CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application is a continuation of application Ser. No. 10/047,674, filed Jan. 14, 2002, now U.S. Pat. No. 6,722,008, which claims the benefit of U.S. Provisional Patent Application Ser. No. 60/315,630, filed Aug. 29, 2001. 


   FIELD OF THE INVENTION 
   The present invention relates generally to heat shrink tools and more particularly to a device for accurate assembly of a tool to a tool holder by the heat shrink method. 
   BACKGROUND OF THE INVENTION 
   Connecting a tool to a tool holder by the heat shrink method is a well-known process. An example of the general process is described in U.S. Pat. No. 5,311,654 issued to Harold D. Cook on May 17, 1994. The heat shrink process is typically used with a tool holder having a bore for receipt of a tool having a shank. The tool holder is heated to expand the tool holder bore. The shank of the tool is then inserted into the bore. As the tool holder cools, the bore shrinks around the shank holding the shank within the tool holder. 
   The heat shrink method is an effective method for connecting a tool to a tool holder. However, in most applications, the tool must be precisely mounted within the tool holder or the tool holder cannot be used. It should be appreciated that these tools are typically used in operations that require very precise alignment and positioning. Slight variations in the alignment between tool and tool holder results in the production of defective parts. One of the major disadvantages of known methods for connecting a tool to a tool holder using the heat shrink method is the need to measure each tool and tool holder and the inaccuracy that can result from these repetitive measuring operations. Human error is a significant factor. A worker must measure the tool length and the tool holder length and then adjust the position of the tool to get the appropriate overall length. To reduce human error somewhat, another method employs a pre-qualified measuring rod to determine the appropriate depth of the tool within the tool holder. When this rod wears, the positioning is wrong and resultant tools and tool holders cannot be used. Furthermore, the heat shrink process must be done quickly to avoid down time when changing tools. If the heat shrink method is slow, tool changes will be slow resulting in the overall slowing of the entire operation in which the tool and tool holder are being used. 
   Accordingly, it would be advantageous to provide a tool assembly unit for rapidly and precisely connecting a tool to a tool holder. 
   SUMMARY OF THE INVENTION AND ADVANTAGES 
   It is an object of the present invention to provide a tool assembly unit for coupling a tool and a tool holder. The unit includes a measuring device adapted to determine the position of the tool with respect to the tool holder, an alignment device coupled to the measuring device and being adapted to receive the tool holder, a moveable rod slideably disposed on the alignment device and coupled to the tool, with the rod being adapted to move the tool with respect to the tool holder to a desired position as measured by the measuring device. 
   It is another object of the present invention to provide a tool assembly unit for coupling a tool and a tool holder by heat shrinking. The unit includes a measuring device adapted to determine the position of the tool with respect to the tool holder, an alignment device coupled to the measuring device and being adapted to receive the tool holder, a heating device slideably mounted on the alignment device and defining a bore for sliding a tool therethrough with the heating device adapted to be removably mounted on the tool holder for heating the tool holder, a moveable rod slideably disposed on the alignment device and being adapted to be coupled to the tool, with the rod being further adapted to move the tool with respect to the tool holder to a desired position as measured by the measuring device. 
   It is still another object of the present invention to provide a method for coupling a tool with a tool holder using a tool assembly unit including a measuring device coupled to an alignment device and a moveable rod slideably disposed on the alignment device. The method includes the steps of mounting the tool holder on the alignment device, coupling the moveable rod to the tool, measuring an actual relative position between the tool and tool holder, moving the tool within the tool holder until the actual relative position of the tool relative to the tool holder is equal to a desired position, and removing the tool holder and the tool from the alignment device. 
   It is still another object of the present invention to provide a method for coupling a tool with a tool holder by heat shrinking using a tool assembly unit including a measuring device coupled to an alignment device having a heating device slideably mounted thereon and a moveable rod slideably disposed on the alignment device. The method includes the steps of mounting the tool holder on the alignment device, heating the tool holder, coupling the moveable rod to the tool, measuring an actual relative position between the tool and the tool holder, moving the tool within the tool holder until the actual position of the tool relative to the tool holder is equal to a desired position, shrinking the tool holder around the tool, and removing the tool holder and the tool from the alignment device. 
   The subject invention provides many advantages over conventional tool assembly units by providing a tool assembly unit that rapidly and precisely couples a tool and a tool holder. One of the major advantages is reducing or eliminating the need to measure each tool and tool holder, thereby significantly reducing the inaccuracy that can result from these repetitive measuring operations due to human error. Another advantage is that rod wear does not result in improper positioning of the tool relative to the tool holder, thereby reducing cost by reducing the number of resultant tool assembly units that cannot be used. Furthermore, the tool assembly unit of the present invention permits the heat shrink process to be done quickly to avoid down time when changing tools, thus reducing tool change time and encouraging an efficient assembly operation. 


   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other advantages of the present invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
       FIG. 1  is a perspective view of a tool assembly unit; 
       FIG. 2  is a perspective view of an alignment device used in the tool assembly unit of  FIG. 1 ; and 
       FIG. 3  is an elevational view of the alignment device of FIG.  2 . 
   


   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring to the Figures, wherein like numerals indicate like or corresponding parts throughout the several views, a tool assembly unit is generally shown at  10 . The tool assembly unit  10  includes a measuring device shown generally at  12 , a heating device shown generally at  14 , and an alignment device shown generally at  16 . A controller  15  controls the various operations of the tool assembly unit  10 . The controller  15  includes a control panel  18  and a display screen  20 . In the disclosed embodiment, a work table  22  is also shown for supporting the tool assembly unit  10 . 
   The measuring device  12  is a standard tool measuring device such as, for example, a microset unit sold by Tooling Systems Division of Frankenmuth, Mich. The measuring device  12  includes an optical viewer  24  mounted on a vertical tower  26 . The optical viewer  24  in the disclosed embodiment is connected to the controller  15 . In use, the desired length of the assembled tool and tool holder is inputted into the controller  15  which automatically adjusts the optical viewer  24  to the correct height along the tower  26 . In operation, once the tool  36  is correctly positioned with respect to viewer  24 , the correct height is known for that particular desired tool and tool holder assembly. 
   In another embodiment, the optical viewer  24  is adapted for continuously determining the position of the tool  36  with respect to the tool holder  34 . In addition, the controller  15  may be connected to the viewer  24  and the tool  36  and tool holder  34  such that the optical viewer  24  continuously detects the actual position of the tool  36  with respect to the tool holder  34  and sends an electronic signal to the controller  15  indicating the actual position. In response, the controller  15  compares the actual position with the desired position and moves the tool  36  with respect to the tool holder  34  until the desired position is achieved. 
   The heating device  14  includes a heater  28  mounted on a slide tower  30 . The position and operation of the heater  28  is controlled by the controller  15 . Although two controllers  15  have been disclosed, it will be appreciated by those of ordinary skill in the art that a single controller or any other type of control unit could be used to perform the operation and positioning of the heater  28  and optical viewer  24 . 
   With reference to  FIG. 2 , the alignment device  16  will be described. The alignment device  16  includes a spindle  32  having an aperture  31  for holding the tool bolder  34 . In the preferred embodiment, the tool holder  34  is held within the spindle  32  through a vacuum clamp. The tool to be mounted within the tool holder  34  is shown generally at  36 . A push rod  38  is adapted to reciprocate through the spindle  32  and tool holder  34  to engage the shank  40  of the tool  36 . The engagement of the rod  38  with the shank  40  may be such that they are removably attached, coupled so that the tool  36  rests on top of the rod  38  or any other suitable means of coupling or mating such that the rod  38  may move the tool  36  within the tool holder  34  to the desired position. 
   The rod  38  is removably mounted to an adjustable mount  42 . In the disclosed embodiment, the rod  38  is mounted to the mount  42  through an adjustable screw  44 . The rod  38  is removably mounted so that different rod sizes can be used or the rod  38  can be replaced if it becomes worn. However, it should be appreciated that wear of the rod is not important to the proper operation of the present invention since the rod itself is only used as a push rod for positioning the tool  36  with respect to the tool holder  34  and the viewer  24 . This operation will be described in greater detail below. 
   The mount  42  is cconnected to an adjustment device comprising an air slide  46  and an adjustment shaft  48 . In the preferred embodiment, the air slide  46  provides for rapid adjusment and the shaft  48  provides for fine adjustment. The fine adjustment in the disclosed embodiment is achieved through a gear box  50  and an elrctonic control  52 . System air is controlled through electronic controls  54 , which control pressurized air through air lines  56 . The electronic controls  52 , 54  are coupled to the controller  15 . 
   A housing top surface is shown at  58  and a mounting bracket is shown at  60 . The top surface  58  and the mounting bracket  60  form the support for supporting the alignment device  16  with respect to the heating device  14  and measuring device  12 . 
   With reference to  FIG. 3 , the operation of unit  10  will be described. In operation, the push rod  38  is initially moved to its lowest position. In this position, the push rod  38  can be replaced if necessary. As discussed above, replacement of the push rod may be required if there has been damage to the push rod or undue wear or if a different size push rod is required for a specific mounting operation. The control panel  18  for controlling the push rod  38  is illustrated schematically. The down button  61  would be engaged to move the push rod  38  down. 
   After the push rod  38  is down, the tool holder  34  is then placed in the spindle  32 . The vacuum clamp is energized by pushing button  63  on the control panel  18 . This holds the tool holder  34  within the spindle  32 . It is contemplated that a standard vacuum clamp would be employed or any other suitable means of retaining the tool holder  34  within the spindle  32 . 
   At this point in the operation, if there is an existing tool  36  mounted within the tool holder  34 , i.e., the intent is to replace the tool  36 , the push rod  38  would be raised to touch the bottom of the cutting tool  36 . This would be controlled by the push rod up button  65 . Then either manual measurement of the tool  36  and tool holder  34  would be done or the measuring device  12  would be set at the predetermined dimension for the tool  36  and tool holder  34 . 
   The heating unit  14  would then be programmed through the controller  15  which in this embodiment is being shown with the same numeric indication as the push rod controller  15  and vacuum control. Again, as indicated above, these various controllers could be a single unit or various units to control the various operations of unit  10 . The controller  15  would initiate heating of the heater  28  and also move the heater  28  into position so that the bore  64  in the heater is positioned over the bore of the tool holder  34  to heat that region and expand it for receipt of the shank  40  of tool  36 . 
   As illustrated in  FIG. 3 , the heater slide  30  is mounted through bracket  62  to the spindle  32  of the alignment device  16 . Once the tool holder  34  is properly heated, the heating device  28  will move away from the tool holder  34  and either the existing tool  36  can be removed and a new tool inserted into the bore. Or if it is a first time assembly, a new tool is inserted. A fine adjustment knob  67  is then used to raise or lower the tool  36  to the crosshairs of the optical viewer  24 . Once the tool  36  is properly within the crosshairs of optical viewer  24 , the proper alignment between tool  36  and tool holder  34  has been achieved. The vacuum clamp is then released by pushing vacuum clamp button  63  and the tool holder  36  and tool  34  are removed from the spindle  32  and placed into a cooling rack for complete cooling. 
   The foregoing detailed description shows the preferred embodiments of the present invention are well suited to fulfill the objects of the invention. It is recognized that those skilled in the art may make various modifications or additions to the preferred embodiments chosen herein to illustrate the present invention, without departing from the spirit of the present invention. Accordingly, it is to be understood that the subject matter sought to be afforded protection should be deemed to extend to the subject matter defined in the appended claims, including all equivalents thereof. 
   The invention has been described in an illustrative manner, and it is to be understood that the terminology that has been used is intended to be in the nature of words of description rather than limitation. It will be apparent to those skilled in the art that many modifications and variations of the present invention are possible in light of the above teachings. Therefore, it is to be understood that the invention may be practiced otherwise than as specifically described within the scope of the amended claims.
The present invention provides a tool assembly unit for coupling a tool and a tool holder including a measuring device which determines the position of the tool with respect to the tool holder, an alignment device coupled to the measuring device which receives the tool holder, a moveable rod slideably disposed on the alignment device and coupled to the tool which moves the tool with respect to the tool holder to a desired position as measured by the measuring device. The tool may be affixed to the tool holder by heat shrinking.