CROSSREFERENCE TO RELATED APPLICATIONS

This application claims the priority benefit under 35 U.S.C. §119(e) of U.S. Provisional Application No. 62/335,647, entitled "Shaped Pressure Die System" filed May 13, 2016, which is incorporated herein by reference in its entirety.

FIELD OF THE INVENTION

This invention relates to the field of wire drawing and shaping. More specifically, this invention is related to a die assembly for the cold drawing and shaping of wire and/or bar stock.

BACKGROUND

As described in U.S. Patent Number 5,402,664 (the "'664 Patent," incorporated herein by reference in its entirety). In wire drawing processes, it is common practice continuously to draw the wire stock through a die assembly which includes a pressure die followed by a drawing die which performs the sizing and shaping operation on the wire. Lubricant for the drawing die may be forced under pressure into a pressure chamber defined between the respective dies.

Traditional pressure die systems comprise a wire drawing die, a pressure die, a holder base, and a cap. In some systems the cap is coupled to the holder base by threads as shown in the '664 Patent, interlocking flanges U.S. Patent 6,026,672 (incorporated herein by reference in its entirety), and pressure rings U.S. Patent 7,290,432 (incorporated herein by reference in its entirety).

Shaped wire or wire with a non-circular cross-section is traditionally made by drawing a round cross-sectional wire through a sequence of non-circular drawing dies that progressively change the shape of the wire from its initial round cross-section to a final non- circular shape.

In an effort to lower wear on the multiple drawing dies during the shaping process and increase the speed of the wire drawing process, die companies have integrated non-circular geometry drawing dies into traditional pressure die systems with mixed results.

SUMMARY OF THE INVENTION

The present invention is directed to a shaped pressure die system that comprises a pressure die having an inner wall with a non-circular cross-section, and a drawing die having an internal wall having a non-circular cross-section, wherein the non-circular cross-section of the pressure die matches the non-circular cross-section of the drawing die and where the pressure die and the drawing die further are configured to be aligned using an alignment pin that aligns each die in relation to each other.

In some embodiments, the pressure die is radially oriented in in a predisposed manner and attached to a die alignment sleeve ring. In other embodiment, the die alignment sleeve ring further comprises a die alignment opening. In yet a further embodiment, the system comprises an alignment pin. The system also includes a holder cap and a holder base. The holder cap connects to the holder base by one of a threaded or a slip-fit connection. The holder base comprises a holder base alignment opening configured to receive the alignment pin. The pressure and drawing die, in some embodiments, have a die guide that aligns the dies with respect to each other. In other embodiments, the holder base comprises a holder base guide that aligns the system with a drawing machine.

In another embodiment, the system's pressure die is secured to the holder cap by heat shrinking or cold press. In an alternative embodiment, the holder cap has a cap opening configure to accept the alignment pin. The holder base, in one embodiment, comprises a holder base opening configured to accept the alignment pin. In yet a further embodiment, the drawing die is tapered or configured to have an interference fit. One system in accordance with an embodiment of the present invention comprises a rotational support ring that maintains axial alignment of the system, where the system comprises one or more of radial bearings, thrust bearings, or tapered roller bearings. Another embodiment comprises a drawing die that has a non-circular bell section that matches a pressure die with a non- circular protrusion that mates with the non-circular bell section of the drawing die to create a pressure chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features, aspects, and advantages of the present invention are considered in more detail, in relation to the following description of embodiments thereof shown in the accompanying drawings, in which:

Figure 1 is a schematic diagram of a shaped pressure die and shaped drawing die.

Figure 2 is a cross-section of a shaped pressure die and shaped drawing die with alignment sleeve ring and pin features.

Figure 3 is a schematic diagram of a standard pressure system as currently available showing the progression for shaping wire using circular pressure dies and a shaped drawing dies. 3A shows a side view of a series of die holders for shaping a wire. 3B shows a cross- section of the dies shown in the holders of 3A. 3C shows a cross-section of each die including the wire geometry as it is progressively changed from circular to non-circular. 3D is another cross-section that shows the gap in the pressure die and the fit of the drawing die.

Figure 4 is a schematic diagram of the pressure system of the present invention showing the progression for shaping wire using a shaped pressure die and a shaped drawing die. 4A shows a side view of a series of die holders for shaping a wire. 4B shows a cross- section of the dies shown in the holders of 4A. 4C shows a cross-section of each die including the wire geometry as it is progressively changed from circular to non-circular. 4D is another cross-section that shows the gap in the pressure die and the fit of the drawing die.

Figure 5 is a cross-sectional view of a die system in which the pressure die is secured to the holder cap, which includes a holder guide opening and cap alignment pin.

Figure 6 is a cross-sectional view of a die system where the non-circular drawing die a has either a tapered outside diameter or an interference fit onto a rotational support ring.

Figure 7 is a cross-sectional view of a die system where the non-circular drawing die has a pre-shaped bell section.

Figure 8A and 8B are perspective views of the system described in figure 7.

DETAILED DESCRIPTION

The inventions summarized above and defined by the enumerated claims may be better understood by referencing to the following description, which should be read in conjunction with the accompanying drawings in which like reference numbers are used for like parts. This description of an embodiment, set out below to enable one to build and use an implementation of the invention, is not intended to limit the invention, but to serve as a particular example thereof. Those skilled in the art should appreciate that they may readily use the conception and specific embodiments disclosed as a basis for modifying or designing other methods and systems for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent assemblies do not depart from the spirit and scope of the invention in its broadest form.

This invention relates to a pressure die system in which the drawing and pressure dies may have non-round internal cross sections. This system also includes a means to radially orient the pressure die such that its internal geometry aligns, in a pre-disposed manner, relative to the internal geometry of the drawing die. In one embodiment of the present invention a die system 100 is disclosed as shown in Figures 1 and 2. The die system 100 has a holder cap 103, a shape die alignment sleeve ring 106, an alignment pin 109, a holder base 1 12, a non-circular drawing die 115, and a non- circular pressure die 1 18. As described herein, a die system refers to the combination of a drawing die 1 15, pressure die 1 18, a holder base 112, and holder cap 103. The non-circular drawing die 1 15 has an inner wall 129 and an outer wall 133. The inner wall 129 has non- circular cross-section. It is contemplated that the non-circular cross-section has a regular or an irregular shape or a combination of regular and irregular shapes. In some embodiments, the non-circular cross-section of the drawing die matches the non-circular cross-section of the pressure die. In some embodiments, the match is identical, while in other embodiments that match is not identical. The non-circular pressure die 1 18 has an internal wall 139 and an outer wall 136, where the internal wall 139 has a non-circular cross-section. The non-circular pressure die 118 radially oriented in a predisposed manner and attached to alignment sleeve ring 106 which has a pressure die alignment opening 121. The pressure die alignment opening 121 on the alignment sleeve ring 106 is configured to couple with the alignment pin 109. The holder base 112 has a holder base alignment opening 124. The holder base alignment opening 124 on the holder base 1 12, is configured to couple with the alignment pin 109.

One of the most critical factors in determining the efficacy of using a pressure die system is the proper calculation of the optimal spacing between the surface of the incoming wire and the inside wall of the pressure die. The clearance around the incoming wire needs to be large enough to allow for lubricant to get dragged in by the wire past the pressure die yet small enough to limit the amount of lubricant that can come out in the opposite direction, which creates high enough pressure to force the lubricant between the drawing die and the wire. In round cross-section wire the pressure and lubrication requirements described above are achieved easily as the diameter of the pressure die is adjusted to be a certain size larger than that of the incoming round wire.

In non-circular drawing dies, however, in most circumstances, the change in geometry from the round wire 300 to a desired shape is so significant that it requires the wire to go through multiple sequential dies which will progressively change the shape of the wire as shown on Figure 3. To achieve the desired shape, the stress level at the wire as well as at the die is kept at a manageable level so neither the wire 300 nor the shaped drawing dies break in the shaping process.

As the wire 300 moves through multiple drawing or shaping dies, it progressively changes from its original round cross-section. Figure 3A shows the sequence of dies used to change the shape of the wire. In figure 3B a cross-section of the sequence of dies is shown. Finally in figure 3C a cross section of the wire as it passes through various dies is shown. Traditional pressure die systems used in a shaping wire drawing process become less efficient the closer the wire comes to its ultimate non-circular cross section because they utilize round cross-section pressure dies as shown in figure 3D. As the pressure die gap 303 between the surface of the wire and the pressure die widens in some sections of its circumference, less pressure builds in the pressure chamber and less lubricant is forced between the wire and the drawing or shaping die.

To overcome this limitation and provide maximum efficiency in a pressure die system, one embodiment of the present invention comprises a pressure die system 100 in which the cross-section of the pressure die 118 is shaped in order to maintain specific and controlled spacing between the entire surface of the incoming wire 300 and the inside wall of the pressure die 118. As shown on figure 4, the geometry of the wire changes at each step in the die progression so does the cross-section of the pressure die 118 in order to provide an even clearance around the entire surface of the wire 300. The pressure die gap 303 remains constant throughout the cross-section of the wire 300 and the pressure die 118. Similarly, the drawing die gap 306 remains constant throughout the cross-section surface of the wire 300.

Secondly, in traditional pressure die systems, the angular orientation of the pressure and drawing dies bears no influence in the wire drawing process given that pressure inserts are round and therefore there is no need to align it angularly in any way with the non-circular cross section drawing die.

In one embodiment of the present invention a means of angularly orienting the non- circular cross section pressure die 118 with the non-circular cross section drawing die 115 within the pressure system 100 in order for their geometries to match each other in a predisposed manner. In the present embodiment, the pressure 118 and the drawing 1 15 dies include a die guide 309 that angularly aligns their respective non-circular cross-sections in a predetermined manner. In one embodiment, the die guide 309 is an etched line on the side of the dies. Also, in one embodiment, a flat portion of the holder base 1 12 has a holder base guide 310 that is used to radially align the pressure holder with the wire drawing machinery. Holder base guide 310 is aligned with the holder base alignment opening 124. The holder base alignment opening 124 is drilled into the pressure holder base 1 12 aligned with the location of the drawing die guide 309 and an alignment pin 109 is pressed into said holder base alignment opening 124. Separately, a shape die alignment sleeve ring 106 is pressed onto the outside diameter of the pressure die 1 18 and a pressure die alignment opening 121 is drilled onto said alignment sleeve ring 106 angularly aligned with the location of the pressure die die guide 309. The alignment pin 109 fits on an upper side into the pressure die alignment opening 121 and on the lower side to the holder base alignment opening 124. When the shaped pressure die system 100 is assembled, the pressure die 118 will remain angularly aligned in a predetermined manner with the drawing die 1 15 in order to insure maximum efficiency of the pressure die system 100 at every drawing or shaping die in the progression of the shape wire drawing process.

In one embodiment of the invention, the holder cap 103 and the holder base 1 12 are threaded so that they can be coupled together. In other embodiments, the holder cap 103 is not threaded but is a slip-fit type cap that stays in place by pressure fitting.

In a further embodiment as sown on figure 5, the pressure die 1 18 is secured to the holder cap 103. The pressure die 118 can be secured to the holder cap 103 by heat shrinking, cold press, or any other suitable method that ensures the holder cap 103 and the pressure die 118 are joint such that they will remain in place during the wire shaping process. The holder cap 103 has a cap opening 503 that aligns the pressure die 1 18 and the drawing die. The alignment pin 109 is connected at an upper portion of the alignment pin 109 to the cap opening 503 and a lower portion of the alignment pin 109 to the base alignment opening 124. The combination of the alignment pin 109 and the openings in the base and the cap ensure a proper fit for the pressure die system to work properly.

A further embodiment as shown in figure 6, the non-circular drawing die 1 15 has either a tapered outside diameter or an interference fit onto a rotational support ring 601. This rotational support ring 601 maintains axial alignment with the die system 100 (and therefore die box and wire drawing direction) and allows for free rotation about the wire drawing axis by the use of radial bearings 607 on its outside diameter and thrust bearings 604 and hardened washers 609 located on the bottom or exit side of the wire 300. These bearings are what connects the rotational support ring to the holder base 112. The use of a radial bearing and thrust bearing may be replaced by the use of tapered roller bearings. The rotational supporting ring 601 has a rotational support ring alignment opening 61 1. The non-circular pressure die 118 is radially oriented in a predisposed manner and attached to alignment sleeve ring 106, which has a pressure die alignment opening 121. The pressure die alignment opening 121 on the non-circular alignment sleeve ring 106 is configured to couple with the alignment pin 109. The rotational holder ring 601 has a rotational ring alignment opening on the rotational holder ring is configured to couple with the alignment pin 109.

On the top of the non-circular pressure die 1 18, a thrust bearing 604 and hardened washer 609 assembly allow the shaped pressure ring to rotate in concert with the drawing die/rotational support ring assembly even if under axial pressure from the tightening of the holder cap 103 to the holder base 1 12.

This will allow for the pressure die 1 18 and drawing die 1 15 to rotate freely and allow the wire to maintain the orientation best suited to align the various capstans of the wire drawing machine, therefore not impart any undesired torsional stresses on the wire 300 during drawing, overstress the wire drawing die 1 15, or allow for the surface of the wire 300 to rub against the non-circular pressure die 1 18 internal wall 139 leading to breakage or damage of the wire 300, the non-circular pressure die 1 18, or the non-circular drawing die 115.

In yet another embodiment as shown in Figure 7, the drawing die 1 15 has a pre- shaped bell section 900. Regular wire drawing dies have a circular bell section to aid in lubricant flow into the drawing die; in one embodiment the pre-shaped bell section 900 would have non-circular features such as a hexagonal pattern of conical surfaces 901 as shown in Figures 8A and 8B. The pre-shaped bell section aligns the drawing die 1 15 with the pressure die 118. The shaped pressure die 1 18 has a smaller yet matching protrusion 902 with surfaces 903 of a specific geometry to match those of the shaped drawing die bell section 900. By having the geometries of the bell section of the shaped pressure die and the protrusion of the shaped pressure insert match one another, a sealed pressure chamber between the two dies is generated.. When the bell section of the drawing die 1 15 couples with the protrusion of the pressure die 118, it allows the two elements to self-align with each other and create a seal for the pressure chamber. The invention has been described with references to a preferred embodiment. While specific values, relationships, materials, and steps have been set forth for purposes of describing concepts of the invention, it will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the basic concepts and operating principles of the invention as broadly described. It should be recognized that, in the light of the above-teachings, those skilled in the art can modify those specifics without departing from the invention taught herein. Having now fully set forth the preferred embodiment and certain modifications of the concept underlying the present invention, various other embodiments as well as certain variations and modifications of the embodiments herein shown and described will obviously occur to those skilled in the art upon becoming familiar with such underlying concept. It is intended to include all such modifications, alternatives, and other embodiments, in so far they come within the scope of the appended claims or equivalents thereof. It should be understood, therefore, that the invention may be practiced otherwise than as specifically set forth herein. Consequently, the present embodiments are to be considered in all respects as illustrative and not restrictive.

INDUSTRIAL APPLICABILITY

The invention is applicable to wire drawing systems and methods. A system and method for drawing and shaping wire is disclosed. The system can be made in industry and practiced in wire drawing applications.