Linear cut to length system for inline production of processed tubing

A system for cutting medical tubing sourced from a spool of tubing uses two actuator groups that each reciprocate along a respective track, which are parallel to each other. Each actuator group has a clamp and a cutting tool which have an operative position along a common axis. The tubing is fed along the common axis to be operated on by the actuator groups. A forward actuator group clamps onto the tubing and is then moved along its track, pulling the tubing. A rearward actuator group then clamps onto the tubing and cuts the tubing. While still clamped onto the tubing, the rearward actuator group is moved forward, pulling more tubing, and the actuator group that was forward is moved to the rearward position and the process is repeated iteratively to produce tubing sections cut to the desired length. The tubing is pressurized and kept under pressure to straighten the tubing.

CROSS REFERENCE

This application is a non-provisional conversion of U.S. Provisional Application No. 63/034,217, filed Jun. 3, 2020, the entirety of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The present invention relates generally to cutting shrink tubing that is produced on expansion equipment, and, more particularly, relates to cutting such tubing to a desired precision length for catheter applications while avoiding the problem of curvature created by storing tubing on a spool.

BACKGROUND

Fluorinated ethylene propylene (FEP) shrink tubing is a key material consumed in the production of guided or reinforced catheters. The production of FEP tubing to its ready to use state, on a spool, involves heating and pressurization of FEP tubing in a continuous process. The tubing is provided on a first spool, and to provide it in a state for use in catheters, it is internally pressurized with nitrogen and moved through an expander where it is expanded radially and cooled rapidly. The tubing that emerges from the expander is then collected on a second spool until the tubing on the first/supply spool is all processed.

The problem with spooling up the output tubing is that the tubing relaxes on the spool and adopts the curvature of the spool. The curved tubing needs to be straightened before it can be used in the production of catheters. Standard cut to length equipment currently available uses pinch rollers or rolling belts to squeeze and maintain pressure in the expanded tubing while conveying the tubing before cutting. As a result, this flattening of the tubing by the pinch rollers produces two seam edges along the tubing that adversely affects its performance as shrink tubing in the catheter production process.

SUMMARY

In accordance with some embodiments of the inventive disclosure, there is provided a linear cut to length tubing cutting system that includes a first track and a second track, wherein the first track and the second track are parallel to each other. The system also includes a first actuator group disposed on the first track, a second actuator group disposed on the second track, wherein the first and second actuator groups are movable, forward and rearward, on their respective tracks. Each actuator group having, from front to rear, a holding clamp, a cutting tool, and a sealing clamp; and wherein the first and second actuator groups are alternately moved forward and rearward on their respective tracks while engaging a pressurized tubing to iteratively cut the pressurized tubing to a desired length.

In accordance with a further feature, the holding clamp, cutting tool, and sealing clamp of each of the first and second actuator groups are moveable between an operative position and a raised position, and wherein when the first and second actuator groups are moved rearward the holding clamp, cutting tool, and sealing clamp are moved from the operative position to the raised position.

In accordance with a further feature, each of the first and second actuator groups has a non-operative end, and wherein the non-operative ends of the first and second actuator groups are angled away from each other and the operative position of the first and second actuator groups are maintained in common.

In accordance with a further feature, the holding clamp, cutting tool, and sealing clamp of each of the first and second actuator groups are mounted together on a frame that is movable by a position actuator.

In accordance with a further feature, the position actuator of each of the first and second actuator groups are mounted on a respective vertical plate that is further mounted on a carriage on the respective first and second tracks.

In accordance with a further feature, the system further includes a control unit that is operably connected to each of the first and second actuator groups, which causes the first and second actuator groups to move on the first and second tracks, respectively, to control a distance between the first and second actuator groups to a desired cut tube length.

In accordance with a further feature, the first and second tracks are mounted on a common frame.

In accordance with some embodiments of the inventive disclosure, there is provided a method for producing tubing sections for medical use. The method includes providing a first actuator group and a second actuator group that are each moveable along a linear direction parallel to each other, between a home position and a forward position. Each of the first and second actuator groups having a cutting tool and a sealing clamp, wherein the sealing clamp is rearward of the cutting tool. The method also includes feeding tubing between the first and second actuator groups, and iteratively and reciprocally moving the first and second actuator groups such that one actuator group of the first and second actuator groups is moved forward to the forward position while the sealing clamp of the one actuator group is clamped onto the tubing, thereby pulling the tubing, and at the other of the first and second actuator groups which is in the home position, clamping the sealing clamp onto the tubing and cutting the tubing with the cutting tool, and then moving the one actuator group at the forward position back to the home position while the one actuator group at the home position is then moved forward.

In accordance with a further feature, the method further includes providing the tubing on a spool.

In accordance with a further feature, the method further includes pressurizing the tubing, and wherein reciprocally moving the first and second actuator groups maintains pressure in the tubing.

In accordance with a further feature, reciprocally moving the first and second actuator groups further comprises raising the cutting tool and the sealing clamp of the one actuator group at the forward position as it is moved rearward.

In accordance with a further feature, providing the first actuator group and the second actuator group comprises positioning the first and second actuator groups such that they have a common operative position with respect to the tubing, and wherein a non-operative end of each of the first and second actuator groups are angled away from each other.

In accordance with a further feature, providing the first actuator group and the second actuator group comprises providing the first actuator group and the second actuator group each further having a holding clamp that is located in front of the cutting tool, and when in the home position, clamping the holding clamp onto the tubing with the sealing clamp to hold the tubing while the cutting tool cuts the tubing.

In accordance with a further feature, feeding the tubing between the first and second actuator groups comprises passing the tubing through a feed guide.

In accordance with some embodiments of the inventive disclosure, there is provided a method for producing tubing sections for medical use. The method includes providing a cutting apparatus having a pair of actuator groups. Each of the actuator groups being moveable in a parallel linear direction, and each of the pair of actuator groups having a holding clamp, a cutting tool, and a sealing clamp, in order from front to back. The method further includes providing a roll of tubing, wherein the tubing is created by expansion, and the roll of tubing having a free end and a tail end. The method also includes connecting the tail end of the tubing to a pressurized gas source, and feeding the free end of the tubing into the cutting apparatus. The method includes, at a forward one of the pair of actuator groups, clamping at least one of the holding clamp or the sealing clamp onto the free end of the tubing, and pressurizing the tubing by the pressurized gas source. While clamping at the forward one of the pair of actuator groups, with the tubing being pressurized, the method includes moving the forward one of the pair of actuator groups along a linear track to a desired distance, thereby pulling the tubing. Upon the forward one of the pair of actuator groups reaching the desired distance, at the rearward one of the pair of actuator groups, the method includes clamping both the holding clamp and the sealing clamp of the rearward one of the pair of actuator groups onto the tubing. The method further includes, while both the holding clamp and sealing clamp of the rearward one of the pair of actuator groups are clamped onto the tubing, cutting the tubing with the cutting tool of the rearward one of the pair of actuator groups, and after cutting the tubing by the rearward one of the pair of actuator groups, while maintaining the sealing clamp of the rearward one of the pair of actuator groups clamped on the tubing, releasing the holding clamp of the rearward one of the pair of actuator groups and the sealing clamp of the forward one of the pair of actuator groups to release a cut length section of tubing. The method further includes, after releasing the holding clamp of the rearward one of the pair of actuator groups, and while maintaining the sealing clamp of the rearward one of the pair of actuator groups clamped on the tubing, moving the forward one of the pair of actuator groups rearward and moving the rearward one of the pair of actuator groups forward whereby the rearward one of the pair of actuator groups becomes the forward one of the pair of actuator groups, and the one of the pair of actuator groups that was forward become a rearward actuator group.

“In the description of the embodiments of the present invention, unless otherwise specified, azimuth or positional relationships indicated by terms such as “up”, “down”, “left”, “right”, “inside”, “outside”, “front”, “back”, “head”, “tail” and so on, are azimuth or positional relationships based on the drawings, which are only to facilitate description of the embodiments of the present invention and simplify the description, but not to indicate or imply that the devices or components must have a specific azimuth, or be constructed or operated in the specific azimuth, which thus cannot be understood as a limitation to the embodiments of the present invention. Furthermore, terms such as “first”, “second”, “third” and so on are only used for descriptive purposes, and cannot be construed as indicating or implying relative importance.

In the description of the embodiments of the present invention, it should be noted that, unless otherwise clearly defined and limited, terms such as “installed”, “coupled”, “connected” should be broadly interpreted, for example, it may be fixedly connected, or may be detachably connected, or integrally connected; it may be mechanically connected, or may be electrically connected; it may be directly connected, or may be indirectly connected via an intermediate medium. As used herein, the terms “about” or “approximately” apply to all numeric values, whether or not explicitly indicated. These terms generally refer to a range of numbers that one of skill in the art would consider equivalent to the recited values (i.e., having the same function or result). In many instances these terms may include numbers that are rounded to the nearest significant figure. To the extent that the inventive disclosure relies on or uses software or computer implemented embodiments, the terms “program,” “software application,” and the like as used herein, are defined as a sequence of instructions designed for execution on a computer system. A “program,” “computer program,” or “software application” may include a subroutine, a function, a procedure, an object method, an object implementation, an executable application, an applet, a servlet, a source code, an object code, a shared library/dynamic load library and/or other sequence of instructions designed for execution on a computer system. Those skilled in the art can understand the specific meanings of the above-mentioned terms in the embodiments of the present invention according to the specific circumstances.

DETAILED DESCRIPTION

FIG.1is a perspective view of a linear cut-to-length system100for cutting tubing to a desired length, in accordance with some embodiments. More specifically, the disclosed system is used to cut tubing that has been stored on a spool, and therefore portions of tubing cut from the spooled tubing would otherwise be disposed to being curved. The system100includes a support structure102or support frame that supports a pair of parallel tracks104,106, which can be horizontally oriented as shown, but in some embodiments can be oriented at an angle to horizontal, including vertically. On each one of the tracks104,106is a respective actuator group108,110. Each of the actuator groups108,110can be moved in a linear direction along its respective track104,106. Each actuator group108,110includes a plurality of actuators that control respective tools that engage and operate on the tubing. In particular, each actuator group108,110can include a controllable holding clamp, cutting tool, a sealing clamp, and a position actuator such as an extending slide, in that order, from front to back. The controllable holding clamp, cutting tool, sealing clamp, and position actuator are all electrically actuated and controllable by separate actuators, as is each actuator group's position on its respective track. The front of each actuator group108,110is the portion of the actuator group108,110closest to the front116of the system100. A feed guide112is provided to guide tubing under pressure into the system100to be clamped and cut by the actuator groups108,110. A control unit114receives user input regarding a length to which to cut tubing, as well as the number of pieces to cut, and controls the operation and movement of the actuator groups108,110.

In general, the actuator groups108,110alternately travel down, and back, on their respective tracks104,106for each length of tubing being cut. That is, for example, actuator group108will clamp and hold the tubing using its sealing clamp, travel down track104while actuator group110remain in the home position substantially as shown. Then actuator group110clamps with both its holding clamp and sealing clamp, and cuts the tubing with its cutting tool, and, while maintaining the sealing clamp closed (clamped onto the tubing), actuator group110moves forward on track106while actuator group108moves rearward to the home position, and then clamps and cuts the tubing the same way actuator group110did in the home position. When an actuator group108,110returns to its home position, as the other travels down its track from its home position, the tools of the returning actuator group are lifted by its position actuator so that the actuator group traveling down its track while holding the tubing passes under the returning actuator group. The tubing is fed into the system100through a guide112and is inflated under pressure, such as by nitrogen gas or some other gaseous fluid, being pumped into the tubing. As one actuator group moves forward, the tubing remains under pressure, and expanded, without any edge seams being formed by pinch rollers, as is used in the prior art.

FIG.2is a perspective view detail of a pair of actuator groups108,110including the clamp/cutting tools that are each individually controllable, in accordance with some embodiments. As shown here, in each actuator group there is a sealing clamp200with a cutting tool202in front the sealing clamp200. A holding clamp, which is not shown here (seeFIG.5), would be located in front of the cutting tool202. The holding clamp is used to hold tubing when the actuator group is in the home position, when the cutting tool202cuts the tubing. The cutting tool202cuts the tubing while the tubing is secured between the holding clamp and the sealing clamp200. The holding clamp includes two jaw members, at least one of which is movable, so that the tubing can be held fixedly between the jaw members. The holding clamp therefore applies pressure to the tubing sufficiently to move the tubing, but not with so much pressure that it distorts the shape of the tubing. The cutting tool202likewise includes two jaw members, at least one of which is edged for cutting the tubing. The sealing clamp200includes two jaw members for holding the tubing, but further to seal the tubing to prevent depressurization of the tubing. The clamps and cutting tool of each actuator group are moved in unison on the actuator group as indicated by arrows208,210, as well as along the tracks104,106during operation of the system. In general, the clamps and cutting tool are raised by a position actuator when either of the actuator groups108,110are traveling back, and then lowered to engage the tubing being processed.

FIGS.3&4show rear and front side perspective views of one track104and actuator group108, with a sealing clamp200and cutting tool204(again, lacking the holding clamp in these views). Further, in these views, a portion of tubing300is shown being engaged by the actuator group108. The tubing300can be FEP tubing, or any other polymeric tubing that is created by expansion equipment under pressure that is cut to desired lengths. That can include, for example, polypropylene, PVC, PTFE, polyolefin, nylon, and other similar forms of tubing materials. The sealing clamp200is shown clamping the tubing behind the cutting tool202. The forward end of the tubing, which is out of view in these drawings, is clamped at the forward end of the tubing by the other actuator group (e.g.110). Accordingly, the section of tubing between actuator group108and actuator group110, although clamped by sealing clamp200here at the rearward side of the system100, is still under pressure. As will be shown, the holding clamp prevents sudden depressurization of the section of tubing being cut-off. The tools200,202can be pneumatically or electrically actuated and are mounted on a plate402that is attached to a carriage400that moves along the track104. As used here, the term “actuated” refers to the closing or opening of the end effectors that engage the tubing of the various tools. It can also refer to the moving of the tools for clearance when moving the actuator groups108,110rearwards.

The tubing300can be provided on a spool301, and a free end of the tubing300can be connected to a pressure source302, such as a nitrogen gas source, that pressurizes the tubing to a specified pressure, such as through an adjustable pressure regulator304. The working end of the tubing300is then fed through the apparatus to be cut, under pressure, into sections of a desired length. The cut sections of tubing, having been pressurized, have much less curve to them than if they had been cut without being under pressure as the pressure is sufficient to change the intermolecular tension in the polymeric material resulting from having been stored on a spool301. It is further contemplated that the tubing can be provided directly from an expansion machine that expands the tubing, rather than from a spool. In either case, the tubing will have a free end that is either coming off the spool or out of the expanding machine, and a tail end at the other end of the tubing.

FIG.5is a detail view of an actuator group including both the sealing and holding clamps arranged on opposite sides of the cutting tool of the actuator group, in accordance with some embodiments. In this view of the actuator group108, the holding clamp204can be seen forward of the cutting tool202and sealing clamp200. The sealing clamp200is configured to clamp the tubing300with enough force that the tubing behind the sealing clamp200(e.g. coming from the source of the tubing) remains sufficiently pressurized. The holding clamp204provides some sealing effect, but mostly holds the tubing to ensure a precise cut by the cutting tool202, and releases pressure in the cut-off section of tubing. Both actuator groups108and110have a sealing clamp, cutting tool, and holding clamp as shown here.

These tools of the actuator group108are mounted on a frame508that is connected to a series of parallel shafts506that are moveable along their axis by position actuator504. Wiring to control operation of each tool200,202,204and the position actuator504is carried by the actuator group108. The position actuator504is electrically or pneumatically operable to move the shafts up or down, thereby raising or lowering the tools200,202,204. The position actuator504is mounted fixedly on a vertical plate402that is mounted on a carriage500. The carriage500moves linearly, along the track104. In general, when the carriage400is in the position shown, abutting back stop502for example, the tools200,202,204are in the lowered position. The tools200,202,204remain in the lowered position as well as while the carriage400is moved forward (away from back stop502) along the track104. Prior to returning to the position shown from a forward position, the position actuator504is actuated to raise the tools200,202,204by drawing shafts506upward. Then the tools200,202,204are again lowered once the carriage400is in the home position.

FIGS.6A and6Bshow an overhead view of system100in which alternating positions of the pair of actuator groups of a linear cut to length system for cutting tubing are shown, in accordance with some embodiments. InFIG.6A, actuator group110has been lowered and clamped onto the tubing300and moved to a forward position such that the forward end of the tubing is at a distance from the location of the cutting tool of actuator group108which is the desired length of the tubing. Actuator group108in the home position is lowered until actuator group110approaches the desired length. As shown, the sealing clamp200of both actuator groups are closed, and the holding clamp204of actuator group110is released (i.e. open). Accordingly, the holding clamp204of actuator group108is closed to secure the tubing300, the cutting tool202of actuator group108is operated to cut the tubing300, and the holding clamp204of actuator group108is released to let out the pressurized gas in the cut-off section of tubing (500) in a controlled manner as to prevent the tubing300from rocketing as the gas pressure is released slowly. That is, the holding clamp204is slowly released to allow the pressurized gas inside the tube to escape slowly. In some embodiments, the holding clamp204is released from its fully closed state to its fully open state over 1-2 seconds of time. The sealing clamp200of actuator group110is then released to free the cut-off section600of tubing300. Then with the sealing clamp200of actuator group108still engaged, actuator group108is moved forward, and actuator group110is raised and moved rearward, as indicated inFIG.6B. During movement of actuator group110to the rear, the clamps and cutting tool can be raised so as not to interfere (contact) with the clamps and cutting tool of actuator group108and they pass by each other. A cut-off section600of tubing is produced by the operation ofFIG.6A, and inFIG.6Bthe process is repeated with the roles of the actuator groups reversed. InFIG.6Bactuator group110does the cutting and sealing after actuator group108is moved to the correct point along track104. The process is then alternated among the actuator groups108,110to produce each successive section of cut-off tubing. The position of the forward actuator group is determined by the desired length of the cut-off section500of tubing, as input by a user (e.g. using controller114).

FIG.7is a flow chart diagram of a process for cutting tubing to length, in accordance with some embodiments. In step701a source of tubing of the type described hereinabove is obtained. The tubing source has a free end that is fed into the apparatus and into position with the more forward actuator group. The other end of the tubing, the tail end, is connected to a pressure source, such as nitrogen gas, and the nitrogen gas is then released into the tubing to pressurize it above atmospheric pressure, and to a pressure level that is sufficient to stretch the tubing, radially, in order to prevent creasing or other deformation of the tubing during the process of cutting sections to a desired length. Of course, the pressure needs to be applied at a level lower than that which could damage the tubing and render it unusable. The source of the tubing can be a spool of tubing, or the tubing can be provided directly from the expansion machine creating the tubing.

In step702a forward actuator group (e.g.108or110, whichever is forward) engages its sealing clamp (e.g.200) on the pressurized tubing. In actuality, when a clamp is first applied to the free end of the tubing is when the tubing become pressurized as the gas being used to pressurize the tubing will simply be expelled from the free end until the free end is clamped. In step704the forward actuator group is moved on its respective track forward to a position such that the distance from the end of the tubing at the forward actuator group, which will be just forward of the forward actuator group's sealing clamp (about equal to the position of the cutting tool of the forward actuator group), to the location of the cutting tool of the rearward actuator group is at a desired length. Once the forward actuator group is in position, the sealing and holding clamps of the rearward actuator group are engaged, and the cutting tool of the rearward actuator group is then engaged to cut the tubing. After the tubing is cut by the rearward actuator group the holding clamp of the rearward actuator group can be released. The sealing clamp of the rearward actuator group is maintained in a clamped engagement to keep the tubing pressurized. In step708, the sealing clamp of the forward actuator group is released to release the cut-off section of tubing. Then in step710the rearward actuator group, while maintaining its sealing clamp in a clamped engagement of the tubing, is moved forward, and forward actuator group, having been completely disengaged from the tubing, is moved rearward. In moving the forward actuator group rearward, the forward actuator group's clamps and cutting tool are raised or otherwise moved out of the way of the rearward actuator group to allow the actuator groups to pass by each other. The rearward actuator group, while maintaining its sealing clamp closed on the tubing, is then forward to the desired position, pulling the tubing with it. Once the positions of the actuator groups are swapped, the process is repeated; the previously forward actuator group is then the rearward actuator group, and vice versa.

The process is shown inFIGS.8A-8Cfrom a front view of the actuator groups. InFIG.8A, the second actuator group110is shown in the forward position, with the first actuator group108behind it. The sealing clamp of the second actuator group110is closed on tubing300, as are both the holding clamp and sealing clamp of the first actuator group108. The cutting tool of the first actuator group108then cuts the tubing300. After the tubing is cut, the holding clamp of the first actuator group108is released while the sealing clamp of the first actuator group108remains closed. Likewise, the sealing clamp of the second actuator group is then opened to release a cut section of tubing (e.g.600). InFIG.8Bit can be seen that the tools of the second actuator group110are raised. This allows the first actuator group, still clamping the tubing with its sealing clamp, to be moved to the forward position, and second actuator group to be moved to the rear or home position as shown inFIG.8C. InFIG.8C, the first actuator group108is in the forward position such that the distance from cut end of the tubing300to the cutting tool of the second actuator group110is the desired tubing section distance. The tools of the second actuator group110are then lowered. Then the holding clamp and sealing clamp of the second actuator group110are clamped onto the tubing. Then the cutting tool of the second actuator group110is actuated to cut the tubing again. The process is then repeated, with the actuator group108,110moving back and forth to draw out and cut section of tubing under pressure. As seen here, the tools on each actuator group are each oriented at an angle with respect to vertical, and each of the actuator group108,110are angled away from each other. If the actuator groups108,110were commonly oriented, then a more complex movement and structure would be required to allow the two actuator groups to linearly reciprocate along their respective tracks without interfering with each other. Thus, it is preferred that the actuator group108,110not be commonly oriented, and have some degree of opposition (e.g. tilt, angle) with respect to the axis of the tubing. Here the actuator groups each have a tilt of about thirty degrees from vertical in opposite directions, resulting in about a sixty degree offset between them. The actuator groups108,110could be oriented 180° from each other so that they are directly opposing each other about the tubing. The tools200,202,204of each actuator group have a common operative position with respect to the axis of the tubing300so that the tubing300passes between the opposing jaw members of each tool so that they can each act on the tubing300. The non-operative ends of the actuator groups108,110, which are opposite the operative position on each actuator group108,110, are angled away from the non-operative end of the other actuator group while maintaining the common operative position.

FIG.9shows a side view of an actuator group108, in accordance with some embodiments. The actuator group includes a vertical plate402or similar support structure on which the position actuator504is mounted. The position actuator504is operable to move one or more shafts506through the position actuator504along the axis of the shafts506. The shaft(s)506is connected to a frame508on which the tools, including sealing clamp200, cutting toll202, and holding clamp204are mounted. Each of the tools200,202,204have a pair of jaw members900,902,904, respectively, between which a section of tubing passes. Jaw members900and904present opposing flat surfaces on either side of the tubing, and when actuated the opposing jaw members900,904come together to squeeze the tubing between them. The opposing jaw members902of the cutting tool202include at least one edged member that is oriented to that the edge cuts through the tubing. The opposing jaw members902of the cutting tool202can operate in a bypass/scissors cutting style, or one jaw member can present a flat surface against which an opposing edged jaw member is pressed to cut through the tubing. The vertical plate402can be mounted on a carriage (e.g.400inFIG.5) which is attached to a track (e.g.104) to move the actuator group108back and forth on the track as described.

A linear cut to length tubing cutting system has been disclosed that avoid the use of a pinch roller system to keep the tubing under pressure, but which also produces undesirable edge seams along the tubing. The inventive system disclosed herein uses to actuator groups that each have a holding clamp, and cutting tool, and a sealing clamp. Each actuator group is on a respective parallel track, and they are alternatively moved back and forth on their respective tracks to cut the tubing to a desired length while maintaining pressure in the tubing. Although certain embodiments have been disclosed herein, alternative and equivalent structures will occur to those skilled in the art that can be used in an interchangeable manner to accomplish the same function. For example, to raise the holding clamp, cutting tool, and sealing clamp, the carriage can raise the entire actuator group vertically, rather than using the position actuator to raise these tools.