Patent Publication Number: US-7707731-B2

Title: Marking device for rotational machines

Description:
CROSS REFERENCE TO RELATED APPLICATION 
   This application does not claim priority from any other application. 
   TECHNICAL FIELD 
   This invention pertains to a marking device for use on rotating machines to impart markings such as words and numbers in metal parts and other objects. 
   BACKGROUND OF THE INVENTION 
   For many manufactured work pieces it is desirable or required to place more permanent types of markings or identifying symbols and indicia there-on. Examples of such markings might be a trademark, a manufacturer, a part number, or some sort of design element. 
   In the more typical situation today, the parts are first manufactured by machining or otherwise and then marked by a separate stand alone marking or stamping device which must be separately acquired by the manufacturer. This is obviously an additional expense and an additional step in the manufacturing process which is desirable to eliminate. 
   It is desirable to have a tool or device which accomplishes the marking but eliminates the need to acquire or possess an additional marking device. Such a marking device may for instance utilize the drive or rotation from a CNC or other machine or device, and the marking device convert the rotation provided thereby to an axial movement to impart markings on a work piece. The programming and X-Y movement (as well as the Z plane) capability and programming of the CNC or other machine may then be utilized to accomplish the marking task. While there is a prior marking device which utilizes a CNC or other machine for its rotation to impart markings on a work piece, as described in U.S. Pat. No. 6,427,357, it does not provide all the desirable features, advantages and drive mechanisms as this invention. U.S. Pat. No. 6,427,357, for instance, utilizes an off-set marking stylus (off-set from the axis of rotation of the spindle from the CNC machine). From a programming, process control and mechanical perspective, it is desired to have a marking device wherein the stylus is at or very near the axis of rotation of the machine or device providing the rotation (substantially or approximately co-axial), such as a CNC machine or other device. 
   It may also be desirable from a reliability and wear perspective to utilize impact ball (preferably impact ball) technology to transform the rotation force provided by the CNC machine (or other machine tool) to axial impact force on a stylus and rapid axial movement of a stylus at a relatively low revolutions per minute (RPM) in order to strike two or more times per revolution of the CNC with sufficient force to throw it against the work piece and thereby produce the indentations, marks and/or dots. 
   It is an object of some embodiments of this invention to provide a reliable, longer lasting, marking device to convert the rotation of the CNC or other machine to axial impact force on a stylus marking a work piece. 
   It is a further object of some embodiments of this invention to provide such a marking device which reliably provides an impact force downward on the stylus marking point, which utilizes a more reliable mechanism in hammering the stylus down, and which may reduce wear. 
   While the invention was motivated in addressing certain identified problems or desired advantages, it is not so limited. The invention is only limited by the accompanying claims as literally worded, without interpretative or other limiting reference to the specification, and in accordance with the doctrine of equivalents. 
   Other objects, features and advantages of this invention will appear from the specification, claims, and accompanying drawings which form a part hereof. In carrying out the objects of this invention, it is to be understood that its essential features are susceptible to change in design and structural arrangement, only practical a preferred embodiment being illustrated in the accompanying drawings, as required. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Preferred embodiments of the invention are described below with reference to the following accompanying drawings. 
       FIG. 1  is a front elevation view of one example of an embodiment of this invention; 
       FIG. 2  is an elevation cross-sectional view of an example of an embodiment of this invention; 
       FIG. 3  is a cross-sectional elevation view of the embodiment of this invention illustrated in  FIG. 2  with the stylus in an upward or retracted position; 
       FIG. 4  is a cross-sectional elevation view of the embodiment of this invention illustrated in  FIG. 3  with the stylus in a downward, extended or striking position; 
       FIG. 5  is an exploded perspective view of one example of a hammer carrier or guide, hammer and other components which may be utilized in some embodiments of this invention, showing two hammer pins; 
       FIG. 6  is an exploded perspective view of one example of a hammer carrier, hammer, hammer pin and other components which may be utilized in some embodiments of this invention, showing four hammer pins; 
       FIG. 7  is a top view of impact ball holder with four impact balls shown; and 
       FIG. 8  is a part cross-sectional view of the impact ball holder with impact balls and impact plate shown in an exploded view above the cross-sectional of the impact ball holder. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Many of the fastening, connection, manufacturing and other means and components utilized in this invention are widely known and used in the field of the invention described, and their exact nature or type is not necessary for an understanding and use of the invention by a person skilled in the art or science; therefore, they will not be discussed in significant detail. Furthermore, the various components shown or described herein for any specific application of this invention can be varied or altered as anticipated by this invention and the practice of a specific application or embodiment of any element may already be widely known or used in the art or by persons skilled in the art or science; therefore, each will not be discussed in significant detail. 
   The terms “a”, “an”, and “the” as used in the claims herein are used in conformance with long-standing claim drafting practice and not in a limiting way. Unless specifically set forth herein, the terms “a”, “an”, and “the” are not limited to one of such elements, but instead mean “at least one”. 
     FIG. 1  is a front elevation view of one example of an embodiment of this invention.  FIG. 1  shows the dot marking device  100 , CNC machine component  101  which provides rotation as indicated by arrow  106  to the dot marking device  100 . The CNC machine provides X-Y lateral movement and Z axis movement.  FIG. 1  further shows marking device body  102  (non-rotating), spring-loaded stop arm  103 , stylus housing  104 , marking device rotating body  108 , non-rotating housing cover  107 , and work piece  105 . The stylus housing  104  and housing cover  107  may also be considered part of the overall housing of the marking device. 
     FIG. 2  is an elevation cross-sectional view of an example of an embodiment of this invention.  FIG. 2  shows the dot marking device  100  wherein the CNC machine is rotating the shank or machine spindle interface  120  as indicated by arrow  106 , thereby rotating spin body portions  108  while device body  102  is stationary as stop arm  103  prevents its rotation.  FIG. 2  further illustrates hammer  128 , hammer pins  133 , hammer pin guide  135  and hammer guide  139  within non-rotating hammer carrier  140 , with hammer spring  138  providing the biasing force toward the retraction of the hammer  128 . 
   It will be appreciated by those of ordinary skill in the art that the machine spindle interface  120  shown in this example or embodiment, is a shank or straight shank; however any one of a number of other interfaces may be utilized depending on what machine spindle the embodiment is being used with. It may for example but not by way of limitation, be referred to as an adapter, a taper mount, a threaded mount, or a straight shank, with no one being required to practice the invention. In some other examples a second adapter piece may be provided to further adapt the machine spindle interface  120  to the machine spindle, all within the contemplation of this invention and all as known in the art. 
   As can be seen from  FIG. 2 , impact balls  126  and  127  are in an impact ball holder  125  comprised of holder side walls and impact ball plate  129  (which is shown in  FIG. 7  for a four impact ball configuration) for impact ball  126  and holder side walls and impact ball plate  129  for impact ball  127 .  FIG. 2  further illustrates a small shoulder  125   a  on holder side walls  125  which retains the impact balls  126  and  127  in that location while still allowing them to rotate. The small shoulders are also believed to reduce the wearing on the surface of the hammer carrier  140  and/or hammer pins  133 . It should also be noted that while two impact balls  126  and  127  are shown in  FIG. 2 , more balls may be used in more compartments in order to achieve the operating characteristics desired, such as more strikes per minute if four impact balls are used, or six impact balls are used, all within the contemplation of this invention. While it is preferred that the impact balls be spherically shaped and made of suitable steel or other metal, it should be noted that this invention is not limited to any particular material. 
   As the machine spindle interface  120  is rotated as shown by arrow  106 , this causes the impact ball holder  125  to rotate and causes the impact balls  126  and  127  to impact hammer pins  133 , thereby driving the hammer  128  downwardly against the spring biased force provided by spring  138 , and consequently throwing or pounding stylus  121  downwardly as indicated by arrow  171 . The stylus point  122  is thrown downwardly to impart indentations, dots or markings on a work piece. The downward throwing of the stylus overcomes the force of the stylus spring  138  holding it and moves the stylus  121  downward out of the stylus housing  104  to hit the work piece (an extended position), and then the hammer spring  144  force pushes the hammer back upward and the force from the stylus spring  144  pushes the stylus  121  back upward and into the stylus housing  104  (into a retracted position), in a reciprocating motion. The stylus  121  is shown co-axial or approximately co-axial with the machine spindle interface  120  within reasonable tolerances. 
   While it will be appreciated by those of ordinary skill in the art that any one of a number of different materials may be utilized for the components described herein, in some embodiments the hammer pin axle  134  may be comprised of aluminum bronze, as well as the hammer  128 . The placement of the hammer pins  133  on hammer pin axle  134  gives the hammer pins  133  the ability to rotate as they are struck by the impact balls, thereby potentially spreading out the wear over the entire circumference and reducing the wear on the hammer pins  133  and/or on the impact balls  126  and  127 . 
     FIG. 2  further shows that the hammer  128  in this embodiment includes an impact portion  162  which is the impact portion that is thrown into and pounds the top of stylus  121 . Stylus spring  144  provides resistance from the downward movement of the stylus  121  and then asserts the biasing force which moves the stylus  121  vertically to return to its retracted position after the over-powering force imparted by the hammer  128  ceases. The stylus  121  is thrown downwardly to an extended position by the impact of the hammer  128  overcoming the biasing force of the stylus spring  144 , in what may be referred to as a reciprocating motion. While the terms retracted position and extended position are used herein, they do not refer to any one specific position, but instead may vary with the application of the invention. For instance the extended position for a given marking may be any one or more specific positions of extension. 
     FIG. 2  also illustrates the rotational buffer between rotating and non-rotating components, as described more fully herein. Bearings  137  combine with wall  152  and  153  to provide an interface between the spindle interface  120  and the non-rotating housing for example. Said interfaces are well known and used in the art and will not therefore be described in more detail hereon. 
     FIG. 3  is a cross-sectional elevation view of the embodiment of this invention illustrated in  FIG. 2  with the stylus in an upward position, which may also be referred to as a retracted position. The like numbered items in  FIG. 3  are the same as those in  FIG. 2  and will not therefore be repeated here.  FIG. 3  illustrates hammer pin cavity  135 , which is also a hammer pin guide, and a distance between the bottom of hammer pin cavity  135  and the hammer pins  133  as represented by distance  161 . The hammer pins  133  are shown overlapping impact balls  126  and  127  and as the impact balls  126  and  127  rotate about the machine spindle interface axis with the spindle, the impact balls  126  and  127  impact the hammer pins  133  causing them to be thrown or driven downwardly as the outer arcuate or curved surface of the impact balls  126  and  127  interact with the generally cylindrical outer striking surface of hammer pins  133 . This may cause both the impact balls  126  and  127 , and the hammer pins  133  to rotate about their axis while causing the downward movement of the hammer pins  133 , the downward movement of the hammer into the stylus  121  and consequently the downward movement of the stylus  121  for imparting a dot, indentation or marking as desired on a work piece. 
     FIG. 4  is a cross-sectional elevation view of the embodiment of this invention illustrated in  FIG. 3  with the stylus in a downward, extended or a striking position (into the work piece). The like numbered items in  FIG. 4  are the same as those in  FIG. 2  and  FIG. 3 , and will not therefore be repeated here.  FIG. 4  illustrates the position or configuration when impact balls  126  and  127  have impacted the hammer pins  133  and moved the hammer pins downwardly to an extended position. The impact between the impact balls  126  and  127  and the hammer pins  133  causes the downward movement of the hammer pins  133  so that the impact balls  126  and  127  are above (instead of overlapping) the hammer pins  133 . Distance  161  between the hammer pins  133  in the bottom of the hammer pin guide  135  in hammer carrier  140  illustrates the amount of downward movement, and the indentation  178  illustrated on work piece  105  shows that downward movement of stylus  121  in response to the impact of the hammer  128  on the stylus  121 , thereby causing indentations, dots or markings on work piece  105 . Arrow  171  indicates the downward movement of stylus  121 . Hammer guide  139  is shown in hammer carrier  140  and which provides the guide and aperture to control the reciprocal movement of the hammer  128 . 
   The software or programming for the CNC machine may then be utilized for engraving by moving the machine spindle to produce letters, marks or designs consisting of a series of dots, markings or indentations, such as shown by arrow  173  in  FIG. 4 . The speed of rotation for the marking of dots or indentations may be any one or more of a number of different speeds, for example, but not by way of limitation, three hundred (300) revolutions per minute (rpm) and up to one thousand (1000) rpm&#39;s or more, depending on the number of impact balls being used. The distance between dots or indentations may be controlled by the feed rate program into the CNC machine itself. The desired depth of the dot, indentation or mark may be determined by the distance the stylus moves before contacting the work piece surface and the velocity of the stylus which is controlled by the revolutions per minute of the machine spindle, or any one of a number of other parameters, all within the contemplation of this invention. 
     FIG. 5  is an exploded perspective view of one example of a hammer carrier  140 , hammer  128  and other components which may be utilized in some embodiments of this invention, showing two hammer pins  133 .  FIG. 5  illustrates hammer carrier  140 , hammer  128 , hammer pins  133  and hammer pin axle  134 . In order to better facilitate the impact between hammer pin&#39;s  133  and the impact balls  126  and  127  as shown in  FIG. 4 , the hammer pins  133  may be rotatably mounted such as on hammer pin axle  134  to allow the rotation of hammer pins  133  about hammer pin axle  134  to reduce the wear on both hammer pins  133  and on impact balls  126  and  127 . The hammer carrier  140  is shown with hammer pin cavity  135 , which is a hammer guide and a hammer pin guide. The hammer spring  138  is in this application inserted over a lower portion of the hammer  128  within hammer carrier  140  (in this embodiment) and provides a biasing force upward on the hammer  128  to remain in the retracted position until thrown downwardly by the impact of impact balls (not shown in this figure) on hammer pins  133 . Stylus  121  is shown with stylus spring  144  and as it is assembled within an aperture in stylus housing  104 . 
   Since the hammer pins  133  are each independently and rotatably mounted on hammer pin axle  134 , each rotates independently of the other because they are each being hit by the impact balls, which would make one hammer pin rotate the opposite direction from the other hammer pin opposite it on the hammer pin axle  134 : The hammer pins  133 , which also may be referred to as rollers in some embodiments, may be rotatably mounted about an axle, and are positioned or contained within a portion of the hammer  128  (through an aperture in the hammer) in this embodiment to impart the impact from the impact balls through the hammer pins  133  to the hammer  128 . The hammer  128  may but need not be constructed from aluminum bronze or from a material referred to as “nylatron GS” (as two examples of many possibilities, within the contemplation of this invention). The material may be chosen for a given application as desired to reach the anti-friction and hardness properties desired. The rollers or pins  133  for example may be steel hardened to 62 RC hardness. 
   In general, by containing the hammer pins  133  or rollers within the hammer and utilizing a centralized hammer which has the same approximate axis of rotation as the machine spindle, this ensures that the impact from the hammer  128  to the stylus directly results from the impact of the impact balls  126  and  127  against the hammer pins  133 , and it is all axial or approximately axial to the axis of the machine spindle interface. In contrasting the center line device from an off-center device, side impact on the stylus is eliminated and wear is believed to be minimized as a result. The impact balls  126  and  127  are contained within compartments or areas defined by impact ball holder  125  and impact ball plate  129  (as shown more fully in  FIG. 8 ), which may be any material with desirable characteristics or properties, such as aluminum bronze plating, tool quality steel or other suitable material (with no particular material is required to practice this invention). The combination of the impact ball compartments  125   b  in the impact ball holder  125 , with the impact ball plate  129  retain or contain the impact balls in position (the small shoulders  125   a ) such that they are not clamped or fixed, and are permitted to rotate. 
     FIG. 6  is an exploded perspective view of one example of a hammer carrier, hammer and other components which may be utilized in some embodiments of this invention, showing four hammer pins  133  and  150 . The like numbered items in  FIG. 6  are the same as those in  FIG. 5 , and will not therefore be repeated here.  FIG. 6  illustrates the additional two hammer pins  150  and hammer pin cavities  151  for the second set of hammer pins  150  within hammer pin carrier  140 , which are also hammer pin guides. The hammer pin guides  140  and the hammer guide (the center portion of the hammer carrier) allow vertical movement of the hammer  128  and hammer pins  133  and  150  in the direction of the axis of the machine spindle interface and stylus, but restrict the lateral movement, including rotational movement about the axis of the spindle holder. 
     FIG. 6  illustrates that the invention may be utilized with either one set of hammer pins  133  or two sets of hammer pins  133  and  150 , and it is preferable that they be mounted ninety degrees apart from one another as shown in  FIG. 6  if two sets are going to be used. If a configuration is utilized with four hammer pins as shown in  FIG. 6 , it allows for more dots or markings per second to be imparted on the work piece by the stylus  121  which can provide improved markings or lettering sported signs on the work piece. 
     FIG. 7  is a top view of impact ball holder  125  with four impact ball compartments  125   b  or areas shown therein. It will be noted that the impact ball holder  125  is a rotating part operatively attached to the machine spindle interface (shown in other figures) and which provides the rotation for the impact balls to impact the hammer pins (also shown in other figures). 
     FIG. 8  is a part cross-sectional view of the impact ball holder  125  with two impact balls  126  and  127  shown in an exploded view way above the impact ball holder (although four impact balls would be likely be used in the example of this embodiment of the invention shown) and above the impact ball compartments  125   b  in the impact ball holder  125 . Impact ball plate  129  is also shown in an exploded view way above the impact balls  126  and  127 , and above the cross-sectional of the impact ball holder  125 . 
   The exploded view shown in  FIG. 8  would appear above the exploded view from  FIG. 5  for example above hammer  128 . 
   As will be appreciated by those of reasonable skill in the art, there are numerous embodiments to this invention, and variations of elements and components which may be used, all within the scope of this invention. 
   In one embodiment for example, a marking device for use with a CNC machine or other machine tool is provided and that marking device comprises: a non-rotating housing; a stylus movably supported by the housing from a retracted position to an extended position; a stylus spring mounted relative to the stylus to move it to its retracted position; a machine spindle interface rotatably mounted to the housing and disposed to be rotated by a CNC or other machine tool; at least two impact balls rotatably supported within the housing and operatively attached to rotate with the machine spindle interface; a non-rotating hammer disposed at an upper end to be approximately simultaneously impacted by the at least two impact balls, and disposed at a lower end to drive the stylus to an extended position; and wherein the stylus is approximately co-axial with the machine spindle interface. 
   It will be noted that the preceding embodiment may be wherein the hammer comprises a vertically oriented hammer with hammer pins rotatably mounted and laterally disposed, and including a cylindrically shaped outer striking surface disposed to be impacted by the at least two impact balls rotating with the machine spindle interface. This application may be still further wherein the at least two impact balls are configured to simultaneously strike the hammer pins spaced approximately one hundred eighty degrees apart and further wherein the at least two impact balls and the hammer pins may rotate upon impact. The foregoing application may be still further wherein the hammer and hammer pins are disposed within a hammer guide and hammer pin guide which guides vertical movement of the hammer and the hammer pins, but which restricts lateral movement thereof. 
   It will be noted that the foregoing may be further comprising at least four impact balls rotatably supported within the housing and further wherein the hammer is disposed at an upper end to be approximately simultaneously impacted by the at least four impact balls. 
   In compliance with the statute, the invention has been described in language more or less specific as to structural and methodical features. It is to be understood, however, that the invention is not limited to the specific features shown and described, since the means herein disclosed comprise preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted in accordance with the doctrine of equivalents.