Patent Publication Number: US-2012027532-A1

Title: Pull stud bolt with external and internal coolant and methods

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The embodiments of the subject matter disclosed herein generally relate to machining equipment and more particularly to pull stud bolts used in machining equipment. 
     2. Description of Related Art 
     Machining generally refers to a group of processes used to remove material from a workpiece to obtain a desired shape or geometry. Machining is often performed on metal workpieces to create a piece for a specific application. Examples of machining processes include milling, turning and drilling. In milling processes, the cutting tool is rotated with the cutting surfaces being brought against the workpiece to remove the metal. In turning processes, the workpiece is rotated against the cutting tool. For drilling, holes are produced by a rotating cutting tool. 
     Historically, these machining processes began in a generally manual form. As technology advanced, both with respect to power generation and machining, these machining processes became more automated by, for example, the use of cams, which allowed for mass producing of a same shape or cut. From cams, the technology has continued to move forward, with programmable machines being the norm in the more modern machine shops of today. An example of a programmable machine would be a computer numerical control (CNC) machine which allows for a single machine to be able to perform close tolerance machining which can be reprogrammed between jobs. 
     These machining processes use a cutting tool to create a metal chip from the workpiece which is then removed. This forming and removal of the metal chip occurs from the relative motion between the cutting tool and the workpiece when the cutting tool and the workpiece are in contact with each other. The cutting tool and the workpiece are often operating at high speeds relative to each other which generates heat in addition to the formation of the chip. In order to cool and lubricate the cutting tool, a fluid is often distributed in the area of the operation. 
     Depending upon the process used and the specific job to be performed, a fluid, e.g., a coolant, can be delivered either internally or externally to the cutting tool. When the coolant is applied internally, the coolant is often routed through an internal portion of the machine, then through a tool holder and then delivered to the cutting tool. For external coolant delivery, coolant can be routed to an external opening, or flange, on the tool holder and then delivered to the cutting tool. An example of this is shown in  FIG. 1 . The tool holder  2  is attached to a pull stud bolt  4 . External coolant  6  enters the tool holder  2  and flows through a channel  8  before exiting the tool holder  2  and lubricating a cutting tool (not shown). A more detailed example of a conventional pull stud bolt  4  (also referred to as “DIN69872/B”) for use in external coolant systems is shown in  FIG. 2 . Alternatively, coolant can also be delivered externally via coolant lines which are not part of the machine spindle and/or tool holder. 
     When the coolant is applied internally, the coolant is often routed through an internal portion of the machine to the tool holder and then delivered to the cutting tool. An example of this is shown in  FIG. 3 . The pull stud bolt  302  is attached to the tool holder  304 . Coolant  306  enters the pull stud bolt  302  and flows through channel  308  into a channel  310  in the tool holder  304 . The coolant  306  then exits the tool holder  304  enroute to the cutting tool (not shown). A more detailed example of a conventional pull stud bolt  302  (also referred to as “DIN69872/A”) for use in internal coolant systems is shown in  FIG. 4 . Since different machining jobs can require different coolant needs, having the necessary parts for changing over from the internal coolant operation to the external coolant operation and then performing the changeover can increase down time between jobs and add cost which reduces overall operating efficiency of the machine. Additionally, if the pull stud bolt  302  for internal coolant operations is used with a tool holder  2  for external coolant operations, damage caused by the coolant can occur because the coolant can enter into the spindle and damage electrical parts which need to remain dry. 
     Accordingly, systems and methods for improving machine efficiency are desirable. 
     BRIEF SUMMARY OF THE INVENTION 
     According to an exemplary embodiment there is a pull stud bolt for connecting a tool holder to a collet in a spindle. The pull stud bolt includes: a body having a longitudinal passage fluidly connected to a cavity, the cavity fluidly connected to a plurality of longitudinal channels; a sealing ring disposed between an end of the longitudinal passage and the cavity; a spring disposed in the cavity; and a sphere configured to be biased by the spring. The sphere is configured to unblock the end of the longitudinal passage by losing contact with the sealing ring when a first force applied to the sphere from the spring is less than a second force applied by a fluid flowing through the longitudinal passage, wherein the first and second forces are substantially opposite in direction of application. 
     According to another exemplary embodiment there is a method for assembling a pull stud bolt which uses both an internal coolant path and an external coolant path. The method includes: configuring a body to receive a tool holder the body having a longitudinal passage fluidly connected to a cavity, the cavity fluidly connected to a plurality of longitudinal channels; disposing a sealing ring between an end of the longitudinal passage and the cavity; disposing a spring in the cavity; and configuring a sphere to be biased by the spring, the sphere is configured to unblock the end of the longitudinal passage by losing contact with the sealing ring when a first force applied to the sphere from the spring is less than a second force applied by a fluid flowing through the longitudinal passage, wherein the first and second forces are substantially opposite in direction of application. 
     According to another exemplary embodiment, there is a computer numerical control (CNC) machine which has at least two coolant paths. The CNC machine includes: a spindle, the spindle includes: a drawing bolt; an inner sleeve; and a collet; a tool holder; and a pull stud bolt. The pull stud bolt includes: a body configured to receive a tool holder, the body having a longitudinal passage fluidly connected to a cavity, the cavity fluidly connected to a plurality of longitudinal channels; a sealing ring disposed between an end of the longitudinal passage and the cavity; a spring disposed in the cavity; and a sphere configured to be biased by the spring. The sphere is configured to unblock the end of the longitudinal passage by losing contact with the sealing ring when a first force applied to the sphere from the spring is less than a second force applied by a fluid flowing through the longitudinal passage, wherein the first and second forces are substantially opposite in direction of application. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The accompanying drawings illustrate exemplary embodiments, wherein: 
         FIG. 1  depicts a tool holder and a pull stud bolt for use in external coolant applications; 
         FIG. 2  shows the pull stud bolt for use in external applications; 
         FIG. 3  shows a tool holder and a pull stud bolt for use in internal coolant applications; 
         FIG. 4  illustrates the pull stud bolt for use in internal coolant applications; 
         FIG. 5  shows parts used for attaching a tool holder to a spindle according to exemplary embodiments; 
         FIG. 6  shows a pull stud bolt for use in both internal and external coolant operations according to exemplary embodiments; 
         FIG. 7  illustrates an end of the pull stud bolt which mates with the tool holder according to exemplary embodiments; 
         FIG. 8  depicts an open position, a closed position and a stroke of a spring in the pull stud bolt according to exemplary embodiments; 
         FIG. 9  shows a coolant flow for external coolant operations according to exemplary embodiments; 
         FIG. 10  shows the coolant flow for internal coolant operations according to exemplary embodiments; 
         FIG. 11  depicts the pull stud bolt according to exemplary embodiments; 
         FIG. 12  illustrates an end of the pull stud bolt which mates with the tool holder according to exemplary embodiments; 
         FIGS. 13-17  show parts included in the pull stud bolt according to exemplary embodiments; 
         FIG. 18  shows a flowchart for a method of operating with either the internal or the external coolant flow according to exemplary embodiments; and 
         FIG. 19  shows a flowchart for a method for assembling a pull stud bolt according to exemplary embodiments. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. 
     Reference throughout the specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout the specification is not necessarily referring to the same embodiment. Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. 
     As described in the Background section, systems and methods for improving machine efficiency are desirable for machines which use a tool holder and a pull stud bolt in environments with at least two possible coolant paths, e.g., an internal and an external coolant path. Prior to describing exemplary embodiments which can improve machine efficiency, the environment in which a tool holder  504  and a pull stud bolt  502  are used is now described with respect to  FIG. 5 . According to exemplary embodiments, a machine spindle  506  can contain a drawing bolt  508 , an inner sleeve  510  and a collet  512  which is used to clamp down and hold the pull stud bolt  502 . The machine spindle  506 , can be a machine spindle used in, for example, a computer numerical control (CNC) machine. 
     The pull stud bolt  502  can be connected via threads to the tool holder  504 . A cutting tool (not shown) is attached to the end of the tool holder  504  which is opposite from the end of the tool holder  504  which is attached to the pull stud bolt  502 . Also shown, in this exemplary embodiment, is a coolant passage  514 . While the tool holder  504  is shown with only an internal coolant path, tool holder  504  can be of a version which uses an external coolant path similar to the one as shown in, for example,  FIG. 1 . More details associated with the exemplary pull stud bolt  502  and the coolant passage  514  are described below. 
     According to exemplary embodiments the pull stud bolt  502  which can be used in applications which use either the internal or the external coolant flow path is shown in  FIGS. 6 and 7 .  FIG. 6  shows a longitudinal cross section of the pull stud bolt  502  and  FIG. 7  shows an end view where a plurality of coolant channels  618  exit the pull stud bolt  502 . As shown in  FIG. 6 , the pull stud bolt  502  includes a body section  602  which contains a longitudinal passage  604  for receiving and channeling a coolant flow when operating in an internal coolant mode. At one end of the longitudinal passage  604  there is a sealing ring  606  which surrounds the end of the longitudinal passage  604  and which is in contact with a cavity  608 . The sealing ring  606  can also be in contact with a sphere  610 , with the sealing ring  606  being shaped such that the sphere  610  when seated against the sealing ring  606  blocks the longitudinal passage  604 . When fully seated, the sphere  610  blocks the transmission of fluid in either of the two possible flow directions. This fully seated or closed position of the sphere  610  is shown in  FIG. 6 , however, according to other exemplary embodiments, the sphere  610  can be located in other positions, e.g., an open position, to allow the flow of coolant based upon the force of the coolant moving through the longitudinal passage  604  as compared to the force applied by the spring  612  (as shown in  FIG. 8  and described in more detail below). 
     According to exemplary embodiments, the sphere  610  is in contact with a spring  612 , which in turn is in contact with a washer ring  614 . The washer ring  614  is also in contact with another ring, e.g., a Seeger ring  616 . A plurality of fluid channels  618  are also connected to the cavity  608 . As described above,  FIG. 7  shows an end view where a plurality of coolant channels exit the pull stud bolt  502 . While four fluid channels  618  are shown, other combinations can be manufactured and used as needed for the desired fluid transmission into the mating tool holder  504 . 
     According to exemplary embodiments, as described above, the pull stud bolt  502  can be opened or closed based on the position of the sphere  610 . The open and closed position for the pull stud bolt  502  is shown in  FIG. 8 . The upper pull stud bolt  502  diagram in  FIG. 8  shows the closed position with the sphere  610  being seated on the sealing ring  606  and blocking access for fluid between the longitudinal passage  604  and the cavity  608 . This occurs when a force F 1  of any fluid being transmitted though the longitudinal passage  604  and applied to the sphere  610  is less than a force F 2  applied on the sphere  610  by the spring  612 . The lower pull stud bolt  502  diagram in  FIG. 8  shows the open position with the sphere  610  not being seated on the sealing ring  606  and not blocking access for fluid between the longitudinal passage  604  and the cavity  608 . This occurs when the force F 1  of any fluid being transmitted though the longitudinal passage  604  and applied to the sphere  610  is greater than the force F 2  applied on the sphere  610  by the spring  612 . Both positions, i.e., the open and closed position, for the exemplary pull stud bolt  502  are illustrated in  FIG. 8 . The difference in positions of the sphere  610  show an exemplary stroke, i.e., a distance “d” moved by the spring  612 , e.g., 5.0 mm and/or a range of 3.0 mm-6.0 mm. According to an exemplary embodiment, the coolant can be under a pressure of approximately 6 bar, however according to other exemplary embodiments, the coolant can be under other pressures. 
     According to exemplary embodiments, the pull stud bolt  502  and the tool holder  504  can operate in an external coolant configuration as shown in  FIG. 9 . The arrows show the direction of flow for the coolant. Coolant enters the tool holder through the openings of an adaptor flange  902  and arrives at a center channel  904  in the tool holder  504 . Most of the coolant will go “down” towards an exit  906  for lubricating the cutting tool. However, some of the coolant may attempt to go “up” towards the pull stud bolt  502 . When entering the pull stud bolt  502 , the coolant will be blocked by the seated sphere  610  so that electrical parts within the machine spindle  506  are protected. 
     According to another exemplary embodiment, the pull stud bolt  502  and the tool holder  504  can operate in the internal coolant configuration as shown in  FIG. 10 . The arrows show the direction of flow for the coolant. Coolant enters the pull stud bolt  502  and follows the longitudinal passage  604 . The force F 1  of the coolant applied to the sphere  610  is greater than the force F 2  of the spring  612  applied to the sphere  610  which moves the sphere  610  to the open position. The coolant then flows through the cavity  608  to the plurality of coolant channels  618 . From there the coolant flows into the center channel  904  in the tool holder  504  and on to the exit  906  for lubricating the cutting tool. 
     According to an exemplary embodiment, the pull stud bolt can be manufactured using the dimensions shown below in Table 1 as matched to  FIGS. 11 and 12 . 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
               
                   
                   
               
               
                   
                 Reference Character 
                 Value 
               
               
                   
                   
               
             
            
               
                   
                 A 
                 Ø 36 +/− 2.0 mm  
               
               
                   
                 B 
                 Ø 28 +/− 2.0 mm  
               
               
                   
                 C 
                 Ø 7 +/− 1.5 mm  
               
               
                   
                 D 
                 9.5 +/− 1.5 mm  
               
               
                   
                 E 
                 Chamfer (e.g., 1 × 45°) 
               
               
                   
                 F 
                 34 +/− 2.0 mm 
               
               
                   
                 G 
                 74 +/− 4.0 mm 
               
               
                   
                 H 
                 40 +/− 2.0 mm 
               
               
                   
                 I 
                 30 +/− 2.0 mm 
               
               
                   
                 J 
                 15 +/− 2.0 mm 
               
               
                   
                 K 
                  1 +/− 0.5 mm 
               
               
                   
                 L 
                  3 +/− 1.5 mm 
               
               
                   
                 M 
                 Chamfer (e.g., 2 × 45°) 
               
               
                   
                 N 
                 Chamfer (e.g., 1 × 45°) 
               
               
                   
                 O 
                 Ø 12 +/− 1.5 mm  
               
               
                   
                 P 
                 Ø 13 +/− 1.5 mm  
               
               
                   
                 Q 
                 M 24 6 g (Screw Tolerance) 
               
               
                   
                 R 
                 Radius (e.g., R 175) 
               
               
                   
                 S 
                 Radius (e.g., R 7) 
               
               
                   
                 T 
                 30 +/− 2.0 mm 
               
               
                   
                   
               
            
           
         
       
     
     However, according to other exemplary embodiments, dimensions of the pull stud bolt  502  can be modified to fit the tool holder  504  as used, to ensure the desired coolant flow and house the desired spring  612 . Other dimensions, tolerances, materials and heat treatments can be taken from the DIN69872 normative dimensions as a baseline, and modified as needed to accommodate the exemplary embodiments described herein. 
     According to exemplary embodiments, other parts which are used in the pull stud bolt  502  are shown in  FIGS. 13-17 , with  FIG. 13  showing the seal ring  606 ,  FIG. 14  showing the spring  612 ,  FIG. 15  showing the washer ring  614 ,  FIG. 16  showing the Seeger ring  616  and  FIG. 17  showing the sphere  610 . A purely illustrative range of dimensions and materials are shown below in Table 2 for the parts shown in  FIGS. 13-17 . 
     
       
         
           
               
               
               
             
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 Value (or reference part 
               
               
                 Component 
                 Reference Character 
                 number or material) 
               
               
                   
               
             
            
               
                 Seal Ring 606 
                 A1 
                  Ø 7 +/− 1.5 mm 
               
               
                 Seal Ring 606 
                 B1 
                  10 +/− 1.5 mm 
               
               
                 Seal Ring 606 
                 C1 
                 Angled Edge (e.g., 45°) 
               
               
                 Seal Ring 606 
                 D1 
                 Ø 12 +/− 1.5 mm 
               
               
                 Seal Ring 606 
                 E1 
                 Chamfer (e.g., 1 × 45°) 
               
               
                 Seal Ring 606 
                 Materials 
                 Brass CuZn37, 
               
               
                   
                   
                 UNI EN 12449 
               
               
                 Spring 612 
                 F1 
                  Ø 1 +/− 0.5 mm 
               
               
                 Spring 612 
                 G1 
                  13 +/− 2.0 mm 
               
               
                 Spring 612 
                 H1 
                 Ø 11 +/− 1.5 mm 
               
               
                 Spring 612 
                 I1 
                 Ø 10 +/− 1.5 mm 
               
               
                 Spring 612 
                 # of Active Coils 
                 3 
               
               
                 Spring 612 
                 Compression Force 
                 2 N/mm  
               
               
                 Spring 612 
                 Materials 
                 UNI X10CrNi1707 
               
               
                 Washer Ring 614 
                 J1 
                  Ø 7 +/− 1.5 mm 
               
               
                 Washer Ring 614 
                 K1 
                    1 +/− 0.5 mm 
               
               
                 Washer Ring 614 
                 L1 
                 Ø 11.5 +/− 1.5 mm     
               
               
                 Washer Ring 614 
                 Materials 
                 UNI6592-DIN125A, Other 
               
               
                   
                   
                 Stainless Steels 
               
               
                 Seeger Ring 616 
                 M1 
                    1 +/− 0.5 mm 
               
               
                 Seeger Ring 616 
                 N1 
                 Ø 13 +/− 2.0 mm 
               
               
                 Seeger Ring 616 
                 Materials 
                 UNI 7437(3654)-DIN 472, 
               
               
                   
                   
                 Other Stainless Steels 
               
               
                 Sphere 610 
                 O1 
                 Radius (e.g., R 5) 
               
               
                 Sphere 
                 Materials 
                 100Cr6, UNI3097 
               
               
                   
               
            
           
         
       
     
     However, according to other exemplary embodiments, dimensions can be modified to fit the tool holder  504  as used, to ensure the desired coolant flow and house the desired spring  612 . Similarly, modifications to the materials used can be made as well as desired. 
     According to exemplary embodiments, there is a method for operating a machining device which can use either the internal coolant path or the external coolant path as shown in the flowchart of  FIG. 18 . The method includes: at step  1800  unblocking the internal coolant path, when operating in an internal coolant mode, in a pull stud bolt by having a coolant apply a first force on a sphere to move the sphere a sufficient distance to unblock the internal coolant path, wherein the first force applied by the coolant on the sphere is greater than an opposing second force applied by a spring on the sphere; and at step  1804  blocking the internal coolant path, when operating in an external coolant mode, in the pull stud bolt by having the spring apply the second force on the sphere which seats the sphere on a sealing ring to block the internal coolant path, wherein the second force applied to the sphere by the spring is greater than all opposing forces applied on the sphere. 
     According to exemplary embodiments, there is a method for assembling a pull stub bolt which uses either the internal coolant path or the external coolant path as shown in the flowchart of  FIG. 19 . The method includes: at step  1902  configuring a body to receive a tool holder the body having a longitudinal passage fluidly connected to a cavity, the cavity fluidly connected to a plurality of longitudinal channels; at step  1904  disposing a sealing ring between an end of the longitudinal passage and the cavity; at step  1906  disposing a spring in the cavity; and at step  1908  configuring a sphere to be biased by the spring, the sphere is configured to unblock the end of the longitudinal passage by losing contact with the sealing ring when a first force applied to the sphere from the spring is less than a second force applied by a fluid flowing through the longitudinal passage, wherein the first and second forces are substantially opposite in direction of application. 
     The above-described exemplary embodiments are intended to be illustrative in all respects, rather than restrictive, of the present invention. Thus the present invention is capable of many variations in detailed implementation that can be derived from the description contained herein by a person skilled in the art. All such variations and modifications are considered to be within the scope and spirit of the present invention as defined by the following claims. For example, exemplary embodiments described herein can be applied to other pull stud bolts, e.g., DIN69871 IS 40-50-60 and others. No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. 
     This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other example are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements within the literal languages of the claims.