Patent Publication Number: US-10759025-B2

Title: Positive interlock network (PIN) vise and mold

Description:
REFERENCE TO RELATED APPLICATION 
     This application claims priority from U.S. Provisional Patent Application Ser. No. 62/505,464, filed May 12, 2017, the entire content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a device and method for holding a workpiece and, in particular, relates to an adjustable vise. 
     BACKGROUND OF THE INVENTION 
     Irregularly shaped parts are frequently encountered in cast and forged components which require finishing operations. These irregularly shaped parts present significant challenges when being held with a typical vise, as shown in  FIG. 1 . These irregularly shaped parts may lack symmetry or flat surfaces or must be positioned in an orientation that complicates typical workpiece holding methods. The disadvantage of standard vise jaws, shown in  FIG. 1 , is that flat surfaces do not provide good support for round or abnormally shaped parts. Although round parts can be accommodated through the use of accessories such as V-blocks, this does not address irregular geometries. 
     SUMMARY OF THE INVENTION 
     The present invention provides a vise for holding irregularly-shaped parts with maximum functionality and minimum complexity. Referred to as the Positive Interlock Network vise, or PIN vise, it may be characterized by the following three aspects: Positive, Interlock and Network 
     The Positive aspect is characterized by the existence or presence of features, rather than by their absence. The positive aspect of the PIN vise of the present invention is that it fits around or even within the part to create a custom contour based on the features of the object being held. 
     Interlock means that two or more things engage with each other by overlapping or by the fitting of projections and recesses together. The interlock is provided by the physical barrier to movement the pins create. 
     The Network aspect is achieved through the connection and cooperation of the pin array which allows the object to be held securely. 
     The present design of the PIN vise reproduces a shape through an array of pins. In a PIN vise according to the present invention, the pins are in physical contact with each other and fit flush together, allowing the pins to be clamped from the top and held in place due to the compressive force and resulting friction created by their intimate contact. 
     According to an embodiment of the present invention, a vise includes a base and two opposed jaws. At least one of the jaws may be movable with respect to the other so that an object can be gripped therebetween. 
     The at least one of the two opposed jaws may include a frame having a bottom side and two opposed sides tapering towards the bottom side. The jaw may further include an array of polygon-shaped pins stacked in a bundle, the pins being parallel to one another and disposed on and received by the bottom side and within the frame. 
     Each pin may have a cross-sectional shape such that when slacked together, the pins fit flush with one another along a minimum functional distance lengthwise and an area defined by the frame is tiled by the pins without any substantial gaps therebetween. 
     Each pin has an inner end in cooperation for conforming to an object and gripping the object and an outer end against which the pin can be pushed. In some version, the inner end and the outer end are the same and interchangeable. 
     When stacked together, the pins may be oriented such that the pins form a network and the tapering opposed sides direct force vectors to increase a pin-to-pin clamping force. The pins may be in contact with one another to an extent such that each pin may assert a clamping force against its neighboring pins. 
     The frame may further include a top plate for clamping down on the pins such that the pins are held in place by the frame. 
     In some version, the other jaw may be a flat jaw. 
     In some version, the top plate may have a bottom surface with grooves for complementing and receiving the pins. In other versions, the top plate may have a flat bottom surface to be in contact with the flat sides of the pins. 
     In some version, the frame may include a bottom plate as the bottom side and a pair of angled plates forming the two angled sides, the bottom plate disposed between the pair of angled plates. 
     The top surface of the bottom side of the frame may be flat or with grooves for receiving the pins. The slopes of the two opposed sides of the frame are different. 
     In some version, the pins may each have an identical cross-sectional shape. The shape may be triangle, square or hexagon, or any other shape that can tile a plane without having any overlaps or leaving any gaps. 
     In some versions, the array of pins may have at least two different cross-sectional shapes. The pins within the external layer in contact with the frame may have a partial or incomplete shape of a triangle, hexagon or trapezoid, or other shapes. 
     In some version, the pins may have the same cross-sectional shape but some may have different sizes. 
    
    
     
       BRIEF DESCRIPTION OF THE INVENTION 
         FIG. 1  is a perspective view of flat jaws of a common vise; 
         FIG. 2  is a perspective view of a jaw of a positive interlock network (PIN) vise in accordance with an embodiment of the present invention; 
         FIG. 3  is an end view of the jaw in  FIG. 2 ; 
         FIG. 4  is a side view of the jaw in  FIG. 2 ; 
         FIG. 5  is a side view of a pin vise in accordance with an embodiment of the present invention; 
         FIG. 6  is a perspective view showing basic clamping on a hitch ball using a PIN vise in accordance with the present invention; 
         FIG. 7  is a perspective view of a PIN vise showing that the hitch ball in  FIG. 6  is held in place even after unclamping; 
         FIG. 8  is a perspective view of a PIN vise showing that an object can be held at a predetermined angle such as 45 degrees as shown; 
         FIG. 9A  is a schematic showing detail of the pins having a shape of a triangle; 
         FIG. 9B  is a schematic showing detail of the pins having a shape of a triangle with varying sizes; 
         FIG. 9C  is a schematic showing detail of the pins having a shape of a square oriented at a 45-degree angle with respect to a horizontal axis; 
         FIG. 9D  is a schematic showing detail of the pins having various trapezoidal shapes and that the slopes of two sides of the frame may be different; 
         FIG. 9E  is a schematic showing detail of the pins having a shape of a hexagon; 
         FIG. 9F  is a schematic showing detail of the pins having a shape of a hexagon and an hourglass; 
         FIG. 10  is a graph showing that the PIN vise in  FIG. 5  provides a higher resistance to rotation; 
         FIG. 11  is a graph showing that the PIN vise in  FIG. 5  provides a higher resistance to sliding; 
         FIG. 12A  is a schematic showing the steps of using a PIN Mold with an array of pins to replicate a desired geometry; 
         FIG. 12B  is a schematic showing that the pins can be finish machined to create a smooth surface; and 
         FIG. 12C  is a schematic showing that the hole size can be tailored for each application by choosing pins with appropriate corner radii. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The concept of the design of a PIN vise in accordance with an embodiment of the present invention is shown in  FIGS. 2-5 . 
       FIG. 5  shows an example of a pin vise  300  according to an embodiment of the present invention. The pin vise  300  may be mounted on a base  302 . The vise includes two jaws  100 ,  200 . Only one of the jaws can be moved relative to the base so that the distance between the jaws  100 ,  200  can be adjusted. Alternatively, both jaws may be movable. When an object is placed between two jaws, the jaw  100  is moved to approach the jaw  200 , the pins will come in contact with the object and form a shape of the object. The object will be eventually clamped by the pins. 
     The two jaws may be same. The jaws may also be different. For example, a vise may include a jaw with pins and a flat jaw. A vise may include two jaws with pins but the pins on one jaw may be different from the pins on the other jaw.  FIGS. 2-4  show different views of one of the jaws  100  of the pin vise  300  in  FIG. 5 . The jaw  100  includes a frame  140  and a bundle of pins  114  clamped within the frame. The frame defines an area  106  which may take the shape of an inverted trapezoid. The frame  140  may be an integral piece including several sections. The frame may also be comprised of several pieces connected by connecting means such as screws. 
     In one embodiment, the frame  140  includes a bottom side  108  and two opposed sides  110 ,  110 ′ tapering towards the bottom side  108 . The tapered sides  110 ,  110 ′ may have the same or different slopes. The bottom side may have an upper surface having grooves  112  that match the shapes of the pins for the pins to rest on. 
     A bundle of pins are clamped by the frame. The pins may have substantially the same cross-sectional shape. The pins may also have different cross-sectional shapes so long as when stacked together, the side surfaces of the pins are in contact with one another and there are no substantial gaps between the pins. 
     The pins may have the same length or different lengths. Each pin has two ends and multiple side surfaces. Two ends may be similar and not distinguishable. Each pin may have a substantially same dimension along its length. When the pins are bundled together, the pins are parallel to one another. 
     The frame may further include a top brace placed on the top of the pins. The top brace may be tightened by threading members such as screws. The top brace works in corporation with the opposed tapering sides and the bottom side for clamping down the pins such that the pins are held in place. 
     When the pins are clamped in place within the frame, one end may be called an outer end. The end for gripping the object may be called an inner end. 
     The slope of the tapering sides of the frame may be selected according to the shape of the pins and the orientation of the pins. In one example, the pins are oriented such that each side of the pin is pushing against a side surface of another pin or the frame. There will be no side which is oriented vertically. In other words, all sides of the pins are oriented at an angle with respect to a vertical axis. 
     In one embodiment, as shown in  FIG. 9C , the pins are square pins which are oriented such that each side of the pins is at a 45 degree angle with respect to a vertical axis. The slope of the tapering sides of the frame is also selected to be 45 degrees with respect to either the horizontal axis x or the vertical axis y in order to be aligned with the sides of the pins. At the bottom, half-triangle shaped pins  932  can be utilized so that the bottom side  934  is flat without any grooves. Likewise, half-triangle shaped pins  936  can be used at the top so that the top side  938  is flat without any grooves. 
     There are two principal forces to assess: 1) the clamping force which retains the pins in a desired position (Pin Clamping Force), and 2) the damping force of the vise on the part to be held (Vise Clamping Force). The pin clamping force is determined by the force applied to the top brace, achieved by simple screw force for example, and the vise clamping force is applied using a vise handle, seen in  FIG. 5 . 
     The jaw may include a mounting plate  104 . The mounting plate  104  is similar to a flat jaw  10  of a common vise shown in  FIG. 1 . In one example, the mounting plate  104  is connected to the base by threaded members. Although no new vise must be purchased, a dedicated vise body could be used for more critical applications where greater rigidity is needed. As an add-on to existing standard flat vises, the benefit of a vise in the present invention is the easy incorporation into any current machine shop or production facility. 
     In another embodiment, the vise is comprised of a number of independent members. A pair of angled plates  128 ,  130  resting on the mounting plate  104 , along with the mounting plate, form a tapered frame in which an array of pins  114  are held. Directly on the top of the mounting plate and between the pair of angle plates is a fixed plate  132 , the surface of which is designed with grooves  112  that match and receive the shape of the pins. Likewise, an adjustable insert plate  124  is designed with a surface having grooves  126  that mate to and receive the shape of the pins to be disposed between the array of pins and a top brace  120 . 
     The adjustable insert plate  124  is not rigidly held, but rather it rests on top of the pins. It can be clamped down by simple screw force or by any other standard means such as cam-action, toggle or hydraulic clamping. The top brace  120  may be clamped by a two-point clamping using two threaded members or by a three-point clamping using three threaded members. The top brace  120  may also be clamped by a uniform clamping by a toggle. The adjustable insert plate  124  may be made from materials with high hardness, such as brass or steel, for the benefit of its rigidity. 
     To set the vise, an object is placed between two jaws. In the example shown in  FIG. 6 , the object is a round ball  202 . This example was chosen to exemplify a contoured surface. In an ideal circumstance, both sides of the jaw would be engaged. The outer ends of the pins from both of the jaws are pushed by hand towards the object until all the pins fit around the object and the object is surrounded to the level desired. Once this is achieved, the pins are locked into position. One of the jaws can be moved along the track by rotating the vise handle. As the jaw is retracted, the object is continued to be held by the other jaw, as shown in  FIG. 7 . If the part design changes slightly or significantly, the process can be easily repeated to reset the shape. The vise of the present invention can eliminate the need of casting a jaw. This saves time and money. 
     The geometry of the pins can act as a locating surface for elevating a part or holding flat parts at a particular angle, e.g., a 45 degree angle using the square pins, as shown in  FIG. 8 . In an existing standard vise with flat jaws, an object is often likely to be slipping when the clamp is being tightened. The vise of the present invention can also be used to prevent the object from slipping and rotating relative to the vertical axis. 
     One of the jaws may be flat  400 , working together with a pin vise jaw  100 , as shown in  FIG. 8 . 
     Many variations may be applied to the design. Instead of using square pins, other shapes may be used. The shapes of the pins may be triangle, square, rectangle, hexagon, or any shape that can tile a plane without having any overlaps or leaving any appreciable or substantial gaps. The size of the pins can be varied to produce “high-definition” workpiece holding. The pin material can be readily changed to a softer type for delicate workpieces. The length of the pins can be adjusted as well. 
       FIGS. 9A-9F  illustrate several examples of various shapes of the pins. Note that the side edges in some cases are a cut plane and not representing the entire array.  FIG. 9A  shows an array of triangle-shaped pins. The pins are oriented such that each triangle is symmetric with respect to the vertical axis y. The slope of the sides  904  of the frame is selected to be at 30 degrees relative to the vertical axis so that the sides of the frame are aligned with one side of the pins.  FIG. 9B  shows an array of triangle-shaped pins having two different sizes  906  and  908 . The pins having larger sizes  908  may be arranged at the bottom to provide more support for smaller pins on the top. The pins on the external layer  901  may have an incomplete shape to accommodate the shape of the boundary. 
       FIG. 9D  shows an array of the pins having various non-identical trapezoid shapes  914 . The slopes of two sides  916 ,  918  may be different, as the angles a and b might be different to accommodate different shapes of the pins. 
       FIG. 9E  shows an array of hexagon-shaped pins  920 . The pins are oriented such that each hexagon is symmetric with respect to the vertical axis y and one side of the hexagon is aligned with the horizontal axis x. The slope of the sides of the frame is selected to be at 60 degrees relative to the horizontal axis x so that the sides  922 ,  924  of the frame are aligned with the pins. 
       FIG. 9F  shows an array of pins having either a hexagon shape  926  or an hourglass shape  928  complementing one another, leaving no gap or overlap within the area within the frame. 
     The presently disclosed design makes exchange of the pins extremely simple, and the exchange can be done within minutes to reset the pin array. With the addition of a simple setup jig, that time could be reduced greatly. 
     The PIN vise was found to be more resistant to an applied torque on a spherical part than flat jaws or the more commonly used V-blocks. As shown in  FIG. 10 , the flat jaws only exceed the PIN vise at high clamping pressures where the ball surface was physically deformed to create a flat spot. By increasing the pin clamping force so that higher vise clamping force can be used, it is expected that the benefit can be extended. In addition to the torque resistance, translation was also tested using a load frame to measure force and displacement simultaneously, as shown in  FIG. 11 . In these tests, the PIN vise has been found to exhibit higher retaining force than standard flat jaws, and the only limit reached is the rigidity of the vise jaws, not actual slipping of the ball gripped by the pins. That is, the jaws were found to flex before the ball slips. Additional testing identified that it is not the pins that flex, but the entire assembly, and reversal of the applied force elastically restores the original position. The top brace can be of increased cross-sectional area to resist bending, and the whole assembly can be thicker such that the design can be more robust. 
     Many possibilities of applications of the present invention exist outside of workpiece holding in manufacturing. This basic design can be applied in any industry that requires complex surfaces which change on a regular or semi-regular basis. For example, the technology could be modified and advanced for use in applications such as vacuum forming or molding for packaging in shipping, where the product to be shipped is used to create a positive mold and the pins are retained in the shape by clamping. Large companies in the thermoforming industry are actively engaged in research to develop technology to eliminate the need for back drilling. Some have attempted to use nano-foamed metals instead of traditional castings as the starting block for the mold piece. The holes are too small, however, and clog too quickly at the molecular level as the device is used, even in clean rooms. Alternatively, 3D printing is capable of complex geometries, but it is limited and/or costly for production operations. 
     The disclosed design has been demonstrated to allow for fine detail replication, and that without any refinement for the purpose. Indeed, the very same prototype, which was used to hold objects, was also used in vacuum forming for proof-of-concept. The greatest drawback is that highly smooth objects cannot be created as with machined molds. Although it is potentially viable that the pins may be machined and still provide some benefit by the reduction in hole drilling, non-critical surface detail may not require such processing. 
     For example, when shipping items, the appearance and detail replication is not of first-importance. Function is the primary necessity. Competitor products in the packing industry include enclosed-bag foam, bubble wrap, brown paper wadding, air packs, Styrofoam peanuts, and biodegradable peanuts. These items have a similar function of filling volume rather than directly forming to the product(s). If a customizable form could be created to shape sheet plastic to any desired geometry, the space requirement for storage and the commensurate waste would be greatly reduced. 
       FIG. 12  illustrates an example of the operation of a PIN mold. The operation of the PIN Mold requires a desired geometry which is placed against pins to move them relative to each other. Once the pins are moved, they are clamped in place to hold the shape. The molded shape can be used on either side to create a negative or positive mold. The plastic sheet is heated and formed to the molded pins creating a rough replication of the shape, as shown in  FIG. 12A . In cases that require a smoother surface, the pins can be finish machined, as shown in  FIG. 12B . The hole size determines the flow of air and can be chosen based on pin geometry, as shown in  FIG. 12 . 
     As will be clear to those of skill in the art, the embodiments of the present invention illustrated and discussed herein may be altered in various ways without departing from the scope or teaching of the present invention. Also, elements and aspects of one embodiment may be combined with elements and aspects of another embodiment. It is the following claims, including all equivalents, which define the scope of the invention.