The invention relates to a vise and, more particularly, to an automated vise for holding workpieces during manufacturing runs utilizing a shaping machine such as a Computer Numerical Control (“CNC”) machine.
CNC automation systems rely on remote actuated vises to hold a workpiece in place during cutting operations. Certain vises create high clamping forces using pneumatic or hydraulic pressure exerted either through one moving jaw or through both jaws using input/output (“I/O”) signals from, e.g., a robot system used to load workpieces into the CNC machine for subsequent forming processing. The stroke of the jaws with these systems is typically small (i.e., no more than about 6 millimeters (“mm”)).
During certain manufacturing runs, a single CNC machine will be used to shape workpieces of different initial sizes. If the workpiece dimension to be clamped by the vise (i.e., a workpiece dimension along a particular trajectory, e.g., coincident with or parallel to one of the three axes of a standard Cartesian coordinate system defined within the workpiece—hereinafter, “clamp dimension” will be used at times as a shorthand for this dimension) differs by more than the stroke of the jaws of the vise, then the aforementioned vise cannot be utilized to automatically effect holding of the disparately sized workpieces during the manufacturing run. To clamp such differently sized workpieces during such a run, an operator must halt production to mechanically loosen and move the moveable vise jaw(s) to position the moveable vise jaw(s) to be able to hold the workpiece within the stroke of the jaws.
With this vise design, there is no way to automatically adjust the vise to accommodate workpieces having differing clamp dimensions in an automation system using the same vise to hold the different workpieces. To automate production of batches of high-mixes of workpieces would require multiple vises on the machine tool's table covering the range of sizes of workpieces to be machined (
The present disclosure provides a vise capable of automatically (i.e., without human intervention) holding a number of workpieces having disparate clamp dimensions.
In an exemplification thereof, the present disclosure provides a vise for holding a workpiece in a forming machine, comprising: a moveable jaw moveable between an open position and a clamp position, whereby the moveable jaw allows a workpiece to be positioned in the vise in the open position and the moveable jaw clamps the workpiece in the vise in the clamp position; a gross moveable jaw drive connected to the moveable jaw and operable to actuate the moveable jaw between the open position and the clamp position, the gross moveable jaw drive comprising a lock selectively restricting a movement of the moveable jaw toward the open position; and a fine moveable jaw drive connected to the moveable jaw and operable to actuate the moveable jaw between the open position and the clamp position, whereby the gross moveable jaw drive is operable to actuate the moveable jaw to a near clamp position and the fine moveable jaw drive is operable to actuate the moveable jaw from the near clamp position to the clamp position to hold the workpiece during a forming operation.
In certain alternative forms of the exemplifications of the disclosure, the lock is moveable between an unlock position allowing the gross moveable jaw drive to actuate the moveable jaw between the open position and the clamp position, and a lock position restricting a movement of the moveable jaw toward the open position within one of a plurality of gross increments; and the fine moveable jaw drive is operable to actuate the moveable jaw within one of the plurality of gross increments.
In further alternative forms of the exemplifications of the disclosure, the gross moveable jaw drive comprises a drive screw and the lock comprises an inefficiency in the drive screw, whereby the inefficiency in the drive screw prevents back-driving of the gross moveable jaw drive to restrict a movement of the moveable jaw toward the open position.
In further alternative forms of the exemplifications of the disclosure, the fine moveable jaw drive comprises a pneumatic moveable jaw drive or a hydraulic moveable jaw drive.
In further alternative forms of the exemplifications of the disclosure, the gross moveable jaw drive comprises a drive gear. In alternatives, the lock restricts movement of the drive gear in the lock position.
In additional alternative forms of the exemplifications of the disclosure, the vise further comprises a controller communicatively connected to the gross moveable jaw drive to allow the controller to control an actuation of the gross moveable jaw drive. In alternatives, the vice further comprises a proximity sensor positioned to detect a preset position of the moveable jaw relative to the workpiece, the proximity sensor communicatively connected to the controller, the controller ceasing actuation of the gross moveable jaw drive if the proximity sensor detects the preset position of the moveable jaw relative to the workpiece. In additional alternatives, the vise further comprises a motor sensor operable detect the when the moveable jaw has contacted the workpiece. In alternatives, the motor sensor comprises: a motor load sensor operable to detect a motor load, the motor load sensor communicatively connected to the controller, the controller ceasing actuation of the gross moveable jaw drive if the motor load sensor detects that the moveable jaw has contacted the workpiece. In further alternatives, the vice further comprises an input communicatively connected to the controller, the controller configured to receive via the input a workpiece dimension to be clamped by the vise, the controller ceasing actuation of the gross moveable jaw drive when the moveable jaw reaches the near clamp position, whereby the fine moveable jaw drive is operable to actuate the moveable jaw from the near clamp position to the clamp position to hold the workpiece during a forming operation.
In further alternative forms of the exemplifications of the disclosure, the moveable jaw comprises a moveable jaw assembly comprising a moveable jaw carriage and a moveable jaw moveable by the fine moveable jaw drive relative to the moveable jaw carriage, the lock operable to restrict movement of the moveable jaw carriage while movement of the moveable jaw relative to the moveable jaw carriage via the fine moveable jaw drive is still allowed.
In additional forms of the exemplifications of the disclosure, the gross moveable jaw drive comprises a drive gear having a plurality of teeth, and wherein the lock comprises a pawl moveable into locking engagement with the plurality of teeth.
In further alternative forms of the exemplifications of the disclosure, the lock comprises a torque coupling.
In additional forms of the exemplifications of the disclosure, the vise further comprises a stationary jaw, the moveable jaw clamping the workpiece with the moveable jaw and the stationary jaw in the clamp position.
In further alternative forms of the exemplifications of the disclosure, a jaw opening is defined between the stationary jaw and the moveable jaw, the workpiece positioned in the jaw opening in the clamp position.
In additional forms of the exemplifications of the disclosure, the vise further comprises a second jaw, wherein the moveable jaw is moved away from the second jaw to position the vise from the open position to the clamp position.
In further alternative forms of the exemplifications of the disclosure, the moveable jaw comprises a plurality of moveable jaws.
In another exemplification thereof, the present disclosure provides a method of machining a plurality of workpieces, comprising: placing one of the plurality of workpieces in a vise having a moveable jaw and a fine moveable jaw drive operable to actuate the moveable jaw within a fine moveable jaw drive travel distance; grossly actuating the moveable jaw to a near clamp position spaced a distance less than the fine moveable jaw drive travel distance from a dimension of the one of the plurality of workpieces; locking the moveable jaw to prevent the moveable jaw from moving away from the dimension of the one of the plurality of workpieces to a distance of more than the fine moveable jaw drive travel distance, whereby the locking step positions the moveable jaw so that actuation of the moveable jaw by the fine moveable jaw drive within the fine moveable jaw drive travel distance will position the moveable jaw to clamp the one of the plurality of workpieces along the dimension of the one of the plurality of workpieces; and clamping the workpiece with the moveable jaw by actuating the fine moveable jaw drive to actuate the moveable jaw from the near clamp position to a clamp position where the moveable jaw clamps the workpiece.
In alternatives forms of the exemplary method, the method further comprises: detecting a position of the moveable jaw relative to the workpiece during grossly actuating the moveable jaw; and ceasing grossly actuating the moveable jaw in response to detecting that the moveable jaw has achieved the near clamp position spaced a distance less than the fine moveable jaw drive travel distance from the dimension of the one of the plurality of workpieces. In certain further alternative forms, the detecting step comprises detecting with a proximity sensor. In other alternative forms, the detecting step comprises detecting with a motor sensor.
In alternatives forms of the exemplary method, the method further comprises: inputting the workpiece dimension into a controller controlling the grossly actuating step; calculating with the controller a gross travel distance needed to position the moveable jaw in the near clamp position spaced the distance less than the fine moveable jaw drive travel distance from the dimension of the one of the plurality of workpieces; and wherein the grossly actuating step comprises actuating the moveable jaw over the gross travel distance needed to position the moveable jaw in the near clamp position spaced the distance less than the fine moveable jaw drive travel distance from the dimension of the one of the plurality of workpieces.
In alternatives forms of the exemplary method, clamping comprises clamping the workpiece with the moveable jaw and a stationary jaw. In further alternatives of this form of the disclosure, grossly actuating comprises moving the moveable jaw away from the stationary jaw. In alternatives forms of the exemplary method, the moveable jaw comprises a plurality of moveable jaws and grossly actuating comprises grossly actuating the plurality of moveable jaws.
The above mentioned and other features and objects of this invention, and the manner of attaining them, will become more apparent and the invention itself will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates an exemplary embodiment of the invention and such exemplification is not to be construed as limiting the scope of the invention in any manner.
The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings.
The disclosure provides a vise capable of automatically holding a number of workpieces having disparate clamp dimensions during a manufacturing run.
In certain embodiments of the disclosure, a gross moveable jaw drive actuates one or more moveable jaws of the vise by gross increments within a gross moveable jaw stroke, while a fine moveable jaw drive actuates the one or more moveable jaws within a fine moveable jaw stroke. The gross moveable jaw stroke is longer than the fine moveable jaw stroke. With this construction, the gross moveable jaw drive can be utilized to actuate the one or more moveable jaws of the vise over a distance greater than the fine moveable jaw drive stroke to a position in which actuation of the fine moveable jaw drive is capable of positioning the one or more moveable jaws in a clamp position holding the workpiece for machining by the CNC machine. In certain embodiments, the fine moveable jaw drive actuates the one or more moveable jaws within one of the plurality of gross increments.
Referring to
As described above, a vise featuring a typical pneumatic or hydraulic clamp would have a limited stroke (typically 6 mm or less). During a manufacturing run, a robot could be used to sequentially position workpieces for shaping by CNC machine 14. In such a process, the following sequential steps would be followed: the vise would be opened to allow the robot to position the workpiece within the jaws of the vise, the vise would be closed to clamp the workpiece in position during the forming operation of the CNC machine, the vise would be opened to allow removal of the shaped workpiece by a robot and the process would repeat. As mentioned above, such a vise would not be able to automatically accommodate different workpieces that could not be accommodated by the limited stroke of the vise.
Vise 10 alleviates this shortcoming by incorporating both a gross moveable jaw drive and a fine moveable jaw drive. Referring to
Jaw opening 24 is defined by the distance between moveable jaw 20 and fixed jaw 26 along the direction of travel of moveable jaw 20, which, in this embodiment, will be parallel to the longitudinal axis of drive screw 18. To effect gross translation of moveable jaw 20, drive screw 18 is rotatable relative to moveable jaw carriage 20a and threadably engaged therewith. Moveable jaw carriage 20a is prevented from rotating with drive screw 18; therefore, as drive screw 18 is rotated by motor 22, the threaded engagement of moveable jaw carriage 20a with drive screw 18 translates the rotation of drive screw 18 into linear translation of moveable jaw carriage 20a (and moveable jaw 20 therewith) along the longitudinal axis of drive screw 18.
Gross moveable jaw drive 16 is able to translate moveable jaw 20 by gross increments.
Pawl 38 includes stop flank 40 engageable with a stop flank 42 (only one of which is numbered in
With pawl 38 positioned as shown in
Gross moveable jaw drive 16 is operable to actuate moveable jaw 20 through a plurality of gross increments. For example, with moveable jaw 20 in a fully open position of vise 10, i.e., with jaw opening 24 maximized, and pawl 38 positioned as shown in
Pawl actuation rod 54 is rotatably connected to pawl 38 at one end and fixedly secured to piston 56 at the other. Piston 56 is configured to reciprocate within cylinder 58 against the spring force of compression spring 60. Spring 60 works to bias piston 56 to the position shown in
While lock 28 allows moveable jaw carriage 20a to carry moveable jaw 20 from a position having a relatively larger jaw opening 24 to a position having a relatively smaller jaw opening 24 with pawl 38 positioned as shown in
Pawl 38′ includes stop flank 40′ engageable with a stop flank 72 (only one of which is numbered in
With pawl 38′ positioned as shown in
Gross moveable jaw drive 16 (
Pawl actuation rod 54′, piston 56′, cylinder 58′, spring 60′, and actuator 62′ operate in the same fashion as described with respect to the corresponding elements of the embodiment illustrated in
Fine moveable jaw drive 64 is interposed between and connects moveable jaw carriage 20a and moveable jaw 20. Fine moveable jaw drive 64 comprises one of the pneumatic or hydraulic vise mechanisms well known in the art. For the sake of brevity, a detailed description of these well know devices is not provided here. With moveable jaw 20 positioned by gross moveable jaw drive 16, fine moveable jaw drive 64 can, in certain embodiments, be used to actuate moveable jaw 20 within a gross increment defined by lock 28 or lock 28′.
In an exemplary vise 10 of the present disclosure, gross moveable jaw drive 16 will cooperate with lock 28 to create a gross increment of 6 mm. In this exemplification, fine moveable jaw drive 64 will have a stroke of 6 mm. In an exemplary manufacturing run in which CNC machine 14 is used to shape first workpieces having a clamp dimension (as that term is defined above) of 20 mm, gross moveable jaw drive 16 will actuate moveable jaw 20 to a near clamp position (i.e., a clamp position in which moveable jaw 20 is not further than the fine moveable jaw drive stroke from the workpiece, with the workpiece positioned against fixed jaw 26). For example, the gross moveable jaw drive 16 would actuate moveable jaw 20 to create a jaw opening 24 of 24 mm. from this position, fine moveable jaw drive 64 could be actuated to a clamp position holding the workpiece firm and fast for machining. In the same manufacturing run second workpieces having a clamp dimension of 10 mm could be shaped by CNC machine 14. When transitioning from a first workpiece to a second workpiece in this example, gross moveable jaw drive 16 would actuate moveable jaw 20 from a position creating a jaw opening 24 of 24 mm to a position creating a jaw opening 24 of 12 mm.
In a first exemplification of the present disclosure, proximity sensor 66 is embedded in moveable jaw 20 and is operable to detect the proximity of moveable jaw 20 to a workpiece positioned in jaw opening 24. Proximity sensor 66 is communicatively connected to controller 68, which controls actuation of gross moveable jaw drive 16. An exemplary manufacturing process implementing proximity sensor 66 is illustrated in
At step 84, controller 68 actuates fine moveable jaw drive 64 to supply the desired clamping pressure to the workpiece during the forming process. Lock 28 or 28′ creates a backstop for the pressure exerted by fine moveable jaw drive 64 at step 84. The workpiece is shaped by CNC machine 14 at step 92. At step 94, fine moveable jaw drive 64 is disengaged (i.e., no longer supplies clamping to the workpiece) and finally, at step 96, the workpiece is removed from vise 10. A robot receiving input from controller 68 may be utilized to effect step 96. At this point in the manufacturing run, the method returns to step 86 and the steps illustrated in
In a second exemplification of the present disclosure, proximity sensor 66 is abandoned in favor of input 98. Input 98 can be utilized to input the clamp dimension of the part to be shaped in CNC machine 14. An exemplary manufacturing process implementing input 98 is illustrated in
A third exemplification of the present disclosure incorporates part detection with a motor sensor, e.g., a motor load sensor for monitoring the load on the motor, or a motor sensor configured to detect when the motor or motor drive stops while being commanded to move. This exemplification will follow the steps of
Locks 28, 28′ described to this point in this document provide for limited movement of moveable jaw 20a toward and away from fixed jaw 26. Specifically, locks 28, 28′ allow for ratcheting movement of moveable jaw 20a toward fixed jaw 26 and also allow movement of moveable jaw away from fixed jaw within a gross increment, as detailed above. In alternative forms of the automatic clamping system of the present disclosure, a fixed lock may be implemented. A fixed lock will lock gross moveable jaw drive 16 such that no movement of moveable jaw 20 along drive screw 18 will be allowed.
A fixed lock may take the form of a spline or Hirth joint, or other torque coupling preventing movement of moveable jaw 20 along drive screw 18 by, e.g., resisting rotational movement of drive screw 18. In the case of a spline or Hirth joint, one of two rotationally locking elements will be carried by drive screw 18 and rotatable therewith, with the other of two rotationally locking elements moveable into and out of engagement therewith while being non-rotatable. In this type of a locking arrangement, the two rotationally locking elements can be disengaged to allow actuation of gross moveable jaw drive 16 to actuate moveable jaw 20 toward or away from fixed jaw 26 and can be engaged to prevent movement of moveable jaw 20 along drive screw 18.
If a lock incorporated in the automatic clamping system of the present disclosure comprises a fixed lock in the form of a spline or Hirth joint, and is utilized in accordance with the method of
Gross moveable jaw drive 16 may itself comprise a fixed lock. Locks 28, 28′, and the fixed locks described above should be considered to form a part of gross moveable jaw drive 16; however, in certain embodiments, the gross moveable jaw drive 16 will be designed such that the clamping force of fine moveable jaw drive 64 is not capable of back-driving gross moveable jaw drive 16. In these circumstances, no additional components (beyond those necessary to actuate moveable jaw 20 as described above) are needed to form a lock useable in the automatic clamping system of the present disclosure. More particularly, a highly inefficient drive screw 18 can act as a fixed lock.
The properties of a highly inefficient screw system can be leveraged to provide the necessary locking characteristics for gross moveable jaw drive 16, albeit with a near-infinite locking number of locking positions. Gross moveable jaw drive 16 itself will not be strong enough to provide the sole clamping force to the workpiece, so the fine moveable jaw drive will remain necessary for the vise application to provide the clamping force to hold the workpiece. Highly inefficient screws can eliminate the possibility of gross moveable drive 16 to be back-driven and opened when an axial force is applied to the jaw connected to the fine moveable jaw drive if the inefficiency of the transmission system (the lead screw, i.e., drive screw 18) of gross moveable jaw drive 16, which based on the amount of friction in the assembly, is greater than the back driving torque (force applied to the clamping jaw of the fine moveable jaw). If the friction is high enough, gross moveable jaw drive 16 can effectively be locked and hold its position when clamping a part with fine moveable jaw drive 64.
The efficiency of a lead screw (such as drive screw 18) is determined by how well a screw converts rotational energy (torque) into linear motion. Equation #1 can be used to compute a screw's efficiency. Using Equation #2 below, the back-driving torque can be compared to the friction of the screw transmission of gross moveable jaw drive 16 to ensure that the design cannot be back-driven and will thus hold the clamping pressures resulting from fine moveable jaw drive 64.
% E=efficiency of a lead screw
ø=helix angle of the screw thread
f=coefficient of friction
Tb=back driving torque (Nm)
F=axial load on the clamping jaw (N)
P=screw lead (m)
% E=effiency of the screw (0.2-0.5 typical for lead screws)
The automatic clamping system of the present disclosure incorporates a control unit (e.g., controller 68 and an associated display) that indicates when vise 10 is clamped, unclamped, and when in process of finding the part when readjusting to the part dimensions (e.g., in the embodiment illustrated in
To handle a high mix of parts of different geometry types, the jaws can have a V-groove in their centers to allow clamping onto cylindrical parts. Also, to hold rectangular and flat-edged parts, a small lip will be machined into the jaws that will allow the robot to hold the workpiece against the jaws. Examples of these geometries are shown in
In variations of the present disclosure, the vise may incorporate more than one moveable jaw. For example, fixed jaw 26 described above may comprise a moveable jaw articulatable in the same way as described above with respect to moveable jaw 20. Furthermore, the present disclosure can be implemented in a 3-jaw automated chuck for purely cylindrical parts (see
The automatic vise systems of the present disclosure can also be applied for both outside and inside clamping or ID (inner diameter) or OD (outer diameter) clamping of cylindrical stock by using a similar ratchet locking system mechanism used in ratchet drivers (see
In the preceding specification, the present invention has been described with reference to specific exemplary embodiments thereof. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broadest spirit and scope of the present invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.
This application claims the benefit of U.S. Provisional Patent Application No. 62/983,199, filed Feb. 28, 2020, the entire disclosure of which is expressly incorporated by reference herein.
Number | Date | Country | |
---|---|---|---|
62983199 | Feb 2020 | US |