tube forming apparatus includes a core tube adjustment system (30). The core tube adjustment system (30) includes one or both of an axial displacement device (40) configured to axially position the core tube assembly (14) for adjusting wall thickness of the tube (20) and an angular displacement device (50) configured to adjust the inner core tube, relative to a longitudinal axis (L), for adjusting concentricity of the tube (20).SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims the benefit of U.S. Provisional Patent Application No. 62 / 912,898, filed October 9, 2019, which is incorporated herein by reference in its entirety.

[0002] The present invention relates generally to an apparatus for forming polymeric tubing, and more particularly to a polymeric tubing forming apparatus having an adjustment system for multidimensional control of the wall thickness and concentricity of the polymeric tubing. [Background technology]

[0003] As shown in FIG. 1 , a prior art tube forming apparatus is designated by the element number 100. The tube forming apparatus 100 includes a housing 112 having a core tube 114 disposed within the housing 112. The core tube 114 includes a tip 116 for forming an inner diameter D10 of a tube 120. A die assembly 118 is disposed at the discharge portion of the housing 112. An annular die bushing 118B is disposed within the die assembly 118. The tip 116 is disposed within the die bushing 118B, and an annular die opening G1 is formed between the tip 116 and the inner surface of the die bushing 118B. The die opening G1 is often referred to as a gum space. Molten material, such as a polymeric material, is fed into housing 112 via inlet 124, flows within housing 112 via flow path FP around mandrel 117 and tip 116, and exits die assembly 118 through die opening G1 in the form of a hollow tube 120 having an outer diameter D21, an inner diameter D10, and a wall thickness T1. Flow path FP is configured to produce flow distributions for a range of extrusion rates and a number of different polymeric materials.

[0004] It is difficult to control the wall thickness T1 and concentricity of the tube 120 emerging from the die assembly 118. In a typical prior art tube forming apparatus 100, the die bushing 118B must be manually positioned relative to the tip 116 to adjust the size of the die opening G1, which controls the wall thickness T1 and concentricity of the tube 120. Such adjustment of the die opening G1 is typically accomplished by manually rotating an adjustment screw 122 that threads into the housing 112 and is configured to move the die bushing 118B relative to the tip 116. Using measurements, adjustment of the die opening G1 is typically performed while the prior art tube forming apparatus 100 is at rest. Adjusting the die bushing 118B to establish the proper wall thickness and concentricity of the tube 120 using the prior art tube forming apparatus 100 is a time-consuming, iterative process that can result in material that does not meet specifications and can result in significant material waste.

[0005] Attempts have been made to automate the adjustment of the die opening G1, however, such attempts have resulted in overly complex systems requiring additional maintenance and components, and additional space to accommodate such additional components. Summary of the Invention [Problem to be solved by the invention]

[0006] Therefore, there is a need for an automated system for adjusting the wall thickness and concentricity of tubes to address the above-mentioned problems. [Means for solving the problem]

[0007] The present invention relates to a tube forming apparatus for multi-dimensionally controlled forming of polymeric tubes. The tube forming apparatus includes a housing extending about a longitudinal axis from a rear end to a discharge end. The housing has an inner surface extending between the rear end and the discharge end. The inner surface defines an interior region within the housing. The tube forming apparatus includes a core tube assembly having an outer core tube extending between a pivot end and a tip engagement end. The outer core tube extends into the interior region such that the tip engagement end is located near the discharge end of the housing and the pivot end is located near the rear end of the housing. The tube forming apparatus includes an inner core tube extending between a first inner tube end and a second inner tube end. The first inner tube end is disposed within the outer core tube, and the second inner tube end extends outside the outer core tube. The tube forming apparatus includes a die in a fixed relationship to the housing, the die having an inner die surface. The tube forming apparatus includes a diverter tip attached to and extending from the first inner tube end. The diverter tip has an outer tip surface. The diverter tip extends into the die such that a die opening is formed between the inner die surface and the outer tip surface. The tube forming apparatus includes a core tube adjustment system mounted near the rear end of the housing. The core tube adjustment system includes one or both of an axial displacement device configured to axially position the core tube assembly to adjust the wall thickness of the tube exiting the die opening and an angular displacement device configured to adjust the inner core tube relative to the longitudinal axis to adjust the concentricity of the tube exiting the die opening.

[0008] In some embodiments, the core tube adjustment system includes one or more servo motors.

[0009] In some embodiments, the axial displacement device is configured to automatically effect axial positioning of the core tube assembly during operation of the tube forming device.

[0010] In some embodiments, the angular displacement device is configured to automatically effect adjustment of the inner core tube during operation of the annuloplasty device.

[0011] In some embodiments, the tube forming device includes a sensor system including one or both of a tube wall thickness sensor system configured to measure the wall thickness of the tube and generate a tube wall thickness signal, and a tube concentricity sensor system configured to measure the concentricity of the tube and generate a tube concentricity signal. The tube forming system includes a control system in communication with the core tube conditioning system. The control system includes a computer processor configured with executable software. The computer processor is configured to receive signals (e.g., the tube wall thickness signal, the tube inner diameter signal, and the tube outer diameter signal) and / or the concentricity signal. The executable software is configured to analyze the signals and / or the concentricity signal and control the tube conditioning system to automatically adjust the wall thickness and concentricity of the tube.

[0012] In some embodiments, the tube forming device includes a thrust bearing in communication with the outer core tube and the housing to facilitate achieving axial positioning of the core tube assembly during operation of the tube forming device.

[0013] In some embodiments, the axial displacement device comprises a drive screw on the exterior surface of the outer core tube and a gearing in communication with the drive screw, whereby operation of the gearing causes axial movement of the core tube assembly.

[0014] In some embodiments, the diverter tip has a spherical outer sleeve surface and the tip engagement end of the outer core tube has a spherical inner engagement surface that slidably engages with the outer sleeve surface in response to adjustment of the inner core tube relative to the outer core tube.

[0015] In some embodiments, the tube forming device includes a spherical bearing having an outer member disposed about an inner member, the outer member having a cylindrical outer surface and a spherical inner bearing surface, the inner member having a spherical outer bearing surface and a cylindrical inner surface, and the outer surface of the outer core tube slidably engaging the cylindrical inner surface of the inner member.

[0016] In some embodiments, the inner core tube is adjustable in angle relative to the outer tube.

[0017] In some embodiments, the angular displacement device comprises a first actuator configured to adjust the inner core tube in a first radial direction (Y-axis) and a second actuator configured to adjust the inner core tube in a second radial direction (X-axis) perpendicular to the first radial direction (Y-axis), whereby cooperation of the first actuator and the second actuator enables adjustment of the inner core tube about the longitudinal axis.

[0018] In some embodiments, the axial displacement device is configured to axially move the core tube assembly through communication with the outer core tube.

[0019] In some embodiments, the inner core tube is in axially fixed relationship to the outer core tube by a locking assembly comprising a bushing and a lock nut threaded over the inner core tube, whereby the inner core tube is axially secured between the bushing and the spherical outer sleeve surface of the diverter tip. An axial surface of the bushing angularly slidably engages the pivot end of the outer core tube. In some embodiments, the axial surface has a spherical contour.

[0020] In some embodiments, a wear-resistant coating is applied to the inner die surface, the outer tip surface, and / or the inner bushing surface. In some embodiments, the wear-resistant coating is a chromium-based material.

[0021] In some embodiments, the mandrel assembly has a tapered region configured to facilitate installation and removal of the mandrel assembly from the housing.

[0022] In some embodiments, the flow channels produce uniform flow distribution and uniform wall thickness of the tube for a range of extrusion rates and a number of different polymer materials.

[0023] In some embodiments, the tube forming device further includes a first linear bearing and a second linear bearing. The first linear bearing is located between the housing and the first actuator and facilitates second radial (X-axis) movement of the first actuator relative to the housing. The second linear bearing is located between the housing and the second actuator and facilitates first radial (Y-axis) movement of the second actuator relative to the housing.

[0024] The present invention includes a core tube assembly including an outer core tube and an inner core tube. The outer core tube extends between a pivot end and a tip engagement end. The outer core tube extends into an interior region such that the tip engagement end is located near the discharge end of the housing and the pivot end is located near the aft end of the housing. The core tube assembly includes an inner core tube extending between a first inner tube end and a second inner tube end. The first inner tube end is disposed within the outer core tube, and the second inner tube end extends outward from the outer core tube. A diverter tip is mounted within and extends from the first inner tube end. The diverter tip has an outer tip surface and a spherical outer sleeve surface extending axially inward from the outer tip surface. The tip engagement end of the outer core tube has a spherical inner engagement surface that slidably engages with the outer sleeve surface. The inner core tube is in axially fixed relationship to the outer core tube by a locking assembly that includes a bushing and lock nut threaded over the inner core tube, whereby the inner core tube is axially secured between the bushing and the spherical outer sleeve surface of the diverter tip, with the axial surface of the bushing angularly slidably engaging the pivot end of the outer core tube. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a top cross-sectional view of a prior art tube forming device.

[0026] [Figure 2A] 1 is a top cross-sectional view of a tube forming device of the present invention.

[0027] [Figure 2B] FIG. 2B is an enlarged view of detail 2B of FIG. 2A.

[0028] [Figure 2C] FIG. 2B is an enlarged view of detail 2C of FIG. 2A.

[0029] [Figure 2D] 1 is a cross-sectional view of a core tube assembly of the present invention with an angular displacement device of the present invention installed therein;

[0030] [Figure 2E] 1 is a cross-sectional view of a core tube assembly of the present invention showing an angular displacement device adjusting an inner core tube.

[0031] [Figure 3] 1 is a perspective view of the tube forming device of the present invention, viewed from the rear end of the device, showing the core tube adjustment system.

[0032] [Figure 4A] 4 is another perspective view of the angioplasty device of FIG. 3.

[0033] [Figure 4B] 4 is another perspective view of the angioplasty device of FIG. 3.

[0034] [Figure 5A] FIG. 1 is a schematic diagram of a computer screen display of a measurement of the wall thickness of a tube before adjustment.

[0035] [Figure 5B] FIG. 10 is a schematic diagram of a computer screen display of a measurement of the wall thickness of a tube after adjustment.

[0036] [Figure 6] 1 is a graph showing tube wall thickness and conditioning as a function of time.

[0037] [Figure 7] 1 is a graph showing tube wall concentricity and alignment as a function of time.

[0038] [Figure 8] 1 is a display showing measurements of tube wall concentricity, tube wall eccentricity, and tube wall thickness.

[0039] [Figure 9] FIG. 10 is a cross-sectional view of an axial displacement device for axially moving the core tube assembly.

[0040] [Figure 10] FIG. 10 is a perspective view of the axial displacement device of FIG. 9. DETAILED DESCRIPTION OF THE INVENTION

[0041] As best shown in FIG. 2A, a tube-forming apparatus of the present invention for multidimensionally controlled formation of polymeric tubes is generally designated by the numeral 10. Tube-forming apparatus 10 includes a housing 12 extending about a longitudinal axis L from a rear end 12A to a discharge end 12B. Housing 12 has an interior surface 12F (best seen in FIG. 2C) extending between rear end 12A and discharge end 12B. Interior surface 12F forms an interior region 12C inside housing 12. As described further herein, a die 18 is disposed near discharge end 12B of housing 12.

[0042] As shown in FIG. 2A , the tube forming apparatus 10 includes a core tube assembly 14 disposed in the interior region 12C of the housing 12. The tube forming apparatus 10 includes a mandrel 17 disposed in the interior region 12C. The mandrel 17 surrounds a portion of the core tube assembly 14 and is fixedly secured to the rear end 12A of the housing 12. As described further herein, a diverter tip 16 is disposed in the portion of the core tube assembly 14. As described further herein, a hollow tube 20 (e.g., having a circular cross-section) is shown ejecting from a portion of the die 18 adjacent the diverter tip 16. While the tube forming apparatus 10 is useful in forming hollow tubes having circular cross-sections, the invention is not limited in this respect, as the tube forming apparatus 10 can also be used to form products and tubes of other geometric shapes, such as tubes having rectilinear, oval, triangular, and star-shaped cross-sections, as well as tubes having ribs or protrusions.

[0043] As shown in FIG. 2A , a core tube adjustment system 30 is mounted near the rear end 12A of the housing 12. The core tube adjustment system 30 includes (a) an axial displacement device 40 configured to axially position the core tube assembly 14 to adjust the wall thickness of the tube 20 exiting the housing 12, as described further herein, and (b) an angular displacement device 50 configured to adjust a portion of the core tube assembly 14 (i.e., the inner core tube 14B as shown in FIGS. 2B and 2C ) relative to the longitudinal axis L (e.g., tilt, incline, skew, or tilt relative to the longitudinal axis L over a range of angles that form a conical region). The angular displacement device 50 is useful for adjusting the concentricity of the tube 20 exiting the die 18. The angular displacement device 50 includes a bearing 60 in communication with a portion of the core tube assembly 14, as described further herein.

[0044] 2A, the tube forming apparatus 10 includes a control system 75 for automatic control of the thickness, inner diameter, outer diameter, and concentricity of the tube 20. The tube forming apparatus 10 includes a sensor system 70 including (a) a tube size sensor system 71 configured to measure the wall thickness of the tube 20, the inner diameter of the tube 20, and / or the outer diameter of the tube 20 to generate a tube size signal 71F (e.g., a tube wall thickness and diameter signal), and (b) a tube concentricity sensor system 72 configured to measure the concentricity of the tube 20 to generate a tube concentricity signal 72F. The control system 75 is in communication with the core tube adjustment system 30 and the sensor system 70. The control system 75 includes a computer processor 75P configured with executable software 76 including algorithms for analyzing and controlling the wall thickness and concentricity of the tube 20. The computer processor 75P is configured to receive the tube size signal 71F and / or the concentricity signal 72F. Executable software 76 is configured to analyze tube size signal 71F and / or concentricity signal 72F and to control tube conditioning system 30 to automatically adjust the wall thickness and concentricity of tube 20. A plurality of displays 75D1, 75D2 (e.g., computer screens, tablet screens, control panel displays, cell phone displays) are in communication with computer processor 75P. In some embodiments, tube size sensor system 71 and / or tube concentricity sensor system 72 use x-ray gauges, ultrasonic gauges, nuclear gauges, and / or other suitable gauges.

[0045] As best shown in FIG. 2D , the core tube assembly 14 includes an outer core tube 14A with a portion of an inner core tube 14B disposed within the outer core tube 14A. The outer core tube 14A extends between a pivot end 14M and a tip engagement end 14C. The inner core tube 14B has an outer surface 14F and extends between a first inner tube end 14G and a second inner tube end 14H. The first inner tube end 14G of the inner core tube 14B is disposed within the outer core tube 14A, and the second inner tube end 14H of the inner core tube 14B extends from the outer core tube 14A near the rear end 12A (see FIG. 2A ) of the housing 12 (see FIG. 2A ).

[0046] As best shown in Figure 2D, the tube forming device 10 includes a diverter tip 16 attached (e.g., threaded, welded, or secured by other suitable fixed connection) to and extending outward from a first inner tube end 14G of an inner core tube 14B. The inner core tube 14B is in a fixed axial relationship with respect to the outer core tube 14A between the diverter tip 16 and a locking assembly 39. Details of the diverter tip 16 and the locking assembly are described further herein with respect to Figures 2C and 2B, respectively.

[0047] As best shown in FIG. 2C , the diverter tip 16 has a tapered outer tip surface 16F. The tapered outer tip surface 16F is generally conical and tapers radially inward from the outer core tube 14A as it moves axially away from the first inner tube end 14G of the inner core tube 14B. The diverter tip 16 extends into a die 18. The die 18 has an inner die surface 18F that is generally conical and has a shape complementary to the tapered outer tip surface 16F of the diverter tip 16. A die opening G1 is formed between the inner die surface 18F and the outer tip surface 16F.

[0048] As best shown in FIG. 2C , the diverter tip 16 includes a convex outer spherical surface 16C extending radially and axially inward from the diverter tip 16 from the radially outermost portion of the tapered outer tip surface 16F toward the inner core tube 14B. The tip engagement end 14C of the outer core tube 14A has a concave engaging spherical surface complementary in shape to the convex outer spherical surface 16C of the diverter tip 16. The convex outer spherical surface 16C slidably engages the stationary tip engagement surface 14C of the outer core tube 14A in response to adjustment of the inner core tube 14B relative to the stationary outer core tube 14A, as further shown and described herein with respect to FIG. 2E .

[0049] 2C, a flow channel FP is formed between the mandrel 17 and the inner surface 12F of the housing 12. The flow channel FP extends between the tapered outer tip surface 16F and the inner die surface 18F, terminating at the die opening G1 where the tube 20 is formed and discharged from the tube forming apparatus 10.

[0050] 2B, the locking assembly 39 includes a bushing 31 and a lock nut 32 that thread onto the inner core tube 14B such that the outer core tube 14A engages the axial surface 31M of the bushing 31 and the lock nut 32 engages the bushing 31 to axially secure it to the inner core tube 14B. The axial surface 31M of the bushing 31 has a concave, spherical profile, and the pivot end 14M of the outer core tube 14A has a convex, spherical profile that is complementary in shape to the concave, spherical profile of the axial surface 31M of the bushing 31. The axial surface 31M slidably engages the stationary pivot end 14M of the outer core tube 14A upon adjustment of the inner core tube 14B caused by the angular displacement device 50, for example, as further shown and described herein with respect to FIG. 2E.

[0051] As best shown in FIG. 2B , the axial displacement device 40 includes an L-shaped collar 41 having a longitudinal leg 41L extending parallel to the longitudinal axis L and having an internally threaded (e.g., internally threaded) 41T. A radial leg 41R extends radially outward from the longitudinal leg 41L. The L-shaped collar 41 threads onto a drive screw 14ET (e.g., externally threaded) on the outer surface 14E of the outer core tube 14A. A thrust bearing 38 is disposed between the radial leg 41R and the housing 12 to support thrust loads. For example, the thrust bearing 38 is disposed between and engages the radial leg 41R and a cover plate 35A fixed to the rear end 12A of the housing 12.

[0052] As generally shown in full cross-section in FIG. 2B, the axial displacement device 40 includes a drive screw 14ET formed on the outer surface 14E of the outer core tube 14A and a gearing 37 (see FIGS. 9 and 10 for further cross-sectional and perspective views, respectively) in communication with the drive screw 14ET such that operation of the gearing 37 causes axial movement of the core tube assembly 14. For example, FIG. 9 shows the gearing 37 including a bull gear 37A (e.g., main gear) secured to an L-shaped collar 41 with a key 41K. Returning to FIG. 2B, the bull gear 37A is mounted between a cover plate 35A and an end plate 35B. As shown in FIG. 9, the bull gear 37A is driven by a pinion gear 37B rotatably mounted in a housing 37H. The pinion gear 37B is rotated by a drive shaft 92A of a drive unit 92, such as a servo motor. Rotation of bull gear 37A causes axial translation of core tube assembly 14. Axial displacement device 40 is configured to achieve axial positioning of core tube assembly 14 during operation of tube forming device 10.

[0053] 2B and 2D, the angular displacement device 50 includes a spherical bearing 60 having an outer member 62 disposed about an inner member 64. The outer member 62 has a cylindrical outer surface 62E and a concave, spherical inner support surface 62F. The inner member 64 has a convex, spherical outer support surface 64F and a cylindrical inner surface 64E. The outer surface 14F of the inner core tube 14B slidably engages the cylindrical inner surface 64E of the inner member 64 when the axial position of the core tube assembly 14 is adjusted, for example, using the axial displacement device 40 (see FIG. 2B).

[0054] 2B, 2D, 3, 4A, and 4B, the angular displacement device 50 includes a first actuator 51 configured to adjust the inner core tube 14B in a first radial direction (Y-axis). As shown in Figures 3, 4A, and 4B, the angular displacement device 50 includes a second actuator 52 configured to adjust the inner core tube 14B in a second radial direction (X-axis) perpendicular to the first radial direction (Y-axis), and cooperation between the first actuator 51 and the second actuator 52 allows the inner core tube 14B to be adjusted in a wide range of angular directions relative to the longitudinal axis L (e.g., within a conical range).

[0055] As best shown in FIG. 4A, the first actuator 51 is in a fixed relationship with respect to the housing 12 except that it is movable in a second radial direction (X-axis) relative to the housing 12, and the second actuator 52 is in a fixed relationship with respect to the housing 12 except that it is movable in a first radial direction (Y-axis) relative to the housing 12.

[0056] 3, the first actuator 51 includes a first servo motor 90Y having an actuator rod 51R engaged with an outer surface 53X (i.e., the X-axis plane) of the adjustment collar 53. The second actuator 52 includes a second servo motor 90X having an actuator rod 52R engaged with an outer surface 53Y (i.e., the Y-axis plane) of the adjustment collar 53. As shown in FIGS. 2B, 2E, and 2D, the adjustment collar 53 has an inner cylindrical surface 53F that surrounds and engages the cylindrical outer surface 62E of the outer member 62 of the spherical bearing 60.

[0057] 3, angular displacement device 50 includes a first linear bearing 51B disposed between housing 12 (see FIG. 4A) and first actuator 51 to facilitate movement of first actuator 51 in a second radial direction (X-axis) relative to housing 12. A second linear bearing 52B is disposed between housing 12 (see FIG. 4A) and second actuator 52 to facilitate movement of second actuator 52 in a first radial direction (Y-axis) relative to housing 12 (see FIG. 4A).

[0058] As shown in FIG. 2E, the inner core tube 14B is adjustable to an angle θ of up to 5 degrees relative to a reference line RL parallel to the longitudinal axis L, with the total included angle between opposing maximum adjustment angles θ being 10 degrees (i.e., the included angle is equal to twice θ). As shown in FIG. 2E, adjustment of the inner core tube 14B through angle θ results in adjustment of the diverter tip 16 on the die 18 to adjust the concentricity of the die opening G1. The angular displacement device 50 is configured to achieve adjustment of the inner core tube 14B from a position axially outward from the rear end 12A of the housing 12 during operation of the tube forming apparatus 10. As shown in FIG. 2D, the core tube assembly 14 is illustrated in a neutral position in which the inner core tube 14B is shown coaxial with the outer core tube 14A and the longitudinal axis L. In the neutral position, the actuator rod 51R is positioned to engage the outer surface 53X of the adjustment collar 53 at the reference line R1. As shown in Figure 2E, extending the actuator rod 51R by a stroke length L10 causes the actuator rod 51R to engage the outer surface 53X at a reference line RE that is a distance away from the reference line R1 equal to the stroke length L10. Extending the actuator rod 51R by the stroke length L10 also adjusts the inner core tube 14B by an angle θ. Adjusting the inner core tube 14B results in an adjustment of the size of the die opening, as indicated by element numbers G1 and G2 in Figure 2E.

[0059] In one embodiment, a wear-resistant coating is applied to the inner die surface 18F, the outer tip surface 16F, and the axial face 31M of the inner bushing 31. In one embodiment, the wear-resistant coating is a chromium-based material.

[0060] In one embodiment, the mandrel assembly 17 has a tapered region configured to facilitate installation and removal of the mandrel assembly 17 from the housing 12 .

[0061] FIG. 5A shows a reproduction of a screen image 200 that appears on one or more of the displays 75D1, 75D2 shown in FIG. 2A. The screen image 200 shows the wall thickness of the tube 20 as measured by the tube size sensor system 71 of the sensor system 70 shown in FIG. 2A. The tube size sensor system 71 measures the wall thickness "T" of the tube 20 at eight distinct points T1, T2, T3, T4, T5, T6, T7, and T8 that are equally spaced around the circumference of the tube 20 as it exits the die opening G1. The tube 20 exiting the die opening G1 is passed through a gauge (e.g., an x-ray gauge, an ultrasonic gauge) to measure the wall thickness at the eight distinct points T1, T2, T3, T4, T5, T6, T7, and T8, for example, during operation of the tube forming apparatus 10. In the embodiment shown in FIG. 5A, the thickness T2 is below the minimum wall thickness set by the user or operator, and the thickness T6 is above the maximum wall thickness set by the user or operator. A computer processor 75P (shown in FIG. 2A) analyzes the tube wall thickness signal 75F and controls the tube conditioning system 30 to adjust the wall thickness of the tube 20 exiting the die opening G1. FIG. 5B shows a screen image 200' illustrating the wall thickness of the tube 20 at eight distinct points T1, T2, T3, T4, T5, T6, T7, and T8 after the wall thickness of the tube 20 has been adjusted by the tube conditioning system 30. The screen image 200' shown in FIG. 5B indicates that the thickness measurements at all eight points T1, T2, T3, T4, T5, T6, T7, and T8 are within acceptable ranges.

[0062] 6 is a graph 220 illustrating the wall thickness T of the pipe 20 as a function of time as the pipe conditioning system 30 automatically adjusts the wall thickness T of the pipe 20, as discussed herein with reference to FIGS. 5A and 5B. Graph 220 illustrates time on the X-coordinate axis, indicated as element number 222 in the graph 220. Graph 220 illustrates the wall thickness T of the pipe 20 on the Y-coordinate axis on the left, indicated as element number 224 in the graph 220. Graph 220 illustrates the adjustment made by the pipe conditioning system 30 (see FIG. 2A) on the Y-coordinate axis on the right, indicated as element number 225 in the graph 220. While eight distinct points T1, T2, T3, T4, T5, T6, T7, and T8 are shown and described, the present invention is not limited in this regard, as more or fewer than eight points may be measured by the sensor system 70.

[0063] As shown in graph 220 of Figure 6, plot 228 shows the thickness measurement point T6 shown in Figure 5A as a function of time, and plot 226 shows the thickness measurement point T2 as a function of time. Additionally, graph 220 includes a plot 229 of the number of adjustments as a function of time (shown as a dotted line in Figure 6). Graph 220 also includes a horizontal line 223 that specifies the target nominal wall thickness (e.g., shown in graph 220 as being approximately 0.054 inches).

[0064] Executable software 76 within computer processor 75P (see FIG. 2A ) automatically initiates adjustments by pipe conditioning system 30 when the wall thickness of pipe 20 exceeds target nominal wall thickness 223 (see FIG. 6 ) for a predetermined period of time. The adjustments automatically adjust the wall thickness of pipe 20 at measurement point T6 based on the pipe size signal 71F processed by computer processor 75P decreasing and approaching target nominal wall thickness 223 shown in FIG. 6 . As the thickness T of pipe 20 at measurement point T6 decreases, the thickness of pipe 20 at measurement point T2 increases accordingly. As shown in FIG. 6 , both plot 228 of the thickness of pipe 20 at measurement point T6 and plot 226 of the thickness of pipe 20 at measurement point T2 approach target nominal wall thickness 223 in response to adjustments 229 by pipe conditioning system 30. Referring to FIG. 6 , adjustments 229 are automatically initiated at the appropriate time as shown on graph 220. The pipe conditioning system 30 automatically decreases the thickness of the pipe 20 at measurement point T6 and increases the thickness of the pipe at measurement point T2. Each time the pipe conditioning system 30 adjusts the thickness of the pipe at measurement points T6 and T2, the measurements are compared to the target nominal wall thickness 223.

[0065] 7 is a graph 230 showing the concentricity of the tube 20 exiting the die opening G1 on the left Y-axis 232 versus time shown on the X-axis 234. The graph 230 also shows the adjustment of the angular displacement device 50 (see FIG. 2A) by the motors 90X and 90Y on the right Y-coordinate axis, shown as element number 225 in the graph 230.

[0066] Referring to FIG. 7, initially, the tube 20 exiting the die opening G1 has a concentricity 236 of approximately 70% due to the tube thickness being significantly thinner than the target nominal wall thickness 223 at one thickness measurement point T2 and significantly thicker than the target nominal wall thickness 223 at another thickness measurement point T6. Adjustments by the tube conditioning system 30 result in an improvement in the concentricity 236 of the tube 20 exiting the die opening G1. The initial concentricity is expected to be approximately 70-80%. Once the motor adjustments are automatically initiated, an algorithm within the executable software 76 (see FIG. 2A) directs the tube conditioning system 30 (shown generally in FIG. 2A) to adjust the thickness at both points T2 and T6 to approach the target nominal wall thickness 223, resulting in a final concentricity 236 of the tube 20 exiting the die opening G1 of approximately 97%. Automatic adjustments by computer processor 75P in cooperation with tube adjustment system 30 maximize concentricity 236 of tube 20 exiting die opening G1 and minimize eccentricity 237 (shown in FIG. 8) of tube 20 exiting die opening G1. Computer processor 75P of tube forming apparatus 10 continues to monitor the thickness and concentricity of tube 20 exiting die opening G1 and continues to send tube size signal 71F and / or concentricity signal 72F as needed. Computer processor 75P accounts for variations as tube 20 exits die opening G1, including variations based on day or night constraints and variations necessary to compensate for gum space adjustments.

[0067] FIG. 8 shows a reproduction of an exemplary display 75D1′ as shown in FIG. 2A. The illustrated display 75D1′ includes a screen image 200″ showing the thickness of the tube 20 as measured by the tube size sensor system 71 of the sensor system 70 shown in FIG. 2A. In the embodiment shown in FIG. 8, the thickness measurements at all points T1, T2, T3, T4, T5, T6, T7, and T8 are all within tolerance. In the illustrated embodiment, the computer processor 75P (see FIG. 2A) adjusts the servo motors 90X, 90Y (see FIG. 3) to maintain the tube thickness measurements T1, T2, T3, T4, T5, T6, T7, and T8 within a tolerance range of 0.049 to 0.061 inches while reducing the eccentricity 237 from 0.06 inches to 0.005 inches and improving the concentricity 236 from approximately 80% to 98%. The exemplary display 75D1′ shows the thickness measurements, concentricity 236, and eccentricity 237 at each point in real time so that an algorithm contained in the computer processor 75P or a user can adjust the axial displacement device 40 and / or the angular displacement device 50 (shown in FIGS. 5A and 5B) to maintain the thickness, concentricity 236 of the tube 20, and / or eccentricity 237 of the tube at each point T1, T2, T3, T4, T5, T6, T7, and T8 within tolerances.

[0068] Although the present invention has been disclosed and described with reference to specific embodiments thereof, it should be noted that other variations and modifications may be made and that the following claims are intended to cover such variations and modifications as fall within the true scope of the invention.

Claims

1. A tube forming apparatus (10) for multi-dimensional controlled forming of polymeric tubes, comprising: a housing (12) extending about a longitudinal axis (L) from a rear end (12A) to a discharge end (12B), the housing (12) having an inner surface (12F) extending between the rear end (12A) and the discharge end (12B), the inner surface (12F) defining an interior region (12C) inside the housing (12); A core tube assembly (14) comprising: (a) an outer core tube (14A) extending between a pivot end (14M) and a tip engagement end (14C), the outer core tube (14A) extending into the interior region (12C) such that the tip engagement end (14C) is located near the discharge end (12B) of the housing (12) and the pivot end (14M) is located near the rear end (12A) of the housing (12); (b) an inner core tube (14B) extending between a first inner tube end (14G) and a second inner tube end (14H), whereby the first inner tube end (14G) is disposed within the outer core tube (14A) and the second inner tube end (14H) is in communication with the inner core tube (14B) extending outside the outer core tube (14A); a core tube assembly (14) comprising: a die (18) in fixed relation to said housing (12) and having an inner die surface (18F); a diverter tip (16) mounted within and extending from the first inner tube end (14G), the diverter tip (16) having an outer tip surface (16F) and extending into the die (18) such that a die opening (G1) is formed between the inner die surface (18F) and the outer tip surface (16F); a core tube adjustment system (30) mounted near the rear end (12A) of the housing; It is equipped with The core tube adjustment system (30) comprises: (a) an axial displacement device (40) configured to axially position the core tube assembly (14) to adjust the wall thickness of the tube (20) discharged from the die opening (G1); and (b) an angular displacement device (50) configured to adjust the inner core tube (14B) relative to the longitudinal axis (L) to adjust the concentricity of the tube (20) exiting the die opening (G1); A tube forming device (10) comprising:

2. 2. The tube forming device (10) of claim 1, wherein the core tube adjustment system (30) comprises at least one servo motor (90Y), (90X), (92).

3. 3. The tube forming device (10) of claim 1 or 2, wherein the axial displacement device (40) is configured to automatically perform axial positioning of the core tube assembly (14) during operation of the tube forming device (10).

4. The tube forming device (10) of any one of claims 1 to 3, wherein the angular displacement device (50) is configured to automatically adjust the inner core tube (14B) during operation of the tube forming device (10).

5. (a) a tube size sensor system (71) configured to measure the wall thickness of the tube (20) and generate a tube size signal (71F); and (b) a sensor system (70) comprising at least one tube concentricity sensor system (72) configured to measure the concentricity of the tube (20) and generate a tube concentricity signal (72F); a control system (75) in communication with the core tube adjustment system (30); Furthermore, 5. The tube forming apparatus of claim 1, wherein the control system comprises a computer processor configured with executable software configured to receive at least one of the tube size signal and the concentricity signal, and wherein the executable software is configured to analyze at least one of the tube size signal and the concentricity signal and to control the core tube adjustment system to automatically adjust the wall thickness and concentricity of the tube.

6. 6. The tube forming apparatus (10) of claim 1, further comprising a thrust bearing (38) in communication with the outer core tube (14A) and the housing (12) for facilitating axial positioning of the core tube assembly (14) during operation of the tube forming apparatus (10).

7. 7. The tube forming device (10) of claim 1, wherein the axial displacement device (40) comprises a drive screw (14ET) on the outer surface (14F) of the outer core tube (14A) and a gearing in communication with the drive screw (14ET), whereby operation of the gearing causes axial movement of the core tube assembly (14).

8. 8. The tube forming device (10) of claim 1, wherein the diverter tip (16) comprises a spherical outer sleeve surface (16C), and the tip engagement end (14C) of the outer core tube (14A) comprises a spherical inner engagement surface that slidably engages with the outer sleeve surface (16C) in response to adjustment of the inner core tube (14B) relative to the outer core tube (14A).

9. The present invention further includes a spherical bearing (60) having an outer member (62) disposed around an inner member (64), the outer member (62) having a cylindrical outer surface (62E) and a spherical inner support surface (62F), and the inner member (64) having a spherical outer support surface (64F) and a cylindrical inner surface (64E); 9. The tube forming device (10) of claim 1, wherein the outer surface (14F) of the inner core tube (14B) is slidably engaged with the cylindrical inner surface (64E) of the inner member (64).

10. 10. A tube forming device (10) according to any one of claims 1 to 9, wherein the inner core tube (14B) is angle adjustable relative to the outer core tube (14A).

11. 11. The tube forming device (10) of claim 1, wherein the angular displacement device (50) comprises a first actuator (51) configured to adjust the inner core tube (14B) in a first radial direction (Y-axis) and a second actuator (52) configured to adjust the inner core tube (14B) in a second radial direction (X-axis) perpendicular to the first radial direction (Y-axis), whereby cooperation of the first actuator (51) and the second actuator (52) enables adjustment of the inner core tube (14B) around the longitudinal axis.

12. 12. The tube forming device (10) of claim 1, wherein the axial displacement device (40) is configured to axially move the core tube assembly (14) through communication with the outer core tube (14A).

13. 13. A tube forming device (10) according to any one of claims 1 to 12, wherein the inner core tube (14B) is in axially fixed relationship to the outer core tube (14A) by a locking assembly (39), the locking assembly (39) comprising a bushing (31) and a lock nut (32) threaded onto the inner core tube (14B), whereby the inner core tube (14B) is axially fixed between the bushing (31) and a spherical outer sleeve surface (16C) of the diverter tip (16), and an axial surface (31M) of the bushing (31) angularly slidably engaging the pivot end (14M) of the outer core tube (14A).

14. 14. The tube forming device (10) of claim 13, wherein the axial surface (31M) has a spherical contour.

15. an outer core tube (14A) extending between a pivot end (14M) and a tip engagement end (14C), the outer core tube (14A) extending into an interior region (12C) such that the tip engagement end (14C) is located near the discharge end (12B) of the housing (12) and the pivot end (14M) is located near the rear end (12A) of the housing (12); an inner core tube (14B) extending between a first inner tube end (14G) and a second inner tube end (14H), the first inner tube end (14G) being disposed within the outer core tube (14A) and the second inner tube end (14H) extending outside the outer core tube (14A); a diverter tip (16) mounted within and extending from the first inner pipe end (14G), the diverter tip having an outer tip surface (16F) and a spherical outer sleeve surface (16C) extending axially inward from the outer tip surface (16F); It is equipped with the tip engagement end (14C) of the outer core tube (14A) includes a spherical inner engagement surface that slidably engages the outer sleeve surface (16C); the inner core tube (14B) is in axially fixed relationship to the outer core tube (14A) by a locking assembly (39), the locking assembly (39) comprising a bushing (31) and a lock nut (32) threaded onto the inner core tube (14B), whereby the inner core tube (14B) is axially secured between the bushing (31) and a spherical outer sleeve surface (16C) of the diverter tip (16); A core tube assembly (14) in which the axial surface (31M) of the bushing (31) is engaged with the pivot end (14M) of the outer core tube (14A) so as to be capable of angular sliding.

Images