GB2451569A

GB2451569A - Tool and method for die milling

Info

Publication number: GB2451569A
Application number: GB0813753A
Authority: GB
Inventors: Rizal Masingkan; Jeffery H Daigle; David A Buck; Daniel Stephen Bangert
Original assignee: McCoy Corp
Current assignee: McCoy Corp
Priority date: 2007-07-27
Filing date: 2008-07-28
Publication date: 2009-02-04
Also published as: GB0813753D0; CA2638314A1

Abstract

A die milling machine 1 comprises a clamping table 30 with die slots formed therein, the clamping table 30 having a table positioning unit 80 connected thereto. A cutting head support frame is positioned adjacent to the clamping table 30 and a first cutting head 10 is mounted on the support frame in a first orientation relative to said clamping table 30. A second cutting head 15 is positioned adjacent to the clamping table 30 in a second orientation which is approximately perpendicular to the first orientation. This arrangement therefore enables the manufacture of die inserts (50, figures 11A-D), particularly those used in gripping tools, with criss-cross grooves to aid gripping. A loading table 35 may also be provided, with both the clamping table 30 and the loading table 35 being provided on a travelling bed 40 to enable transfer of die blanks from the loading table 35 onto the clamping table 30 prior to milling. The first cutting head 10 is fixed, and grooves in the first direction are milled by movement of the clamping table 30, while the second cutting head 15 is movable to create the grooves in the second direction.

Description

Tool and Method for Die MiIIin This application claims the benefit under 35 Usc � 119(e) of US Provisional Application Serial Number 60/952,268 filed July 27, 2007, which is incorporated by reference herein in its entirety.

Field of Invention.

The invention relates to apparatuses and methods for milling articles of manufacture. In a particular embodiment, the present invention relates to an apparatus and method for milling die inserts used in gripping tools.

Backuround of Invention.

Many devices, particularly tools designed to grip tubular members, will utilize die inserts as the actual elements which grip the tubular member. Nonlimiting examples of such tools include power tongs, backup tongs, manual rig tongs, slips, spiders, elevators, and pipe vises.

While die inserts may take on many shapes, one conventional die insert is the dove-tail strip die such as seen in Figure 15 of US Patent No. 7,036,397.

One conventional method used to manuthcture die inserts requires two different manual or computer numerical controlled (CNc) milling machines or shapers and two different setup operations. Each machine performs a single dedicated operation. In a first step, one machine having a first fixture to hold blank die inserts in place is used to cut the teeth in the longitudinal direction of a die blank. In a second step, a second machine with another fixture is used to cut the cmss grooves (aka mud grooves) perpendicular to the longitudinal teeth. Typically, these fixtures hold a number of inserts with manually positioned clamping devices so that after the first cutting operation, an operator must release the clamps of the first fixture, remove the die inserts, move them to the second fixture and then re-clamp the die inserts in the second fixture.

Alternately, a single milling machine or shaper could be used with two different setup and machining operations.

These manual processes are time consuming and significantly reduce the production rate for the die inserts. Methods and apparatuses which automate die insert milling and increase production rates would be a significant improvement in the art.

Summary of Selected Embodiments of the Invention.

One embodiment of the present invention comprises a method of milling dies employing a milling machine having: i. a clamping table capable of holding a plurality of die blanks; ii. a first cutting head oriented in a first direction relative to the die blanks; and iii. a second cutting head oriented substantially perpendicular to the first direction. The clamping table is moved beneath the first cutting head to mill grooves in the die blanks in the first direction. Next, the second cutting head is moved over the blanks to cut grooves in a second direction substantially perpendicular to the first direction.

Another embodiment of the invention comprises a die milling machine. The die milling machine has a clamping table with die slots formed therein and the clamping table has a table positioning unit connected thereto. A cutting head support frame is positioned adjacent to the clamping table and a first cutting head is mounted on the support frame in a first orientation relative to said clamping table. A second cutting head is positioned adjacent to the clamping table in a second orientation which is approximately perpendicular to the first orientation.

Brief Descrrntion of the Drawings.

Figure lA and lB are perspective views of one embodiment of the present invention.

Figure 2 is a perspective view of a cutting head used in the piesent invention.

Figures 3A and 3B are more detailed views of the cutting head of Figure 2.

Figure 4 illustrates a loading table and clamping table in the embodiment of Figure 1.

Figure 5 is a side view of the view seen in Figure 4.

Figures 6A and 6B are top and side views of the loading table and clamping table seen in Figure 4.

Figures 7A to 7D are sectional views from cuts shown by section lines in Figure 6A.

Figures 8A and 8B are opposing end views of the loading table and clamping table.

Figure 9 illustrates details of the die rake assembly.

Figure 1 OA and I OB illustrate details of the mechanism for moving the die rake assembly.

Figures 1 lA to 1 lD show a die blank at various stages of completion.

Figures 12A to 12D illustrate one operational sequence of one embodiment of the die milling machine.

Figures 13A to 13C illustrate a modified end segment of one embodiment of the clamping table in the die milling machine.

Detailed Descrintion of Selected Embodiments.

Figures 1 A and lB illustrate one embodiment of the present invention, die milling machine 1. However, the die inserts being milled are hidden from view and are too small to be readily seen in Figures IA and lB. Figures 1 1A to 1 1D more clearly illustrate one type of die insert, a dove tail strip die, which could be produced by die milling machine I, although die milling machine 1 is in no manner limited to milling this particular type of die insert. Figures 11 A to 11 D show a die insert at various stages of completion. Figure 11 B is a perspective view of a "die blank" 50, i.e., a piece of material that generally has the shape of the die body, but does not yet have any features (such as grooves forming teeth) formed on the die body. The end view of Figure 1 1A illustrates how the base or rear 101 of the die body 100 will be wider than the top or lace 103 of the die body 100 and how sloping shoulders 102 transition from rear 101 to thee 103. This trapezoidal shape of the die body 100 gives rise to the term "dove tail" die insert.

Figures II C and lID illustrate one example of how teeth may be cut into the die blank 50. In Figure 1IC, a series of grooves are cut longitudinally along the long axis of the die body 100. In Figure liD, second series of grooves 105 are cut perpendicular to the first series of grooves 104.

In one example embodiment of the die inserts, grooves 104 have a pitch of 0.420 inches and a depth of 0.13 inches, while grooves 105 have a pitch of 0.183 inches and a depth of 0.07 inches.

However, the features illustrated cut into die blank 50 in Figures 11 C and 11 D are only one example and the number, depth, orientation, and relative position of grooves or other features can vary greatly in different embodiments. The present invention should be considered to encompass any feature formed on a die blank or other article of manufacture. For convenience in this specification, "die blank" will generally refer to the die insert at all stages of its manufacture, whether discussing a die body having no grooves, having only intermediate grooves, or having the final number of grooves intended for the completed die insert design.

Returning to Figures 1A and lB. this embodiment of die milling machine I will generally comprise a cutting head support frame 2, a first cutting head 10 and a second cutting head 15.

Positioned below the cutting heads are clamping table 30 and loading table 35, both of which are positioned on traveling bed 40. As a general overview of operation best visualized from Figure lB. bed positioning mechanism 80 (the details of which are described below) will move bed 40 (and thus clamping table 30 containing die blanks) upward such that die blanks may come into contact with cutting heads 10 and 15. Bed positioning mechanism 80 can also move bed 40 laterally (i.e., left and right as seen in Figure 1B) in order to position clamping bed 30 under either first cutting head 10 or second cutting head 15. In the embodiment shown in the figures, first cutting head 10 is fixed in position on (relative to) support frame 2 and positioning mechanism 80 is used to move the die blanks on clamping table 30 underneath first cutting head to allow that cutting head to mill features into the die blanks.

On the other hand, as better shown in Figure 2, second cutting head 15 is capable of moving relative to support frame 2. Cutter head frame 16 is supported on a head positioning unit 24, which in this embodiment includes positioning unit frame 25, connector plate 26, power screw or threaded rod 27, and motor 28. Connector plate 26 will be connected to thread block 29 and to guide blocks 90 which ride upon guide rails 91. The top plate of cutter head frame 16 will attach to connector plate 26 and positioning unit frame 25 will be secured to support frame 2 as suggested in Figure 2. Powering of motor 28 will cause power screw 27 to move thread block 29 (an thus connector plate 26 and cutting head 15) forward or rearward (depending on the direction of rotation) along the length of power screw 27. Naturally, the power screw mechanism shown in Figure 2 is merely one example of the cutter head positioning unit 24. The positioning unit could be formed by any number of alternate conventional or future developed mechanisms, including but not limited to hydraulic or pneumatic piston and cylinder assemblies, rack and pinion drives, chain and sprocket drives, or belt and pulley assemblies.

Figures 3A and 3B illustrate in more detail the embodiment of second cutter head 15 described for the particular embodiment shown. Second cutter head 15 will include a shaft 17 with a cutting roller 19 having a series of cutting teeth 20 formed thereon. A motor 22 (in this embodiment a hydraulic motor) will rotate shaft 17 and cutting roller 19. In the embodiment shown, cutting roller 19 is a series cylindrical cutter bodies fitted with a series of circumfrential rows of standard industrial cutting tool inserts constructed of carbide compounds or similar materials. The cutting inserts on each body may be arranged in a staggered pattern (e.g., some blades lagging behind others) for progressive cutting of features into the die blank. Distances between adjacent cutter bodies may be adjusted with the positioning shims or spacers between bodies (thus accommodating different fixtures and widths of die blanks). Adjusting the spacing between features cut into the die blanks is accomplished by changing cutter bodies. First cutter head 10 is substantially similar in design to second cutter head 15, but first cutting head 10 is driven by power input shaft 81 (in the embodiment of Figure 5). The particular cutter head used is not critical and alternative cutter heads might include traditional solid cylindrical cutters having teeth ground into the cutter body or any other conventional or future developed cutter head appropriate for this type of milling operation.

Figure 4 illustrates one embodiment of clamping table 30 and loading table 35 engaging traveling bed 40. Traveling bed 40 will include a series of positioning slots which will be engaged by positioning bolts 42 on clamping table 30 and loading table 35 such as seen in Figure 6B. It will be understood from Figure 4 that clamping table 30 and loading table 35 may be positioned in a particular relative lateral position on bed 40 and then locked into place with positioning bolts 42. The position on traveling bed 40 at which claiming table 30 is fixed will be controlled by parameters such as the travel distance of the bed 40, the number of die blanks positioned on clamping table 30, and the length of the die blanks being milled.

Figure 5 illustrates a conceptual view of bed positioning mechanism 80. Bed positioning mechanism 80 may be any conventional or fhture developed means for elevating, translating, and/or rotating traveling bed 40. Figure 5 suggests one embodiment known in the art where power screws with attachment blocks for connection to the bed structure will carry out translational (left/right) movement and elevation of traveling bed 40.

Thus, bed positioning mechanism 80 is capable of lifting bed 40 upward to engage the cutting heads 10 and 15 as suggested in Figure lB and can move bed 40 laterally as part of the milling process or to facilitate loading die blanks as described below.

Figures 6A and 6B provide a more detailed view of clamping table 30 and loading table 35. This embodiment of clamping table 30 and loading table 35 will share a common bottom plate 31, but will have different top plates, side plates, and internal structures. Viewing Figuie 6A, clamping table 30 will comprise a series of guide rails 33 and hold down rails 32 and in operation (as shown in Figure 6A), will have die blanks 50 positioned there between. The cross-section seen in Figure 7A (taken at A-A in Figure 6A) better illustrates the inter-action of guide rails 33 and hold down rails 32 in gripping die blanks 50. The basic frame for clamping table 30 will be formed from bottom plate 31, side plates 51, and top plate 53. Guide rails 33 and hold down rails 32 are positioned along the top of top plate 53, with hold down rails 32 being partially recessed in slots 39 milled into top plate 53 (see detail of Figure 7C). It can be seen that hold down rails 32 and guide rails 33 (see detail of Figure 7A) have side angles which are supplemental to the side angles on the shoulders of the die blanks. The spaces between guide rails 33 and hold down rails 32 will effectively create "die slots" having angles mirroring the die blanks and in which the dove tail die blanks can slide. A series of bolts 34 will extend through hold down rails 32, extend through top plate 53, and engage positioning plate 47 located within clamping table 30. In the embodiment of Figure 7C, the bolts 34 are counter sunk into hold down rails 32, but are not actually threaded into hold down rails 32 and may slide up and down relative thereto unless otherwise constrained. The individual bolts 34 extending from hold down rails 32 to positioning plate 47 allow adjustment of the clamping force at several points along each hold down rail 32 to insure uniform clamping force is applied to die blanks acmss the

clamping table 30.

Viewing Figures 7A and 7C, it can be seen that positioning plate 47 will also secure a series of piston and cylinder assemblies 44 within the clamping table 30. In this embodiment, piston and cylinder assemblies 44 are double acting assemblies, but the fluid lines have been eliminated from the figures for clarity. The cylinder bodies 45 of piston and cylinder assemblies 44 will be fixed to positioning plate 47 (e.g., by a threaded connection, tack welding, etc.) and the piston arms 46 (sec detail of Figure 7A) will be secured to top plate 53 by way of bolts 43 being counter sunk into top plate 53 (so as not to interfere with guide rails 33) and then threading into the top of piston arm 46. The detail of Figure 7C shows how screws 49 will extend through guide rails 33 and thread into top plate 53 on clamping table 30.

It will be understood that the cumulative effect of this arrangement is that when piston rods 46 extend, they push positioning plate 47 and bolts 34 downward and thereby pull hold down rails 32 firmly into recess slots 39. The angled sides of hold down rails 32 pull die blanks against top plate 53 and securely clamp die blanks 50 in place. When piston rod 46 is retracted, positioning plate 47 is pulled upward causing bolt 34 to travel upward. While bolt 34 is not threaded into hold rail 32, the second level detail seen in Figure 7C shows a snap ring 48 positioned on a groove in bolt 34. When bolt 34 moves upward, snap ring 48 will engage and lift upward hold down rail 32. This insures that when bolts 34 are in the upper position, hold down rails 32 will be lifted clear of die blanks 50 and allows die blanks 50 to slide in the slot created between guide rails 33 and hold down rails 32. Thus, the extension and retraction of piston arm 46 will result in clamping table 30 moving between a die clamped (or fixed) position and a die released position, i.e., released in the sense that the die blanks 50 can readily slide in the slot between guide rails 33 and hold down rails 32.

Many different techniques could be use for allowing bolt 34 to lift hold down rails 32.

For example, although less preferred because it requires expensive and complex machining operations and manufacturing tolerance, bolt 34 could be threaded into hold down rail 32 as well as positioning plate 47.

The piston and cylinder assemblies 44 are merely one type of automated actuator which may be used in positioning hold down rails 32 or any other element of the die milling machine 1 which is moved in multiple positions. For example, another automated actuator could be a magnetic based such as a magnetic chuck, which could be based either on electm-magnetic technology or permanent magnet technology such as provide by WEN Technology Inc. of Raleigh, NC. Other nonlimiting examples of automated actuators could possibly be solenoid devices, pneumatic bladders or power screws under a common control system. As used herein, an "automated actuator" may include any conventional or future developed device which may be used to non-manually move elements of die milling machine 1.

A fi.irther element of clamping table 30 is retaining gate 55. Best seen in Figum 8A, retaining gate (or gate) 55 is formed of a plate section 56 which has an alternating series of die passages 57b and blocking teeth 57a. Gate 55 will further have a series of slots 58 engaging bolts 59. It will be apparent that when gate 55 is positioned as shown in Figure 8A, the die passages are aligned with the die slots in clamping table 30 and the finished dies 50 can pass through passages 57b and exit clamping table 30 (assuming hold down rails 32 are raised). On the other hand, when gate 55 is shifted (to the left in Figure 8A) on bolts 59, blocking teeth 57a are positioned across the die slots and prevent any dies from exiting clamping table 30. The gate may be moved between its open and shut position by way of gate actuator 83 (seen in Figure 6B), which in one embodiment is a small hydraulic piston and cylinder assembly, but could also be any other appropriate automated actuator. Gate 55 functions not only as a stop for the insertion of die blanks from loading table 35, but also provides support against lateral movement of the die blanks when the die blanks are subject to the considerable force of the cutter heads during the milling operation which might otherwise tend to dislodge or shift the die blanks in the clamping table. However, the present invention is not limited to clamping tables with retaining gates and other embodiments may not incorporate such gate devices.

The cross-section of loading table 35 seen in Figure 7D is taken at section D-D seen in Figure 6A. Although loading table 35 shares a common bottom plate 31 as seen in Figure 613, Figure 7D shows how loading table 35 has a separate top plate or alignment plate 37 and does not have side plates constraining the vertical movement of alignment plate 37. Loading table 35 will have a series of guide rails 36 which have angles supplemental to the sides of the die blanks and thus form die slots into which die blanks 50 may be inserted and freely slide. Unlike the hold down rails 32 on clamping table 30, all guide rails 36 arc fixed in position on loading table by screws extending through them and into alignment plate 37 (similar to the detail seen in Figure 7C). However, a series of piston and cylinder assemblies 38 are positioned to raise and lower alignment plate 37. Piston and cylinder assemblies 38 will be mounted on and fixed in position within loading table 35 by cylinder brackets 85. As seen in the detail of Figure 7D, a bolt 43 extends through alignment plate 37 and engages piston rods 46, thereby fixing alignment plate to piston rods 46. Upper side plates 86 will attach to alignment plate 37 and lower side plates 87 will connect to bottom plate 31. Both upper side plates 86 and lower side plates 87 will have complementary shoulder portions 88 with a gap between the shoulder portions 88.

Attached to upper side plates 86 are frames 66 of finger carrier positioning assembly 65 which will be explained in more detail below.

From the structure seen in Figure 7D, it will be apparent that the extension and retraction of piston rod 46 in piston within cylinder assemblies 38 operates to raise and lower alignment plate 37. The shoulders 88 on upper and lower sides plates 86 and 87 will limit the distance of upward travel by alignment plate 37. Likewise, the height of lower side plate 87 will limit the downward travel of alignment plate 37. The effect of raising and lowering loading table 35 can be understood with reference to Figure 613. In that figure, loading table 35 is in its lower position and it can be seen that the die blanks 50 on loading table 35 are not level with die blanks 50 on clamping table 30. This means that the die slots on loading table 35 and clamping table 30 are not aligned and die blanks 50 carmot slide from loading table 35 onto clamping table 30. On the other hand, when loading table 35 is in its raised position, the respective die slots are aligned and die blanks 50 are able to slide into the die slots on clamping table 30 (assuming hold rails 32 are raised), thus loading clamping table 30 with die blanks 50 from loading table 35. In addition to selectively blocking the movement of loaded die blanks, the lowering of loading table 35 may serve the puipose of placing the die blanks on loading table 35 out of the cutting radius of cutter heads in those embodiments where the loading table 35 passes beneath cutter heads.

In certain embodiments, the cross-sections of guide rails 36 are not uniform along their entire length. The details of Figure 9 illustrate guide rails 36 having rear portion 95 which does not have angles supplemental to the shoulders of the die blanks and the guide rails are spaced sufficiently far apart that die blanks can drop between guide rails 36 (i.e., from a position above the loading table). This allows die blanks to be dropped between the guide rails 36 from above rather than requiring insertion into a close tolerance die slot from a rear position. The ability to insert die blanks into the die slots from above makes manual loading easier and make the loading table more readily adapted to automated loading systems. After a certain distance along guide rails 36, the cross-section will transition from the detail shown in Figure 9 back to the cross-section seen in the detail of Figure 7D.

Some embodiments of guide rails 36 could also incorporate another variation on the opposite end of the guide rails 36 (i.e., the end nearest the clamping table 30) as illustrated in the detail of Figure 1 OA. This section of guide rail 36 will include spreading slot 97 cut through guide rail 36 and a bore to accommodate tapered plug screw 98. It will be understood that torquing plug screw 98 deeper into its bore will cause spreading slots 97 to widen and to incrementally narrow the die slots between guide rails 36. This helps insure precise die blank positioning as the die blanks approach the dies slots on clamping table 30, particularly in embodiments where guide rails 33 on clamping table 30 will feature milled portions or bevels on ends adjacent to the loading table 35 creating a gap between the guide rails 33 and clamping rails 32 which is wider than the die blank. Reducing the width of the die channel between loading table guide rails 36 serves to center die blanks 50 to prevent them from hanging as they initially pass the ends of the rails 32 and 33 when being moved from the loading table 35 to the clamping

table 30.

Another element of loading table 35 is the die pusher rake or die rake 60 shown in Figures 9 and 10. Generally, die rake 60 will comprise finger carrier 61 (Figure 9) and rake positioning assembly 65 (Figure lOB). The die rake 60 seen in Figure 9 is formed of top section 63 and side sections 64 with a series of finger projections 62 attached to top section 63. In the illustrated embodiment, finger projections 62 generally have a dovetailed shape similar to die blanks 50 and are fixed to the underside of top section 63. Figure projections 62 can engage the die slots on loading table 35 and can slide along inside the die slots as top section 63 moves across the top of loading table 35.

The embodiment of rake positioning assembly 65 seen in Figure lOB comprises a guide frame 66, a traveling bracket 67 and a threaded rod or power screw 68. Viewing the detail A in Figure 1 OB, it can be seen how traveling bracket 67 includes the thread receiving bracket 69 which engages the threads on power screw 68 and will move traveling bracket 67 along guide frame 66 when power screw 68 rotates. As suggested by detail B in Figure 9, the side sections 64 of finger carrier 61 will be attached to traveling bracket 67 such that rotation of power screw 68 will move finger carrier 61 down the length of loading table 35. One mechanism for powering die rake 60 is seen in Figure 1 OA. A pulley 73 will be attached to power screw extension 70 and pulley 73 is coupled to a hydraulic motor 71 by belt 72. Thus activation of motor 71 (in either direction) will rotate power screw 68 and cause the movement of die rake 60 either up or down loading table 35 depending on the motor direction. The die rake seen Figures 9 and 10 is just one embodiment and many other embodiments are possible. For example, channels could be cut through the loading table's bottom plate along the length of the die slots and blades extend though the channels to engage and push the die blanks forward.

A typical operation sequence of the embodiment illustrated above can be described with reference to Figures 12A to 12D. Initially, traveling bed 40 will be moved to its right-most position (see Figure 1 2A), resulting in loading table 35 extending beyond support frame 2 and allowing an operator to place die blanks into loading table 35. The operator will slide die blanks along the dies slots until loading table 35 is filled. If clamping table 30 has no blanks position in it, the hold down rails 32 will be raised, loading table 35 will be raised level with clamping table to align the die slots, and die rake 60 will be activated to push die blanks into position on clamping table 30. Gate 55 will be in a closed position, so blanks will stop sliding in the die slots when the lead die blank comes into contact with gate 55. With the clamping table 30 filled with die blanks, clamping rails 32 will be lowered to secure the die blanks in place. Loading table 35 may then be lowered to its position where its die slots are out of alignment with those of clamping table 30. If desired, die rake 60 may be retracted to its starting position at the rear of loading table 35 and a further series of die blanks may be inserted into the die slots in loading table 35. Because loading table 35 is in its lower position, the die blanks being pushed forward in loading table 35 will not engage the die blanks on clamping table 30.

J

With die blanks positioned on clamping table 30 and loading table 35 filled with die blanks, the bed 40 may be raised as seen in Figure 12B such that the die blanks on clamping table 30 may be brought into contact with cutting head 10. Bed 40 will then traverse laterally moving the die blanks beneath cutting head 10 (Figure 12C) and milling a first groove 104 in the die blanks such as is suggested in Figure 11 C. When the first groove has been cut in all die blanks, bed 40 can traverse further to the left and position the clamping table 30 beneath second cutter head 15 as suggested in Figure 12D. Positioning unit 24 will then cause second cutter head 15 to move across the die blanks in clamping table 30 and mill the second groove 105 as seen in Figure 11 D. When all milling steps are completed, bed 40 will lower clamping table 30 out of contact with cutting head 15 and cutting head 10. The gate 55 is shifted to the open position, the hold down rails 32 are raised, and the loading table is raised to bring the die slots of both tables back into alignment. As die rake 60 again advances, the unmilled die blanks in loading table 35 will push the milled die inserts out of the clamping table and into a collection bin (not shown) loca ted below gate 55. The die rake will continue its forward motion until all milled die inserts are ejected from clamping table 30. The ejection of the last milled die insert may be detected by a limit switch, a proximity sensor, computer vision detection or any other conventional or future developed method. The ejection of the last milled die insert may also be estimated by monitoring the travel of die rake 60 or simply by the observation of an operator.

With the ejection of the last milled die insert, the gate 55 will shift closed and the die blanks will accumulate in clamping table 30 to begin the process again.

Although the present invention has been described in terms of specific embodiments, those skilled in the art will recognize many modifications and variations. For example, while many of the automated actuators are shown as hydraulic devices, the actuators could also be appropriate mechanical, electrical, electro-mechanical, or magnetic devices. Further, while the die slots are shown as being formed by two rails, the dies slots could be formed in many other ways, one nonlimiting example being the milling channels on the upper surface of the top plates.

And while the bed has largely be described as only moving laterally and vertically, there may be emobidments where the bed may rotate or move in other dimctions. Likewise, alternative embodiments might have both cutting heads moving (laterally and vertically) while the bed remains stationary; or have neither of the cutting heads moving and allowing the bed to make all movements needed. Nor is the invention limited to two cutter heads and could possibly operate with one or more than two cutter heads. Nor is the sequence of cutting steps limited to the longitudinal groove being cut first, but could be reversed to have the transverse groove cut first.

While the above described embodiments showed the loading table moving relative to the clamping table, this could be reversd with the loading table fixed and the clamping table changing elevation. Another embodiment could have a loading table which is fixed in position relative to the frame of the die milling machine. In this embodiment, the clamping table would move into engagement (both laterally and vertically) with the fixed loading table and then (after receiving a new set of die blanks) move away from the loading table to engage the cutting head(s).

Likewise, many further automated systems could be combined with the milling machine.

For example, rather than an operator loading die blanks by hand into load table 35, an automated system could drop a die blank between guide rails 36 at rear portion 95. Die rake 60 would advance to push the die blank forward just beyond the rear portion 95, then die rake 60 would return to its starting position in order to clear rear portion 95 for the insertion of the next die blank. A supply of die blanks could be positioned above rear portion 95 in a conventional feed clip or magazine which drops another die blank into rear portion 95 on every cycling of die rake (until the loading table is filled).

Another variation would involve the shape of the die slots at the exiting end of the clamping table 30 as seen in Figures 1 3A to 1 3C. The end segment 92 of the hold down rails 32 and guide rails 33 in this particular embodiment will have a segment length appmximately equal to half the length of the shortest die insert expected to be machined. Hold down rails 32 and guide rails 33 would be shaped along end segment 92 to have vertical sidewalls (see Figure 1 3C) wider than the base of the die blank rather than sidewalls which are supplemental angles to the die blank shoulders 102 (i.e., the sidewalls of the end segment have a width all along their height which is greater than a width of a die blank, similar to the starting end of guide rails 36 seen in the detail of Figure 9). Thus, the die blanks may be lifted vertically out of these end segments of the die slots. In operation, as more than half the length of a die blank passes the end edge of the clamping table (see Figure 1 3B), the finished die blank 50a will tend to rotate forward and the tail end the die blank will lift out of the end segment of the die slot, thereby causing the die blank to more efficiently exit the clamping table. In this embodiment, the movement of the die rake could be momentarily halted (for example by using a limit switch) as the last of the milled die blanks 50a reach their tilt point and exit the clamping table. This would serve as the signal (e.g., to a system controller) that the gate 55 should be closed. The closure of gate 55 would then signal the die rake to finalize its travel and push the new set of die blanks 50b against the gate 55. All such modifications and variations should be considered within the scope of the following claims.

Claims

We Claim: 1. A method of milling dies comprising the steps of: a. providing a milling machine comprising: i. a clamping table capable of holding a plurality of die blanks; ii. a first cutting head oriented in a first direction relative to said die blanks; iii. a second cutting head oriented substantially perpendicular to said first direction; b. moving said clamping table beneath said first cutting head to mill grooves in said die blanks in said first direction; c. moving said second cutting head over said blanks to cut grooves in a second direction substantially perpendicular to said first direction.
2. The method of milling dies according to claim 1 wherein said first direction is substantially parallel to a long dimension of said die blanks in said clamping table.
3. The method of milling dies according to claim I wherein said milling machine further comprises hold down rails and a loading table and further comprising the step of feeding dies from said loading table into said clamping table.
4. The method of milling dies according to claim 1 wherein said clamping table further comprises die slots and a gate, and further comprising the step of moving said gate to selectively block said die slots.
5. The method of milling dies according to claim 3, further comprising the steps of raising said hold down rails, moving die blanks from said loading table to said clamping table, and lowering said hold down rails to secure said die blanks in place.
6. The method of milling dies according to claim 5, further comprising the steps of raising the hold down rails, pushing milled dies out of said clamping table by advancing a new set of die blanks into the clamping table from the loading table.
7. The method of milling dies according to claim 6, further comprising the steps of moving dies slots on said hold down table out of alignment with die slots on said loading table after said new set of dies blanks have been advanced onto said loading table.
8. The method of milling dies according to claim 1, wherein said milling machine further comprises a die rake with fingers engaging die slots in a loading table, and further comprising the step of advancing die blanks onto said clamping table with said die rake.
9. The method of milling dies according to claim 1, wherein said milling machine further comprises a loading table, and further comprising the step of inserting die blanks in said loading table while said first cutting head mills die blanks on said clamping table.
10. A die milling machine comprising: a. a clamping table having die slots formed therein, said clamping table having a table positioning unit connected thereto; b. a cutting head support frame positioned adjacent to said clamping table; c. a first cutting head mounted on said support frame in a first orientation relative to said

clamping table;

d. a second cutting head positioned adjacent to said clamping table in a second orientation which is approximately perpendicular to said first orientation.
11. A die milling machine according to claim 10, wherein said second cutting head is positioned on said support frame.
12. A die milling machine according to claim 11, further comprising a head positioning unit connected to said second cutting head and adapted to move said second cutting head over said

clamping table.
13. A die milling machine according to claim 12, wherein said first cutting head is fixed relative to said frame and said table positioning unit moves said clamping table beneath said first cutting head to mill a first feature into die blanks positioned on said clamping table.
14. A die milling machine according to claim 13, wherein said head positioning unit moves said second cutting head over said clamping table to mill a second feature into said die blanks.
15. A die milling machine according to claim 10, wherein said clamping table further comprises hold down rails which releasably secure die blanks in said die slots.
16. A die milling machine according to claim 15, wherein hold down rails are connected to at least one automated actuator.
17. A die milling machine according to claim 16, further comprising a plurality of automated actuators wherein said actuators are hydraulic piston and cylinder assemblies.
18. A die milling machine according to claim 15, further comprising a loading table positioned adjacent to said clamping table, said loading table having dies slots which may align with said die slots on said clamping table.
19. A die milling machine according to claim 18, wherein said loading table is adapted to selectively move into and out of alignment with said clamping table.
20. A die milling machine according to claim 18, wherein said loading table further comprises a die rake having a series of pushing fingers engaging said die slots of said loading table, said die rake connected to an automated actuator adapted move said pushing fingers in a diiection parallel to said die slots.
21. A die milling machine according to claim 10, wherein said clamping table further comprises a gate at on end, said gate selectively blocking and unbiocking said die slots.
22. A die milling machine according to claim 20, wherein said automated actuator is a power screw positioned along said loading table.
23. A die milling machine according to claim 18, wherein said loading table comprises guide rails spaced apart a distance greater than a width of a die blank.
24. A die milling machine according to claim 23, wherein said distance between said guide rails is greater on an entry end than on an exit end of said loading table.
25. A die milling machine according to claim 10, wherein said guide rails on said exit end comprise a slot with an adjustable spacer.
26. A die milling machine according to claim 19, wherein said loading table is moved into and out of alignment by fixing said clamping table at one elevation relative to said loading table and raising or lowering said loading table.
27. A die milling machine according to claim 10, wherein said die slots on said clamping table comprise an end segment with sidewalls, said sidewalls of said end segment having a width all along their height which is greater than a width of a die blank.
28. A die milling machine comprising: a. a clamping table having die slots formed therein, said clamping table having a table positioning unit connected thereto; b. hold down rails for securing die blanks in said die slots, said hold down rails having automatic actuators connected thereto; c. a loading table having die slots which align with said clamping table die slots, said loading table adapted to move in order to align and disalign dies slots on said clamping table and said

loading table;

d. a cutting head support frame positioned adjacent to said clamping table; e. a first cutting head mounted on said support frame in a first orientation relative to said

clamping table;

f. a second cutting head positioned adjacent to said clamping table in a second orientation which is approximately perpendicular to said first orientation.