Patent Abstract:
A plunger with interchangeable handle system for machine tools. The plunger includes a shank adapted to engage a machine tool and having a retractable plunger and a threaded adapter, the interchangeable handle system includes a plurality of knobs, each having a discrete shape differing from the others and a socket to receive the threaded adapter of the shank.

Full Description:
BACKGROUND  
       [0001]     The present invention relates to machine tools and, more particularly, to hand-retractable plungers for use with machine tools.  
         [0002]     Hand-retractable plungers are a common component of machine tools and are used to position parts of the tool, such as cutting implements, workpiece supports and the like, relative to the rest of the tool. Typically, such plungers include a handle portion of a pre-selected shape permanently attached to a spring-loaded plunger slidably received within a threaded barrel. The barrel is threaded into a component of a machine tool such that the end of the plunger opposite the handle portion protrudes from the component. The handle portion can be pulled to retract the plunger end into the barrel to provide clearance so that the component can be moved relative to the machine tool. When the component has been positioned as desired, the handle is released, thereby releasing the plunger, which then protrudes from the barrel and component into a locating hole on the machine tool.  
         [0003]     The handle portion of a hand-retractable plunger may be a pull ring, bar, knurled knob or any other like knob or handle that allows a user to grip the plunger firmly. However, a disadvantage with current hand-retractable plungers is that a user may desire to use a plunger with a specific handle portion, or may wish to change the type of handle portion used on a particular plunger. Such a decision is typically based on user comfort, safety, or the particular application of the plunger. However, at present, changing the type of handle portion requires replacing the entire hand-retractable plunger. Accordingly, there is a need for a hand-retractable plunger that can be adapted to accommodate a plurality of handle types and sizes.  
       SUMMARY  
       [0004]     The present invention provides an interchangeable handle system for use with a hand-retractable plunger that includes a plunger body and a plurality of knobs of different shapes. Each of the knobs attaches to a shank portion, comprised of a plunger portion and a threaded adapter, of the plunger body. A threaded insert is positioned in a socket of each of the various types of knobs. The knobs each may be attached to the shank portion by screwing the threaded insert of an individual knob onto the threaded adapter of the shank portion.  
         [0005]     The various shapes of knobs of the present invention provide a user the opportunity to select a knob for the plunger that is best suited for that user and for the application. Also, once a plunger is mounted on a machine tool or other device, a user may change the knob to one of a different shape or replace a knob that has become damaged, thereby reducing the cost of changing or replacing a plunger simply to change or replace the knob.  
         [0006]     Other features, objects and advantages of the present invention will become apparent to those with ordinary skill in the art in view of the following drawings, detailed description and the appended claims. It is intended that all such additional features and advantages be included herein within the scope of the present invention. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]     The invention can be understood with reference to the following drawings. In the drawings, like reference numerals designate corresponding parts throughout the several views. Also, the components in the drawings are not necessarily to scale.  
         [0008]      FIG. 1  is a side elevational view of a threaded adapter of the interchangeable handle system of the present invention;  
         [0009]      FIG. 2  are end elevational views of differently shaped knobs of the system of the present invention that may be attached to the threaded adapter of  FIG. 1 ;  
         [0010]      FIG. 3  is a side elevational view, in section, of the cube-shaped knob of  FIG. 2  attached to a shank portion of the interchangeable handle system of the present invention;  
         [0011]      FIG. 4  is a side elevational view of a threaded barrel portion, in section, and a biasing spring of the present invention; and  
         [0012]      FIG. 5  is a side elevational view, in section, of the shank portion of  FIG. 3  attached to the threaded barrel portion of  FIG. 4 .  
     
    
     DETAILED DESCRIPTION  
       [0013]     As shown in  FIG. 1 , the plunger and interchangeable handle system of the present invention, generally designated  10  (see  FIG. 5 ), includes a threaded adapter  11  having a threaded shaft  12 , mating flange  14 , barrel engaging wings  16 A,  16 B, and plunger receiving-recess  18 . Recess  18  extends the entire length of shaft  12  and flange  14 . Preferably, recess  18  may include a hex socket  19 . Flange  14  may be circular in shape, but also may be other shapes, such as hexagonal, without departing from the scope of the invention.  
         [0014]     As shown in  FIG. 2 , the plunger and interchangeable handle system  10  includes knobs  20 ,  21 ,  22 ,  23 ,  24 . Knobs  20 ,  21 ,  22 ,  23 ,  24  may be of various shapes, sizes and compositions. For example, knob  20  may be spherically shaped, knob  21  T-shaped, knob  22  cube shaped, knob  23  hex shaped and knob  24  cruciform in shape. Each of the knobs  20 - 24  includes a central threaded insert or socket  26  shaped to engage the threads of threaded adapter  11 . Knobs  20 - 24  comprise the handle system, generally designated  27 , of the plunger and handle adapter  11 . However, it is within the scope of the invention to provide additional knobs of different shapes.  
         [0015]     It is the purpose of the present invention to provide a retractable plunger with an interchangeable handle system that utilizes many different knob geometries. Increasing the number of optional knob geometries, sizes and compositions, increases the probability that a user will have a plunger having a knob of a desired, or more practical, shape for a specific application.  
         [0016]     The socket  26  of knobs  20 - 24  may be comprised of metal, polymer or other rigid material. Similarly, the knobs  20 - 24  may be comprised of rigid material such as metal, a polymer such as nylon, phenolic resin or polycarbonate, wood, or other material.  
         [0017]     As shown in  FIG. 3 , knob  22  (for example) is attached to threaded adapter  11  by screwing the threaded shaft  12  into the socket  26 . The knob  22  is tightened onto the threaded adapter  11  until the knob  22  is flush against mating flange  14 . According to the present invention, if desired, the cube-shaped knob  22  may then be unscrewed from the threaded adapter  11  and replaced with, for example, spherical-shaped knob  20  or cruciform-shaped knob  24  (see  FIG. 2 ).  
         [0018]     Elongated pin  30 , having a tapered tip  31 , may be press-fitted into recess  18  of threaded adapter  11 , thereby forming a shank portion  35 . The press-fitting process creates such a solid, unitary component comprised of elongated pin  30  and threaded adapter  11 . The elongated pin  30  may include a circular flange  32  and an engaging tip  34 .  
         [0019]     As shown in  FIG. 4 , the threaded barrel portion  40  of the present invention includes adapter-engaging wings  42 A,  42 B, equipment-engaging threads  44 , biasing spring  46  and cylindrical plunger recess  48 . The equipment-engaging threads  44  of the threaded barrel portion  40  may be threaded into a threaded recess of a machine tool (not shown) so that the hand retractable plunger can be used as a positioner, loading pin, indexing device or the like.  
         [0020]     As shown in  FIG. 5 , the threaded barrel portion  40  mates with the threaded adapter  11  such that barrel-engaging wings  16 A,  16 B slidably fit into a gap  49  between adapter-engaging wings  42 A,  42 B. The threaded barrel portion  40  and threaded adapter  11  are interconnected by biasing spring  46  and fixed in mating position when elongated pin  30  is moved through cylindrical plunger recess  48  and press-fitted into plunger-receiving recess  18  of threaded adapter  11 .  
         [0021]     The elongated pin  30  moves axially through the threaded barrel portion  40  and is biased such the engaging tip  34  protrudes from the threaded barrel portion  40 , as shown in  FIG. 5 . The biasing spring  46  biases the elongated pin  30  into an engaging position by exerting a force on flange  32 , thereby moving the elongated pin  30  into a protruding engagement position.  
         [0022]     The elongated pin  30  may be retracted by grasping the knob  22  and pulling the knob relative to the barrel portion  40 , thereby withdrawing the engaging tip  34  within the recess  48 . The pin  30  may then be locked in a retracted position by rotating the knob  22  and adapter  11  relative to barrel portion  40  such that shank portion  35  rotates and the flat end surfaces  17  of wings  16 A,  16 B are in contact with the flat end surfaces  45  of wings  42 A,  42 B (see  FIG. 1 ). In an alternate embodiment, wings  16 A,  16 B may be shortened such that a position of the tip  34  protrudes when the pin  30  is locked in the retracted position so that the plunger will engage a part even when in the retracted position.  
         [0023]     Although the invention is shown and described with respect to certain embodiments, it is obvious that equivalents and modifications will occur to those skilled in the art upon reading and understanding the specification. The present invention includes all such equivalents and modifications and is limited only by the scope of the claims.

Technology Classification (CPC): 8