Automated assembly device to tolerate blade variation

An automated device facilitates the assembly a surgical instrument that includes a knife with a high aspect ratio. The automated device includes a fixture for restraining a subassembly of the surgical instrument that includes the knife. A blade grip on the device is movable relative to the fixture, and is configured to urge the knife into a restrained position in the subassembly suitable for the subsequent assembly of an additional instrument component. A grip actuator is provided to move the blade grip.

BACKGROUND

1. Technical Field

The present disclosure relates to a device for assembling a surgical instrument. In particular, the device automates certain steps of an assembly process to ensure components of the instrument are properly aligned and connected.

2. Background of Related Art

Many surgical instruments include a blade or knife for mechanical tissue cutting. Often these knives are positioned at a distal end of the instrument and are operable from a proximal location on the instrument to traverse a particular path through the tissue. This arrangement may be particularly evident in surgical instruments configured for minimally invasive surgery. In a minimally invasive surgical procedure, a narrow tube or cannula may be inserted through a small incision made in a patient to provide access to a surgical site. Surgical instruments configured for minimally invasive surgery are thus typically equipped with an elongate shaft coupling a working head at the proximal end of the instrument to the end effector at the distal end of the instrument. The knife typically forms a component of the end effector, and control surfaces for activating the knife are typically located on the working head. Positioning the elongate shaft through the cannula thus permits a surgeon to manipulate the knife at an internal surgical site from the control surfaces that remain on the exterior of the patient.

To facilitate this remote operability, an aspect ratio of the knife may be relatively high, i.e., the geometry of the knife may be long and narrow. A knife exhibiting a long and narrow geometry may tend to bend, warp or otherwise deviate from a flat or straight configuration. These deviations may be relatively random such that each knife manufactured to a particular specification is distinct from other such knives, and these distinctions may present difficulties in defining an assembly procedure for instruments including the knives.

Typically, a knife may be manually assembled with other instrument components such as a support structure or knife guide. The knife guide may have an opening configured to receive the knife such that the knife may be visually aligned and threaded through the opening. The knife guide may be subsequently assembled into the instrument with the knife protruding from the opening. Such a process is labor intensive and presents various opportunities for error and damage to the instrument components. For example, a manually assembled knife could be damaged by unintended contact with the knife guide. Accordingly, the assembly of a surgical instrument may be facilitated by an assembly device that automates certain steps of the assembly process while accounting for variations in blade geometry.

SUMMARY

The present disclosure describes an automated device, which may facilitate the assembly a surgical instrument that employs a knife with a high aspect ratio. The automated device includes a fixture for restraining a subassembly of the surgical instrument that includes a knife. A blade grip on the device is movable relative to the fixture, and is configured to urge the knife into a restrained position in the subassembly suitable for the subsequent assembly of an additional instrument component. A grip actuator is provided to move the blade grip.

The grip actuator may be configured to move the blade grip in a lateral direction relative to the subassembly, and the device may further comprise at least one tapered finger extending in the lateral direction, such that a leading portion of the tapered finger encounters the knife in an unrestrained position and a trailing portion of the tapered finger encounters the knife in the restrained position. The blade grip may be configured to urge the knife toward the restrained position in a vertical direction relative to the subassembly, and the grip actuator may include a pneumatic slide.

The device may further include a component block configured to restrain the additional assembly component, and the component block may be moveable in a longitudinal direction relative to the fixture to approximate the additional assembly component and the subassembly. The device may also include a knife block configured to move relative to the fixture to define a longitudinal position of the knife within the subassembly.

According to another aspect of the disclosure, a device for facilitating the assembly of a surgical instrument may include a fixture for restraining a subassembly of the surgical instrument including a knife, a knife block moveable in a longitudinal direction relative to the fixture to define a longitudinal position of the knife within the subassembly, and a component block configured to restrain an additional assembly component. The knife block and the component block may be configured for concurrent movement to facilitate assembly of the additional assembly component to the subassembly.

The knife block and the component block may also be selectively configured for selective independent movement relative to one another. The device may include a blade grip, which is moveable in a lateral direction to define a vertical position of the knife within the subassembly. The device may further include a jaw block for restraining a jaw member to be installed onto the subassembly, the jaw block mountable relative to the fixture such that the jaw member operably engages the knife upon movement of the knife block.

According to still another aspect of the disclosure, a method of assembling a surgical instrument including a knife includes may include loading a subassembly of the instrument that includes the knife into a fixture such that the knife is movable within the subassembly, advancing a blade grip to urge the knife to a restrained position within the subassembly, approximating an additional instrument component relative to the subassembly to constrain the additional instrument component within the subassembly, and moving the instrument component and the knife concurrently to install the additional instrument component.

DETAILED DESCRIPTION

The devices and processes of the present disclosure may facilitate accurate assembly of a surgical instrument such as an electrosurgical forceps10. A more detailed description of the assembly and operation of forceps10may be found in commonly assigned U.S. Patent Application Publication No. 2007/0078456 to Dumbauld et al. The attached figures illustrate exemplary embodiments of the present disclosure and are referenced to describe the embodiments depicted therein. Hereinafter, the disclosure will be described in detail by explaining the figures wherein like reference numerals represent like parts throughout the several views

Referring initially toFIG. 1, the electrosurgical forceps10includes a distal end12and a proximal end14. An end effector18near the distal end12is configured to manipulate tissue at a surgical site by clamping, electrosurgically energizing, cutting and/or otherwise contacting the tissue. Two jaw members22,24of the end effector18are configured to move between an open position as shown inFIG. 1, in which the distal-most ends are substantially spaced and a closed position wherein the distal most ends are closer together. The end effector18is coupled to an elongate shaft26. Elongate shaft26facilitates the use of forceps10in a minimally invasive surgical procedure, wherein the elongate shaft26is inserted through a cannula as discussed above. At the proximal end of forceps10is a working head28including several control surfaces, which a surgeon uses to remotely manipulate the end effector18. For example, handles30may be drawn together to approximate jaws22,24or drawn apart to separate jaws22,24. Other control surfaces may include a knob32, which may be used to rotate the end effector18, buttons34,36, which may be used to initiate various modes electrosurgical energy delivery to the jaws22,24, a slide38, which may be used to control the intensity of electrosurgical energy delivered, and trigger40, which may be used to advance a knife42(FIG. 2A) through tissue clamped by jaws22,24.

Referring now toFIG. 2A, an arrangement of a distal portion of forceps assembly10is described that permits a surgeon to operate end effector18from the proximal end14of the forceps10. Within elongate shaft26, several components are arranged in a generally concentric relation and moveable relative to one another in order to transmit motion from the proximal end14to the end effector18. For example, a drive sleeve50is received within elongate shaft26in a manner permitting the drive sleeve50to longitudinally translate or reciprocate relative to the elongate shaft26. A rotating shaft54is similarly received within the drive sleeve50such that the drive sleeve50may reciprocate relative to the rotating shaft54. A knife bar58is received within the rotating shaft54such that the knife bar58may reciprocate relative to the rotating shaft54. A knife60is coupled to a distal end of the knife bar58, such that the knife60reciprocates along with the knife bar58. The knife60may be attached to the knife bar58in any suitable way, e.g., snap-fit, fiction-fit, pinned, welded, glued, etc.

A knife guide62is supported in the rotating shaft54and remains stationary with respect to the rotating shaft54. Knife guide62may be press fit into an opening in the distal end of the rotating shaft54and includes a tapered interior channel therein (seeFIG. 9C) to receive knife60. The knife guide may thus urge knife60into a central position within the rotating shaft54and ensure proper alignment of knife60as it reciprocates within upper and lower jaw members22,24(seeFIG. 2D). Knife guide62may also serve to protect the knife60and other components from damage throughout the assembly process as will be described in greater detail below.

A pivot pin66and a drive pin68are included to operatively associate the upper and lower jaws22,24to both drive sleeve50and rotating shaft54. An insulating boot70is positioned over a distal end of the drive sleeve50and a portion of upper and lower jaws22,24. The boot70may be formed from a flexible or resilient material such that the boot70may accommodate the movement of upper and lower jaws22,24as the jaws are approximated and separated.

Referring now toFIG. 2B, jaw member22is equipped with a proximal flange72and jaw member24is equipped with a proximal flange74. Each of the proximal flanges72,74includes a pivot hole76to receive pivot pin66and a drive slot78to receive drive pin68therein. The pivot hole76and the drive slot78are configured to permit appropriate relative motion of the jaw members22,24about the pivot pin66and drive pin68. Drive sleeve50and rotating shaft54are each equipped with a bifurcated distal end to accommodate the proximal flanges72,74of jaw members22,24. Drive sleeve50includes a bore80extending through both portions of its bifurcated end, and similarly, rotating shaft54includes a bore84extending through both portions of its bifurcated end. Bores80,84are configured to fixedly retain respective pins66,68therein by a press-fit or similar connection. Rotating shaft54also includes a longitudinal slot86extending through both portions of its bifurcated end. Longitudinal slot86is configured to accommodate longitudinal movement of drive pin68there through. Knife60also includes an elongate slot90that permits knife60to reciprocate without interfering with pins66,68.

When fully assembled, pivot pin66is positioned through bore84, pivot holes76and elongate slot90to permit the jaw members to pivot about the pivot pin66. Drive pin68is positioned through bore80, longitudinal slot86, drive slots78, and elongate slot90. As depicted inFIGS. 2C and 2D, this arrangement provides for a closed configuration of jaw members22,24(jaw member22and boot70are removed for clarity) in which drive slots78are oriented in general alignment with a longitudinal axis of the instrument10. When jaw members22,24are in the closed configuration, drive pin68is disposed in a proximal position within the drive slots78and within longitudinal slot86. If the drive sleeve50is caused to move in a distal direction with respect to the rotating shaft54, drive pin68moves distally within the drive slots78toward pivot pin66. This motion causes the drive slots78to move to an oblique orientation out of the general alignment with the longitudinal axis of the instrument10. Thus jaw members22,24are moved into an open configuration as depicted inFIG. 2E. In this open configuration, drive pin68assumes a distal position within the drive slots78. Imparting an opposite relative motion between drive sleeve50and rotating shaft54, i.e., moving drive sleeve50proximally, when the jaw members22,24are in the open configuration serves to move the jaw members to the closed configuration. Handles30are configured such that manipulation of the handles30effects relative motion between the drive sleeve50and rotating shaft54to move jaw members22,24between the open and closed configurations.

If knife bar58is caused to move distally with respect to the rotating shaft54, knife60is advanced into the jaw members22,24as depicted inFIG. 2C. Elongated slot90in the knife60permits this motion without interference from pins66,68. Trigger40is configured such that manipulation of the trigger40effects motion of the knife bar58to effect advancement of the knife60.

As can be appreciated, the functionality of instrument components described above may require an intricate assembly process. Each of the instrument components must be properly positioned and oriented in a manner appropriate for a particular step in the assembly process. Such a process may be difficult to accomplish manually as access to a particular instrument component may be limited once the component is installed. Also, any variations in the knife60from an entirely straight and flat configuration may further complicate the assembly process. Accordingly, an automated assembly device may facilitate the assembly of the electrical forceps10and other instruments that require complicated assembly of components, e.g., a surgical stapler.

Referring now toFIG. 3, an automated assembly device in accordance with the present disclosure is depicted generally as100. Assembly device100includes a base plate102, that may be configured to be placed on a table-top or other structure to provide an operator convenient access to a forward interior region104of the device100. A hinged safety cover106is provided to selectively enclose the forward interior region104, and to protect the operator during various stages of an assembly process in which automated movement occurs. An interlock108is mounted within the forward interior region104such that a key110mounted on the safety cover106is approximate to the interlock108when safety cover106is in a closed configuration (not shown). A controller (not shown) is included and configured to permit automated movement when safety cover106is in a closed configuration, and disable automated movement when safety cover106is in an open configuration. Thus, the operator may safely load, unload and manipulate instrument components when safety cover106is open.

Removing safety cover106reveals a rear interior region112of the assembly device100as depicted inFIG. 4. A quick-disconnect coupling114provides a pneumatic input for compressed air provided by an external source to enter device components housed in the rear interior region112. For example, coupling114may communicate with device components such as an air pressure regulator116or valve bank118. Components of the assembly device, to which access less frequently required, may be housed in the rear interior region112. Regulator116, for example, may require adjustment only once to provide a suitable air pressure for the assembly device100, and thereafter many forceps10or other instruments may be assembled using the device100.

Extending from regulator116is a pneumatic fitting120. Pneumatic fittings120or similar fittings are operatively connected to fluid conduits (not shown) to provide fluid communication between components of assembly device100. Such fluid conduits are used to deliver compressed air to the forward interior region104of the device110through either one of gates122. Gates122are equipped with tie-down anchors124attached to the base plate to facilitate organization of the fluid conduits. Tie down anchors124may be located at various locations throughout the assembly device100and provide an opening through which a cable tie or other restraint may be secured.

The forward interior region104houses four main device components or assembly blocks, which are used to restrain or manipulate instrument components within the assembly device100. These include a fixture130, a knife block132, a component block134, and guide block136. A fifth device component, jaw block138, is removable from the assembly device100to conveniently load smaller instrument components such as jaw members22,24as described in greater detail below.

The four main assembly blocks130,132,134,136are arranged as depicted inFIG. 4to define an initial configuration wherein each assembly block is located in an initial position with respect to the base plate102. Fixture130is centrally located within the forward interior region104and is fixedly mounted to the base plate102. Knife block132is mounted to an actuator or carrier component such as precision pneumatic slide150. Pneumatic slide150is configured to selectively advance knife block132from an initial position in a longitudinal direction with respect to fixture130as indicated by arrow “A.” Pneumatic slide150may be retracted to return knife block132to an initial position. Component block134is mounted to pneumatic slide152, and pneumatic slide152is mounted to pneumatic slide154. Pneumatic slide152is configured to selectively advance component block134in a longitudinal direction with respect to pneumatic slide154as indicated by arrow “B.” Pneumatic slide154is configured to selectively carry component block134, pneumatic slide152, and a guide block136together in a longitudinal direction with respect to the base plate102as indicated by arrow “C.” Guide block136is mounted to a pneumatic slide156, which is configured to selectively carry guide block136in a lateral direction with respect to the base plate102as indicated by arrow “D.” Each of the pneumatic slides150,152,154, and156are also configured to selectively return the assembly blocks130,132,134,136to respective initial positions.

Referring now toFIG. 5, fixture130includes a shaft reception channel160across a top surface thereof. Shaft reception channel160is configured to receive a slender instrument component such as rotating shaft54therein, and a pair of toggle clamps162is provided to secure the instrument component within the channel160. A sensor housing168is disposed on an end of fixture130such that a narrow channel170across a top surface thereof may receive a distal portion of the instrument component. Narrow channel170is in general alignment with channel160, and is adjustable to precisely define the location of the distal end of the instrument. Sensor housing168supports jaw block138in a releasable manner on an end opposite of channel160, and houses a sensor172(FIG. 9C), which is configured to detect the presence of jaw block138as described in greater detail below.

Component block134includes a guide mount174projecting therefrom upon which the knife guide62may be mounted. The guide mount174includes a thin tongue176configured to extend into an interior region of the knife guide62in order to support the knife guide62thereon. A leading face178of the guide mount174provides a stop for mounting knife guide62and leading face178enables the guide mount174to press the knife guide62into position within the rotating shaft54upon longitudinal translation of component block134during an assembly process described below.

Component block134also includes a bumper post180, which limits the travel distance of component block134. Bumper post180extends from component block134in the direction of fixture130to define a minimum distance therebetween. Alternatively, bumper post180may extend from fixture130in the direction of component block134.

Guide block136is bifurcated including two complementary components. At least one of the components of assembly block136includes a blade grip182(seeFIG. 8A) that supports the knife42during an assembly process described below. Blade grip182may be configured to accommodate blade deviations or variances to facilitate the assembly process.

Also visible inFIG. 5is a control surface190. Control surface190may take the form of a push button, and may be electrically coupled to the controller (not shown) to perform a variety of functions. For example, control surface190may be configured to advance and retract guide block136, or alternatively provide an emergency stop for the assembly device100.

Referring now toFIG. 6, an assembly process for the distal end of forceps10is summarized in which certain steps are automated to account for variations or deviations in knife60. An initial preparatory step, which precedes the process outlined inFIG. 6, may be to manually remove jaw block138and retain the jaw block138for use in later assembly steps. Many of the other steps summarized inFIG. 6are described in greater detail below with reference toFIGS. 7Athough10C.

An initial assembly step is to manually preassemble some of the instrument components before loading into the forward interior region104of assembly device100. For example, the knife42may be fixedly preassembled to knife bar58by pinning, welding or any other appropriate means. Once the knife60is coupled to the knife bar58, the knife bar58is manually inserted into the rotating shaft54in a manner permitting longitudinal translation there between as described above. A subassembly of instrument components is thus be defined by this arrangement of the knife60, knife bar58, and rotating shaft54.

Once these components have been preassembled into a subassembly, they may be loaded into the assembly device100. As depicted inFIG. 7A, the rotating shaft54is positioned to rest in the shaft reception channel160of fixture130. Toggle clamps162are arranged to fix the position of the rotating shaft54relative to the stationary fixture130. The knife bar58extends from rotating shaft54such that the rotating shaft54is separately restrained in knife block132as depicted inFIG. 7B. Knife block132includes a post192projecting there from to provide a locating and orienting mechanism for knife bar58. Post192permits only a single orientation of knife bar58and thus ensures knife bar58is properly oriented. A locating pin194is installed through a prefabricated hole (visible inFIG. 2A) to fix the location of knife bar58relative to knife block132. This arrangement provides for the reciprocation of knife bar58along with knife42within rotating shaft54at such time pneumatic slide150may be activated.

As depicted inFIG. 7C, knife guide62is loaded onto component block134before any automated movement occurs. Knife guide62is positioned onto the tongue176until the knife guide62abuts leading face178. At this point, with rotating shaft54, knife bar58, knife60, and knife guide62loaded into the assembly device100, the safety cover106is closed and automated movement may be initiated.

Pneumatic slide154is initially activated or extended to deliver guide block136into proximity to fixture130and sensor housing168as depicted inFIG. 8A. Knife60projects into the bifurcated end of rotating shaft54due to the positioning of the proximal end of knife bar58in the knife block132. Knife block132remains at a retracted or initial position thus defining the longitudinal position of the knife bar58and knife60within rotating shaft54. The knife60may deviate from a central position between the two portions of the bifurcated end of the rotating shaft54due to blade variations, tolerance buildups, or other concerns. In particular, the knife60may be disposed off center in a vertical direction such that subsequent assembly of instrument components is complicated.

To ensure that the knife60is not damaged upon the assembly of subsequent instrument components, pneumatic slide156is activated to deliver guide block136from a retracted position to an extended position to restrain knife60. As depicted inFIG. 8B, blade grip182on guide block136includes a pair of opposed tapered fingers with inclined surfaces that urge knife60into a central disposition as guide block136is extended in a lateral direction. A leading portion of the tapered fingers may encounter the knife60in an unrestrained position and a trailing portion of the tapered fingers may encounter the knife60in the restrained position. Thus a vertical position of knife60may be defined. Once knife60is centrally disposed, knife guide62may be safely constrained.

Knife guide62is constrained by temporarily positioning the knife guide62between the two portions of the bifurcated end of rotating shaft54as depicted inFIG. 9A. Pneumatic slide152is activated and moved to a partially extended position to deliver the knife guide62to the bifurcated end of rotating shaft54. Since the blade grip182maintains the knife60in a central disposition, the distal tip of the knife60avoids contact with the knife guide182and any damage resulting there from. Once constrained, knife guide62partially encloses a distal tip the knife60.

Next, pneumatic slide156is activated to return guide block136to a retracted position and release knife60from the blade grip182as depicted inFIG. 9B. With the knife60protected within knife guide62, the knife guide62may be fully installed. Pneumatic slide150is extended concurrently with the further extension of pneumatic slide152. The extension of pneumatic slide150will cause knife block132to draw knife bar58from rotating shaft in a proximal direction, and thus draw knife60in a proximal direction. The further extension of pneumatic slide152will move knife guide62proximally until knife guide62is pressed into position in rotating shaft54. This concurrent movement may protect knife60from any damage that may result from contact with interior walls of knife guide62. As depicted inFIG. 8C, the distal tip of knife60remains protected within the knife guide62throughout this assembly step.

With knife guide62installed, pneumatic slides152and154are retracted returning134and136to their retracted positions. Pneumatic slide150remains extended as depicted inFIG. 9Dsuch that knife block132remains in an extended position and knife60remains in a proximal position within knife guide62for the next assembly step.

As depicted inFIG. 10A, jaw block138is manually loaded with jaw members22,24. A transfer pin196is positioned between two locating pegs198on jaw block138to locate and orient the jaw members22,24. Transfer pin196includes a lower pin portion configured to be received within pivot holes76or drive slots78in the proximal flanges74of jaw members22,24. When transfer pin196is installed, jaw members22,24are properly arranged for assembly onto rotating shaft54.

Safety cover106may be opened, and jaw block138pre-loaded with jaw members22,24may be installed into the assembly device100. As depicted inFIG. 10B, jaw block138includes a pair of locating prongs202, which are received in a corresponding pair of holes in the sensor housing168. Transfer pin196is removed prior to installation of jaw block138to allow proximal flanges72,74of jaw members22,24to be move between the two portions of the bifurcated distal end of rotating shaft54.

As depicted inFIG. 10C, sensor housing168includes a sensor such as proximity switch172configured to detect the presence of jaw block138. When jaw block138is installed and proper alignment of the jaws,22,24is confirmed, proximity sensor172sends an appropriate signal to the controller. When safety cover106is closed and the appropriate signal has been received, the controller permits pneumatic slide150to retract, thereby advancing knife bar58and knife60in a distal direction into jaw members22,24.

The knife60is advanced until the longitudinal slot68therein is situated between pivot holes76in the proximal flanges72,74of the jaw members22,24. The safety cover106may then be opened, and transfer pin196is replaced. When replaced, transfer pin196is positioned through bore84, or longitudinal slot86in the rotating shaft54. As transfer pin196is replaced, the lower pin portion of transfer pin196will extend through the longitudinal slot68in the knife60, thereby temporarily coupling the knife60to jaw members22,24.

This arrangement facilitates the manual installation of pivot pin66into pivot hole84, and drive pin68into bore80, thus capturing jaw members22,24and knife60. Manual installation of the boot70may complete the assembly of the distal portion of forceps10. The distal portion is subsequently assembled with working head28to complete the forceps10.

The process described above involves the use of pneumatic slides150,152,154, and156to automate certain steps of the assembly process. Other automated actuators may be substituted for one, or any number of the pneumatic slides150,152,154, and156such as servo or step motors. Alternatively, manually prompted movement is contemplated. For example, the step of restraining knife60within blade grip182may be accomplished manually. Guide block136may be configured to permit manual motion to slide blade grip182over knife60. Control surface190may also be configured to facilitate any manual or semi-automatic movement.

Although the foregoing disclosure has been described in some detail by way of illustration and example, for purposes of clarity or understanding, it will be obvious that certain changes and modifications may be practiced within the scope of the appended claims.