METHOD AND APPARATUS FOR THE MANUFACTURE OR PHARMACEUTICAL CELLULOSE CAPSULES

Abstract: Pharmaceutical hard-shell cellulose capsules, each capsule consisting of a capsule body and a capsule cap, are made from an aqueous solution of a thermogelling cellulose ether composition in a capsule machine using pins (22) as molds. Solution is gelatinized and dried on the surface of a pin (22) to form a cellulose capsule part (28). Adhesion between the cellulose capsule part (28) and the pin (22) is broken by using a gripper (24) and applying a grip of predefined force and a frictional force on a selected sacrificial portion of the outer circumferential surface of the capsule part (28), the frictional force aligned with the pin axis. After breaking adhesion, gripping is released and the part (28) is moved off the pin (22).

Description: METHOD AND APPARATUS FOR THE MANUFACTURE OF PHARMACEUTI AL CELLULOSE CAPSULES Technical Field The invention relates generally to the methods and apparatus used in the manufacture of pharmaceutical hard¬ shell capsules and, in particular, to the removal of hard- shell capsules from their forming pins. Background of the Invention The stripping system that is currently used on modern US commercial capsule machines to remove gelatin capsule parts from their forming pins is disclosed in US Patent No. 1,787,777 to Colton. Colton discloses a "stripper" for removing gelatin capsule parts from their forming pins (page 6, lines 61-81 & 91-119 and Figs. 34-37) . The stripper includes a pair of stripper fingers that "engage the pin back of the capsule part". A frame 435, carrying holders 436, is moved forward so that each holder is "aligned with and close to the end of a pin and the capsule part thereon" . Force applied by the stripper fingers to the dip-line edge of the dried gelatin part overcomes any adhesion of the part to the pin and conveys the part into its holder. This process can be viewed as including four sequential steps: engaging the pin back of the part, breaking the adhesion of the part to the pin by applying pushing force against the dip-line edge of the part, conveying the part to the holder by further pushing against the dip-line edge, and holding the part in the holder. Muto, in US Patent No. 4,993,137, discloses a system for removing cellulose capsule parts from their forming pins that is similar in important respects to the stripper system discussed above. Muto discloses a removal system (column 6, line 59 - column 7, line 25) that uses a pair of air- actuated nipping bars to "slidably hold the capsule pins 2 at a part of pin 2 to which dried capsule is not adhering" (i.e. to engage the pin back of the capsule part) . In the Muto system the capsule part, after it is dried and while it is still on the pin, is pushed into and thereafter retained within a hole 38a in a female die. The "hole 38a has such a diameter that a capsule pin 2 to which dried capsule still adheres fits closely to hole 38a." The nipping bars "have semi-circular cuts, the inner diameter of which fits the outside diameter of capsule pins". As in the Colton system, force required to overcome adhesion of the part to the pin is applied to the dip-line edge of the part. Unlike Colton, however, the parts are "kept fitted closely" within (i.e. passively held by) the female die while the capsule pins are withdrawn from the parts. This process can be viewed as including three sequential steps: enclosing the part while the part is on the pin; engaging the pin back of the part; and breaking the adhesion of the part to the pin by applying restraining force to the dip-line edge of the enclosed capsule part while withdrawing the pin. US Patent No. 4,627,808 to Hughes, issued December 9, 1986, is directed to making two-part, hard-shell capsules having more than one chamber. Hughes discloses cleft dipping pins and corresponding stripping rings for removing the capsule parts from the pins. The stripping rings are connected by slide rods. Hughes strips the capsule parts by causing the stripping rings to apply force to the dip-line edge of the capsule part. All of the above-described methods force the part off the pin by applying force to the dip-line edge of the capsule part. US Patent No. 4,247,006 to Bodemann discloses a mechanism in which parts 20 and 22 "radially engage the solidified layer" (i.e. the capsule part) on the pin, thereby holding the capsule part while the pin is withdrawn from the capsule part. International Application WO 92/21311, published on December 10, 1992, discloses a capsule part removal system for removing hard-shell cellulose capsules. One disclosed method includes gripping the outer circumferential surface of the part, and applying a frictional force via the outer circumferential surface. A gripper applies frictional force to the capsule part in a direction parallel to the axis of the pin so as to (i) break adhesion between the capsule part and its forming pin, and (ii) slide the part off the pin. The gripper grips the outer circumferential surface of the part tightly enough to provide sufficient frictional force to break adhesion. In the manufacture of pharmaceutical cellulose capsules, the cellulose capsule parts are found to adhere strongly to the forming pins. Cellulose capsule parts adhere more strongly to the forming pins than do gelatin capsule parts. Of the methods discussed above, only the method disclosed in international application WO 92/21311 is believed to be effective in removing cellulose capsule parts from forming pins without damaging a significant proportion of the capsule parts . The present invention is directed to improvements over methods disclosed in international application WO 92/21311. Summary of the Invention The present invention provides a method and apparatus for manufacturing pharmaceutical hard-shell capsules for filling by capsule filling machines. Each capsule consists of two parts, a capsule body and a capsule cap. The parts are made from an aqueous solution of a thermogelling cellulose ether composition, in a capsule machine using pins as molds. The thermogelling cellulose ether composition used is preferably that disclosed by Sarkar in US Patent No. 4,001,211. In the manufacture of pharmaceutical cellulose capsules, solution is gelatinized and dried on the surface of a pin to form a cellulose capsule part. In a first embodiment of the present invention, adhesion between the cellulose capsule part and the pin is broken by applying a grip of predefined force and a frictional force on a selected sacrificial portion of the outer circumferential surface of the capsule part, the frictional force aligned with the pin axis, the predefined force defined by a spring. After breaking adhesion, gripping is released and the part is pushed clear of the pin by applying force to an end of the capsule part via an outer edge of the gripper arms. In a second embodiment, after breaking adhesion in a break- adhesion section, the capsule part is pushed back onto the pin and the part is pushed clear of the pin in an automatics section. In a third embodiment, breaking adhesion by gripping and pushing the capsule part off the pin are both performed in a single movement. In a fourth embodiment, the part is pushed clear of the pin by applying force to an end of the capsule part via an outer edge of a stripper arm located on the inner side of the gripper arms. In a fifth embodiment, a refinement of the second embodiment, the capsule part is pushed back onto the pin after breaking adhesion, the gripper face includes spikes, and the grippers are opened by direct drive, eliminating the wedge. In a sixth embodiment, a refinement of the fifth embodiment, a capsule is gripped between a pair of captive spring-loaded gripper blocks protruding from two opposed gripper bars. Brief Description of the Drawings FIG. 1 is a partial schematic, partial cut-away view of a first embodiment of a capsule removal system according to the present invention. FIG. 2A is a schematic view of a capsule machine in which a capsule removal system according to the present invention may be used. FIG. 2B is a perspective view of an automatics section in which capsules are removed by a first embodiment of the present invention. FIG. 3 shows detail of region P in FIG. 2B: a row of gripper/strippers, and a corresponding row of wedges. FIG. 4 shows detail of region Q in FIG. 2B: pins mounted to a pinbar showing the dip-line edge. FIG. 5 is a perspective view of a gripper/stripper and its associated wedges. FIG. 6 shows the capsule part in cross-section, and shows the several positions of the gripper/stripper in relation to the pin, the dip-line edge, and the trim-line. FIGS. 7A-7E illustrate several steps in capsule removal according to the first embodiment of the present invention. FIG. 8 is a perspective view of a second embodiment. FIG. 9 is a partial schematic, partial cut-away view of a third embodiment. FIG. 10 is a perspective view of the gripper and the stripper of the third embodiment. FIG. 11 is a perspective view of the gripper/stripper of a fourth embodiment. FIGS. 12A and 12B show operational detail of the fourth embodiment. FIG. 13 shows a fifth embodiment having a pair of actuator-driven, direct-action gripper drive bars. FIG. 14 is a perspective view of the gripper drive bars of FIG. 13. FIG. 15 shows a gripper having a spring. FIG. 16 shows a pusher plate and a wide gripper. FIG. 17 shows a gripper face with spikes. FIG. 18 shows a gripper system of a sixth embodiment having upper and lower gripper bars with gripper blocks. FIG. 19 is a partial cut-away view of a gripper bar with spring-loaded gripper blocks. FIG. 20 is a perspective view of a gripper block. Detailed Description of the Invention l. General The present invention provides a capsule part removal system for use in the manufacture of hard-shell cellulose capsules made from a thermogelling cellulose ether composition, including the composition disclosed by Sarkar in US Patent No. 4,001,211. Modern US commercial capsule machines use a stripping system to remove gelatin capsule parts from their forming pins. This stripping system is acceptable for gelatin capsules. However, it is quite difficult to remove cellulose parts from their forming pins without damage. When the stripping system that is used to remove gelatin capsule parts is used to remove cellulose capsule parts made from the composition disclosed by Sarkar, the walls of the capsule parts tend to break, split or crumple. Hard-shell cellulose capsule parts made from the Sarkar cellulose tend to adhere more tightly to their forming pin than do hard¬ shell gelatin capsules. Furthermore, such hard-shell cellulose capsules are less rigid, less robust, and more vulnerable to out-of-round deformation than hard-shell gelatin capsules having the same dimensions. US application serial no. 08/377,669, filed January 24, 1995, of which the present inventor is a co-inventor, discloses a capsule part removal system for removing hard¬ shell cellulose capsules. One embodiment of the method of US S/N 08/377,669 includes gripping the outer circumferential surface of the part, and applying a frictional force via the outer circumferential surface. The frictional force is applied in a direction parallel to the axis of the pin so as to (i) break adhesion between the capsule part and its forming pin, and (ii) slide the part off the pin. The outer circumferential surface of the part is gripped tightly enough to provide sufficient frictional force to break adhesion. A disadvantage of this method is that after a portion of the capsule part clears the pin, that portion is no longer supported by the pin and the capsule part is vulnerable to out-of-round deformation by the gripping force. (A member of the patent family of US S/N 08/377,669, International Application WO 92/21311, was published on December 10, 1992.) The present application discloses a capsule part removal system for hard-shell cellulose capsules that is an improvement over that disclosed in US S/N 08/377,669. A preferred embodiment includes gripping the outer circumferential surface of the capsule part; applying a frictional force via the outer circumferential surface to break adhesion; releasing the gripping after breaking adhesion and before the gripped portion clears the pin; and separating the part and the pin by applying force to the dip-line edge of the part. In a preferred embodiment of the present invention, frictional force is used only to overcome the adhesion of the part to the pin. Release of gripping before separating the part from the pin reduces the risk of out-of-round deformation that might be caused by continued gripping. After gripping is released, force is applied to the dip-line edge of the part, to push the part off the pin. In a preferred embodiment, gripping is applied only to that portion of the capsule part between the dip-line edge and the trim line, and gripping is released as soon as adhesion is broken. While Colton, Muto and Hughes only engage the part on the dip-line edge, Bodemann radially engages the part. However, none apply a predefined forceful grip. First Embodiment FIG. 1 is a partial schematic, partial cut-away view of a first embodiment of a capsule removal system according to the present invention. FIG. 2A is a schematic view of a capsule machine in which a capsule removal system according to the present invention may be used. Pins are preferably preheated prior to dipping so that solution begins to gelatinize on the pins in the dipper. Drying takes place in the upper and lower drying kilns. Capsules are removed from pins in the automatics section. FIG. 2B is a perspective view of an automatics section in which capsules are removed by a first embodiment of the present invention. Plane X-Y in FIG. 2B defines the cross section portion of FIG. 1. FIG. 1 shows "T" slide 21 of a Colton-style capsule machine in cross-section. Line A-A is the center line of the capsule machine. Body parts are made on one side of the machine and cap parts are made on the other side of the machine. Body pins 22 are mounted to pinbar 27, and the pinbar rides in the "T" slide on one side of the machine. Cap pins 23 are mounted to a pinbar riding in the "T" slide on the other side of the machine. Each pinbar, with its pins carrying capsule parts, is alternately transported in the "T" slide from one section to the next and held stationary within each section in turn for machine operations. A row of gripper/strippers are mounted to stripper bar 25. The number of gripper/strippers on a stripper bar equals the number of pins on a pinbar, providing one gripper/stripper per pin. Wedges 32 mounted to wedge bar 34 are used to open the gripper/strippers. Wedge 32 includes wedge body 33 and wedge blade 31. In FIG. 1 wedge blade 31 is shown in the raised position holding gripper/stripper 24 open so that the gripper/stripper is not touching capsule part 28 or pin 22. Operation of the wedge is further illustrated in FIGS. 3 and 5. As shown in FIG. 1, first actuator 41, which is mounted to frame 46, drives the tip of the wedge bar, via actuator rod 43, between position WI, in which position the gripper/stripper is open, and position W2, in which the gripper/stripper is gripping. The extent of movement of the wedge blade is the distance TI. Second actuator 42, also mounted to frame 46, drives gripper/stripper 24, via actuator rod 44 and stripper bar 25, between the three positions Gl, G2, and G3. In position Gl the gripper/stripper is clear of the pins. With the gripper/stripper in this position, pinbars may move into and out of the automatics section. Position G2 is the initial position for gripping the circumferential surface of the capsule part to break adhesion between the capsule part and the pin. Position G2 is on the dip-line side of the intended trim line so the gripper never touches any portion of a finished capsule part. Position G3 is the initial position of the gripper/stripper before it pushes the capsule part off the pin. Position G3 is shown beyond the dip-line edge. The maximum extent of movement of the gripper/stripper is the distance T2. Sequencing controller 45 controls actuators 41 and 42, by signals 47 and 48 from outputs 49 and 50 respectively, so as to perform the correct sequence of steps. FIG. 2B is a perspective view of automatics section 51, the section in which capsules are removed from the pins. This view of a capsule machine according to the first embodiment has almost the same appearance as the same view of the standard Colton machine. In both the standard Colton machine and in a machine using the present invention, automatics section 51 includes an automatic head mechanism 52 which includes collets 53 for holding the capsule parts, and trimming knives 54 for trimming the length of the capsule parts. While the collets hold the parts, the knives cut the parts at the trim line. Then the collets move the body parts and the cap parts together to join them. Vacuum overhead scrap collector 55 is shown mounted above the automatics section along the center line of the machine. FIG. 3 shows detail of region P in FIG. 2B. Gripper/stripper 24 is shown in the open condition, held open by wedge blade 31 in the raised position. FIG. 4 shows detail of region Q in FIG. 2B, including a row of pins mounted to pinbar 27, a capsule part 28 on pin 22, and the position of dip-line edge 29. FIG. 5 is a perspective view of the gripper/stripper and its associated wedges. FIG. 6 shows the relative location of the three previously mentioned positions of the gripper/stripper with respect to pin 22, capsule part 28, dip-line edge 29, trim line 61, and pin dome 62. In the gripping position G2, gripper/stripper 24 grips a portion of the capsule part between trim line 61 and dip-line edge 29. The edge of the gripper/stripper closest to the trim line is well clear of the trim line. In stripping position G3, gripper/stripper 24 closes on the pin in back of dip-line edge 29, and the edge of the gripper/stripper closest to the dip-line edge is initially well clear of the dip-line edge. In a variant of this embodiment, the gripper/stripper could move the capsule part a distance in excess of the distance between the trim line and the dip-line edge before releasing gripping, in which case the gripper/stripper could return to position G2 for stripping, i.e. G2 and G3 become the same line. FIGS. 7A-7E illustrate the several steps in removing the capsule part of the pin in the general case, shown in FIG. 6, where G2 and G3 are separate. FIG. 7A shows the gripper/strippers in the clearance position Gl which allows a new pinbar to enter the automatics section. With pinbar 27 in position as shown and stationary, actuator 41 moves wedge blades 31 up so as to open the gripper/strippers as indicated by arrow 201. FIG. 7B shows actuator 42 (with gripper/strippers still open) moving the gripper/strippers toward the center line of the machine (arrow 202) until each gripper/stripper is positioned between the cut-line and the dip-line in position G2. Actuator 41 then moves the wedge blades down (arrow 203) to position W2, causing the gripper/strippers to grip the capsule part. In FIG. 7C, the gripper/stripper bar moves away from the center line of the machine (arrow 204) a short predefined distance sufficient to ensure that adhesion between the capsule and the pinbar has broken. Then, with the pinbar stationary, actuator 41 moves the wedge blocks up (arrow 205) opening the gripper/strippers and releasing the grip of the gripper/strippers on the capsule parts. FIG. 7D shows collet 71 of the automatic head mechanism in position to receive the capsule part. As shown by arrow 206, actuator 42 moves the gripper/stripper bar until the gripper/strippers are positioned at G3 over the pin in back of the dip-line. Then, as shown by arrow 207, actuator 41 moves the wedge blade down, closing the gripper/strippers on the pin in back of the dip-line. FIG. 7E shows the movement (arrow 208) of the gripper/strippers as actuator 42 moves them away from the center line of the machine causing them to push capsule part 68 into collet 71. Second Embodiment FIG. 8 shows a second embodiment which may permit faster operation of the capsule machine. In this embodiment breaking of adhesion (by gripping, applying force and releasing) is performed in region R of a pre-automatics section ahead of the automatic section. The capsule part is pushed off the pin into the collet in region S within the automatics section. The process of trimming the capsules to length using knives and joining the capsule body parts and the capsule cap parts proceeds in conventional manner as is known in the Colton-style capsule machine. Variants of this embodiment are described in greater detail in embodiments 5 and 6 below. Third Embodiment A third embodiment of the present invention supports breaking of adhesion and removal of the capsule part from the pin in a single stroke. This embodiment includes a gripper, a stripper with a slot, and a gripper release wedge. FIG. 9 is a partial schematic, partial cut-away view of the components of this embodiment, including gripper 82 and gripper release wedge 91. FIG. 10 is a perspective view of gripper/stripper 81 including gripper 82 and stripper 83, stripper 83 having a slot 85. In this third embodiment, breaking adhesion by gripping and pushing the capsule part off the pin into the collet are both performed in a single movement. Gripper release wedge 91 is mounted fixedly to frame 46. After the gripper, gripping the capsule part, has moved the capsule part a predetermined distance, sufficient distance to break adhesion, the drive end 84 of the gripper arm encounters blade 92 of gripper release wedge 91. On further motion of the gripper away from the center line of the machine, wedge blade 91 opens the gripper to release the gripping. Slot 85 provides clearance so that wedge 91 will not open the stripper. The process of trimming the capsules to length using knives and joining the capsule body parts and the capsule cap parts proceeds in conventional manner as is known in the Colton-style capsule machine. Fourth Embodiment A fourth embodiment is shown in FIGS. 11, 12A and 12B. In this embodiment the gripper and stripper of FIG. 10 are replaced by gripper/stripper 101, which includes gripper 102 and stripper arm 103. Stripper arm 103 is springedly attached to gripper 102 by spring plate 104 and screws 105 and includes stripper hand 108. Groove 107 in stripper hand 108 is positioned so that it aligns with groove 106 in gripper 102 when spring 104 is extended as shown in FIG 12A. This fourth embodiment uses a gripper release wedge mechanism similar to that described for the third embodiment. After the gripper, gripping the capsule part, has moved the capsule part a predetermined distance, sufficient distance to break adhesion, the drive end of the gripper arm encounters the wedge blade of the gripper release wedge. On further motion of the gripper away from the center line of the machine, the gripper release wedge blade opens the gripper to release the gripping. In this embodiment, spring tension allows groove 107 of stripper arm 103 to remain in contact with pin 22 for successful stripping as shown in FIG. 12B. The operative direction of movement for breaking adhesion and for pushing the capsule part off the pin is shown in FIG. 11 by arrow 109. In a variant of the above embodiments, after adhesion is broken, the capsule part could be moved off the pin by applying air pressure to the open (dip-line edge) end of the capsule part, or by applying vacuum to the dome end. Comments on Other Problems Other problems encountered when using the several capsule removal methods discussed above include: a) In using smooth-face grippers to break adhesion between a cellulose capsule part and a pin, a high gripping force is needed to support the necessary high frictional force. In capsule removal systems that use wedges to open stripper-like grippers, the heavy duty springs put extra strain on the wedge blocks and the wedge block driving linkages. The resulting wear of the wedge blocks and in the wedge block driving linkages causes unreliable operation. b) Gripper springs are subjected to a constant, rapid duty cycle. As the springs deteriorate and over time the spring rate drops. This significantly reduces the gripping force available. It is difficult to determine when this will happen. The effect appears to differ from spring to spring. c) The gripping face of the gripper grips on a relatively small portion of the surface area of the capsule part. d) The gripping face provides only modest texture for gripping, and once the edge wears flat or smooth, the cheek edge may slip along and over the surface of the capsule wall without breaking adhesion of the capsule. e) Lubricants that are natural and vegetarian, and that will withstand the high heat used in the process, do not generally provide a good barrier against adhesion. In the traditional Colton machine stripper, the stripper spring is required to absorb positional errors between the stripper faces and the pin. Likewise, the break- adhesion mechanism in the present invention is required to absorb positional errors between the stripper faces and the capsule part on the pin. However, unlike the prior art stripper, the break-adhesion mechanism is also required to provide a large and repeatably constant gripping force on the capsule wall when the gripper grips the outer circumferential surface of the capsule part. The fifth and sixth embodiments address these problems as described below. The fifth and sixth embodiments both use the two-stage approach of the second embodiment which is discussed above and illustrated in FIG. 8. The two-stage process involves breaking adhesion between the capsule part and the pin in a break-adhesion section, and then removing the capsule part from the pin in an automatics section. The two-stage process permits more reliable operation at higher throughput rates. Fifth Embodiment The fifth embodiment, as illustrated in FIGS. 13-17, uses direct drive to open the grippers. This eliminates the wedge mechanism and the associated wear problem. FIG. 13 shows a row of grippers 112 mounted to a gripper bar 113. FIG. 13 shows grippers 112 in the open condition. FIG. 15 shows grippers 112 in the closed condition. FIG. 14 shows two gripper drive bars 115 and 116. These are shown mounted below the grippers in FIG. 13. The two drive bars are slidably mounted with respect to each other, for limited movement parallel to the gripper bar. Each gripper drive bar has a series of teeth 117, one tooth per gripper on the gripper bar, and each tooth has a drive face 118. When the drive bars move in the direction shown in the arrows in FIG. 14, faces 118 push on the drive end 123 of each gripper arm so that the gripper arms rotate about pivot 114 and operating ends 122 move apart. Each arm rotates about 3 degrees. The width of drive bars 115 and 116 are approximately one half of the width of gripper arms 124. To open the grippers, the drive bars are actuator- driven in the direction of the arrows in FIG. 14. Actuator 120, when energized, moves drive bar 115. When actuator 120 and its counterpart for drive bar 116 are de-energized, the drive bars return to their previous position by action of gripper spring 127. Gripper spring 127, shown in FIG. 15, provides a grip of predefined force. In an alternative embodiment, actuator 120 and its counterpart may be positively driven in the direction shown in the arrows in FIG. 14 to open the grippers, and in the opposite direction to close the grippers. This alternative may reduce the stress on gripper spring 127. Movement of drive bars 115 and 116 is limited by stops (not shown) . After a grip is applied to a capsule part on a pin, frictional force is applied in a direction aligned with the axis of the pin and in a direction so as to move the capsule towards the dome end of the pin. This frictional force breaks adhesion. In breaking adhesion, the movement of the capsule part may be small, approximately 1/8 inch (3mm), but it is desirable to push the capsule part back onto the pin for transport to the automatics. FIG. 16 shows pusher plate 131 having a shaped groove 132 parallel to the domes of pins 22 on bar 27. Alternatively, instead of groove 132, individual indentations may be provided, the indentations shaped to match the shape of the dome end of a capsule part. Pusher plate 131 is fixedly mounted parallel to gripper bar 113 by standoffs 133, and is driven towards and away from the pins in concert with the gripper bar by actuator rod 134. It can be seen from FIG. 16 that if gripper 112 were open and capsule part 28 were partially moved off the pin, then movement of pusher plate 131 toward the pin would push capsule part 28 back onto the pin, gripper 112 temporarily occupying a position just short of T-slide 21. To provide a better grip on the capsule, spikes 138 are provided on face 137 of gripper 112 as illustrated in FIG. 17. Additionally, a wide gripper is provided having width "W" , as shown in FIG. 16. In a preferred embodiment a longer pin is used with a deeper dip to permit a longer distance "D" between dip-line edge 29 and trim line 61. This provides a bigger gripping area. It ensures that the wide gripper with its spikes only grips a sacrificial portion of the capsule part, that portion of the capsule part that is to be trimmed off in the capsule manufacturing process. The sacrificial portion is the portion of the capsule part between the dip line and the trim line. This use of a sacrificial portion of the capsule part for gripping allows the use of spikes and a high predefined gripping force to provide a reliable grip. The use of a forceful grip and spikes to grip on the wall of the capsule part between the trim line and the dome end would almost certainly cause unacceptable damage to the capsule. Sixth Embodiment A sixth embodiment is shown in FIGS. 18-20. When breaking adhesion between the capsule part and the pin by applying a grip and a frictional force on a selected portion of the outer circumferential surface of the capsule part, the frictional force must be sufficient to break adhesion, and the gripping force must be large enough to support the necessary frictional force. The gripping force should also be substantially equal pin-to-pin. When using a gripper design based on a conventional stripper, as in FIG. 15, spring 27 is least compressed when it is gripping. So when gripping, the gripper spring is operating in its region of least spring rate, and may be operating close to the edge of, or even outside of the linear range. In the sixth embodiment the problem of achieving a sufficient, constant and reliable gripping force is addressed by providing spring-loaded captive gripper blocks, the captive gripper blocks mounted in a pair of facing gripper bars. This structure eliminates the stripper-like grippers. It allows the use of larger, heavy-duty springs. It also allows the springs to operate in an optimum mode of maximum compression while gripping. Also, any force variation due to differences between one spring and the next can be minimized by the built-in spring force adjustment. A consistent gripping force in the range 10-40 pounds (4.5-18 kilograms) is needed and can be conveniently provided by this structure. FIG. 18 shows gripper system 140 of the sixth embodiment. The system includes upper gripper bar 141 and lower gripper bar 142 above and below, respectively, a row of pins 22. Each gripper bar includes a row of spring-loaded captive gripper blocks 150. Each gripper bar includes one captive gripper block for each pin of the pinbar. For a pinbar having 30 pins, each gripper bar would have 30 gripper blocks. The upper and lower gripper bars are driven by gripper actuators 144 towards the pins to grip on the capsule parts. Gripper bars are stopped in their travel toward the bars by stops 146 so that a grip of predefined force on a top and bottom portion of the circumferential surface of each capsule part is defined by the spring of each spring-loaded gripper block 150. Alternatively, force on each capsule part could be defined by actuators 144 directly. Return movement of the gripper bars to release a grip is accomplished by driving actuators 144 in reverse. Return movement is limited by another stop (not shown) . Arrows in FIG. 18 show direction of movement of the gripper bars. FIGS. 19 and 20 give detail of a gripper bar. Gripper block 150 is located in a hole in the gripper bar. The hole has a partially threaded large diameter region 147 and a smaller diameter region 148, together defining a shoulder 149 which acts as a stop. FIG. 20 shows gripper block 150 having a gripper face 151 with spikes 152. Lip 155 provides a surface to limit travel making the capsule block a captive element within the gripper bar. Key 157, attached to the block within slot 158 with two screws, keeps gripper face 151 aligned with pin 22 by engaging with a corresponding slot 145 in gripper bar 141. In FIG. 19 gripper block 150 is shown with lip 155 against shoulder 149. Gripper block 150 is held in place by spring 159. Spring 159 is held by adjustment screw 161 and lock nut 162. Adjustment screws 161 may be used to set the compression in each of springs 159 to equalize the predefined grip force of all the gripper blocks.

Claims: What is claimed is: 1. A method for the manufacture of pharmaceutical cellulose capsules for filling by capsule filling machines, each capsule consisting of two capsule parts, a capsule body and a capsule cap, from an aqueous solution of a thermogelling cellulose ether composition, using capsule body pins and capsule cap pins as molds, each pin having a pin axis and a dome, comprising the steps of: gelatinizing solution on the surface of a pin to produce gelatinized solution; drying the gelatinized solution to form a capsule part on the pin, the capsule part having an outer circumferential surface; applying a grip of predefined force and a frictional force on a selected portion of the outer circumferential surface of the capsule part, the frictional force aligned with the pin axis and sufficient to break adhesion between the capsule part and the pin; releasing the grip; and applying force to an end of the capsule part so as to move the capsule part off the pin. 2. A method according to claim 1, further comprising the step of driving opposing gripping surfaces towards each other. 3. A method according to claim 1, wherein the selected portion is a sacrificial portion. 4. A method according to claim 1, wherein the predefined force is a spring-defined force. 5. A method according to claim 1, further including the steps of: heating a pin; and dipping the pin into the solution to cause solution to gelatinize on the surface of the pin. 6. A method according to claim 1, further comprising the steps of: pushing the capsule part back onto the pin after releasing the grip; and moving the pin to a next position before applying force to an end of the capsule part. 7. An apparatus for the manufacture of pharmaceutical cellulose capsules for filling by capsule filling machines, each capsule consisting of two capsule parts, a capsule body and a capsule cap, the apparatus comprising: a transport system; pins mounted for transport on the transport system, each pin having a pin axis; a dipping section having means for gelatinizing an aqueous solution of a thermogelling cellulose ether composition to produce gelatinized solution on a pin; a drying section having means for drying the gelatinized solution to form a capsule part on the pin; and an automatics section; wherein the transport system includes means for transporting the pin through the sections in a closed path; and wherein the automatics section includes: a frame; a gripper/stripper, mounted to the frame for linear translation towards and away from the pin in a direction aligned with the pin axis, the gripper/stripper including a first arm and a second arm, the arms rotatably attached to each other for rotation about an axis parallel to the pin axis, each arm having a drive end and an operating end, the operating end having a shaped gripping surface, and a substantially flat pushing surface transverse to the gripping surface; and controller means, coupled to the gripper/stripper and to the drive ends, for sequencing translation of the gripper/stripper and rotation of the arms such that the gripper/stripper (1) grips a capsule part and applies frictional force via the gripping surface, (2) releases the grip, and (3) applies force to an end of the capsule part via the pushing surface. 8. An apparatus for the manufacture of pharmaceutical cellulose capsules for filling by capsule filling machines, each capsule consisting of two capsule parts, a capsule body and a capsule cap, each capsule part having a dome end and a dip-line edge, the apparatus comprising: a transport system; pins mounted for transport on the transport system, each pin having a pin axis and a dome region; a dipping section having means for gelatinizing an aqueous solution of a thermogelling cellulose ether composition to produce gelatinized solution on a pin; a drying section having means for drying the gelatinized solution to form a capsule part on the pin; a break-adhesion section including gripper means for gripping the capsule part on the pin and for applying sufficient frictional force so as to break adhesion between the capsule part and the pin, and break-adhesion sequencing controller means for sequencing the gripper means; and an automatics section having means for applying force to che dip-line edge of the capsule part so as to move the capsule part off the pin; wherein the transport system includes means for transporting the pins through the sections in a closed path. 9. An apparatus according to claim 8, wherein the break-adhesion section further includes a pusher plate, mounted to the gripper means for movement in concert with the gripper means, adapted to push the dome end of the capsule part toward the pin, and wherein the break-adhesion sequencing controller means includes means for sequencing the pusher plate to push the dome end of the capsule part after adhesion is broken. 10. An apparatus according to claim 8, wherein the gripper means includes: a pair of gripper arms adapted to establish a grip on the capsule part on the pin, and a gripper release bar having a long axis, the gripper release bar mounted to the gripper means for linear motion along the long axis and transverse to the gripper arms, and coupled to the gripper arms so that motion of the gripper release bar along the long axis in a first direction releases the grip. 11. An apparatus according to claim 8, wherein the means for gripping includes a first gripper bar and a second gripper bar, each gripper bar having a face with plurality of spring-loaded gripper blocks, the first gripper bar and the second gripper bar mounted face to face for movement toward and away from each other, such that a gripper block of the first gripper bar faces a corresponding gripper block of the second gripper bar. 12. An apparatus according to claim 10, wherein the gripper block includes a spring mounted to provide adjustable gripping force. 13. An apparatus according to claim 8, wherein the means for gripping includes opposed gripper faces having sharp spikes. 14. An apparatus for the manufacture of pharmaceutical cellulose capsules for filling by capsule filling machines, each capsule consisting of two capsule parts, a capsule body and a capsule cap, the apparatus comprising: a transport system; pins mounted for transport on the transport system, each pin having a pin axis; a dipping section having means for gelatinizing an aqueous solution of a thermogelling cellulose ether composition to produce gelatinized solution on a pin; a drying section having means for drying the gelatinized solution to form a capsule part on the pin; and an automatics section; wherein the transport system includes means for transporting the pin through the sections in a closed path; and wherein the automatics section includes: a frame; a gripper/stripper, mounted to the frame for linear translation towards and away from a pin in a direction aligned with the pin axis, the gripper/stripper including a gripper and a stripper; and means, mounted to the frame and coupled to the gripper/stripper, for causing the gripper/stripper to apply a grip on a capsule part on a pin and for releasing the grip after the gripper/stripper has translated a predetermined distance while the grip is applied. 15. An apparatus for the manufacture of pharmaceutical cellulose capsules for filling by capsule filling machines, each capsule consisting of two capsule parts, a capsule body and a capsule cap, the apparatus comprising: a transport system; pins mounted for transport on the transport system; a dipping section having means for gelatinizing an aqueous solution of a thermogelling cellulose ether composition to produce gelatinized solution on a pin; a drying section having means for drying the gelatinized solution to form a capsule part on the pin; and an automatics section; wherein the transport system includes means for transporting the pin through the sections in a closed path; and wherein the automatics section includes: a frame; and a gripper/stripper including a pair of gripper arms, each gripper arm having a gripper groove, and a stripper arm having a hand portion with a stripper groove, the stripper arm springedly mounted to the gripper arm so as to define a spring-extended gripper mode with the gripper groove aligned with the stripper groove, and a spring-relaxed stripper mode with the gripper groove retracted.

Inventors: GROSSWALD RALPH R, THORNOCK SCOTT D, GROSSWALD, RALPH, R., THORNOCK, SCOTT, D.
Applicants: GS TECHNOLOGIES INC, GS TECHNOLOGIES, INC.
Application year: 1996
Main classification: B29C33
IPC codes: A61J3, B29C33, B29C41