SELF-CENTERING ACCESSORIES FOR AN INDUSTRIAL ENVIRONMENT

Abstract: A new accessory (10) is configured to facilitate location of the axis of a generally cylindrical hole that has been drilled or otherwise formed in a workpiece. The accessory includes, at one end, an arrangement (22) configured to maintain the accessory centered in the hole when the arrangement has been inserted into the hole, and at least proximate a second end, a second arrangement (20) that is also configured to maintain the accessory centered in the hole when the first arrangement has been inserted into the hole. The accessory is preferably of sufficient length so that, when the first arrangement is positioned in the hole, the second end is observable from a position external to the workpiece, and the axis of the hole can be determined by determining the center of the second end.

Description: SELF-CENTERING ACCESSORIES FOR AN INDUSTRIAL ENVIRONMENT FIELD OF THE INVENTION The invention relates generally to the field of tools and accessories, and more particularly to accessories for locating axes of holes drilled or otherwise formed in workpieces. BACKGROUND OF THE INVENTION In a number of industrial applications, it is necessary to accurately determine the location of the axis of a hole that has been drilled or otherwise formed in the surface of a workpiece. For example, in industrial metrology, which is directed to measurement of industrial parts, there is often a necessity to measure the location of the theoretical axis of a drill that will be used to form a hole in a workpiece. This is difficult to accomplish for a number of reasons. For example, when holes of a particular diameter are formed, they are formed with a selected tolerance both as to their diameter and also as to their circularity or roundness, which may differ at different depths along the depth of the hole. In addition, since the edges of a hole will be rounded to some degree, which may differ at various points around the edge, the location of the axis of a hole may differ from the center of the circle defined by the rim. In addition, if the axis hole is not perpendicular to the workpiece's external surface, or if the surface is not flat, the rim of the hole will not form a circle, which can exacerbates the difficulty of determining the location of the axis. SUMMARY OF THE INVENTION The invention provides a new and improved accessory that can be used to locate the axis of a hole that has been drilled or otherwise formed in a workpiece. In brief summary, the invention provides a new accessory configured to facilitate location of the axis of a generally cylindrical hole that has been drilled or otherwise formed in a workpiece. The accessory includes, at one end, an arrangement configured to maintain the accessory centered in the hole when the arrangement has been inserted into the hole, and at least proximate a second end, a second arrangement that is also configured to maintain the accessory centered in the hole when the first arrangement has been inserted into the hole. The accessory is preferably of sufficient length so that, when the first arrangement is positioned in the hole, the second end is observable from a position external to the workpiece, and the axis of the hole can be determined by determining the center of the second end. In one embodiment, the first arrangement is in the form of a plurality of leaf springs disposed symmetrically around an axis, which leaf springs are configured to, after they have been inserted into the hole, provide a symmetric force on the sidewalls of the hole, the symmetric force maintaining the one end centered in the hole. In that same embodiment, the second arrangement is in the form of a cap that has a lower surface that, when the leaf springs have been fully inserted into the hole, seats on the exterior surface of the workpiece. The leaf springs are provided with sufficient stiffness so that, when the lower surface of the cap is seated on the workpiece, the cap will also be centered on the axis of the hole. In a second embodiment, the first arrangement is also in the form of a set of leaf springs disposed symmetrically around the axis, which leaf springs are configured to, after they have been inserted into the hole, provide a symmetric force on the sidewalls of the hole. In the second embodiment, the second arrangement is in the form of a second set of leaf springs formed proximate the second end. Like the first set of leaf springs, the second set of leaf springs are disposed symmetrically around the axis, which leaf springs are configured to, after they have been inserted into the hole, provide a symmetric force on the sidewalls of the hole. The two sets of leaf springs maintain the axis of the accessory conform to the axis of the hole. The accessory may also be provided with a cap that may be centered on the accessory's axis, or that may be provided with a marking centered on the accessories axis, which can be used to determine the axis of the accessory and, thus, the axis of the hole. BRIEF DESCRIPTION OF THE DRAWINGS This invention is pointed out with particularity in the appended claims. The above and further advantages of this invention may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which: FIG. 1 is a side elevational view of one embodiment of a self-centering accessory, constructed in accordance with the invention; FIG. 2 is a sectional view of a portion of the accessory depicted in FIG. 1; FIG. 3 is a side elevational view of the self-centering accessory depicted in FIG. 1 , as positioned in a hole formed in a workpiece; FIG. 4 is a side elevational view of a second embodiment of a self-centering accessory, constructed in accordance with the invention; and FIG. 5 is a side elevational view of a portion of a modification of the accessory depicted in FIG. 1. DETAILED DESCRIPTION OF AN ILLUSTRATIVE EMBODIMENT FIG. 1 is a side elevational view of one embodiment of a self-centering accessory 10, constructed in accordance with the invention. With reference to FIG. 1 , the self-centering accessory 10 is to be used to facilitate the location of the axis of a cylindrical hole 11 that has been drilled or otherwise formed in a workpiece 12. The hole 11 has an axis 13 that is orthogonal to an external surface 14 of the workpiece. At least a portion of the hole 11 has a cylindrical interior surface 15, although a portion of the hole 11, particularly a portion relatively distant from the external surface 14, need not be cylindrical. If, for example, the hole 11 has been drilled in the workpiece 12, the hole 11 may have a conical lower surface 16. Generally, the accessory 10 comprises a cap 20 having depending therefrom a self-centering arrangement 21. The self-centering arrangement 21, in turn, is in the form of a plurality of leaf springs 22(1), 22(2),... (generally identified by reference numeral 22(n)) disposed symmetrically around an axis 23. Each leaf spring 22(n), in turn, has an outwardly-extending projection 24(n). Preferably, the outermost points of the proj ections 24(n) are also symmetrically disposed around the axis 23. The cap 20 is preferably in the form of a cylinder that is either coaxial with the axis 23, and/or that has an element on the upper surface 25 thereof (not separately shown) identifying the location of the axis 23. Such an element may include, for example, a marking such as a dot located at the axis 23, two or more lines that cross at the location of the axis 23, and other types of markings that will be apparent to those skilled in the art. The upper surface 25 is preferably orthogonal to the axis 23 to facilitate locating the axis of a hole with which the accessory 10 is used, as will be described below in connection with FIG. 3. FIG. 2 depicts a sectional view of aportion of the accessory 10, in particular, of the cap 20, along with a portion of the self-centering arrangement 21 proximate thereto. With reference to FIG. 2, the cap 20 has a lower surface 26 that is orthogonal to the axis 23, which surface 26 is preferably provided with a circular recess 27 formed proximate the self-centering arrangement 21. The purpose of the recess 26 will be made clear below. As noted above, the self-centering accessory 10 is to be used to facilitate the location of the axis of a cylindrical hole 11 that has been drilled or otherwise formed in a workpiece 12. This will be illustrated in connection with FIG. 3. With reference to FIG. 3, that FIG. depicts the accessory 10 after having been inserted into the hole 11 formed in workpiece 12. As shown in FIG. 3, the lower end of the self-centering arrangement 21 of the accessory 10 is inserted into the hole 11 until the lower surface 26 of the cap 20 is seated on the external surface 14 of workpiece 12. Preferably, to accommodate insertion of the self-centering arrangement 21, the diameter of the cylinder defined by the leaf springs 22(n) will be smaller than the diameter of the hole 11. However, the projections 24(n) will be dimensioned to extend far enough outwardly from the respective leaf springs 22(n) that they will cause the leaf springs 22(n) to flex and deform. Preferably, the leaf springs 24(n) will be formed of a material that is relatively stiff so that they will be deformed in a uniform manner, in which case the axis 23 of the accessory 10 will correspond to the axis 13 of the hole 11. The self- centering arrangement 21 will preferably be shorter than, or at most as long as, the cylinder formed by surface 15 so that the arrangement 21 will not extend into the portion of the hole 11 that is defined by conical surface 16, since the surface may not be symmetric around the axis 13. As noted above, the lower surface 26 of the self-centering accessory 10 is provided with a circular recess 27 formed proximate the self-centering arrangement 21. The recess can accommodate a ridge or bur that may be formed along the upper boundary of the hole 11 in the external surface 14 of the workpiece 12 and that may make it difficult or impossible to seat the lower surface 26 of the accessory 10 onto the external surface 14 around its entire circumference. It will be appreciated that, with the lower surface 26 of the cap 20 has been positioned on the external surface of the workpiece 12, the axis 23 of the self-centering accessory 10 will correspond to the axis 13 of the hole 11, and so an observer can determine the location of the axis of the hole 11 in relation to the center of the upper surface 25 of the cap 20. Alternatively, if the upper surface 25 of the cap 20 is provided with a mark (not separately shown) indicating the location of the axis 23 of the accessory 10, the observer can determine the location of the axis of the hole 11 in relation to the position of the mark. As noted above, the leaf springs 22(n) will preferably be formed of a relatively stiff material. In addition, preferably the projections 24(n) will also be formed of a relatively stiff material that will neither deform nor abrade when the self-centering arrangement 21 is inserted into the hole 11. In one embodiment, the entire accessory 10 is formed from a hard and flexible material, such as an H900 heat-treated 17-4PH steel. The material from which the accessory 10 is formed preferably has high yield strength to generate a relatively force of, illustratively in one embodiment, on the order of 1100 mega Pascals. On the other hand, the material from which the accessory is formed, and the accessory's dimensions relative to the dimension of the hole 11 in which the accessory 10 is used, preferably are such that the material's yield-point stress is exceeded. The extent to which the projections 24(n) project from their respective leaf springs 22(n) will preferably provide that the diameter of the self-centering arrangement 21 across the projections 24(n) will be such that, when the self-centering arrangement 21 is inserted into the hole 11, the leaf springs 22(n) will not be deformed by an extent that would provide that the yield point of the material would be exceeded. It will be appreciated that the leaf springs will also be dimensioned laterally so that, when they are flexed when being inserted into the hole 11 , the leaf springs 22(n) will not interfere with each other. As indicated above, the accessory 10 described above in connection with FIGS. 1 through 3 is useful in connection with locating the axis of a hole 11 whose axis 13 is perpendicular to the external surface 14 of the workpiece 12 in which the hole 11 is formed. FIG. 4 depicts a portion of an accessory, in particular, a self-centering arrangement 30, that may be used in connection with a hole whose axis is not perpendicular to the external surface 14 of the workpiece in which the hole is formed. The self-centering arrangement 30 includes a plurality of sets of leaf springs 31 and 33, each set including a plurality of leaf springs 34(1) through 34(N) (generally identified by reference numeral 34(n)) and 35(1) through 35(N) (generally identified by reference numeral 35(n)), each of which has a respective projection 36(n), 37(n) extending therefrom. A cap (not shown) similar to cap 20 may be provided attached to the upper end 36 of the self-centering arrangement 30. The leaf springs 34(n) positioned at the lower end of the self-centering arrangement are similar to the leaf springs 24(n) of accessory 10 and serve to center the lower portion of the accessory 10 in a hole when the accessory that includes self-centering arrangement 30 is inserted therein. With accessory 10, positioning the lower surface 26 of cap 20 on the external surface 14 of the workpiece 12 helps to maintain the upper portion of the accessory 10 centered in the hole 11. The upper leaf springs 35(n) perform a similar function in connection with an accessory that includes the self-centering arrangement 30 depicted in FIG.4. The combination of the lower and upper leaf springs 34(n), 35(n) effectively centers the length of the self-centering arrangement 30 along the axis of the hole into which it is inserted. Accordingly, an accessory that includes a self-centering arrangement 30 can be used to locate the axis of a hole, regardless of the orientation of the axis relative to the external surface of the workpiece in which the hole is formed. FIG. 5 depicts a detail, partially in section, of an alternate embodiment of a cap, identified by reference numeral 40, that can be used in connection with the accessory 10 (FIGS. 1-3), particularly in connection with holes in workpieces consisting of any of a number of magnetic materials. The cap 40 includes an upper surface 45 and a lower surface 46, which are similar to corresponding surfaces 25 and 26 of the cap 20 depicted in FIG. 1. The cap 40 may also include a circular recess similar to recess 27 described above in connection with FIG. 3. In addition, cap 40 includes a plurality of permanent magnets 41 in cavities that are preferably disposed symmetrically around the axis 43 of the accessory that includes the cap 40. If the accessory that includes cap 40 is used in a hole formed in a workpiece that consists of a magnetic material, the magnets 41 will assist in holding the cap 40, particularly its lower surface 46, tightly against the external surface 14 of the workpiece. It will be appreciated that, instead of providing a plurality of permanent magnets, the cap 40 may make use of a single toroidally-shaped magnet disposed in a toroidally-shaped cavity. In addition, as shown in FIG.5, cap 40 is provided with an axial hole 42 formed therein, with a reflective target 44 inserted therein. The reflective target 44 includes an upper disk 47 having depending therefrom a projection 48. The disk 47 and projection 48 are co-axial with one another. The projection 48 is inserted into the hole 42 formed in the cap 40. The exposed upper surface of disk 47 (not separately shown) may be coated with a reflective layer and the location of the axis 43 of the hole can be determined by identifying the center of the disk 47 using the reflective layer. Alternatively or in addition, the exposed upper surface of the disk 47 may be provided with crosshair target centered on the axis 43. The invention provides a number of advantages. In particular, the invention provides an accessory that can be used to facilitate the location of the axis of a hole formed in a workpiece. Several embodiments have been described, which can be used to locate the axis for holes that are perpendicular to the external surface of the workpiece, as well as at other angular orientations. In addition, the holes can be formed in surfaces on the workpiece that are disposed vertically, horizontally, or any other orientation. In addition, although the accessories described herein have been described in connection with locating axes of holes having cylindrical sides 15, accessories constructed in accordance with the invention can be used in locating axes of holes having a variety of configurations. For example, accessories in accordance with the invention can be used in locating axes of holes that taper, that are formed with multiple diameters, such as may be formed by a counterbore drill, and the like, providing that the accessory used to locate the axis of the respective hole be provided with leaf springs with projections that provide a force on the sidewalls of the hole that is symmetric around the hole's axis. It will be appreciated that numerous changes and modifications may be made to the accessories described herein. For example, the dimensions of an accessory, including the diameter of the cap and the self-centering arrangement can depend on the diameter of the hole with which the accessory is to be used, or diameters if the hole tapers or is formed with multiple diameters. In addition, the length of the self-centering arrangement will depend on the depth of the hole. The foregoing description has been limited to a specific embodiment of this invention. It will be apparent, however, that various variations and modifications may be made to the invention, with the attainment of some or all of the advantages of the invention. It is the object of the appended claims to cover these and such other variations and modifications as come within the true spirit and scope of the invention. What is claimed as new and desired to be secured by Letters Patent of the United States is:

Claims: CLAIMS 1. An accessory configured to facilitate location of the axis of a generally cylindrical hole that has been formed in a workpiece, the accessory including at one end, an arrangement configured to maintain the accessory centered in the hole when the arrangement has been inserted into the hole, and at least proximate a second end, a second arrangement that is also configured to maintain the accessory centered in the hole when the first arrangement has been inserted into the hole, the accessory being of sufficient length so that, when the first arrangement is positioned in the hole, the second end is observable from a position external to the workpiece, and the axis of the hole being determinable by determining the location of the center of the second end. 2. An accessory as defined in claim 1 in which the first arrangement is in the form of a plurality of leaf springs disposed symmetrically around an axis, which leaf springs are configured to, after they have been inserted into the hole, provide a symmetric force on the sidewalls of the hole, the symmetric force maintaining the one end centered in the hole. 3. An accessory as defined in claim 2 in which the second arrangement is in the form of a cap that has a lower surface that, when the leaf springs have been fully inserted into the hole, seats on the exterior surface of the workpiece. 4. An accessory as defined in claim 3 in which the leaf springs are provided with sufficient stiffness so that, when the lower surface of the cap is seated on the workpiece, the cap will also be centered on the axis of the hole. 5. An accessory as defined in claim 2 in which the second arrangement is in the form of a second set of leaf springs formed proximate the second end. Like the first set of leaf springs, the second set of leaf springs are disposed symmetrically around the axis, which leaf springs are configured to, after they have been inserted into the hole, provide a symmetric force on the sidewalls of the hole, the two sets of leaf springs maintaining the axis of the accessory conform to the axis of the hole.

Inventors: GURA RAM, LASKER ISRAEL, GURA, RAM, LASKER, ISRAEL
Applicants: COGNITENS LTD, COGNITENS, LTD.
Application year: 2001
Main classification: B23B
IPC codes: B23B49