Abstract:
A millin tool holder includes a tool holder body having a tool shank opening. The tool shank has an annular shoulder seated on a shoulder on the tool holder. A pair of confronting slots form an opening for receiving a pin which prevents the tool head from rotating with respect to the body.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention is related to a two-part milling tool holder which includes a body adapted to be mounted on a milling tool base. A replaceable head for supporting a pair of indexable inserts has a shank received in an opening in the body. The head can be replaced with another head of the same or a different style. 
     Milling tool inserts are commonly mounted on the end of an elongated tool holder. It is desirable in some cutting situations to use one type of insert for heavy milling and then another insert for cutting a radius or the like. Occasionally, the cutter head becomes damaged or worn. Commercially available heads generally must either be scrapped or repaired. Most of the expense in making the holder is in the body of the holder. Further, replacing a complete toll holder is time consuming. 
     Prior art related to tool holders such as for milling inserts may be found in my U.S. Pat. Nos. 5,468,102 issued Nov. 21, 1995 for “Milling Tool Holder”; and 6,299,394 issued Oct. 9, 2001 for “Milling Tool Holder”. 
     The broad purpose of the present invention is to provide an improved milling tool holder of the type in which a body adapted to be supported on a milling machine base, is connected to a head that supports a pair of indexable inserts. The head has a shank received in a bore in the body. 
     A pair of threaded fasteners mounted on the body have their inner ends engaging the shank to cam a shoulder on the head toward a shoulder on the body. 
     The arrangement is such that the user can readily exchange the head whenever it has become damaged, worn, or needs to be exchanged to accommodate a head having a different cutting configuration. 
     Although the fasteners prevent the shank from rotating with respect to the body, my prior patent disclosed additional means for preventing such rotation. My U.S. Pat. No. 5,468,102 used a pin in the shank-receiving hole, which was received in the slot in the end of the shank when it was inserted in the hole. 
     The present invention discloses an arrangement that accommodates a heavier torque required by high speed machines for a heavier cut. In this case, the body has a shoulder around the shank-receiving hole. The tool has a shoulder around the shank that seats on the shoulder on the body. One of the channels has a pair of channels aligned along an axis that passes through. the center of the shank-receiving hole. The other shoulder has a pair channels so that the two shoulders combine to form a pair of cylindrical openings. 
     A cylindrical pin or key is mounted in each cylindrical opening. Each pin is attached to a channel in one of the shoulders. 
     When the tool shoulder is mounted on the body shoulder in face-to-face contact, the pins prevent the tool from rotating with respect to the body, and increase the torque transmitting properties of the tool holder. This provides a safety feature in the event that the two threaded fasteners should fail to prevent the tool from rotating with respect to the body. 
     A single pin embodiment is also disclosed. Each shoulder has a single channel. When the head is mounted on the body, the pin attached to one of the shoulders is received in the channel in the other shoulder. This arrangement ensures that the fastener openings in the body are aligned with the openings in the shank. 
    
    
     Still further objects and advantages of the invention will become readily apparent to those skilled in the art to which the invention pertains upon reference to the following detailed description of the drawings. 
     DESCRIPTION OF THE DRAWINGS 
     The description refers to the accompanying drawings in which like reference characters refer to like parts throughout the several views, and in which: 
     FIG. 1 is a longitudinal view of a milling tool holder illustrating the preferred embodiment of the invention; 
     FIG. 2 is a view similar to FIG. 1, but in which the body is partially shown in section; 
     FIG. 3 is a view similar to FIG. 2, but in which the body has been rotated 90 degrees and the shank is shown partially in section; 
     FIG. 4 is an enlarged view showing the manner in which the fasteners am the shank toward its fully-seated position; 
     FIG. 5 is an enlarged sectional view as seen along lines  5 — 5  of FIG. 3; 
     FIG. 6 is a view as seen along lines  6 — 6  of FIG. 3; 
     FIG. 7 is an end view of one of the pins; 
     FIG. 8 is an elevational view of one of the pins; 
     FIG. 9 is a view of a tool body showing the shoulder of an embodiment of the invention using only a single pin; 
     FIG. 10 is a sectional view as seen along lines  10 — 10  of FIG. 9; 
     FIG. 11 is a view of a tool shank that may be received in the tool body of FIGS. 9 and 10; 
     FIG. 12 is a view in which the tool of FIG. 11 has been rotated 90°; and 
     FIG. 13 is a view as seen from the right end of FIG.  11 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to the drawings, a preferred tool holder comprises an elongated steel body  10  and an elongated steel tool head  12 . The body is adapted to be mounted in the conventional manner on a milling machine base. Body  10  has a cylindrical inner end  14  and a tapered outer end  16 . The body has an outer annular shoulder  18  formed around the opening of an internal shank-receiving bore  20 . Bore  20  has a cylindrical inner surface formed about a longitudinal axis  22  which also corresponds with the longitudinal axis of both body  10  and head  12 . 
     For illustrative purposes, bore  20  has a depth of about 2″, slightly less than one-half the overall length of body  10 , which has a length of about 4.25″. 
     Bore  20  has a diameter of about {fraction (3/16)}″. 
     The body has a pair of fastener-receiving threaded openings  28  and  30 . The two openings are formed about parallel axes  32  and  34  which are disposed at right angles to and intersect longitudinal axis  22 . Openings  28  and  30  are longitudinally spaced about ⅜″. 
     Head  12  has an enlarged slotted outer end  36  for mounting indexable inserts  42  and  44 . Each insert is releasably fastened to the head by a fastener means  46 . The inserts are relatively flat, with cutting edges  50  and  52 , respectively. The axes of fastener-receiving openings  28  and  30  are disposed perpendicular to the planes of the inserts. 
     Head  12  has an annular seat  54 , and an elongated cylindrical shank  56 , received in bore  20 . Shank  56  has a length less than the depth of bore  20 , and a diameter forming a snug sliding fit in the bore. 
     The shank has a pair of counter-drilled openings or recesses  60  and  62  which are slightly longitudinally offset from fastener-receiving openings  28  and  30 , respectively, when the shank has been fully received in bore  20 . A socket head fastener  64  is threadably received in opening  28 , and a second socket head fastener  66  is threadably received in fastener opening  30 . 
     The two counter-drilled openings are identical except with respect to their location along the shank. Openings  28  and  30  are located on opposite sides of the shank. A typical counter-drilled opening and its fastener is illustrated in FIG.  4 . Counter-drilled opening  60  has a concave, frusto-conical surface  68  adjacent the inner end of fastener opening  28 . Axis  70  of counter-drilled hole  60  is offset from axis  72  of opening  28 . This distance is somewhat exaggerated in FIG. 4 to show that the axis of each counter-drilled opening is closer to shoulder  18  of the body than the axis of the corresponding fastener-receiving opening. 
     Fastener  64  has a rounded inner end  76  that slidably engages frusta-conical surface  68 . As fastener  64  is threadably inserted into opening  28 , inner end  76  engages surface  68  to cam the shank toward the bottom end of the bore, thereby causing shoulder  54  to tightly abut shoulder  18 . 
     Similarly, the rounded inner end of fastener  66  slidably engages the frusto-conical surface of counter drilled opening  62  to cam the shank toward the bottom end of the bore. 
     The diameter of the shank very snugly fits the internal surface of bore  20 , and shoulder  54  tightly abuts shoulder  18  to locate the inserts in a proper cutting position when the head is replaced with a different pair of inserts. 
     Referring to FIGS. 5 and 6, shoulder  54  of the tool head has a pair of aligned semi-cylindrical channels  80  and  82  on opposite sides of the shank, and aligned to intersect the axis of the shank and of bore  20 . Similarly, referring to FIG. 6, the body has a pair of semi-cylindrical openings  84  and  86  formed along an axis  88  that intersects axis  22  of the shank. Channels  84  and  86  are also semi-cylindrical and mate with the corresponding channels on the body when shank  56  is inserted in the shank-receiving opening  20 . Axis  88  of the channels is disposed at right angles to a plane containing the shank axis and the axis of threaded openings  28  and  30 . 
     A pair of cylindrical pins (keys)  90  and  92  are received in the opposed channels of the two shoulders. Referring to FIG. 7 and 8, a typical pin  90  has a outer cylindrical diameter that snugly fits in the two opposed channels in the shoulders of the tool body and the shank. When the tool head is mounted on the body with the shank fully received in the shank-receiving opening, as viewed in FIG. 3, the channels tightly embrace the two pins thereby preventing relative rotation between the shank and the body, and permitting the tool to transmit a heavier torque on a high speed machine. 
     To assemble the tool holder, the inserts are mounted in the usual manner on the outer end of the head. The shank is inserted in bore  20  until the channels mate with the pins (keys)  90  and  92 . Preferably, each pin is attached to a channel in either the body or the tool head as by tack welding at  94 , as viewed in FIG.  3 . 
     Threaded fasteners  64  and  66  are then screwed into their respective counter-drilled openings to cam the shank until shoulder  54  abuts shoulder  18 . 
     The process is reversed, to remove the head. 
     FIGS. 9-11 illustrate another embodiment of the invention in which the primed numbers refer to similar numbers of FIGS. 1-8. Body  10 ′ has a bore  20 ′. The body has an annular shoulder  54 ′ formed about axis  22 ′. Head  12 ′ has a shank  56 ′ which is receivable in shank-receiving opening  20 ′ in the tool body. 
     The body has an annular shoulder  18 ′ formed around shank-receiving opening  20 ′. The head has an annular opening  54 ′ around shank  56 ′, which seats on shoulder  18 ′ when the shank is received in the shank-receiving opening. 
     The body has a pair of threaded fastener-receiving openings  28 ′ and  30 ′. The two openings are formed about parallel axes  32 ′ and  34 ′ which are disposed at right angles to and intersect longitudinal axis  22 ′. The shank has a pair of counter drilled openings or recesses  60 ′ and  62 ′ which are slightly offset longitudinally from fastener receiving opening  28 ′ and  30 ′ when the shank is fully received in the bore. A pair of socket head fasteners (not shown) are threadably received in openings  28 ′ and  30 ′ in the manner described with reference to the embodiment of FIGS. 1-8. 
     In this embodiment, shoulder  18 ′ has a single semi-cylindrical channel  82 ′ formed along an axis that intersects the axis of the shank, as shown in FIG.  9 . Similarly, the body has a single semi-cylindrical channel  86 ′ which is aligned with channel  82 ′ when the shank is received in the shank-receiving bore and the threaded openings  28 ′ and  30 ′ are aligned with respective countersunk openings  60 ′ and  62 ′. 
     A pin  90 ′ is press-fitted into channel  86 ′ and then tack welded in place. When the shank is received in the bore, the pin as seen in FIG. 10, is aligned along an axis disposed at right angles to threaded openings  28 ′ and  30 ′. When the shank is received in the shank-receiving opening, the shoulders of the tool body and the tool holder will only abut one another when the pin is received in channel  82 ′. This arrangement ensures that the fastener-receiving opening in the body is aligned with the counter drilled opening in the shank.